Forests, Volume 6, Issue 3 (March 2015) – 18 articles , Pages 533-858

The authors wish to correct a statement in the published paper [1], doi:10.3390/f5112750, website: https://www.mdpi.com/1999-4907/5/11/2750/htm. After publication, we discovered that two numbers were mistakenly switched. Section, 4.1, should read “Oregon slender salamanders were detected in 144/420 (34%) plots and 101/378 (27%) plots in 2013 and 2014, respectively; ensatina salamanders were detected in 53/420 (13%) plots and 73/378 (19%) plots in 2013 and 2014, respectively”. The authors would like to apologize for any inconvenience caused to the readers by these changes.[...] Full article

Polyploid breeding is important in Populus genetic improvement programs because polyploid trees generally display increased height growth compared to their diploid parents. However, the genetic mechanism underlying this phenomenon remains unknown. In the present study, apical bud transcriptomes of vigorous, fast growing Populus allotriploid progeny genotypes and their diploid parents were sequenced and analyzed. We found that these allotriploids exhibited extensive transcriptomic diversity. In total, 6020 differentially expressed genes (DEGs) were found when the allotriploid progeny and their parents were compared, among which 791 overlapped between the allotriploids and both parents. Many genes associated with cell differentiation and meristem development were preferentially expressed in apical buds of the fast growing Populus allotriploids compared to their diploid parents. In addition, many auxin-, gibberellin-, and jasmonic acid-related genes were also preferentially expressed in the allotriploids compared to their parents. Our findings show that allotriploidy can have considerable effects on duplicate gene expression in Populus. In particular we identified and considered DEGs that provide important clues for improving our mechanistic understanding of positive heterosis of vigor- and growth-related traits in Populus allotriploids. Full article

Forestry practices are placing ever increasing emphasis on sustainability and the maintenance of ecological processes, biodiversity, and endangered species or populations. Balancing timber harvest and the management of imperiled species presents a particularly difficult challenge during this shift, as we often know very little about these species’ natural history and how and why silviculture practices affect their populations. Accordingly, investigation of and improvement on current management practices for threatened species is imperative. We investigated the effectiveness of habitat buffers as a management technique for the imperiled Red Hills salamander (Phaeognathus hubrichti) by combining genetic, transect, and body-condition data. We found that populations where habitat buffers have been employed have higher genetic diversity and higher population densities, and individuals have better overall body condition. These results indicate that buffering the habitat of imperiled species can be an effective management tool for terrestrial salamanders. Additionally, they provide further evidence that leaving the habitat of imperiled salamanders unbuffered can have both immediate and long-term negative impacts on populations. Full article

Information on the ecological functions of forests is important for sustainable forest management. In this study, we introduced the national monitoring program which has been used in China to evaluate the overall health status and ecological functions of forests. We also compared it to similar monitoring programs operating in Europe and the United States of America. We revealed the strength and drawbacks of China’s monitoring program by analyzing the initial evaluation results. Our analysis showed that among the three programs, the European program gives the most detailed measurements of conditions of forests while the U.S. program generates the most detailed information on individual trees. In comparison, China’s monitoring program has a higher spatial resolution but is narrowly focused on trees and uses coarse classifications of indicators. The health status of forests in China suggested that more resources should be invested to improve the health of existing forests, especially plantations. The limitations in China’s monitoring program need to be addressed to improve the accuracy of future assessments. Full article

In order to understand how carbon storage and allocation patterns vary among plantation types, we estimated carbon allocation between above- and below-ground compartments in four subtropical plantations and a naturally recovered shrubland (as a control). Results indicated that the carbon storage and allocation pattern varied greatly among forest types and was highly dependent on specific traits of trees and understory vegetation. The fast-growing species, such as Eucalyptus urophylla, accumulated more carbon in plant biomass. The biomass carbon was about 1.9- and 2.2-times greater than the 10-species mixed plantation and Castanopsis hystrix plantations, respectively. Meanwhile, the plantations sequestered 1.5- to 3-times more carbon in biomass than naturally recovered shrubland. The carbon allocation pattern between above- and below-ground compartments also varied with plantation type and stand age. The ratio of tree root carbon to tree aboveground carbon decreased with stand age for Eucalyptus urophylla and the 10-species mixed plantation. In contrast, the ratio increased for Acacia crassicarpa. Our data suggested that planting the fast-growing species in the degraded land of subtropical China was an effective choice in terms of carbon sequestration. The information about carbon allocation patterns was also valuable for decision making in sustainable forest management and climate change mitigation. Full article

