Next Article in Journal
Exon-Enriched Set of Single-Nucleotide Polymorphisms Shows Associations with Climate in European Beech (Fagus sylvatica L.)
Previous Article in Journal
Predicting the Future Distribution and Habitat Suitability of Ilex latifolia Thunb. in China under Climate Change Scenarios
Previous Article in Special Issue
Pinus banksiana Lamb. Regeneration Patterns in a Lacustrine Dune System
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Forests
Volume 15
Issue 7
10.3390/f15071228
forests-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Analysis of the Environments Where Natural Regeneration Is Established in the Absence of a Wildfire in the Open Pinus brutia Forests in the Middle Elevations of the Central Part of Cyprus

by
Petros Petrou
1,
Athanasios Stampoulidis
2,
Elias Pipinis
3,
Kyriaki Kitikidou
4,* and
Elias Milios
4
1
Department of Forests, Ministry of Agriculture, Rural Development and Environment, 1414 Nicosia, Cyprus
2
Department of Forestry and Natural Environment Management, School of Plant Sciences, Agricultural University of Athens, Democratias 3, 36100 Karpenisi, Greece
3
School of Forestry and Natural Environment, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
4
Department of Forestry and Management of the Environment and Natural Resources, Faculty of Agriculture and Forestry, Democritus University of Thrace, Pantazidou 193, 68200 Orestiada, Greece
*
Author to whom correspondence should be addressed.
Forests 2024, 15(7), 1228; https://doi.org/10.3390/f15071228
Submission received: 18 May 2024 / Revised: 4 July 2024 / Accepted: 12 July 2024 / Published: 15 July 2024
(This article belongs to the Special Issue Impact of Disturbance on Forest Regeneration and Recruitment)
Browse Figures
Versions Notes

Abstract

:
The objective of this research was to analyze the P. brutia natural regeneration and the environments where it was established in the absence of a wildfire in the open formations of the species in the middle elevations of the central part of Cyprus. Forty-eight rectangular plots of 0.1 ha were established in three site productivity types. Individuals of the species with a height from 0.1 m to 1.5 m were considered regeneration plants. Within each plot, various measurements and estimations were made. Moreover, 480 hemispherical photographs were taken. Additionally, hemispherical photographs were taken above each of the recorded naturally regenerated P. brutia plants. In all the site productivity types, the most regeneration plants were established and grew under the process of facilitation. In each of the site productivity types, there were no differences in the light condition diversity between the environments where the regeneration plants grew and the existing light conditions. Regeneration exhibited a small number of plants and constituted only a very small proportion of all trees in the three site productivity types. To achieve sustainability in P. brutia forests, forest practices must develop strategies for the enhancement of P. brutia regeneration in the studied area and in analogous environments.

1. Introduction

Pinus brutia Ten. is the dominant tree species in Cyprus. Its formations constitute 65% of the area of forests on the island [1].
Pinus brutia is a species of the eastern Mediterranean and western Asia [2]. It is a site-insensitive, light-demanding species [2,3] that can be found on most types of parent materials [4,5]. Also, it has the ability to grow in dry, barren, and stony soils [2]. Although P. brutia is considered a drought-tolerant species, its water requirements are generally greater than those of Pinus halepensis [4,6,7,8].
The wood from P. brutia forests is used in construction, industry, furniture, as firewood, for charcoal production, and as pulp for paper production [9,10,11,12]. Other products besides wood, which are extracted from the forests of the species, have a great economic contribution, such as honey, mushrooms, resin, and aromatic and medicinal plants [13,14,15,16]. According to [17], the indirect benefits that P. brutia forests offer are many and summarized in the following: protection of soil and water resources, support of agricultural production, sequestration of carbon dioxide from the atmosphere, and mitigation of climate change. Additionally, P. brutia forests are important for biodiversity protection [18].
Ecosystems in the Mediterranean region are characterized by dry and long summers with solar radiation of high intensity, little or no precipitation, and high temperatures [19]. According to [9], even though P. brutia exhibits notable resistance to long periods of high temperatures and drought, in some cases, these climatic elements cause the deaths of trees of the species.
In Cyprus, forest fires are the main threat to forest ecosystems [9]. According to the 2018 National Risk Assessment of the Republic of Cyprus, forest fires present the highest risk compared to other natural disasters, such as earthquakes, coastal erosion, floods, etc. [20]. Nowadays, forest fires are the greatest threat to Mediterranean forests [21]. Over time, their incidence has increased, even in areas of central and eastern Europe [22]. The problem is growing worse since both the number of fires and the burned area are increasing [23]. The occurrence of pines and conifers is related to fires that influence large areas [24]. Both harsh abiotic conditions and forest fires might be extremely dangerous for the survival of the P. brutia formations in many areas. One of them is the middle elevation area in central Cyprus, which is the study area of this research.
In recent decades, a decrease in the density of P. brutia natural regeneration plants has been observed [25,26,27].
The annual timber yield from P. brutia forests in Cyprus for the periods 1988–1992, 1998–2002, and 2003–2007 was 56,100 m3, 27,633 m3, and 14,384 m3, respectively [28]. This wood is used as firewood, to produce charcoal, and by local industries for the production of some building timber products [9].
The significant degradation of P. brutia forests in Cyprus, expressed both through the drastic reduction of the annual yield and the low density of regeneration, has mainly been due to two factors, which are: (1) the silvicultural treatments of the previous decades, and mainly (2) the unfavorable climate and soil conditions prevailing on the island [25,26,29,30].
Natural regeneration of P. brutia has been extensively studied, mainly in post-fire conditions [31,32,33,34,35,36,37,38,39,40,41,42,43,44]. In contrast, the natural regeneration of the species in environments undisturbed by forest fires has received limited study [29,43,45,46].
To achieve sustainability in the management of P. brutia forests in Cyprus, there is an immediate need for a better understanding of P. brutia ecosystem processes in adverse environments in order, in the first phase, to stop their degradation and, in the second phase, to reverse the downgrading course in order to conserve them and, if possible, to expand their area. Achieving these goals is particularly difficult since climate conditions are expected to continue to deteriorate.
Moreover, as time passes, climate change will make many P. brutia ecosystems in northern areas resemble the Cyprus ecosystems and make them more vulnerable to degradation factors.
Open P. brutia formations dominate in the middle elevations of the central part of Cyprus. In these “open” stands, there is a rather low ground cover from the projection of the tree canopy. On the other hand, dense P. brutia stands with large areas appear in very few cases [47].
The objective of this research was to analyze the P. brutia natural regeneration in the open formations of the species and the environments where it was established in the absence of a wildfire in the middle elevations of the central part of Cyprus.

2. Materials and Methods

2.1. Study Area

Middle elevations of central Cyprus (34°56′35.68″ N, 33°17′12.25″ E) were the study area of this research. As middle elevations are considered areas with altitudes from 300 to 750 m above sea level. This area is 14,000 ha (Figure 1). According to the meteorological station in Kornos, the mean yearly temperature is 18.4 °C, and the rainfall annually is 477.1 mm (for 1991–2000). The substrate of the study area belongs to volcanic sequence diabase dykes with pillow lava screens [48]. The soil texture is from sandy loam to sandy clay loam, and the soil pH is from slightly acidic to slightly alkaline [49]. Pinus brutia is the dominant tree species in the area, and its forests in the study area were mainly established in abandoned olive yards and vines [50].
A P. brutia formation is considered as “open” when the projection of the tree canopy covers the ground of the formation in a percentage lower than 75% [47].
Based on site productivity, Petrou [49] refered to three site productivity types in the P. brutia formations. The distinction of the types was based on soil depth and on the mean annual height increment of dominant and codominant trees calculated by the ratio of total tree height to the total age of the tree [51]. The age of trees was determined using cores taken from stump height (30 cm) [49]. The three types of sites were: good productivity sites, where soil depth was over 100 cm; medium productivity sites, having a soil depth of approximately 40–80 cm; and bad productivity sites, where soil depth was approximately 5–30 cm. The classification of sites using the above characteristics was verified by P. brutia site index curves made for central Cyprus by [52]. In good productivity sites, open P. brutia formations have small areas and appear scattered, while the landscape is dominated by P. brutia formations growing in medium and bad productivity sites [47].
About 1000 animals graze in the area (850 goats and 150 sheep) (data from Cyprus Department of Forests). Grazing is practiced unevenly, and animals follow relatively the same routes on a systematic basis. This results in some areas being intensively grazed, while others hardly at all (personal observations and communication with herders).

