Forests, Volume 7, Issue 8 (August 2016) – 31 articles

We investigated local forest management practices in Osaka, Japan aiming to clarify mechanisms that hinder long-term, sustainable forestry operation by carrying out forest surveys and interview surveys. Because mountain districts in Japan now face declining and aging populations, forestry work has shifted to forest owners’ associations, with efficient forest management being required on an ad hoc basis as a result of the subsidy system. We found that the forest management plan for the study site utilized only one-seventh of the economic value of the forest, mainly due to the local forestry structure and an inefficient subsidy system that requires efficiency. The income yielded by timber undergoing such forest management and distribution processes is too low to permit forest owners to carry out sufficient forest cultivation. To effectively utilize the wood, a subsidy system that takes a long-term view and a timber market that puts an appropriate price on wood are needed. We argue that it is important to bolster the management position of the Japanese Forest Owners’ Associations for design an institutional scheme that enables to practice forestry management from a long-term perspective. Full article

This study focuses on two Mediterranean beech forests located in northern and southern Italy and therefore subjected to different environmental conditions. The research goal was to understand C storage in the forest floor and mineral soil and the major determinants. Relative to the northern forest (NF), the southern forest (SF) was found to produce higher amounts of litterfall (4.3 vs. 2.5 Mg·ha⁻¹) and to store less C in the forest floor (~8 vs. ~12 Mg·ha⁻¹) but more C in the mineral soil (~148 vs. ~72 Mg·ha⁻¹). Newly-shed litter of NF had lower P (0.4 vs. 0.6 mg·g⁻¹) but higher N concentration (13 vs. 10 mg·g⁻¹) than SF. Despite its lower Mn concentration (0.06 vs. 0.18 mg·g⁻¹), SF litter produces a Mn-richer humus (0.32 vs. 0.16 mg·g⁻¹) that is less stable. The data suggest that decomposition in the NF forest floor is limited by the shorter growing season (178 days vs. 238 days) and the higher N concentrations in newly shed litter and forest floor. Differences in C stock in the mineral soil reflect differences in ecosystem productivity and long-term organic-matter accumulation. The vertical gradient of soluble and microbial fractions in the soil profile of SF was consistent with a faster turnover of organic matter in the forest floor and greater C accumulation in mineral soil relative to NF. With reference to regional-scale estimates from Italian National Forest Inventory data, the C stock in the mineral soil and the basal area of Italian beech forests were found to be significantly related, whereas C stock in the forest floor and C stock in the mineral soil were not. Full article

There are few allometric equations available for dipterocarp forests, despite the fact that this forest type covers extensive areas in tropical Southeast Asia. This study aims to develop a set of equations to estimate tree aboveground biomass (AGB) in dipterocarp forests in Vietnam and to validate and compare their predictive performance with allometric equations used for dipterocarps in Indonesia and pantropical areas. Diameter at breast height (DBH), total tree height (H), and wood density (WD) were used as input variables of the nonlinear weighted least square models. Akaike information criterion (AIC) and residual plots were used to select the best models; while percent bias, root mean square percentage error, and mean absolute percent error were used to compare their performance to published models. For mixed-species, the best equation was $\text{AGB}=0.06203\times {\text{DBH}}^{2.26430}\times {\mathrm{H}}^{0.51415}\times {\text{WD}}^{0.79456}$ . When applied to a random independent validation dataset, the predicted values from the generic equations and the dipterocarp equations in Indonesia overestimated the AGB for different sites, indicating the need for region-specific equations. At the genus level, the selected equations were $\text{AGB}=0.03713\times {\text{DBH}}^{2.73813}$ and $\text{AGB}=0.07483\times {\text{DBH}}^{2.54496}$ for two genera, Dipterocarpus and Shorea, respectively, in Vietnam. Compared to the mixed-species equations, the genus-specific equations improved the accuracy of the AGB estimates. Additionally, the genus-specific equations showed no significant differences in predictive performance in different regions (e.g., Indonesia, Vietnam) of Southeast Asia. Full article