Short-rotation intensive cultures (SRICs) of willows can potentially sequester carbon (C) in soil. However, there is limited information regarding the factors governing soil organic C (C_org) accumulation following afforestation. The objectives of this study were to: (i) determine whether willow leads to C_org accumulation in the topsoil (0–10 cm) two to six years after establishment in five SRICs located along a large climatic/productivity gradient in southern Quebec, and (ii) assess the influence of leaf litter decomposition and soil organic matter (OM) quality on C_org accumulation in the topsoil. Topsoil C_org concentrations and pools under SRICs were, on average, 25% greater than reference fields, and alkyls concentrations were higher under SRICs. On an annualized basis, C_org accumulation rates in the topsoil varied between 0.4 and 4.5 Mg ha⁻¹ yr⁻¹. Estimated annual litterfall C fluxes were in the same order of magnitude, suggesting that SRICs can accumulate C_org in the topsoil during early years due to high growth rates. Leaf litter decomposition was also related to C_org accumulation rates in the topsoil. It was positively correlated to growing season length, degree-days, and growing season average air and topsoil temperature (r > 0.70), and negatively correlated to topsoil volumetric water content (r = −0.55). Leaf litter decomposition likely occurred more quickly than that of plants in reference fields, and as it progressed, OM became more decay resistant, more stable and accumulated as C_org in the topsoil. Full article

Achieving forest conservation together with poverty alleviation and equity is an unending challenge in the tropics. The Makira REDD+ pilot project located in northeastern Madagascar is a well-suited case to explore this challenge in conditions of extreme poverty and climatic vulnerability. We assessed the potential effect of project siting on the livelihoods of the local population and which households would be the most strongly impacted by conservation measures. Farmers living in hilly areas must resort to slash-and-burn agriculture (tavy) since a combination of topographic and climatic constraints, such as cyclones, makes permanent rice cultivation very difficult. These are the people who suffer most from conservation-related restriction measures. For practical reasons the project, unfortunately, did not target these farmers. The main focus was on communities with a lower cyclonic risk that are able to practice permanent rice agriculture in the lowlands. To reduce deforestation without violating the principles of equity, REDD+ projects in Madagascar need to better target populations facing high climatic risks and invest in efforts to improve the farmers’ agricultural systems. Full article

Morus alba L. is an important tree species planted widely in China because of its economic value. In this report, we investigated the influence of two arbuscular mycorrhizal fungal (AMF) species, Glomus mosseae and Glomus intraradices, alone and together, on the growth of M. alba L. seedlings under greenhouse conditions. The growth parameters and physiological performance of M. alba L. seedlings were evaluated 90 days after colonization with the fungi. The growth and physiological performance of M. alba L. seedlings were significantly affected by the AMF species. The mycorrhizal seedlings were taller, had longer roots, more leaves and a greater biomass than the non-mycorrhizae-treated seedlings. In addition, the AMF species-inoculated seedlings had increased root activity and a higher chlorophyll content compared to non-inoculated seedlings. Furthermore, AMF species colonization increased the phosphorus and nitrogen contents of the seedlings. In addition, simultaneous root colonization by the two AMF species did not improve the growth of M. alba L. seedlings compared with inoculation with either species alone. Based on these results, these AMF species may be applicable to mulberry seedling cultivation. Full article

This paper explores how climate change adaptation concerns were integrated into the Swedish forestry debate and policy process during the period of 1990–2012, and draws lessons on barriers and opportunities identified in this process. Using a framework focusing on “advocacy coalitions”, we analyze how the adaptation debate in the forestry sector evolved over the period; who the main advocates for and against adaptation were; and which main arguments and processes affected the debate and policy. The results show that academics advocating climate change adaptation, aided by outside influences, such as political pressure for adaptation responses and the negative impacts of the 2005 storm Gudrun, contributed to an increased general awareness and understanding of adaptation issues amongst forestry stakeholders. Nonetheless, the strong dominance of actors arguing for increased forest production and the limited number and relatively poor organization of adaptation advocates have acted as barriers to mainstreaming adaptation concerns into forestry policy and practice. The dominant coalitions and their values have also determined the direction of debate and policy. The main conclusions for policymakers aiming to further this integration process are the importance of stimulating adaptation coalitions and the value of creating arenas for multiple stakeholder learning about adaptation. Full article