2.2. Research Method

To investigate the natural regeneration of P. brutia “open” formations in the study area, in 2013, a total of 48 rectangular plots (16 in each type of productivity sites) of 0.1 ha (25 m × 40 m) were established using the stratified random sampling method. The plots in good productivity sites were established in areas where the slope of the ground varied from zero to 10%; in medium productivity sites, from zero to 20%; and finally, in bad productivity sites, from zero to 25%. According to the data provided by the Department of Forests, those areas have not been affected by wildfires since 1960, the year in which data on forest fires began to be systematically recorded [53]. On each plot, the percentage of the area covered by (a) pines, (b) low shrubs, and (c) bare ground (without cover) was estimated. Then, within each plot, the number and species of trees with a height greater than 1.5 m were counted. These trees were considered mature trees. Moreover, the dead trees of P. brutia with a height of over 1.5 were counted. Individuals of P. brutia with a height from 0.1 to 1.5 m were considered regeneration plants, and their numbers were counted while their height was measured using a tape measure. Seedlings less than 0.1 m tall were not counted as regeneration plants because the aim of the present research was to study already established regeneration plants (seedlings that survived at least two growing seasons) [54].
The P. brutia regeneration plants were classified into four categories according to the location where they were established and grown, as follows:
  • “Gap” category (regeneration located on bare ground in the gaps).
  • Category “Pine” (regeneration located below or at the limits of the projection of the crown of mature P. brutia trees).
  • Category “Low Shrub” (regeneration located below or within the area defined by the projection of the crown of low shrubs).
  • Category “Pine and Low Shrub” (regeneration located simultaneously below or at the borders of the projection of the crown of mature P. brutia trees and below or within the area defined by the projection of the crown of low shrubs).
The regeneration plants belonging to the categories ‘Pine’, ‘Low Shrub’, and ‘Pine + Low Shrub’ are located or established essentially under the facilitation of other plants [46] and belong to a broader regeneration category that is hereinafter referred to as “Facilitation”.
Moreover, all P. brutia regeneration plants were evaluated based on the degree to which they were grazed and classified into three categories, as follows:
  • Heavily grazed (plants that had strong signs of grazing).
  • Moderately grazed (plants that had signs of grazing but were not heavily grazed).
  • Not grazed (plants that had no sign of grazing).
Additionally, all P. brutia regeneration plants were classified into three categories according to their height, as follows:
  • Category of height 10–60 cm (plants that had a height from 10 cm to 60 cm).
  • 60–105 cm height category (plants that were between 60 cm and 105 cm high).
  • 105–150 cm height category (plants that were between 105 cm and 150 cm tall).
In each plot of 0.1 ha of the 48 (16 in each type of productivity sites) established for the study of natural regeneration, 10 points were selected using the simple random sampling method, and at a height of 1.5 m above the ground, hemispherical photographs were taken. In total, 480 photographs were taken. In addition, hemispherical canopy photos were also taken above each naturally regenerated P. brutia regeneration plant recorded on the established plots, at a height of 1.5 m above the ground. The photos were taken to determine the light conditions in which the natural regeneration of P. brutia was located and to compare them with the available light conditions that exist in each type of productivity sites separately. The photographs were taken under a clear sky (homogeneous sky conditions) before sunrise or after sunset. A horizontally leveled digital camera (a Nikon Coolpix 900 digital camera with a fish-eye lens) was used to take the hemispherical photographs. All the photos were analyzed with Hemiview software version 2.1 [55]. The part of the sky that is visible as a proportion of the total hemisphere when it is observed from a single point is called Visible Sky (VS) (or canopy openness or gap fraction) [56]. The VS value is related to the amount of solar radiation attaining the specific point [55,56,57]. When the total sky is visible, the VS has the value 1, while the Visible Sky takes the value 0 when the total sky is blocked.

2.3. Statistical Analyses

In the various comparisons of this study, the Duncan test, the Dunnet T3 test, and the Wilcoxon test were used. These comparisons were made using the SPSS v.21.0 software [58].
The Hill Numbers-True Diversity [59,60] was used to investigate the differences in the VS distributions that were compared. The calculations in these processes were made using the template of [61]. The comparisons between the distributions were taken place using the z-test, based on the template of [61], where the proportion of Hill Numbers was defined as the Hill Number divided by the number of classes. The order q refers to the richness and abundance that constitute diversity. As q increases, abundance (i.e., the number of trees per class) has an increased impact on diversity. So, when q is greater than 0, diversity is not only determined by the number of different classes present but also by the uneven number of trees within each class. The higher the value of q, the more weight is given to the uneven Visual Sky distribution in calculating diversity.

3. Results

In good productivity sites, 18.75% of regeneration plants were heavily grazed, 62.5% were moderately grazed, and 18.75% were not grazed. In medium productivity sites, 45.3% of regeneration plants were heavily grazed, 30.2% were moderately grazed, and 24.5% were not grazed. Finally, in bad productivity sites, 16% of regeneration plants were heavily grazed, 30.4% were moderately grazed, and 53.6% were not grazed.
Regeneration plants made up only 2.4% of all trees in the good productivity sites; in the medium productivity sites, they made up 11.2%; and, finally, in the bad productivity sites, natural regeneration plants made up 9.7% of all trees (Table 1). In the good productivity sites, the other species recorded were Olea europaea L., Quercus alnifolia Poech, Crataegus azarolus L., Acer obtusifolium Sm., Pistacia lentiscus L., Pistacia terebinthus L., and Ceratonia siliqua L.; in the medium productivity sites, O. europaea, P. lentiscus, P. terebinthus, and Myrtus communis L.; and finally, in the bad productivity sites, O. europaea and P. terebinthus.
In the good productivity sites, the 105–150 cm height category showed the highest density (p < 0.05) of regeneration plants compared to the densities of plants in the 10–60 cm and 60–105 cm categories, whose densities did not show a difference (p > 0.05) between them. In the medium and bad productivity sites, the density of regeneration plants in the 105–150 cm height category was greater (p < 0.05) compared to the density of regeneration plants in the 10–60 cm category. The density of regeneration plants in the 105–150 cm height class, although numerically higher, was not statistically significantly different (p > 0.05) from the density of regeneration plants in the 60–105 cm height class. Finally, the density of regeneration plants in the 60–105 cm height category was greater numerically, but without being statistically significantly different (p > 0.05) from the corresponding one in the 10–60 cm height category (Table 2).
In all site productivity types, the plants belonging to the broader category Facilitation (all the plants in the categories Pine, Low Shrub, Pine, and Low Shrub) exhibited greater density (p < 0.05) compared to the regeneration plant category Gap (Table 3).
In good productivity sites, the percentage of bare ground cover varied from 10 to 25% (Table 4). In the medium productivity sites, the percentage of bare ground varied from 30 to 60%, while in the bad productivity sites, the percentage of bare ground varied from 35 to 60% (Table 4). In the three site productivity types, approximately 40%–50% of the low shrubs were under the crown of P. brutia trees, while the remaining percentage was in the gaps between the P. brutia trees.
When comparing the density of the regeneration plant category Pine with the regeneration plant categories Low Shrub + Pine and Low Shrub, in each site productivity type, separately, they did not show a statistically significant difference (p > 0.05) between them (Table 5).
The density data for all regeneration plant categories in the three site types is given in Table 6.
Good productivity sites show the lowest (p < 0.05) density of regeneration plants on average, compared to the density of regeneration plants at medium and bad productivity sites, whose means do not exhibit a difference (p > 0.05) between them (Table 7).
In Figure 2, Figure 3 and Figure 4, the VS distributions from the photographs taken in the three site productivity types and from the photographs taken above the regeneration plants in the same site productivity types are presented.
In Figure 5, the distributions of VS values from the photographs taken above the regeneration plants in the three productivity site types are presented.
The bad productivity sites exhibited higher VS values (p < 0.05) than those of the medium and good productivity sites on average, while the good productivity sites exhibited lower VS values (p < 0.05) compared to the other two types of productivity sites (Table 8). The same pattern was observed in the VS values from the photographs taken above the regeneration plants in the three productivity site types (Table 8).
The Hill Numbers index revealed no significant difference (p > 0.05) in VS diversity between photographs taken above the site’s regeneration plants and those taken at the site across all three productivity types (Table 9).
The VS classes were significantly (p < 0.05) fewer in the VS distribution from the photos taken above the regeneration plants in good productivity sites, compared to those of medium productivity sites. The VS classes were significantly (p < 0.05) fewer, and there was a significantly (p < 0.05) lower diversity in VS values in the VS distribution from the photos taken above the regeneration plants in good productivity sites compared to those of bad productivity sites. Lastly, there was a, to the limit, significantly (p < 0.05) lower diversity in VS values in the VS distribution from the photos taken above the regeneration plants in medium productivity sites, compared to those of bad productivity sites (Table 10).