To investigate the dynamics and relative drivers of cellulose degradation during litter decomposition, a field experiment was conducted in three individual ecosystems (i.e., forest floor, stream, and riparian zone) of an alpine forest meta-ecosystem on the eastern Tibetan Plateau. Four litter species (i.e., willow: Salix paraplesia, azalea: Rhododendron lapponicum, cypress: Sabina saltuaria, and larch: Larix mastersiana) that had varying initial litter chemical traits were placed separately in litterbags and then incubated on the soil surface of forest floor plots or in the water of the stream and riparian zone plots. Litterbags were retrieved five times each year during the two-year experiment, with nine replicates each time for each treatment. The results suggested that foliar litter lost 32.2%–89.2% of the initial dry mass depending on litter species and ecosystem type after two-year’s incubation. The cellulose lost 60.1%–96.8% of the initial mass with degradation rate in the order of stream > riparian zone > forest floor. Substantial cellulose degradation occurred at the very beginning (i.e., in the first pre-freezing period) of litter decomposition. Litter initial concentrations of phosphorus (P) and lignin were found to be the dominant chemical traits controlling cellulose degradation regardless of ecosystems type. The local-scale environmental factors such as temperature, pH, and nutrient availability were important moderators of cellulose degradation rate. Although the effects of common litter chemical traits (e.g., P and lignin concentrations) on cellulose degradation across different individual ecosystems were identified, local-scale environmental factors such as temperature and nutrient availability were found to be of great importance for cellulose degradation. These results indicated that local-scale environmental factors should be considered apart from litter quality for generating a reliable predictive framework for the drivers of cellulose degradation and further on litter decomposition at a global scale. Full article

In this study, we classified twenty associations, 179 families, 810 genera, 1897 species, and identified 291 rare species. The vegetation units were named following floristic-sociological approach. A cocktail determination key was used to classify the following vegetation units of association. More of the west side than the east side of the study area was at a higher altitude, and the vegetation experienced significant compression. Follow the result of detrended correspondence analysis (DCA), winter rainfall and average January temperature were the main environmental factors affecting variation in vegetation distribution by elevation gradient in this area. The particular association type on the eastern side of the study area is attributable to the northeast monsoon experienced year-round in this area, which causes relatively low temperature and humidity and wind rush, as well as the compression of the elevation range in each forest. The monsoon deciduous vegetation area exists only on the west of the low altitude mountains. Full article

Seed production, quality, germination and seedling establishment are indicators of reproductive success in conifers. Monitoring of these parameters is essential to determine the viability of populations for the purposes of conservation. We analyze cone and seed traits as indicators of reproductive success in the endangered Rzedowski´s pine (Pinus rzedowskii (Madrigal et Caballero) and near-threatened veitchii pine (Pinus ayacahuite var. veitchii (Shaw)) in west-central Michoacán, Mexico. These traits were systematically quantified and their variation assessed using Generalized Linear Mixed Models (GLMMs). We found that the reproductive success of Rzedowski’s pine seems to be critical, presenting low seed efficiency (17.10%), germination (5.0%) and seedling establishment (27.7%), with high levels of inbreeding (0.79). In contrast, veitchii pine presents moderate seed efficiency (54.9%), high germination (71.5%) and seedling establishment (84%–97%) and low inbreeding (0.33). Reproductive indicators differed significantly among zones and populations for each species, where fragment sizes mainly affected seed production and efficiency. This result indicates that fragmentation has played a more important role in the reproductive success of Rzedowski’s pine than in veitchii pine, perhaps by limiting pollen flow among zones and populations and producing higher levels of inbreeding and lower seed efficiency in the former species. We propose a conservation strategy for these important pine species in order to increase their long-term genetic viability. Full article

Sustained forest management of Cunninghamia lanceolata (Chinese fir) plantations in subtropical China is restricted by the limited availability of quantitative data. This study combines inventory data and tree-ring analysis of Chinese fir from natural and plantation forests that were subjected to controlled burning or brush clearing site preparations. Inter-annual variation of Chinese fir tree-ring widths were measured for the controlled burning, brush clearing and natural forest sites. The mean annual diametric growth of Chinese fir was 0.56 cm·year⁻¹ for the natural forest, 0.80 cm·year⁻¹ for the brush clearing site and 1.10 cm·year⁻¹ for the controlled burning site. The time needed to reach the minimum cutting/logging diameter of 15 cm was 14 years in the controlled burning site, 19 years in the brush clearing site and >40 years in the natural forest. The biological rotation ages for the burning, cutting and natural forest sites were 15, 26 and >100 years, respectively. The total aboveground biomasses for the burning and clearing sites were 269.8 t·ha⁻¹ and 252 t·ha⁻¹, respectively. These results suggest that the current 25-year cutting cycle greatly underestimates the growth rate of Chinese fir plantations. Full article