Species distribution models (SDMs) help identify areas for the development of populations or communities to prevent extinctions, especially in the face of the global environmental change. This study modeled the potential distribution of the tree Picea chihuahuana Martínez, a species in danger of extinction, using the maximum entropy modeling method (MaxEnt) at three scales: local, state and national. We used a total of 38 presence data from the Sierra Madre Occidental. At the local scale, we compared MaxEnt with the reclassification and overlay method integrated in a geographic information system. MaxEnt generated maps with a high predictive capability (AUC > 0.97). The distribution of P. chihuahuana is defined by vegetation type and minimum temperature at national and state scales. At the local scale, both models calculated similar areas for the potential distribution of the species; the variables that better defined the species distribution were vegetation type, aspect and distance to water flows. Populations of P. chihuahuana have always been small, but our results show potential habitat greater than the area of the actual distribution. These results provide an insight into the availability of areas suitable for the species’ regeneration, possibly through assisted colonization. Full article

Current Mexican forest management is the product of a history that dates back to 1926. Earlier approaches were directly or indirectly aimed at attaining the normal forest model. Around 1980, multi-resource and environmental impact considerations were mandated for all private timber operations. Timber-oriented silviculture was deemed insufficient to take proper care of non-timber values in the forest. Concerns about water quality, biodiversity, and natural conservation were the motives for promoting voluntary best management practices, in 2012 and afterwards. In this research, two traditional Mexican forest management schemes, Sicodesi and Plan Costa, enhanced with best management practices, are compared to Mapa, a management method specifically designed to manage landscape attributes. Results from two successive forest inventories 10 and 13 years apart show that Sicodesi and Plan Costa, even when modified to comply with best management practices, failed to maintain proper stewardship of non-timber values. Mapa, however, employed multiple means to drive forest dynamics to fulfill multi-resource objectives, constrained by self-financing and competitive profitability. These capabilities in Mapa enabled some degree of control over non-timber values, but many more important processes occur beyond the property boundary, and beyond the planning scope considered in Mapa and all other forest planning methods. Full article

Evergreen broadleaved forests in subtropical China contain a complicated structure of diverse species. The impact of topographic and soil factors on the assembly of woody species in the forest has been poorly understood. We used Ripley’s K(t) function to analyze the spatial patterns and associations of dominant species and residual analysis (RDA) to quantify the contribution of topography and soil to species assembly. The 1 ha plot investigated had 4797 stems with a diameter at breast height (dbh) larger than 1 cm that belong to 73 species, 55 genera, and 38 families. All stems of the entire forest and four late successional species exhibited a reversed J shape for dbh distribution, while two early successional species showed a unimodal shape. Aggregation was the major spatial pattern for entire forests and dominant species across vertical layers. Spatial associations between inter- and intra-species were mostly independent. Topographic and soil factors explained 28.1% of species assembly. The forest was close to late succession and showed the characteristics of diverse woody species, high regeneration capacity, and aggregated spatial patterns. Topographic and soil factors affected species assembly, but together they could only explain a small part of total variance. Full article

Nitrogen (N) availability and mineralization are key parameters and transformation processes that impact plant growth and forest productivity. We hypothesized that suitable plantation spacing can lead to enhanced soil N mineralization and nitrification, which in turn promote tree growth. Studies were conducted to evaluate seasonal patterns of soil inorganic N pools as well as rates of nitrification and N mineralization of three soil layers under four tree spacing treatments. Results showed tree spacing significantly affected annual net N mineralization, whereas inorganic N content in surface soils was significantly affected by tree spacing only during the growing season. The total annual cumulative net N mineralization ranged from 80.3–136.0 mg·kg⁻¹ in the surface soils (0–20 cm), whereas the cumulative net N mineralization of 6 × 6 m and 4.5 × 8 m spacings was 65% and 24% higher than that of the 5 × 5 m, respectively. In general, tree spacing would affect N availability in soil by altering N mineralization rates, while high annual N mineralization was found in soils of low density plantations, with higher rates in square spacing than rectangular spacing. The obtained results suggest that suitable spacing could lead to enhanced N mineralization, but seasonal variation of soil N mineralization may not only be directly related to plantation productivity but also to understory vegetation productivity. Full article

This study examined the effects of two types of parent material, sandstone and limestone, on the response of vegetation growth after the 1990 Dude Fire in central Arizona. The operating hypothesis of the study was that, given the right conditions, severe wildfire can trigger vegetation type conversion. Overall, three patterns emerged: (1) oak density increased by 413% from unburned sites to burned sites, with the highest densities occurring on sandstone soils; (2) weeping lovegrass (Eragrostis curvula Nees), a very aggressive non-native grass species seeded after the fire, now makes up 81% of the total herbaceous cover in the burned area; and (3) bare ground cover is 150% higher and litter cover is 50% lower in the burned area. Soil analysis was not definitive enough to differentiate impacts between parent materials however it was useful in quantifying the long-term impact of the fire on soils. The results of this study support the idea that catastrophic fire events can trigger vegetation type conversion and that perennial, non-native species used in rehabilitation efforts can persist within the ecosystem for long periods of time. Hence, the recovery period needed for the Dude Fire site to revert back to a pine-oak dominated forest could be on the scale of many decades to centuries. Full article