4. Discussion

In all the site productivity types, a large percentage of regeneration plants was grazed. For many years, human activities have greatly influenced and determined the distribution, composition, and structure of pine forests in various regions of the world [62]. The authors of [63] reported that forests throughout the Mediterranean basin have been disturbed or altered to a great extent by human activities. In addition, [64] pointed out that the forests of the Mediterranean basin countries had been affected for many years by human activities, which ultimately largely determined their present state.
Many animals graze unevenly within the study area, having a greater impact in some areas and less in others. The effect of grazing on young plants is related to the change in the shape and architecture of their crown, thus limiting their growth rates, and in cases where grazing is intense, it can also lead to plant necrosis [65,66,67,68,69].
Within the three site productivity types, regeneration exhibited a very small proportion of all trees, with plant numbers ranging from 10 n/ha in good productivity sites to 35 n/ha in bad productivity sites (Table 1). In successive censuses of both the productive and non-productive P. brutia forests of Cyprus, a decrease in the density of the P. brutia regeneration plants was found, which, according to the Cyprus Department of Forests, may be the most serious problem of the island’s forests [25,26,27]. Furthermore, [9] stated that the mature individuals of P. brutia, which are cut in the productive forests of Cyprus, cannot be replaced by the small number of plants of natural regeneration established in these stands.
There are only a few studies of the density of P. brutia regeneration in environments unaffected by forest fires. In a comparative study of the natural regeneration of P.brutia forests in Greece and Cyprus, the severe problem of natural regeneration of the island’s forests was confirmed [29]. Specifically, in stands that had not been affected by forest fires, the natural regeneration plants (individuals of P. brutia up to 3 m in height) on Thassos Island were 1124 n/ha [43]; on Rhodes Island, they were 383 n/ha; and in Cyprus Adelfi Forest, they were only 152 n/ha. According to the results presented by [46], who studied the establishment and survival of P. brutia seedlings in the first growth period in partially forested areas in central Cyprus, at the end of the growth period, the total density of seedlings that finally survived was 1180 n/ha. The authors of [45] studied the regeneration plants (individuals of P. brutia up to 1 m in height) in mixed stands of P. brutia and P. nigra on Lesvos Island, which had not been affected by forest fires for at least the last 50 years, and presented their density in three different types of mixtures. In the first type of mixture, where P. brutia was the dominant species, the density of P. brutia regeneration plants was 220 n/ha. In the second type of mixture, where neither P. brutia nor P. nigra dominated, the density of P. brutia regeneration plants was 240 n/ha. Finally, in the third type of mixture, where black pine was the dominant species, the density of regeneration of P. brutia was 50 n/ha.
In all the above cases, the density of the regeneration plants of P. brutia was greater than that found in each of the three site productivity types of the present research. Both on Thassos Island and Rhodes Island [29,43], as well as in Lesvos Island [45], the stands of P. brutia that were studied grew in areas with more favorable climatic conditions than those prevailing in the region of the present research, i.e., with higher rainfall, lower air temperatures, and a shorter duration of the dry season. In the Adelfi Forest of Cyprus, although the density of the regeneration of P. brutia was considered low compared to Rhodes Island and Thassos Island [29], it was nevertheless considerably higher than that of the three site productivity types of the present research. It should be noted that in the research of [29], trees with a height of up to 3 m were considered regeneration plants, while in the present research, regeneration plants were considered trees with a height of up to 1.5 m. Nevertheless, the density of the regeneration of P. brutia in the Adelfi Forest of Cyprus, with a height of up to 1 m (and not 3 m), was 88 n/ha, i.e., significantly higher than that of each of the three site productivity types of the present research. The climatic conditions that prevail in the Adelfi Forest of Cyprus do not differ to a great extent from those that prevail in the area of the present research. The main factor favoring the presence of a greater number of regeneration plants in the Adelfi Forest of Cyprus seems to have been the absence of grazing; since 1940, it has been prohibited by law in this area [29].
Ref. [70] found that drought conditions during the summer season, extremely high temperatures, and intense solar radiation could possibly be the main factors that determine the establishment and survival of plants in Mediterranean ecosystems. In addition, Ref. [71] mentioned that the establishment of natural regeneration in Mediterranean ecosystems is very uncertain and faces serious risks, among which is the severity of the summer drought, which is also the main factor in the necrosis of seedlings, as well as the effect of grazing that greatly affects even regeneration survival. The results of the density of P. brutia seedlings presented by [46], although they refer to areas that are within the wider study area of this research, are not directly comparable to the values of regeneration densities found in the three site productivity types of the present research. In the above work, the establishment and survival of P. brutia seedlings were studied for a single growth period. On the contrary, in the present research, the already-established regeneration plants were studied. It is noteworthy that in all three site productivity types, the 10–60 cm height category of P. brutia regeneration plants numerically presented the lowest density, followed by the 60–105 cm height category, while the 105–150 cm height category presented the highest numerical density of regeneration plants of P. brutia (Table 2), which was statistically higher (p < 0.05) than that of the 10–60 cm height category in all three site productivity types. If we consider that there is a positive correlation between the height of the trees and their age [43], then it is understandable that, in recent years, the number of regeneration plants established in the three site productivity types has been gradually decreasing. Similar results were found by [29] for the regeneration of P. brutia stands in the Adelfi Forest of Cyprus, where the regeneration plant density observed in the largest height class (100–300 cm) was greater than that of the two smaller height classes (0–40 cm and 40–100 cm). Ref. [29] also concluded that, over time, there was a decline in the number of regeneration plants in the Adelfi Forest. In addition, Ref. [72] stated that natural regeneration is successful during some periods and occurs in waves, when there is a favorable occasion of biotic and abiotic factors. The decrease in natural regeneration in all the site productivity types in recent years is likely due to the non-existence of these favorable conditions, due to grazing and the deterioration of the climatic conditions taking place in Cyprus [73,74,75,76,77].
Despite the fact that the number of P. brutia regeneration plants was low in all the site productivity types, it is clear that the positive effects (facilitation) from the presence of other plants (pines, low shrubs, pines and low shrubs) played a decisive role in regeneration plant density (Table 3) and dominated the regeneration process of P. brutia in the area. In all comparisons, for each site productivity type, separately, the density of plants in the “Gap” category was lower with a statistically significant difference (p < 0.05) than the density of plants in the broader category of “Facilitation” (“Pine”, “Low Shrub”, and “Pine + Low Shrub”) (Table 3). It should be noted that in all the site productivity types, there was a satisfactory percentage of the presence of all regeneration environments (Table 4). Thus, there is no justification for the absence of regeneration in a category due to the low availability of any regeneration environment.
Ref. [46] studied the establishment and survival of P. brutia seedlings during the first growing season in partially forested areas in central Cyprus. The above researchers found that the facilitation provided by the cover of pines, low shrubs, and pines and low shrubs together to P. brutia seedlings was crucial for the survival of the seedlings at the end of the growing season since they survived only under the crowns of the previous plants. On the contrary, in the bare ground, no P. brutia, out of a relatively satisfactory number initially established in this environment, survived to the end of the growing season. In this study, it was found that the facilitation of the establishment and survival of P. brutia seedlings during the first growing season appeared to be influenced by: (a) the lower temperatures of the surface soil and (b) the increased percentages of the surface soil content in organic matter (thus, the existence of a greater amount of nutrients and greater soil moisture) compared to the uncovered soil. Conversely, the minimal to zero precipitation in the summer, combined with the low organic matter content of the topsoil and the extreme surface soil temperatures that prevailed in the bare ground, led to intense drought conditions in this environment, which ultimately resulted in the zero survival of seedlings at the end of the growing season. In addition to the previous ones, another very important factor that led to this result was the necrosis of seedlings from the extreme temperatures of the surface soil. In addition, [50], based on the results of a sowing experiment in natural P. brutia stands in the same study area as the present research, mentioned that the facilitation process constitutes one of the main factors that defines the establishment as well as the survival of P. brutia seedlings.
Another way of facilitation, in addition to the creation of a favorable microenvironment related to abiotic factors (solar radiation, temperature, soil moisture, nutrients, etc.), is the protection that some plants provide to others from grazing [78,79,80,81,82,83,84,85,86]. In the present research, the mechanism of facilitation of the P. brutia regeneration plants seems to be more related to the creation of a favorable microenvironment regarding abiotic factors than to protection from grazing. The previous conclusion is based on the fact that when comparing the densities of the natural regeneration categories “Pine” and “Low Shrub + Pine and Low Shrub” in each site productivity type separately, they did not show a statistically significant difference between them (p < 0.05) (Table 5). In the “Pine” category, there was no protection from grazing for regeneration plants. In contrast, protection from grazing was provided in the initial stages of establishment in the “Low Shrub” + “Pine and Low Shrub” categories. However, later, the P. brutia regeneration plants surpassed the low shrubs in height and thus became accessible to animals. So, any protection from grazing can be termed temporary. Conversely, facilitation associated with the creation of a favorable microenvironment regarding abiotic factors has a longer-lasting effect on regeneration plant survival.
The results of this research fully confirm the hypothesis made by [46] that in the middle altitudes of central Cyprus, where adverse climatic conditions prevail during the dry season, facilitation is the dominant process that affects the successful establishment of P. brutia. In addition, these results significantly support the concept formulated by [46] that, through the facilitation process, not only the conservation but also the gradual expansion of P. brutia in the middle altitudes of central Cyprus is promoted. The favorable conditions created under the canopies of some plants were, in many cases, the cause of facilitation, which led to the survival of a greater number of regeneration plants of various species under the canopies compared to the bare ground [87,88,89,90,91,92,93,94,95,96]. Facilitation by the cover of other plants has been shown to be important for the survival of regeneration plants of other pine species in various regions of the world [54,97,98,99,100,101,102,103,104,105,106,107,108,109].
Ref. [110] concluded that, in Crete Island, the presence of the phrygana led to the creation of P. brutia forest by facilitating the establishment of the regeneration of the species. Ref. [29] reported that in the Adelfi Forest of Cyprus, Cistus incanus covered a significant percentage of the regeneration plants of the species (up to 40 cm in height), and thus they concluded that it exerted a partial protective effect on P. brutia young seedlings. On the other hand, the results of the same research showed that the regeneration individuals of P. brutia (up to 40 cm in height) on Thassos Island and Rhodes Island appeared exclusively on bare ground and not in places where there were shrubs. Thus, the authors concluded that the survival probability of P. brutia regeneration was higher on bare ground than at sites where shrubs were present. Ref. [43], in a survey carried out on Thassos Island, also found that regeneration plants of P. brutia, in burned and unburned areas, occurred in bare ground in a large proportion rather than in ground covered by shrubs. But they recognized that the Cistus spp. during the summer provided protection to the young P. brutia seedlings from high temperatures and solar radiation. The results of the research of [29] (Rhodes Island and Thassos Island) and [43] (Thassos Island) were contrary to the results of the present research. The previous ones were fully justified based on the theory that states that competition is dominant when conditions are favorable, while on the contrary, facilitation is dominant when there are adverse conditions [111,112,113,114]. In the middle altitudes of central Cyprus, the climatic conditions are much worse than those of Thassos Island and Rhodes Island, and thus facilitation appears to be the dominant force, while on the contrary, in the other two regions, competition seems to have been the dominant process that determined the establishment of natural regeneration [46].
The range of values of VS in medium and bad productivity sites was large. In medium productivity sites, it varied between the classes of 0.25 and 0.75 (Figure 3), and in bad productivity sites, it varied between the classes of 0.35 and 0.85 (Figure 4). In good productivity sites, the range of VS values was limited almost exclusively between the classes of 0.15 and 0.25 (Figure 2). Pinus brutia regeneration plants showed relatively great adaptability in relation to the available light conditions since they appeared in conditions where VS values ranged from 0.2 to 0.9. Thus, no significant difference (p > 0.05) in VS diversity between photographs taken above the site’s regeneration plants and those taken at the site across all three site productivity types was detected (Table 9). VS values below 0.2 appeared to be prohibitive for the survival of P. brutia regeneration plants. Many P. brutia regeneration plants in all the site productivity types belonged to the “Low Shrub” and “Pine and Low Shrub” regeneration categories (Table 6). In these categories, the P. brutia regeneration plants were initially established in shaded conditions, possibly at VS values lower than 0.2, which were estimated to exist under the canopies of low shrubs. Later, when these plants grew in height, they overtook the low shrubs, allowing them to receive more light. The hemispherical photographs of the P. brutia regeneration plants belonging to these categories were taken at a height of 1.5 m above the ground, which, in each case, was greater than the height of the low shrubs. Thus, the VS values of the photographs taken above the plants in these two regeneration categories express the light conditions in which the plants are after they have surpassed the height of the low shrubs. The authors of [50] stated that in the middle elevations of Cyprus, for the artificial regeneration of P. brutia formations through sowing, the sowing has to be practiced during December in areas where the VS values must be well over 0.19 up to 0.30. According to [115], the seedlings of P. pinea (a light demanding species) in the initial stages of their establishment, showed great resistance to shading conditions, but then their light needs increased. Ref. [3] reported that the light requirements of various forest tree species generally increase with increasing age, but also with increasing competition. Thus, P. brutia cannot survive throughout its life in conditions of intense shading [116]. It seems that the availability of light, expressed through the values of the visible part of the sky (VS), was one of the factors that greatly influenced the different densities of P. brutia regeneration plants found at each of the site productivity types. The density of P. brutia regeneration plants in good productivity sites was statistically lower (p < 0.05) compared to those of the other two site productivity types (Table 7). However, there was no statistical difference (p > 0.05) in the density of P. brutia regeneration plants between the medium and bad productivity types. The VS values of the photographs taken above the regeneration plants in good productivity sites were statistically lower (p < 0.05) compared to those of the other two site productivity types. In this case, the photographs taken at bad productivity sites exhibited statistically higher (p < 0.05) VS values than those taken at medium productivity sites (Table 8). This result, combined with the absence (p > 0.05) of a difference in the density of P. brutia regeneration plants between the medium and bad productivity types, leads to the conclusion that the higher light availability in the bad productivity sites did not lead to an increase in the P. brutia regeneration plant density. So, VS values around 0.454 (which is the mean value of VS at medium productivity sites) seem to be a factor that does not strongly negatively affect the survival of P. brutia regeneration plants. Apart from the differences among the mean VS values of the photographs taken above of the regeneration plants in the different site productivity types, there were also differences in the diversity of VS distributions among them. These differences were in the number of VS classes, in the diversity of VS values in the VS distributions, or in both (Table 10 and Figure 5). Finally, the VS values of the photographs taken at the good productivity sites were statistically lower (p < 0.05) compared to those of the other two site productivity types, while the photographs taken at the bad productivity sites exhibited statistically higher (p < 0.05) VS values than those at the medium productivity sites (Table 8). This result agreed with the findings of [47] in the same study area. They referred to the VS values in a bad productivity site as statistically greater (p < 0.05) than those of a medium productivity site.
Ref. [45] also found that the availability of light in mixed stands of P. brutia and P. nigra was a very important factor that affected the regeneration plant density of the two species. In the above research, it was found that the P. nigra regeneration plants (0.11–0.5 m in height) presented their highest density at VS values between 0.2 and 0.4, while the P. brutia regeneration plants had VS values greater than 0.35.
To achieve sustainability in P. brutia forests, forest practice must develop strategies for the enhancement of P. brutia regeneration in the studied area and in analogous environments. In this context, grazing must be forbidden, and the shelterwood silvicultural system must be applied in order to create the appropriate environment for the establishment and growth of the regeneration plants [50].