The 10th-growing season performance of planted eastern white pine (Pinus strobus L.) seedlings was evaluated in response to herbaceous and woody vegetation control treatments within a clearcut and two variants of the uniform shelterwood regeneration system (single vs. multiple future removal cuts). Herbaceous vegetation control involved the suppression of grasses, forbs, ferns and low shrubs for the first 2 or 4 growing seasons after planting. Deciduous woody vegetation control treatments, conducted in combination with the herbaceous treatments within a response-surface design, involved the permanent removal of all tall shrubs and deciduous trees at the time of planting, at the end of the 2nd or 5th growing seasons, or not at all. In general, the average size of planted pine was related positively to the duration of herbaceous vegetation control and negatively to delays in woody control. White pine weevil (Pissodes strobi Peck) altered these trends, reducing the height of pine on plots with little or no overtopping deciduous woody vegetation or mature tree cover. Where natural pine regeneration occurred on these plots, growth was similar but subordinate to the planted pine. Data from the three sites indicate that at least 60% of planted pine may be expected to reach an age-10 height target of 2.5 m when overtopping cover (residual overstory + regenerating deciduous) is managed at approximately 65% ± 10%, and total herbaceous cover is suppressed to levels not exceeding 50% in the first five years. On productive sites, this combination may be difficult to achieve in a clearcut, and requires fairly rigorous vegetation management in shelterwood regeneration systems. Currently, synthetic herbicides offer the only affordable and effective means of achieving such vegetation control. Full article

Global change—particularly climate change, forest management, and atmospheric deposition—has significantly altered forest growing conditions in Europe. The influences of these changes on beech growth (Fagus sylvatica L.) were investigated for the past 80 years in Belgium, using non-linear mixed effects models on ring-width chronologies of 149 mature and dominant beech trees (87–186 years old). The effects of the developmental stage (i.e., increasing tree size) were filtered out in order to focus on time-dependent growth changes. Beech radial growth was divided into a low-frequency signal (=growth rate), mainly influenced by forest management and atmospheric deposition, and into a high-frequency variability (≈mean sensitivity), mainly influenced by climate change. Between 1930 and 2008, major long-term and time-dependent changes were highlighted. The beech growth rate has decreased by about 38% since the 1950–1960s, and growth variability has increased by about 45% since the 1970–1980s. Our results indicate that (1) before the 1980s, beech growth rate was not predominantly impacted by climate change but rather by soil alteration (i.e., soil compaction and/or nitrogen deposition); and (2) since the 1980s, climate change induced more frequent and intense yearly growth reductions that amplified the growth rate decrease. The highlighted changes were similar in the two ecoregions of Belgium, although more pronounced in the lowlands than in the uplands. Full article

Biomass and net primary productivity (NPP) are important factors for studying terrestrial carbon storage and the carbon cycle. Using data from existing literature, this study synthesized and analyzed a comprehensive database of direct field observations of forest biomass and NPP for Southwestern China. The biomass of mature natural forests and mature planted forests range from 81.2 Mg·ha⁻¹ to 692.6 Mg·ha⁻¹ (mean = 288.1 Mg·ha⁻¹) and from 76.8 Mg·ha⁻¹ to 670.1 Mg·ha⁻¹ (mean = 181.5 Mg·ha⁻¹), respectively. Mature natural forests have higher biomass than mature planted ones. The NPP values of natural and planted forests range from 1.4 Mg·ha⁻¹·year⁻¹ to 29.6 Mg·ha⁻¹·year⁻¹ (mean = 13.6 Mg·ha⁻¹·year⁻¹) and from 0.6 Mg·ha⁻¹·year⁻¹ to 26.5 Mg·ha⁻¹·year⁻¹ (mean = 9.9 Mg·ha⁻¹·year⁻¹), respectively. Correlations among biomass, NPP, and environmental factors show that NPP significantly decreases with latitude and increases with mean annual temperature, mean annual precipitation, growing degree-days on a 0 °C base, and mean annual drought index, whereas biomass positively correlates with stand age and leaf area index strongly. Karst forests exhibit almost the same NPP as non-karst forests, but the former have significantly lower biomass compared to the latter. Comprehensive regional data synthesis and analysis based on direct field observations of forest biomass and NPP are important for benchmarking global and regional vegetation and carbon models, estimating regional carbon content, restoring vegetation, and mitigating climate change. Full article