The detection of pest infestation is an important aspect of forest management. In the case of the oak splendour beetle (Agrilus biguttatus) infestation, the affected oaks (Quercus sp.) show high levels of defoliation and altered canopy reflection signature. These critical features can be identified in high-resolution colour infrared (CIR) images of the tree crown and branches level captured by Unmanned Aerial Systems (UAS). In this study, we used a small UAS equipped with a compact digital camera which has been calibrated and modified to record not only the visual but also the near infrared reflection (NIR) of possibly infested oaks. The flight campaigns were realized in August 2013, covering two study sites which are located in a rural area in western Germany. Both locations represent small-scale, privately managed commercial forests in which oaks are economically valuable species. Our workflow includes the CIR/NIR image acquisition, mosaicking, georeferencing and pixel-based image enhancement followed by object-based image classification techniques. A modified Normalized Difference Vegetation Index (NDVImod) derived classification was used to distinguish between five vegetation health classes, i.e., infested, healthy or dead branches, other vegetation and canopy gaps. We achieved an overall Kappa Index of Agreement (KIA) of 0.81 and 0.77 for each study site, respectively. This approach offers a low-cost alternative to private forest owners who pursue a sustainable management strategy. Full article

Pedunculate oak (Quercus robur L.) forests in Slovenia are experiencing widespread mortality. Changes in lowlands are reflected in decline of complete forest complexes, high mortality, uneven stand structure and associated forest regeneration problems. Prediction of the present-tree response in disturbed forest ecosystems may significantly contribute to better guideline policies for the silvicultural and forest management practice in the changing environment in both stressed and stabile forest ecosystems. Data from annual crown condition surveys for the 1995–2014 period from four permanent plots have been compared with parameters from hemispherical photo analysis and hydrometeorological data. Good agreement has been confirmed between crown defoliation and total openness; all parameters from the hemispherical photo analysis, which were corrected for winter period values, also indicated a better agreement. Mortality rate and crown defoliation correlated well with extreme drought events in 2003 and 2013. Pattern of agreement among compared parameters was different for the plots Krakovski gozd, Dobrava and some other plots. Mortality is influenced by the average air temperatures much more than by precipitation and groundwater table oscillations. Full article

The southern region of the U.S. uses prescribed fire as a management tool on more of its burnable land than anywhere in the U.S., with ecosystem restoration, wildlife habitat enhancement, and reduction of hazardous fuel loads as typical goals. Although the region performs more than 50,000 prescribed fire treatments each year, evaluation of their effects on wildfire suppression resources or behavior/effects is limited. To better understand trends in the use and effectiveness of prescribed fire, we conducted a region-wide survey of 523 fire use practitioners, working on both public and private lands. A 1–2 year prescribed fire interval was consistently viewed as effective in decreasing wildfire ignitions, behavior, and severity, as well as reducing suppression resources needed where wildfire occurred. Yet fewer than 15% of practitioners viewed burn intervals of 3–4 years as effective in reducing ignitions, underscoring the importance of high-frequency burning in vegetation communities where fuel recovery is rapid. Public lands managers identified limited budget and staffing as major institutional impediments to prescribed fire, in contrast to private individuals, more of whom chose liability as a key challenge. Differences in responses across ownership type, state, and vegetation type call for a broader perspective on how fire managers in the southern U.S. view prescribed fire. Full article

Integrated forest management is faced with the challenge that the contribution of forests to economic and ecological planning targets must be assessed in a socio-ecological system context. This paper introduces a way to model spatio-temporal dynamics of biomass production at a regional scale in order to derive land use strategies that enhance biomass provision and avoid trade-offs for other ecosystem services. The software platform GISCAME was employed to bridge the gap between local land management decisions and regional planning by linking growth and yield models with an integrative mesoscale modeling and assessment approach. The model region is located in Saxony, Germany. Five scenarios were simulated, which aimed at testing different alternatives for adapted land use in the context of climate change and increasing biomass demand. The results showed, for example, that forest conversion towards climate-change-adapted forest types had positive effects on ecological integrity and landscape aesthetics. In contrast, negative impacts on landscape aesthetics must be expected if agricultural sites were converted into short rotation coppices. Uncertainties with stem from assumptions regarding growth and yield models were discussed. Future developmental steps which consider, for example, accessibility of the resources were identified. Full article