5. Conclusions

Regeneration of P. brutia exhibited a small number of plants and constituted only a very small proportion of all trees in the three site productivity types. A large percentage of regeneration plants were grazed, and in recent years, their number has been gradually decreasing in the three site productivity types. The density of P. brutia regeneration plants in good productivity sites was statistically lower compared to those of the other two site productivity types. Despite the fact that the number of P. brutia regeneration plants was low in all the site productivity types, it is clear that the positive effects (facilitation) from the presence of other plants played a decisive role in regeneration plant density and dominate the regeneration process of P. brutia in the area. Protection from grazing can be termed temporary. Conversely, facilitation associated with the creation of a favorable microenvironment regarding abiotic factors has a longer-lasting effect on regeneration plant survival. Pinus brutia regeneration plants showed relatively great adaptability in relation to the available light conditions since they appeared in conditions where VS values ranged from 0.2 to 0.9. It seems that the availability of light was one of the factors that greatly influenced the different densities of P. brutia regeneration plants found at each of the site productivity types. VS values below 0.2 appeared to be prohibitive for the survival of P. brutia regeneration plants. The higher light availability in the bad productivity sites, compared to that of medium productivity types, did not lead to an increase in the P. brutia regeneration plant density. So, VS values around 0.454 (which was the mean value of VS at medium productivity sites) seem to be a factor that does not strongly negatively affect the survival of P. brutia regeneration plants.

Author Contributions

Conceptualization, P.P., E.M. and K.K.; methodology, P.P., K.K., E.M., A.S. and E.P.; formal analysis, P.P., K.K., E.M., A.S. and E.P.; investigation, P.P.; data curation, P.P., K.K. and A.S.; writing—original draft preparation, P.P., E.M. and K.K.; writing—review and editing, K.K., A.S. and E.P.; visualization, K.K.; supervision, E.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are contained within the article. The data presented in this study are available in the Tables and Figures of this article.