Disturbances can affect forest health and are important modulating factors of tree responses to environmental changes. However, standard methods are needed to assess and elucidate the relative effects of disturbance legacies on forest health among species. Here, structural sustainability was used to evaluate and to compare the impacts of contrasting disturbances on the health of Quercus ilex, Cedrus atlantica, and Abies pinsapo forest stands in Morocco and Spain. Disturbance effects on structural sustainability were related to type, severity, and land-use history, and showed inter-regional variability. Cedrus atlantica was structurally sustainable in its core distribution in Morocco, but not at its southern and northernmost geographical range limits. Quercus ilex was structurally sustainable in Morocco. Abies pinsapo was structurally sustainable at optimal elevation sites in Morocco (Rif Mts.), but considering the whole A. pinsapo dataset including Morocco and Spain, the species is structurally unsustainable due to excessive mortality. However, at the lower elevation plots in Spain, unsustainability was due to insufficient mortality. Although some forests were structurally sustainable, none of them were deemed healthy because none met their management objectives. Results also support the key role of disturbance regimes as drivers of forest structural sustainability and adaptive capacity. Full article

The mountain pine beetle (Dendroctonus ponderosae Hopkins) (MPB) has infested and killed millions of hectares of lodgepole pine (Pinus contorta var. latifolia Engelm) forests in British Columbia, Canada, over the past decade. It is now spreading out of its native range into the Canadian boreal forest, with unknown social, economic and ecological consequences. This review explores the ramifications of the MPB epidemic with respect to mid-term timber supply, forest growth, structure and composition, vegetation diversity, forest fire, climate change, and ecosystem resilience. Research confirms that, in British Columbia, all of these variables are more significantly impacted when salvage logging is used as management response to the outbreak. We conclude that appropriate management in response to MPB is essential to ensuring ecologically resilient future forests and reliable mid-term timber supplies for affected human communities. We highlight knowledge gaps and avenues for research to advance our understanding in support of sustainable post-disturbance forest management policies in British Columbia and elsewhere. Full article

Community forest management (CFM) is identified by many actors as a core strategy for reducing emissions from deforestation and forest degradation in developing countries (REDD+). Others however see REDD+ as a danger to CFM. In response to these contrasting views, we carried out a systematic review of CFM case studies to look at CFM’s potential role in achieving forest carbon benefits and social co-benefits for forest communities. We evaluated the potential impacts of REDD+ on CFM. Our review showed that there is strong evidence of CFM’s role in reducing degradation and stabilizing forested landscapes; however, the review also showed less evidence about the role of CFM in reducing deforestation. For social benefits, we found that CFM contributes to livelihoods, but its effect on poverty reduction may be limited. Also, CFM may not deal adequately with the distribution of benefits within communities or user groups. These insights are important for CFM-based REDD+ intervention; measures should be adopted to overcome these gaps. Innovative incentive structures to existing CFM are discussed. The recognition of rights for forest communities is one first step identified in promoting CFM. We call for sound empirical impact evaluations that analyze CFM and CFM-based REDD+ interventions by looking at both biophysical and social outcomes. Full article

Accurate estimates of aboveground biomass (AGB) are crucial to assess terrestrial C-stocks and C-emissions as well as to develop sustainable forest management strategies. In this study we used Synthetic Aperture Radar (SAR) data acquired at L-band and the Landsat tree cover product together with Moderate Resolution Image Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) time series data to improve AGB estimations over two study areas in southern Mexico. We used Mexican National Forest Inventory (INFyS) data collected between 2005 and 2011 to calibrate AGB models as well as to validate the derived AGB products. We applied MODIS NDVI time series data analysis to exclude field plots in which abrupt changes were detected. For this, we used Breaks For Additive Seasonal and Trend analysis (BFAST). We modelled AGB using an original field dataset and BFAST-filtered data. The results show higher accuracies of AGB estimations using BFAST-filtered data than using original field data in terms of R² and root mean square error (RMSE) for both dry and humid tropical forests of southern Mexico. The best results were found in areas with high deforestation rates where the AGB models based on the BFAST-filtered data substantially outperformed those based on original field data (R²_BFAST = 0.62 vs. R²_orig = 0.45; RMSE_BFAST = 28.4 t/ha vs. RMSE_orig = 33.8 t/ha). We conclude that the presented method shows great potential to improve AGB estimations and can be easily and automatically implemented over large areas. Full article