Acknowledgments

The authors wish to thank the Department of Forests (Cyprus) for its support.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Cyprus Department of Forests. Mapping of Woody Forest Vegetation in Cyprus; Cyprus Department of Forests: Nicosia, Cyprus, 2020.
  2. Korakis, G. Forest Botany. Trees and Shrubs Native in Greece; Athanasiou Altintzi Editions: Thessaloniki, Greece, 2019; p. 520. ISBN 978-960-9465-36-6. [Google Scholar]
  3. Dafis, S. Forest Ecology; Giahoudis-Giapoulis: Thessaloniki, Greece, 1986. [Google Scholar]
  4. Quézel, P. Taxonomy and biogeography of Mediterranean pines (Pinus halepensis and P. brutia). In Ecology, Biogeography and Management of Pinus halepensis and P. brutia Forest Ecosystems in the Mediterranean Basin; Ne’eman, G., Trabaud, L., Eds.; Backhuys Publishers: Leiden, The Netherlands, 2000; pp. 1–12. [Google Scholar]
  5. Boydak, M. Silvicultural characteristics and natural regeneration of Pinus brutia Ten.—A review. Plant Ecol. 2004, 171, 153–163. [Google Scholar] [CrossRef]
  6. Thanos, C.A.; Skordilis, A. The effects of light, temperature and osmotic stress on the germination of Pinus halepensis and P. brutia seeds. Seed Sci. Technol. 1987, 15, 163–174. [Google Scholar]
  7. Boydak, M.; Dirik, H.; Tilki, F.; Çalıkoglu, M. Effect of water stress on germination of six provenances of Pinus brutia seeds from different bioclimatic zones of Turkey. Turk. J. Agric. For. 2003, 27, 91–97. [Google Scholar]
  8. Chambel, R.M.; Climent, J.; Pichot, C.; Ducci, F. Mediterranean Pines (Pinus halepensis Mill. and brutia Ten.). In Forest Tree Breeding in Europe: Current State-of-the-Art and Perspectives; Paques, L.E., Ed.; Managing Forest Ecosystems: New York, NY, USA, 2013. [Google Scholar]
  9. Pantelas, V. The forest of pine brutia in Cyprus. In Options Méditerranéennes: Série Etudes; C.I.H.E.A.M.: Paris, France, 1986. [Google Scholar]
  10. Fady, B.; Semerci, H.; Vendramin, G.G. EUFORGEN Technical Guidelines for Genetic Conservation and Use for Aleppo Pine (Pinus halepensis) and Brutia pine (Pinus brutia); International Plant Genetic Resources Institute: Rome, Italy, 2003; p. 6. [Google Scholar]
  11. Petrakis, P.V.; Ioannidis, C.; Zygomala, A.M. Biotechnology of Pinus brutia and Pinus halepensis as important landscape plants of the East Mediterranean. Tree For. Sci. Biotechnol. 2007, 1, 26–38. [Google Scholar]
  12. Tolunay, A.; Akyol, A.; Özcan, M. Usage of trees and forest resources at household level: A case study of Açagl Yumrutaç Village from the West Mediterranean Region of Turkey. Res. J. For. 2008, 2, 1–14. [Google Scholar]
  13. Sabra, A.; Walter, S. Non-Wood Forest Products in the Near East: A Regional and National Overview; Working paper FOPW/01/2; FAO: Rome, Italy, 2001. [Google Scholar]
  14. Yesil, A.; Gurkan, B.; Saracoglu, O.; Zengin, H. Effect of the pest Marchallina hellenica Gennatius (Homoptera, Margarodidae) on the growth parameters of Pinus brutia Ten. in Mugla region Turkey. Pol. J. Ecol. 2005, 53, 451–458. [Google Scholar]
  15. Satil, F.; Selvi, S.; Polat, R. Ethnic uses of pine resin production from Pinus brutia by native people on the Kazdag Mountain (Mt. Ida) in western Turkey. J. Food Agric. Environ. 2011, 9, 1059–1063. [Google Scholar]
  16. Kizilarslan, C.; Sevg, E. Ethnobotanical uses of genus Pinus L. (Pinaceae) in Turkey. Indian J. Tradit. Knowl. 2013, 12, 209–220. [Google Scholar]
  17. Shater, Z.; de-Miguel, S.; Kraid, B.; Pukkala, T.; Palahí, M. A growth and yield model for even-aged Pinus brutia Ten. stands in Syria. Ann. For. Sci. 2011, 68, 149–157. [Google Scholar] [CrossRef]
  18. de-Miguel, S. Growth and yield modelling for optimal multi-objective forest management of eastern Mediterranean Pinus brutia. Diss. For. 2014, 170, 59. [Google Scholar]
  19. Valladares, F.; Pearcy, R.W. Drought can be more critical in the shade than in the sun: A field study of carbon gain and photo-inhibition in a Californian shrub during a dry El Niño year. Plant Cell Environ. 2002, 25, 749–759. [Google Scholar] [CrossRef]
  20. Cyprus Department of Civil Defence, Ministry of Interior. 3rd Report on the National Risk Assessment of the Republic of Cyprus; Ministry of Interior, Cyprus Civil Defence: Nicosia, Cyprus, 2018.
  21. Vélez, R. Causes of forest fires in the Mediterranean Basin. In European Forest Institute Discussion Paper ‘Risk Management and Sustainable Forestry’; Arbez, M., Birot, Y., Carnus, J.-M., Eds.; European Forest Institute: Joensuu, Finland, 2002; Volume 42, pp. 35–42. [Google Scholar]
  22. Birot, Y. Convivir Con los Incendios Forestales: Lo que nos Revela la Ciencia; European Forest Institute: Joensuu, Finland, 2009. [Google Scholar]
  23. San-Miguel-Ayanz, J.; Durrant, T.; Boca, R.; Maianti, P.; Libertá, G.; Artés-Vivancos, T.; Oom, D.; Löffler, P. Forest Fires in Europe, Middle East and North Africa 2022; Publications Office of the European Union: Luxembourg, 2023. [Google Scholar]
  24. Papatheodorou, I.; Kitikidou, K.; Stampoulidis, A.; Milios, E. Analyzing the impact of reforestation on forest fires and the economic outcome in an area in northern Greece: Should we reforest areas with conifers? Yes or No? Ecol. Quest. 2023, 34, 1–17. [Google Scholar]
  25. Cyprus Department of Forests. Summary of Inventory Results of Productive Scots Pine Forests (Pinus brutia Ten.) in Cyprus 2001–2002; Cyprus Department of Forests, Forest Management and Computerization Sector, Ministry of Agriculture, Natural Resources and Environment, Republic of Cyprus: Nicosia, Cyprus, 2003.
  26. Cyprus Department of Forests. Summary of Inventory Results of Productive Scots Pine Forests (Pinus brutia Ten.) in Cyprus 2006–2007; Cyprus Department of Forests, Forest Management and Computerization Sector, Ministry of Agriculture, Natural Resources and Environment, Republic of Cyprus: Nicosia, Cyprus, 2008.
  27. Cyprus Department of Forests. Summary of Inventory Results of Productive Scots Pine Forests (Pinus brutia Ten.) in Cyprus 2011–2012; Cyprus Department of Forests, Forest management and computerization sector, Ministry of Agriculture, Natural Resources and Environment, Republic of Cyprus: Nicosia, Cyprus, 2013.
  28. Horattas, A.; Christou, A.; Loizou, L.; Papageorgiou, K.; Sarris, A. Global Forest Resources Assessment, Country Report Cyprus; FRA2010/051; Forestry Department, Food and Agriculture Organization of the United Nations: Rome, Italy, 2010. [Google Scholar]
  29. Radoglou, K.; Christodoulou, A. Comparative research of natural regeneration of Pinus brutia forests of Cyprus and Greece. In Scientific and Technological Program of Greece-Cyprus Cooperation 1996–1998 (Final Report). N.AG.R.E.F.; Forestry Department of Cyprus: Nicosia, Cyprus, 1998. [Google Scholar]
  30. Loizou, L. Biomass Estimation from Young Scots Pine Stands (Pinus brutia Ten.) in Cyprus; Cyprus Department of Forests, Forest Management and Computerization Sector, Ministry of Agriculture, Natural Resources and Environment, Republic of Cyprus: Nicosia, Cyprus, 2007.
  31. Eron, Z. Ecological factors restricting the regeneration of Pinus brutia in Turkey. Ecol. Mediterr. 1987, 13, 57–67. [Google Scholar] [CrossRef]
  32. Boydak, M. Silvicultural characteristics of Pinus brutia, applicable natural regeneration methods and application principles. In Book of Papers, International Symposium on Pinus brutia Ten., Marmaris, Turkey, 18–23 October 1993; Ministry of Forestry (Turkey): Ankara, Turkey, 1993; pp. 146–156. (In Turkish) [Google Scholar]
  33. Thanos, C.A.; Markou, S.; Christodoulakis, D.; Yannitsaros, A. Early post-fire regeneration in Pinus brutia forest ecosystems of Samos island (Greece). Acta Oecologica/Oecol. Plant 1989, 10, 79–94. [Google Scholar]
  34. Thanos, C.A.; Daskalakou, E.N.; Nikolaidou, S. Early postfire regeneration of Pinus halepensis forest at Mount Parnes Attica, Greece. J. Veg. Sci. 1996, 7, 273–280. [Google Scholar] [CrossRef]
  35. Thanos, C.A.; Markou, S. Post-fire regeneration in Pinus brutia forest ecosystems of Samos island (Greece): 6 years after. Acta Oecologica 1991, 12, 633–642. [Google Scholar]
  36. Thanos, C.A.; Markou, S. Natural regeneration of Pinus brutia forests in Samos island. Key events during the first 10 years of the postfire period. In Book of Papers, International Symposium on Pinus brutia Ten., Marmaris, Turkey, 18–23 October 1993; Secretariat of the Organizing Committee, Ed.; Ministry of Forestry (Turkey): Ankara, Turkey, 1993; pp. 176–183. [Google Scholar]
  37. Spanos, I.A. Structure Analysis and Natural Regeneration of Pinus brutia Forests in Thasos. Ph.D. Thesis, Aristotle University of Thessaloniki, Thessaloniki, Greece, 1992. (In Greek with English summary). [Google Scholar]
  38. Spanos, I.A. Natural regeneration of Pinus brutia in north-west areas of Thasos Island, burned in 1989. Geotech. Epistimonika Them. 1994, 4, 33–39. [Google Scholar]
  39. Daskalakou, E.N.; Thanos, C.A. Aleppo pine (Pinus halepensis) postfire regeneration: The role of canopy and soil seed banks. Int. J. Wildland Fire 1996, 6, 59–66. [Google Scholar] [CrossRef]
  40. Radoglou, K. Restoration of Pinus brutia forest by natural regeneration 10 years after fire in Rhodes. In Proceedings of the International Symposium on Forest Fires: Needs and Innovations A Delfi Action, Athens, Greece, 18–19 November 1999; CINAR SA: Athens, Greece, 1999; pp. 305–309. [Google Scholar]
  41. Spanos, I.A.; Daskalakou, E.N.; Thanos, C.A. Postfire, Natural Regeneration of Pinus brutia Forests in Thasos Island, Greece. Acta Oecologica 2000, 21, 13–20. [Google Scholar] [CrossRef]
  42. Gitas, I.; Radoglou, K.; Devereux, B.; Spanos, I. Comparative study of post-fire ecosystem recovery by using field plots and geography information systems. In Proceedings of the Intenational Conference “Protection and Restoration of the Environment V”, Thasos Island, Greece, 3–6 July 2000; Tsihrintzis, V.A., Theodossiou, N., Varnavas, H., Stamou, A., Papadopoulos, G., Koussoulis, N., Karatzas, I., Eds.; University of Thrace: Xanthi, Greece, 2000; Volume 1, pp. 651–658. [Google Scholar]
  43. Spanos, I.A.; Radoglou, K.M.; Raftoyannis, Y. Site quality effects on post-fire regeneration of Pinus brutia forest on a Greek island. Appl. Veg. Sci. 2001, 4, 229–236. [Google Scholar] [CrossRef]
  44. Tavsanoglu, C.; Gurkan, B. Post-Fire Regeneration of a Pinus brutia (Pinaceae) Forest in Marmari National Park, Turkey. Int. J. Bot. 2009, 5, 107–111. [Google Scholar] [CrossRef]
  45. Fyllas, M.N.; Dimitrakopoulos, G.P.; Troumbis, Y.A. Regeneration dynamics of a mixed Mediterranean pine forest in the absence of fire. For. Ecol. Manag. 2008, 256, 1552–1559. [Google Scholar] [CrossRef]
  46. Petrou, P.; Milios, E. Establishment and survival of Pinus brutia Ten. seedlings over the first growing season in abandoned fields in central Cyprus. Plant Biosyst. 2012, 146, 522–533. [Google Scholar]
  47. Petrou, P.; Stampoulidis, A.; Kitikidou, K.; Milios, E. Comparison of the Stand Structure Diversity of Open Pinus brutia Ten. Forests in Areas of Different Productivity in Central Cyprus. Forests 2023, 14, 2200. [Google Scholar] [CrossRef]
  48. Cyprus Department of Geological Survey. Geological Map of Cyprus, Revised ed.; Press and Information Office: Nicosia, Cyprus, 1995.
  49. Petrou, P. Regeneration, Growth and Structure of Calabrian Pine (Pinus brutia Ten.) Stands in the Middle Elevations of Central Cyprus. Ph.D. Thesis, Democritus University of Thrace, Orestiada, Greece, 2015. [Google Scholar]
  50. Petrou, P.; Milios, E. Investigation of the Factors Affecting Artificial Seed Sowing Success and Seedling Survival in Pinus brutia Natural Stands in Middle Elevations of Central Cyprus. Forests 2020, 11, 1349. [Google Scholar] [CrossRef]
  51. Husch, B.; Miller, C.I.; Beers, T.W. Forest Mensuration; John Wiley & Sons, Inc.: New York, NY, USA, 1982. [Google Scholar]
  52. Kitikidou, K.; Petrou, P.; Milios, E. Dominant height growth and site index curves for Calabrian pine (Pinus brutia Ten.) in central Cyprus. Renew. Sustain. Energy Rev. 2012, 16, 1323–1329. [Google Scholar]
  53. Petrou, P. Development of Proposals to Improve the Public Policy of Forest Fire Management in Cyprus. Master’s Thesis, School of Economics, Business and Computer Sciences, Neapolis University, Paphos, Cyprus, 2024. [Google Scholar]
  54. Barbeito, I.; Marie-Josee, F.; Fernando, M.; Isabel, C. Response of pine natural regeneration to small-scale spatial variation in managed Mediterranean mountain forest. Appl. Veg. Sci. 2009, 12, 488–503. [Google Scholar] [CrossRef]
  55. Delta-T Devices Ltd. HemiView User Manual; Delta-T Devices Ltd.: Cambridge, UK, 1999. [Google Scholar]
  56. Hale, S.E. Light regime beneath Sitka spruce plantations in northern Britain: Preliminary results. For. Ecol. Manag. 2001, 151, 61–66. [Google Scholar] [CrossRef]
  57. Montgomery, R.A. Effects of understory foliage on patterns of light attenuation near the forest floor. Biotropica 2004, 36, 33. [Google Scholar] [CrossRef]
  58. IBM Corp. Released IBM SPSS Statistics for Windows, Version 21.0; IBM Corp.: Armonk, NY, USA, 2012. [Google Scholar]
  59. Rényi, A. On Measures of Information and Entropy. In Proceedings of the 4th Berkeley Symposium on Mathematics, Statistics and Probability, Berkeley, CA, USA, 20 June–30 July 1960; University of California Press: Berkeley, CA, USA, 1961; pp. 547–561. [Google Scholar]
  60. Jost, L. Entropy and Diversity. Oikos 2006, 113, 363–375. [Google Scholar] [CrossRef]
  61. Kitikidou, K.; Milios, E.; Stampoulidis, A.; Pipinis, E.; Radoglou, K. Within-Forest Stand (or Formation, or Plot) and between-Forest Stand (or Formation, or Plot) Biodiversity Indices. MethodsX 2022, 9, 101919. [Google Scholar] [CrossRef] [PubMed]
  62. Richarson, M.D.; Rundel, W.P.; Jackson, T.S.; Teskey, O.R.; Aronson, J.; Bytnerowicz, A.; Wingfield, J.M.; Proches, S. Human Impacts in Pine Forests: Past, Present, and Future. Annu. Rev. Ecol. Evol. Syst. 2007, 38, 275–297. [Google Scholar] [CrossRef]
  63. Riera-Mora, S.; Esteban-Amat, A. Vegetation history and human activity during the last 6000 years on the central Catalan coast (northeastern Iberian Peninsula). Veg. Hist. Archaeobotany 1994, 3, 7–23. [Google Scholar] [CrossRef]
  64. Thirgood, J.V. Man and the Mediterranean Forest. A History of Resource Depletion; Academic Press: London, UK, 1981. [Google Scholar]
  65. Zamora, R.; Gomez, M.J.; Hodar, A.J.; Castro, J.; Garcia, D. Effect of browsing by ungulates on sapling growth of Scots pine in a Mediterranean environment: Consequences for forest regeneration. For. Ecol. Manag. 2001, 144, 33–42. [Google Scholar] [CrossRef]
  66. Torrano, L.; Valderrabano, J. Impact of grazing on plant communities in forestry areas. Span. J. Agric. Res. 2004, 2, 93–105. [Google Scholar] [CrossRef]
  67. Uytvanck, J.V.; Maes, D.; Vandenhaute, D.; Hoffmann, M. Restoration of woodpasture on former agricultural land: The importance of safe sites and time gaps before grazing for tree seedlings. Biol. Conserv. 2008, 141, 78–88. [Google Scholar] [CrossRef]
  68. Barton, E.K.; Hanley, M.E. Seedling-herbivore interactions: Insights into plant defence and regeneration patterns. Ann. Bot. 2013, 112, 643–650. [Google Scholar] [CrossRef] [PubMed]
  69. Milios, E.; Pipinis, E.; Kitikidou, K.; Batziou, M.; Chatzakis, S.; Akritidou, S. Are sprouts the dominant form of regeneration in a lowland Quercus pubescens—Quercus frainetto remnant forest in Northeastern Greece? A regeneration analysis in the context of grazing. New For. 2014, 45, 165–177. [Google Scholar] [CrossRef]
  70. Puerta-Piñero, C.; Gómez, J.M.; Valladares, F. Irradiance and Oak Seedling Survival and Growth in a Heterogeneous Environment. For. Ecol. Manag. 2007, 242, 462–469. [Google Scholar] [CrossRef]
  71. Calama, R.; Montero, G. Cone and seed production from stone pine (Pinus pinea L.) stands in Central Range (Spain). Eur. J. For. Res. 2007, 126, 23–35. [Google Scholar] [CrossRef]
  72. Smith, D.M. The Practice of Silviculture, 8th ed.; John Willey and Sons: New York, NY, USA, 1986. [Google Scholar]
  73. Price, C.; Michaelides, S.; Pashiardis, S.; Alperta, P. Long term changes in diurnal temperature range in Cyprus. Atmos. Res. 1999, 51, 85–98. [Google Scholar] [CrossRef]
  74. Pashiardis, S.; Michaelides, S. Implementation of the standardized precipitation index (SPI) and the reconnaissance drought index (RDI) for regional drought assessment: A case study for Cyprus. Eur. Water 2008, 23, 57–65. [Google Scholar]
  75. Cyprus Department of Forests. Expected Climate Change and Options for European Silviculture; COST action FP 0703, DRAFT Country Report; Ministry of Agriculture, Natural Resources and Environment: Nicosia, Cyprus, 2009.
  76. Shoukri, E.; Zachariadis, T. Climate Change in Cyprus: Impacts and Adaptation Policies; Environmental Policy Research Group Report 01-12; Cyprus University of Technology: Limassol, Cyprus, 2012. [Google Scholar]
  77. Griggs, C.; Pearson, C.; Manning, W.S.; Lorentzen, B. A 250-year annual precipitation reconstruction and drought assessment for Cyprus from Pinus brutia Ten. Tree-rings. Int. J. Climatol. 2014, 34, 2702–2714. [Google Scholar] [CrossRef]
  78. Garcia, D.; Obeso, J.R. Facilitation by herbivore-mediated nurse plants in a threatened tree, Taxus baccata: Local effects and landscape level consistency. Ecography 2003, 26, 739–750. [Google Scholar] [CrossRef]
  79. Bakker, E.S.; Olff, H.; Vandenberghe, C.; de Maeyer, K.; Smith, R.; Gleichman, J.M.; Vera, F.W.M. Ecological anachronisms in the recruitment of temperate light-demanding tree species in wooded pastures. J. Appl. Ecol. 2004, 41, 571–582. [Google Scholar] [CrossRef]
  80. Oesterheld, M.; Oyarzabal, M. Grass-to-grass protection from grazing in a semi-arid steppe. Facilitation, competition, and mass effect. Oikos 2004, 107, 576–582. [Google Scholar] [CrossRef]
  81. Smit, C.; Ouden, J.D.; Muller-Scharer, H. Unpalatable plants facilitate tree sapling survival in wooded pastures. J. Appl. Ecol. 2006, 43, 305–312. [Google Scholar] [CrossRef]
  82. Vandenberghe, C.; Smit, C.; Pohl, M.; Buttler, A.; Frelechoux, F. Does the strength of facilitation by nurse shrubs depend on grazing resistance of tree saplings? Basic Appl. Ecol. 2009, 10, 427–436. [Google Scholar] [CrossRef]
  83. Rolo, V.; Plieninger, T.; Moreno, G. Facilitation of holm oak recruitment through two contrasted shrubs species in Mediterranean grazed woodlands. J. Veg. Sci. 2013, 24, 344–355. [Google Scholar] [CrossRef]
  84. Louthan, M.A.; Doak, F.D.; Goheen, R.J.; Palmer, M.T.; Pringle, M.R. Mechanisms of plant-plant interactions: Concealment from herbivores is more important than abiotic-stress mediation in an African savannah. Proc. R. Soc. 2014, 281, 20132647. [Google Scholar] [CrossRef] [PubMed]
  85. Perea, R.; Gil, L. Tree regeneration under high levels of wild ungulates: The use of chemically vs. physically-defended shrubs. For. Ecol. Manag. 2014, 312, 47–54. [Google Scholar] [CrossRef]
  86. Talamo, A.; Barchuk, A.; Cardozo, S.; Trucco, C.; Maras, G.; Trigo, C. Direct versus indirect facilitation (herbivore mediated) among woody plants in a semiarid Chaco forest: A spatial association approach. Austral Ecol. 2015, 40, 573–580. [Google Scholar] [CrossRef]