Decaying wood is related to nutrient cycling through its role as either a sink or source of nutrients. However, at micro scales, what is the effect of decaying logs on the physical, chemical, and biotic characteristics of the soil underneath? We took samples from a 0 to 5 cm depth under and a 50 cm distance away from decaying logs (Dacryodes excelsa and Swietenia macrophylla) at 2 stages of decay, and measured soil temperature, total and available nutrients, and root length in a tropical wet forest. We found decaying wood affected physical, chemical, and biotic properties of the underlying soil. Soil temperature was less variable under the decaying logs than away from the logs. Soil under the decaying wood had fewer roots, and lower NO₃⁻ and Mg²⁺ availability than samples collected a distance of 50 cm away from the logs. Tree species and decay stage were important factors defining the effect of decaying wood on the distribution of available nutrients. Ca²⁺, Mg²⁺, and K⁺ levels were higher in the soil associated with the youngest logs, and were higher near S. macrophylla logs. Heavy metals were also higher in the soil located near the younger logs independent of the species; other metal ions such as Al³⁺ and Fe³⁺ were higher in the soil associated with D. excelsa and the oldest logs. These results indicate decaying wood can contribute to and generate spatial heterogeneity of soil properties. Full article

Decomposition of plant litter is a key process for the transfer of carbon and nutrients in ecosystems. Carbon contained in the decaying biomass is released to the atmosphere as respired CO₂, and may contribute to global warming. Litterbag studies have been used to improve our knowledge of the drivers of litter decomposition, but they lack comparability because litter quality is plant species-specific. The use of commercial tea bags as a standard substrate was suggested in order to harmonize studies, where green tea and rooibos represent more labile and more recalcitrant C compounds as surrogates of local litter. Here we examine the potential of the use of standardized material for improving our understanding of litter decomposition across climate regions, and to further develop pertinent models. We measured the decomposition of incubated local and standard litters over two years along an elevation gradient in the Austrian Limestone Alps. The similar response to changes in temperature and precipitation of the pairs of local and standard litter—i.e., Fagus sylvatica and green tea, and Pinus nigra and rooibos tea, respectively—suggests the suitability of the standard litters for further examining the role of environmental drivers of decomposition. Harmonized data obtained from standardized litter experiments would provide a key prerequisite for further developing simulation models for the estimation of the C balance of ecosystem litter pools. Full article

Wildfire emissions in the boreal forests yield an important contribution to the chemical budget of the troposphere. To assess the contribution of wildfire to the emissions of atmospheric trace species in the Great Xing’an Mountains (GXM), which is also the most severe fire-prone boreal forest region in China, we estimated various wildfire activities by combining explicit spatio-temporal remote sensing data with fire-induced emission models. We observed 9998 fire scars with 46,096 km² in the GXM between the years 1986 and 2010. The years 1987 and 2003 contributed 33.2% and 22.9%, respectively, in burned area during the 25 years. Fire activity is the strongest in May. Most large fires occurred in the north region of the GXM between 50° N and 54° N latitude due to much drier weather and higher fire danger in the northern region than in the southern region of the study domain. Evergreen and deciduous needleleaf forest and deciduous broadleaf forest are the main sources of emissions, accounting for 84%, 81%, 84%, 87%, 89%, 86%, 85% and 74% of the total annual CO₂, CH₄, CO, PM₁₀, PM_2.5, SO₂, BC and NO_x emissions, respectively. Wildfire emissions from shrub, grassland and cropland only account for a small fraction of the total emissions level (approximately 4%–11%). Comparisons of our results with other published estimates of wildfire emissions show reasonable agreement. Full article

In this article we introduce a new method for forest management inventories especially suitable for highly-valued timber where the precise estimation of stem parameters (diameter, form, and tapper) plays the key role for market purposes. The unmanned aerial system (UAS)-based photogrammetry is combined with terrestrial photogrammetry executed by walking inside the stand and the individual tree parameters are estimated. We compare two automatic methods for processing of the point clouds and the delineation of stem circumference at breast height. The error of the diameter estimation was observed to be under 1 cm root mean square error (RMSE) and the height estimation error was 1 m. Apart from the mentioned accuracy, the main advantage of the proposed work is shorter time demand for field measurement; we could complete both inventories of 1 hectare forest stand in less than 2 h of field work. Full article

Functional Diversity is considered an important driver of community assembly in environmental and successional gradients. To understand tree assembly processes in a semideciduous tropical forest, we analyzed the variation of Functional Richness (FRic), Functional Divergence (FDiv), and Functional Evenness (FEve) of small vs. large trees in relation to fallow age after slash-and-burn agriculture and topographical position (flat sites vs. hills). FRic of small trees was lower than null model predicted values across the successional gradient, and decreased unexpectedly in older successional ages. FRic of large trees was higher than null model predictions early in succession and lower in late-successional stands on hills. Dominant species were more similar (low FDiv) in early and intermediate successional stands for small trees, and on hills for large trees, suggesting that species that are best adapted to harsh conditions share similar traits. We also found evidence of competitive exclusion among similar species (high FEve) for small trees in early successional stands. Overall, our results indicate that community assembly of small trees is strongly affected by the changing biotic and abiotic conditions along the successional and topographical gradient. For large trees, hills may represent the most stressful conditions in this landscape. Full article

Forests in snow-dominated areas have substantial effects on the snowpack and its evolution over time. Such interactions have significant consequences for the hydrological response of mountain rivers. Thus, the impact of forest management actions on the snow distribution, and hence the storage of water in the form of snow during winter and spring, is a major concern. The results of this study provide the first detailed comparison of the small-scale effect of forest characteristics on the snowpack distribution, assessed prior to and following major modification of the structure of the canopy by pruning of the lower branches of the trees to 3 m above the ground. This is a common management practice aimed at reducing the spread of forest fires. The snowpack distribution was determined using terrestrial laser scanning (LiDAR technology) at a high spatial resolution (0.25 m) over a 1000 m² study area during 23 survey dates over three snow seasons in a small study area in the central Pyrenees. The pruning was conducted during summer following the snow season in the second year of the study (i.e., the study duration encompassed two seasons prior to canopy pruning and one following). Principal component analysis (PCA) was used to identify recurring spatial patterns of snow distribution. The results showed that pruning reduced the average radius of the canopy of trees by 1.2 m, and increased the clearance around the trunks, as all the branches that formerly contacted the ground were removed. However, the impact on the snowpack was moderate. The PCA revealed that the spatial configuration of the snowpack did not change significantly, as the principal components included survey days from different periods of the snow season, and did not discriminate days surveyed prior to and following pruning. Nevertheless, removal of the lower branches reduced the area beneath the canopy by 36%, and led to an average increase in total snow depth of approximately 14%. Full article

Forested catchments throughout the world are known for producing high quality water for human use. In the 20th Century, experimental forest catchment studies played a key role in studying the processes contributing to high water quality. The hydrologic processes investigated on these paired catchments have provided the science base for examining water quality responses to natural disturbances such as wildfire, insect outbreaks, and extreme hydrologic events, and human-induced disturbances such as timber harvesting, site preparation, prescribed fires, fertilizer applications, pesticide usage, rainfall acidification, and mining. This paper compares and contrasts the paired catchment approach with landscape-level water resource monitoring to highlight the information on hydrologic processes provided by the paired catchment approach that is not provided by the broad-brush landscape monitoring. Full article

Do urban residents experience societal benefits derived from urban forests equitably? We conducted a broad-scale spatial analysis of the relationship between urban greenery and socioeconomic factors in the Portland metropolitan area. The Normalized Difference Vegetation Index was derived from National Agriculture Imagery Program images to map urban vegetation cover, and Outdoor Recreation and Conservation Area data were used to identify green spaces. These measures of urban greenery were correlated with census data to identify socioeconomic factors associated with high levels of green inequity. Population density, house age, income, and race were strongly correlated with vegetation cover. However, the distribution of green spaces showed a much weaker relationship with socioeconomic factors. These results highlight the importance of different measures of access to urban greenery and suggest potential solutions to the problem of urban green inequity. Cities can use our methods to conduct targeted urban forest management to maximize urban forest benefits received by residents. Full article

Winter soil respiration (R_s) is becoming a significant component of annual carbon budgets with more warming in winter than summer. However, little is known about the controlling mechanisms of winter R_s in dryland. We made continuous measurements of R_s in four microsites (non-crust (BS), lichen (LC), moss (MC), and a mixture of moss and lichen (ML)) in a desert shrub-land ecosystem northern China, to investigate the causes of R_s dynamics in winter. The mean winter R_s ranged from 0.10 to 0.17 µmol CO₂ m⁻²·s⁻¹ across microsites, with the highest value in BS. Winter Q₁₀ (known as the increase in respiration rate per 10 °C increase in temperature) values (2.8–19) were much higher than those from the growing season (1.5). R_s and Q₁₀ were greatly enhanced in freeze-thaw cycles compared to frozen days. Diurnal patterns of R_s between freeze-thaw and frozen days differed. Although the freeze-thaw period was relatively short, its cumulative R_s contributed significantly to winter R_s. The presence of biocrust might induce lower temperature, thus having fewer freeze-thaw cycles relative to bare soil, leading to the lower R_s for microsites with biocrusts. In conclusion, winter R_s in drylands was sensitive to soil temperature (T_s) and T_s-induced freeze-thaw cycles. The temperature impact on R_s varied among soil cover types. Winter R_s in drylands may become more important as the climate is continuously getting warmer. Full article

To identify genetic diversity, genetic structure and the relationship among accessions, and further establish a core collection for the long-term breeding of cypress (Cupressus funebris Endl.), the genealogy of breeding parents was reconstructed using simple sequence repeat (SSR) molecular markers. Seventeen SSR markers were used to detect molecular polymorphisms among 290 cypress accessions from five provinces and 53 accessions with unknown origin in China. A total of 92 alleles (Na) were detected with 5.412 alleles per locus and an average polymorphism information content (PIC) of 0.593. The haplotype diversity (H) ranged from 0.021 to 0.832, with an average of 0.406. The number of alleles (Na) and the effective number of alleles (Ne) ranged from 4.294 to 5.176 and from 2.488 to 2.817 among five populations, respectively. The pairwise population matrix of Nei’s genetic distance ranged from 0.008 to 0.023. Based on the results of unweighted pair group method average (UPGMA) cluster and population structure analyses, 343 breeding parents were divided into two major groups. Lower genetic differentiation coefficients and closer genetic relationships were observed among cypress breeding parents, suggesting that the genetic basis was narrow, and the genetic relationship was confused by frequent introduction and wide cultivation. Moreover, we reconstructed the genealogy between breeding parents and 30 accessions of breeding parents from an identified core collection. According to the present study, not only geographic origin but also the relationship of the individuals should be considered in future crossbreeding work. Full article

This study uses detailed soil and vegetation data collected in a 30-ha old-growth broad-leaved Korean pine forest to study the effect of soil properties on tree community structures. Spatial distribution patterns are simulated using a homogeneous Poisson process (HomP) and a homogeneous Thomas process (HomT). The simulated distributions are compared with the observed ones to explore correlations between certain tree species and several soil elements. The HomP model shows that all tested tree species are significantly correlated with at least one principal component in the upper-layer soil elements. The HomT model shows that only 36.4% of tree species are significantly correlated with the principal component of at least one upper-layer soil element. This result shows that the impact of dispersal limitation is greater than impact of environmental heterogeneity on species spatial distributions. The spatial autocorrelation of species induced by the dispersal limitation will largely conceal the plant-soil relationships caused by the heterogeneity of soil elements. An additional analysis shows that the elements in the upper soil layer which have the greatest impact on community niche structure are Pb, total phosphorus (TP), total nitrogen (TN), Cu, Cr, Zn and available nitrogen (AN). The corresponding elements in the lower soil layers are Pb, TP, Cu, organic carbon (OC), Mn, total potassium (TK) and AN. Different species seem to be complementary regarding the demands on the available soil resources. The results of this study show that the tree species in the different growth groups have different habitat preferences. Compared with subcanopy and shrub species, the canopy species have more significant correlations with the soil elements. Full article

Understanding the spatio-temporal dynamic of soil moisture is critical in hydrological and other land surface related studies. Until recently, however, there have been controversies about the relationship between spatial mean and spatial variance of soil moisture and the contributions of each of these factors to spatial variability. Therefore, in this study, spatial variability of soil moisture in a 7 km² forest catchment is analyzed by time-series data on soil moisture obtained at a total of 12 observation sites. Results showed that soil moisture spatial mean and spatial variance varied almost synchronously and in three cyclic patterns during the monitoring period from 1 April 2015 to 31 October 2015. The spatial mean-variance relationship during the ascending and descending periods of spatial mean could be well-fitted by upward and downward convex quadratic curves, respectively, indicating possible clockwise hysteresis of this relationship. It was found that all through the monitoring period, contributions of time-invariant factors on total spatial variance increased from 68.9% to 88.2% with depth, and temporally stable ranking of sites was obtained. Because of the high spatial variation of soil moisture in our study area, it should be noted that a large number of sample plots would be needed to adequately estimate the spatial variability of soil moisture. Full article

Fire is a dominant mechanism of forest renewal in most of Canada’s forests and its activity is predicted to increase over the coming decades. Individual fire events have been considered to be non-selective with regards to forest properties, but evidence now suggests otherwise. Our objective was therefore to quantify the effect of forest properties on fire selectivity or avoidance, evaluate the stability of these effects across varying burn rates, and use these results to map local fire risk across the forests of Canada. We used Canada-wide MODIS-based maps of annual fires and of forest properties to identify burned and unburned pixels for the 2002–2011 period and to bin them into classes of forest composition (% conifer and broadleaved deciduous), above-ground tree biomass and stand age. Logistic binomial regressions were then used to quantify fire selectivity by forest properties classes and by zones of homogeneous fire regime (HFR). Results suggest that fire exhibits a strong selectivity for conifer stands, but an even stronger avoidance of broadleaved stands. In terms of age classes, fire also shows a strong avoidance for young (0 to 29 year) stands. The large differences among regional burn rates do not significantly alter the overall preference and avoidance ratings. Finally, we combined these results on relative burn preference with regional burn rates to map local fire risks across Canada. Full article

Pistacia lentiscus (Anacardiaceae; mastic tree) is an evergreen sclerophyll species, largely distributed in dry areas of the Mediterranean basin and well-adapted to severe conditions of drought in very unfertile soils. In the present study, we evaluated the growing responses of two accessions of P. lentiscus to three different levels of salinity under nursery conditions. The two mastic tree accessions (Manfredonia and Specchia) were collected from individual trees in two different sites in the Apulia region (Southern Italy) and subjected to three different levels of salinization by adding 0, 400, and 800 g of salts 100 L⁻¹ of substrate, respectively. The following parameters were recorded: plant height; survival of plants and total root length; total biomass; number of leaves per plant and leaf area; as well as various ecophysiological traits. Salinity reduced the values of all the examined parameters, both morphological and physiological. Results suggested that P. lentiscus can tolerate and accumulate salt at high concentrations in nursery conditions. As a result, it is important to identify germplasm that is highly tolerant to salinity for the production of nursery seedlings that will be planted in saline soils. Full article

Swiss needle cast (SNC), a foliar disease specific to Douglas-fir (Pseudotsuga menziesii), is caused by an endemic Ascomycete fungus (Phaeocryptopus gaeumannii). In the late 1980s and early 1990s significant symptoms began to appear in coastal Oregon, and these have been associated with the planting of Douglas-fir in the Sitka spruce zone, leaf wetness during potential spore dispersal in May–August, and mild winter temperature. The first annual aerial survey was initiated in 1996 and has continued through 2015, which indicates a significant increase in area of visible symptoms from the air, increasing from 53,050 ha in 1996 to 238,705 ha in 2015. Monitoring plots in the NW Oregon Coast Range verified impacts of SNC on tree growth and productivity, with growth reductions averaging about 23% in the epidemic area linked to needle retention. A series of monitoring plots was set up in the western Cascade Mountains of Oregon and 590 10–23-year old Douglas-fir trees in 59 stands were tracked for 10 years, measured in 2001, 2006, and 2011. No measureable growth impacts were noted in this region of Oregon. A new plot network is being installed throughout the Oregon and southwest Washington coastal ranges as a means of monitoring future disease impact and providing framework for additional studies. Full article

Understanding the effects of stand age and forest type on soil respiration is crucial for predicting the potential of soil carbon sequestration. Thus far, however, there is no consensus regarding the variations in soil respiration caused by stand age and forest type. This study investigated soil respiration and its temperature sensitivity at three stand ages (5, 10, and 20 or 30 years) in two plantations of coniferous (Pinus tabulaeformis Carrière) and deciduous (Populus davidiana Dode) species using an automated chamber system in 2013 in the Beijing-Tianjin sandstorm source area. Results showed that mean soil respiration in the 5-, 10-, and 20/30-year-old plantations was 3.37, 3.17, and 2.99 μmol·m⁻²·s⁻¹ for P. tabulaeformis and 2.92, 2.85, and 2.57 μmol·m⁻²·s⁻¹ for P. davidiana, respectively. Soil respiration decreased with stand age for both species. There was no significant difference in soil respiration between the two plantation species at ages 5 and 10 years (p > 0.05). Temperature sensitivity of soil respiration, which ranged from 1.85–1.99 in P. tabulaeformis and 2.20–2.46 in P. davidiana plantations, was found to increase with stand age. Temperature sensitivity was also significantly higher in P. davidiana plantations and when the soil water content was below 12.8%. Temperature sensitivity incorporated a combined response of soil respiration to soil temperature, soil water content, soil organic carbon, and fine root biomass and, thus, provided an ecological metric for comparing forest carbon dynamics of these species. Full article