  87. Cavieres, L.A.; Quiroz, C.L.; Molina-Montenegro, M.A.; Munoz, A.A.; Pauchard, A. Nurse effect of the native cushion plant Azzorella monantha on the invasive non-native Taraxacum officinale in the high-Andes of central Chile. Perspect. Plant Ecol. Evol. Syst. 2005, 7, 217–226. [Google Scholar] [CrossRef]
  88. Gomez-Aparicio, L.; Valladares, F.; Zamora, R.; Quero, J.L. Response of tree seedlings to the abiotic heterogeneity generated by nurse shrubs: An experimental approach at different scales. Ecography 2005, 28, 757–768. [Google Scholar] [CrossRef]
  89. Kennedy, P.; Sousa, W.P. Forest encroachment into Californian grassland: Examining the simultaneous effects of facilitation and competition on tree seedling recruitment. Oecologia 2006, 418, 464–474. [Google Scholar] [CrossRef] [PubMed]
  90. Miriti, M.N. Ontogenetic shift from facilitation to competition in a desert shrub. J. Ecol. 2006, 94, 973–979. [Google Scholar] [CrossRef]
  91. Milios, E.; Pipinis, E.; Petrou, P.; Akritidou, S.; Smiris, P.; Aslanidou, M. Structure and regeneration patterns of the Juniperus excelsa Bieb. stands in the central part of the Nestos valley in the northeast of Greece, in the context of anthropogenic disturbances and plant facilitation. Ecol. Res. 2007, 22, 713–723. [Google Scholar] [CrossRef]
  92. Smit, C.; Den Ouden, J.; Diaz, M. Facilitation of Quercus ilex recruitment by shrubs in Mediterranean open woodlands. J. Veg. Sci. 2008, 19, 193–200. [Google Scholar] [CrossRef]
  93. Gomez-Aparicio, L.; Gomez, J.M.; Zamora, R.; Boettinger, J.L. Canopy vs. Soil effects of shrubs facilitating tree seedlings in Mediterranean montane ecosystems. J. Veg. Sci. 2005, 16, 191–198. [Google Scholar] [CrossRef]
  94. Caldeira, M.C.; Ibáñez, I.; Nogueira, C.; Bugalho, M.N.; Lecomte, X.; Moreira, A.; Pereira, J.S. Direct and Indirect Effects of Tree Canopy Facilitation in the Recruitment of Mediterranean Oaks. J. Appl. Ecol. 2014, 51, 349–358. [Google Scholar] [CrossRef]
  95. Perea, R.; Gil, L. Shrubs Facilitating Seedling Performance in Ungulate-Dominated Systems: Biotic versus Abiotic Mechanisms of Plant Facilitation. Eur. J. For. Res. 2014, 133, 525–534. [Google Scholar] [CrossRef]
  96. Gimeno, T.E.; Escudero, A.; Valladares, F. Different Intra- and Interspecific Facilitation Mechanisms between Two Mediterranean Trees under a Climate Change Scenario. Oecologia 2015, 177, 159–169. [Google Scholar] [CrossRef] [PubMed]
  97. Kellman, M.; Kading, M. Facilitation of Tree Seedling Establishment in a Sand Dune Succession. J. Veg. Sci. 1992, 3, 679–688. [Google Scholar] [CrossRef]
  98. Pederson, N.A.; Robert, H.; Jones, R.H.; Sharitz, R.R. Erratum: Age Structure and Possible Origins of Old Pinus taeda Stands in a Floodplain Forest. J. Torrey Bot. Soc. 1997, 124, 272. [Google Scholar] [CrossRef]
  99. Castro, J.; Zamora, R.; Hódar, J.A.; Gómez, J.M. Use of Shrubs as Nurse Plants: A New Technique for Reforestation in Mediterranean Mountains. Restor. Ecol. 2002, 10, 297–305. [Google Scholar] [CrossRef]
  100. Castro, J.; Zamora, R.; Hódar, J.A.; Gómez, J.M. Seedling Establishment of a Boreal Tree Species (Pinus sylvestris) at Its Southernmost Distribution Limit: Consequences of Being in a Marginal Mediterranean Habitat. J. Ecol. 2004, 92, 266–277. [Google Scholar] [CrossRef]
  101. Castro, J.; Zamora, R.; Hódar, J.A.; Gómez, J.M.; Gómez-Aparicio, L. Benefits of Using Shrubs as Nurse Plants for Reforestation in Mediterranean Mountains: A 4-Year Study. Restor. Ecol. 2004, 12, 352–358. [Google Scholar] [CrossRef]
  102. Mueller, R.C.; Scudder, C.M.; Porter, M.E.; Talbot Trotter, R.; Gehring, C.A.; Whitham, T.G. Differential Tree Mortality in Response to Severe Drought: Evidence for Long-term Vegetation Shifts. J. Ecol. 2005, 93, 1085–1093. [Google Scholar] [CrossRef]
  103. Keyes, C.R.; Maguire, D.A. Positive seedling–shrub relationships in natural regeneration of ponderosa pine. In USDA Forest Service General Technical Report PSWGTR-198; USDA Forest Service: Corvallis, OR, USA, 2005; pp. 95–107. [Google Scholar]
  104. Boulant, N.; Kunstler, G.; Rambal, S.; Lepart, J. Seed supply, drought, and grazing determine spatio-temporal patterns of recruitment for native and introduced invasive pines in grasslands. Divers. Distrib. 2008, 14, 862–874. [Google Scholar] [CrossRef]
  105. Barbeito, I.; Pardos, M.; Calama, R.; Canellas, I. Effect of stand structure on Stone pine (Pinus pinea L.) regeneration dynamics. Forestry 2008, 81, 617–629. [Google Scholar] [CrossRef]
  106. Rodriguez-Garcia, E.; Bravo, F.; Spies, A.T. Effects of overstorey canopy, plant-plant interactions and soil properties on Mediterranean maritime pine seedling dynamics. For. Ecol. Manag. 2011, 262, 244–251. [Google Scholar] [CrossRef]
  107. Redmond, M.D.; Barger, N.N. Tree regeneration following drought- and insect-induced mortality in pinon-juniper woodlands. New Phytol. 2013, 200, 402–412. [Google Scholar] [CrossRef]
  108. Ledo, A.; Canellas, I.; Barbeito, I.; Gordo, J.F.; Calama, A.R.; Gea-Izquierdo, G. Species coexistence in a mixed Mediterranean pine forest: Spatio-temporal variability in trade-offs between facilitation and competition. For. Ecol. Manag. 2014, 322, 89–97. [Google Scholar] [CrossRef]
  109. Kane, M.J.; Dugi, L.F.; Kolb, E.T. Establishment and growth of pinon pine regeneration vary by nurse type along a soil substrate age gradient in northern Arizona. J. Arid. Environ. 2015, 115, 113–119. [Google Scholar] [CrossRef]
  110. Pentarakis, K. Structure and Dynamics of Pinus brutia var. brutia (TEN.) Stands Naturally Established on Abandoned Fields, at Anopolis Plateau, Southern Crete. Master’s Thesis, MAICH, Chania, Greece, 1994. [Google Scholar]
  111. Bertness, M.D.; Callaway, R.M. Positive interactions in communities. Trends Ecol. Evol. 1994, 9, 191–193. [Google Scholar] [CrossRef] [PubMed]
  112. Callaway, R.M.; Walker, L.R. Competition and facilitation: A synthetic approach to interactions in plant communities. Ecology 1997, 78, 1958–1965. [Google Scholar] [CrossRef]
  113. Holmgren, M.; Sheffer, M.; Huston, M.A. The interplay of facilitation and competition in plant communities. Ecology 1997, 78, 1966–1975. [Google Scholar] [CrossRef]
  114. Brooker, R.W.; Callaghan, T.V. The balance between positive and negative plant interactions and its relationship to environmental gradients: A model. Oikos 1998, 81, 196–207. [Google Scholar] [CrossRef]
  115. Adili, B.; Hedi El Aouni, M.; Balandier, P. Unravelling the influence of light and understorey vegetation on Pinus pinea natural regeneration. Forestry 2013, 86, 297–304. [Google Scholar] [CrossRef]
  116. Boydak, M.; Dirik, H.; Çalikoglu, M. Biology and Silviculture of Turkish Red Pine (Pinus brutia Ten.); Lazer Ofset Matbaa Tesisleri: Ankara, Turkey, 2006. [Google Scholar]
Forests 15 01228 g001
Figure 1. Map of the study area.
Figure 1. Map of the study area.
Forests 15 01228 g001
Forests 15 01228 g002
Figure 2. VS distributions from the photographs taken in the good productivity sites (GPS) and from the photographs taken above the regeneration plants in the same sites.
Figure 2. VS distributions from the photographs taken in the good productivity sites (GPS) and from the photographs taken above the regeneration plants in the same sites.
Forests 15 01228 g002
Forests 15 01228 g003
Figure 3. VS distributions from the photographs taken in the medium productivity sites (MPS) and from the photographs taken above the regeneration plants in the same sites.
Figure 3. VS distributions from the photographs taken in the medium productivity sites (MPS) and from the photographs taken above the regeneration plants in the same sites.
Forests 15 01228 g003
Forests 15 01228 g004
Figure 4. VS distributions from the photographs taken in the bad productivity sites (BPS) and from the photographs taken above the regeneration plants in the same sites.
Figure 4. VS distributions from the photographs taken in the bad productivity sites (BPS) and from the photographs taken above the regeneration plants in the same sites.
Forests 15 01228 g004
Forests 15 01228 g005
Figure 5. Distributions of VS values from the photographs taken above the regeneration plants in the three productivity site types (good productivity sites—GPS, medium productivity sites—MPS, and bad productivity sites—BPS).
Figure 5. Distributions of VS values from the photographs taken above the regeneration plants in the three productivity site types (good productivity sites—GPS, medium productivity sites—MPS, and bad productivity sites—BPS).
Forests 15 01228 g005
Table 1. Density of mature P. brutia trees, P. brutia regeneration plants, dead P. brutia trees, and other species trees.
Table 1. Density of mature P. brutia trees, P. brutia regeneration plants, dead P. brutia trees, and other species trees.
Site Productivity TypeDensity, Rounded to the Nearest Integer (n/ha)
Mature
P. brutia Trees		P. brutia
Regeneration Plants		Dead
P. brutia Trees		Mature Other
Species Trees		Total
Good productivity sites383
(87.6%)		10
(2.4%)		8
(1.8%)		36
(8.2%)		437
Medium productivity sites248
(84.1%)		33
(11.2%)		3
(1%)		11
(3.7%)		295
Bad productivity sites297
(82%)		35
(9.7%)		2
(0.6%)		28
(7.7%)		362
Table 2. Regeneration plant density means of the three height categories in the three site productivity types.
Table 2. Regeneration plant density means of the three height categories in the three site productivity types.
Site Productivity TypeHeight Category (cm)Regeneration Plant Density (n/Plot)
MeanS.D.N
Good productivity sites10–600.00 b0.00016
60–1050.06 b0.25016
105–1500.94 a1.34016
Medium productivity sites10–600.44 b0.72716
60–1051.31 ab1.44816
105–1501.56 a1.41316
Bad productivity sites10–600.69 b1.01416
60–1050.88 ab1.08816
105–1501.94 a2.04816
S.D.: standard deviation, N: number of plots. Means, in each productivity site type are statistically different at p < 0.05, when they are not followed by a common letter. The comparisons were made using the Wilcoxon test.
Table 3. Regeneration plant density means of the regeneration plant categories: (a) Gap and (b) Facilitation in each site productivity type.
Table 3. Regeneration plant density means of the regeneration plant categories: (a) Gap and (b) Facilitation in each site productivity type.
Site Productivity TypeRegeneration Plant CategoryRegeneration Plant Density (n/Plot)
MeanS.D.N
Good productivity sitesGap0.00 b0.00016
Facilitation1.00 a1.36616
Medium productivity sitesGap0.00 b0.00016
Facilitation3.31 a2.35816
Bad productivity sitesGap0.31 b0.60216
Facilitation3.19 a2.42816
S.D.: standard deviation, N: number of plots. Means, in each productivity site type are statistically different at p < 0.05, when they are not followed by a common letter. The comparisons were made using the Wilcoxon test.
Table 4. Percentages of the area covered by (a) pines, (b) shrubs and the percentages of (c) bare ground (without cover) in the established plots.
Table 4. Percentages of the area covered by (a) pines, (b) shrubs and the percentages of (c) bare ground (without cover) in the established plots.
Site Productivity TypeArea Covered (%) by
P. brutiaLow ShrubsBare Ground
Good productivity sites70–7540–5010–25
Medium productivity sites35–6515–3530–60
Bad productivity sites30–6010–2535–60
Table 5. Regeneration plant density means of the regeneration plant categories: (a) Pine and (b) Low Shrub + Pine and Low Shrub in each site productivity type.
Table 5. Regeneration plant density means of the regeneration plant categories: (a) Pine and (b) Low Shrub + Pine and Low Shrub in each site productivity type.
Site Productivity TypeRegeneration Plant CategoryRegeneration Plant Density (n/Plot)
MeanS.D.N
Good productivity sitesPine0.38 a0.50016
Low Shrub + Pine and Low Shrub0.63 a1.08816
Medium productivity sitesPine2.06 a2.04816
Low Shrub + Pine and Low Shrub1.25 a1.12516
Bad productivity sitesPine1.50 a1.93216
Low Shrub + Pine and Low Shrub1.69 a1.35216
S.D.: standard deviation, N: number of plots. Means, in each productivity site type are statistically different at p < 0.05, when they are not followed by a common letter. The comparisons were made using the Wilcoxon test.
Table 6. Regeneration plant density data of the four regeneration plant categories in each site productivity type.
Table 6. Regeneration plant density data of the four regeneration plant categories in each site productivity type.
Site Productivity TypeRegeneration Plant
Category		Regeneration Plant
Density (n/ha)		Regeneration Plant Density
(n/Plot)
MeanS.D.N
Good productivity sitesGap0.0000.000.00016
Pine3.7500.380.50016
Low Shrub0.6250.060.25016
Pine and Low Shrub5.6250.561.03116
Medium productivity sitesGap0.0000.000.00016
Pine20.6252.062.04816
Low Shrub5.0000.500.73016
Pine and Low Shrub7.5000.750.77516
Bad productivity sitesGap3.1250.310.60216
Pine15.0001.501.92516
Low Shrub9.3750.940.77216
Pine and Low Shrub7.5000.750.93116
S.D.: standard deviation, N: number of plots.
Table 7. Regeneration plant density means in the three site productivity types.
Table 7. Regeneration plant density means in the three site productivity types.
Site Productivity TypeRegeneration Plant Density (n/Plot)
MeanS.D.N
Good productivity sites1.00 b1.36616
Medium productivity sites3.31 a2.35816
Bad productivity sites3.50 a2.78116
S.D.: standard deviation, N: number of plots. Means, in the column, are statistically different at p < 0.05, when they are not followed by a common letter. The comparisons were made using the Duncan test.
Table 8. VS from the photographs taken in the three productivity sites and from the photographs taken above the regeneration plants in the three productivity sites.
Table 8. VS from the photographs taken in the three productivity sites and from the photographs taken above the regeneration plants in the three productivity sites.
Site Productivity TypeVS Values from the Photographs
Taken in the Site		VS Values from the Photographs
Taken above the Regeneration Plants
MeanS.D.NMeanS.D.N
Good productivity sites0.203 a0.0411600.242 a0.04416
Medium productivity sites0.454 b0.1071600.404 b0.07953
Bad productivity sites0.607 c0.1391600.589 c0.14756
S.D.: standard deviation, N: number of photographs. Means, in a column, are statistically different at p < 0.05, when they are not followed by a common letter in normal print. The comparisons were made using the Dunnet T3 test.
Table 9. Distribution diversity comparisons between VS values from the photographs taken in each site and the corresponding VS values from the photographs taken above the regeneration plants applying the Hill Numbers z-test.
Table 9. Distribution diversity comparisons between VS values from the photographs taken in each site and the corresponding VS values from the photographs taken above the regeneration plants applying the Hill Numbers z-test.
Good Productivity SiteMedium Productivity SiteBad Productivity Site
Order qProportionsz-
Value		p-
Value		Diversity of VS Values in the Site,
Compared with the Diversity of VS Values above the Regeneration Plants of the Site		Proportionsz-
Value		p-
Value		Diversity of VS Values in the Site,
Compared with the Diversity of VS Values above the Regeneration Plants of the Site		Proportionsz-
Value		p-
Value		Diversity of VS Values in the Site,
Compared with the Diversity of VS Values above the Regeneration Plants of the Site
00.6001.5460.124Non-significantly Decreasing0.5451.1480.253Non-significantly Decreasing0.5000.0001.000Not applicable
0.4000.4550.500
10.4211.0070.315Non-significantly Decreasing0.4101.3520.178Non-significantly Decreasing0.449−0.1200.905Non-significantly Increasing
0.2920.3060.458
20.4051.1630.247Non-significantly Decreasing0.3721.5130.132Non-significantly Decreasing0.418−0.0460.963Non-significantly Increasing
0.2560.2580.422
30.4001.2220.224Non-significantly Decreasing0.3531.5400.125Non-significantly Decreasing0.3980.0760.940Non-significantly Decreasing
0.2440.2380.392
40.3971.2380.218Non-significantly Decreasing0.3531.5400.125Non-significantly Decreasing0.3840.1880.851Non-significantly Decreasing
0.2390.2380.370
∞0.3641.0790.282Non-significantly Decreasing0.2851.3270.187Non-significantly Decreasing0.3170.6000.549Non-significantly Decreasing
0,2290.1930.275
Table 10. Distribution diversity comparisons of VS values from the photographs taken above the regeneration plants between the productivity sites applying the Hill Numbers z-test.
Table 10. Distribution diversity comparisons of VS values from the photographs taken above the regeneration plants between the productivity sites applying the Hill Numbers z-test.
Proportionsz-
Value		p-
Value		Diversity of VS Values above the Regeneration Plants of the Good Site Productivity Compared with the Diversity of VS Values above the Regeneration Plants of the Medium Site ProductivityProportionsz-
Value		p-
Value		Diversity of VS Values above the Regeneration Plants of the Good Site Productivity Compared with the Diversity of VS Values above the Regeneration Plants of the Bad Site ProductivityProportionsz-
Value		p-
Value		Diversity of VS Values above the Regeneration Plants of the Medium Site Productivity Compared with the Diversity of VS Values above the Regeneration Plants of the Bad Site Productivity
00.286−3.0880.008Significantly Increasing0.250−3.6720.002Significantly Increasing0.455−0.9490.347Non-significantly Increasing
0.7140.7500.545
10.208−1.9380.072Non-significantly Increasing0.182−3.6030.003Significantly Increasing0.306−2.0580.045Significantly Increasing
0.4810.6870.500
20.183−1.6290.124Non-significantly Increasing0.160−3.3370.005Significantly Increasing0.258−2.195 0.033Significantly Increasing
0.4050.6320.460
30.174−1.4960.155Non-significantly Increasing0.152−3.0750.008Significantly Increasing0.238−2.0930.041Significantly Increasing
0.3750.5880.428
40.171−1.4220.175Non-significantly Increasing0.152−3.0750.008Significantly Increasing0.229−1.9590.055Non-significantly
Increasing
0.3590.5880.403
∞0.163−1.1020.288Non-significantly Increasing0.143−1.9860.066Non-significantly Increasing0.193−1.2910.203Non-significantly Increasing
0.3030.4120.299
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Petrou, P.; Stampoulidis, A.; Pipinis, E.; Kitikidou, K.; Milios, E. Analysis of the Environments Where Natural Regeneration Is Established in the Absence of a Wildfire in the Open Pinus brutia Forests in the Middle Elevations of the Central Part of Cyprus. Forests 2024, 15, 1228. https://doi.org/10.3390/f15071228

AMA Style

Petrou P, Stampoulidis A, Pipinis E, Kitikidou K, Milios E. Analysis of the Environments Where Natural Regeneration Is Established in the Absence of a Wildfire in the Open Pinus brutia Forests in the Middle Elevations of the Central Part of Cyprus. Forests. 2024; 15(7):1228. https://doi.org/10.3390/f15071228

Chicago/Turabian Style

Petrou, Petros, Athanasios Stampoulidis, Elias Pipinis, Kyriaki Kitikidou, and Elias Milios. 2024. "Analysis of the Environments Where Natural Regeneration Is Established in the Absence of a Wildfire in the Open Pinus brutia Forests in the Middle Elevations of the Central Part of Cyprus" Forests 15, no. 7: 1228. https://doi.org/10.3390/f15071228

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop