Search

Societal Impact Statement Increasing atmospheric nitrogen (N) deposition represents a major global change factor, but its long-term effect on tree growth and carbon (C) sequestration remains uncertain. Our manipulation experiment and meta-analysis reveal that N deposition in temperate and boreal forests promoted tree growth and the allocation of more C into wood than into leaves in China and worldwide. Thus, N deposition may increase forest C sequestration through enhanced wood production and distribution of C into stable sinks. In the context of achieving "Carbon Neutrality," understanding how N deposition affect long-term forest C sinks will help us with mitigation strategies under climate change. Increased nitrogen (N) deposition is driving many temperate and boreal forests in the Northern Hemisphere towards N saturation. However, it is uncertain how long-term N deposition affects tree growth and carbon (C) allocation in these forests. To investigate this, we treated temperate larch and mixed forests in northeastern China with N additions for 8 years. In addition, we collected data from 25 N-addition experiments in temperate and boreal forests worldwide to reveal the overall effects of N on tree growth and C allocation. Nitrogen additions significantly promoted total biomass increment by 24% in both study forests, with on average additional 8 kg C per kg N gain into woody biomass over the study period. Nitrogen additions increased the ratio of woody biomass increment to foliage litterfall production in the larch forest (by 34%). Literature data analysis also revealed greater N promotion on wood (24%) over foliage (9%) production. However, the positive effect on foliage diminished over time. These results combined imply that N deposition may promote tree growth in temperate and boreal regions and drive proportionally more photosynthate allocation into wood than leaves, thus may enhance forest C sequestration in the long run.

In tropical regions, the patterns of carbon (C) and nutrient properties among ecosystems dominated by distinct mycorrhizal associations are unknown. We aim to reveal whether the dynamics differ and the ecological drivers and ecosystem functioning implications of such differences. Based on a dataset of 97 tropical forest sites, we related EcM trees abundance (as a proxy for the transition from AM to EcM trees dominance) to different topsoil properties, climatic conditions and microbial abundance proxies through Generalized Additive Models. Higher abundances of EcM trees were correlated with higher topsoil concentrations of total nitrogen and C, extractable phosphorus and potassium, delta C-13, mean annual temperature, precipitation, microbial (bacterial and fungal) biomass and the relative abundance of saprotrophic fungi. Synthesis. Our results reveal consistent differences in carbon and nutrient content between arbuscular mycorrhizal (AM-) and EcM-dominated vegetation across the tropical biome, pointing to lower soil fertility and lower rates of C and nutrient transformation processes in EcM-dominated forests. These patterns associate with lower topsoil C accumulation when compared to AM vegetation, which contrasts with patterns reported for temperate forests. We suggest that different mechanisms of soil organic matter accumulation explain the contrasting impacts of EcM dominance on topsoil properties of temperate and tropical biomes. Global vegetation and C models should account for the contrasting impacts of distinct mycorrhizal vegetation in different climatic zones. Stichting voor de Technische Wetenschappen [016.161.318]

Aim: Assessing the performances of different sampling approaches for documenting community diversity may help to identify optimal sampling efforts and strategies, and to enhance conservation and monitoring planning. Here, we used two data sets based on probabilistic and preferential sampling schemes of Italian forest vegetation to analyze the multifaceted performances of the two approaches across three major forest types at a large scale. Location: Italy. Methods: We pooled 804 probabilistic and 16,259 preferential forest plotsassamplesofvascularplantdiversity across the country. We balanced the two data sets in terms of sizes, plot size, geographical position, and vegetation types. For each of the two data sets, 1000 subsets of 201 random plots were compared by calculating the shared and exclusive indicator species, their overlap in the multivariate space, and the areas encompassed by spatially-constrained rarefaction curves. We then calculated an index of performance using the ratio between the additional and total information collected by each sampling approach. The performances were tested and evaluated across the three major forest types. Results: The probabilistic approach performed better in estimating species richness and diversity of species assemblages, but did not detect other components of the regional diversity, such as azonal forests. The preferential approach outperformed the probabilistic approach in detecting forest-specialist species and plant diversity hotspots. Conclusions: Using a novel workflow based on vegetation-plot exclusivities and commonalities, our study suggests probabilistic and preferential sampling approaches are to be used in combination for better conservation and monitor planning purposes to detect multiple aspects of plant community diversity. Our findings can assist the implementation of national conservation planning and large-scale monitoring of biodiversity.

Understanding the effects of silvicultural practices including single-tree selection on soil properties is essential for forest management in temperate broadleaved beech forests. Changes in physico-chemical and biological soil properties in 15 harvest-created gaps under single-tree selection and the adjacent closed canopies, with five replications for each, were studied 6 years after gap creation in an oriental beech (Fagus orientalis L.) stand of the Hyrcanian forest. Gaps were classified into three size classes: small (85-130 m2), medium (131-175 m2) and large (176-300 m2). Soil cores were collected at the center and at the edge of gaps, and under the adjacent closed canopy. Results indicated that gap size significantly affected soil texture and bulk density, whereas soil organic carbon (SOC), total nitrogen and pH showed a significant gradient from the center to the edge of gap independently form their size. SOC and total nitrogen at the center of gaps were also significantly lower than closed-canopy, in particular for the medium-gap; contrastingly, the bulk density with the highest mean value was found at the center of the large-gap. Gap size had no significant influence on soil microbial biomass. These results highlighted that similar conditions in terms of many soil properties were still present among gaps and adjacent closed-canopy stands six years after logging, though canopy openness triggered a reduction in carbon and nitrogen availability along with the related microbial activity at the center of gaps, independently from their size. Therefore, if aimed at preserving an uneven aged structure along with soil quality in temperate broadleaved deciduous forest as the oriental beech stands in the Hyrcanian region, single-tree selection practice for harvesting trees can be recommended as sustainable forest management type.

Plant community composition and functional traits respond to chronic drivers such as climate change and nitrogen (N) deposition. In contrast, pulse disturbances from ecosystem management can additionally change resources and conditions. Community responses to combined environmental changes may further depend on land‐use legacies. Disentangling the relative importance of these global change drivers is necessary to improve predictions of future plant communities. We performed a multifactor global change experiment to disentangle drivers of herbaceous plant community trajectories in a temperate deciduous forest. Communities of five species, assembled from a pool of 15 forest herb species with varying ecological strategies, were grown in 384 mesocosms on soils from ancient forest (forested at least since 1850) and postagricultural forest (forested since 1950) collected across Europe. Mesocosms were exposed to two‐level full‐factorial treatments of warming, light addition (representing changing forest management) and N enrichment. We measured plant height, specific leaf area (SLA) and species cover over the course of three growing seasons. Increasing light availability followed by warming reordered the species towards a taller herb community, with limited effects of N enrichment or the forest land‐use history. Two‐way interactions between treatments and incorporating intraspecific trait variation (ITV) did not yield additional inference on community height change. Contrastingly, community SLA differed when considering ITV along with species reordering, which highlights ITV’s importance for understanding leaf morphology responses to nutrient enrichment in dark conditions. Contrary to our expectations, we found limited evidence of land‐use legacies affecting community responses to environmental changes, perhaps because dispersal limitation was removed in the experimental design. These findings can improve predictions of community functional trait responses to global changes by acknowledging ITV, and subtle changes in light availability. Adaptive forest management to impending global change could benefit the restoration and conservation of understorey plant communities by reducing the light availability.

Abies pindrow is a keystone tree species of temperate forests in the Himalayan range with immense ecological significance. The current study was designed to investigate the spatial distribution, population structure, associated flora, and sustainability of Abies pindrow in the temperate forests of Azad Jammu and Kashmir (AJK), Pakistan. Vegetation data were collected from 48 forest sites distributed in six districts of AJK with respect to the geography, microclimates, and vegetation structure by employing a systematic quadrate-based methodology. Abies pindrow populations were characterized by an average stem density of 183.9 trees/ha with an average basal area cover of 789 cm. A. pindrow populations showed a regeneration value of 555.6 seedlings/ha. A digital elevation model revealed that A. pindrow exhibited a large extent of distribution in an altitudinal range of 1800–3400 m. GIS analysis identified that north-facing slopes with a moderate degree of slope steepness constitutes the preferred habitat of the species in the Kashmir mountains. A floristic analysis revealed that a total of 282 species from 74 plant families comprised the associated flora of A. pindrow-dominated forests with Pinus wallichiana, Picea smithiana, Aesculus indica, and Viburnum grandiflorum as codominant companion species. A. pindrow forests exhibited significant levels of species diversity and richness with average values of Simpson’s diversity as 0.94, Shannon’s diversity as 3.09, species richness as 1.45, and maturity index value as 45.9%. The A. pindrow populations in the study area were found to be subjected to significant deforestation pressure along with overgrazing and erosion impacts. Results provide valuable scientific information for the conservation management of A. pindrow populations, ensuring the sustainability of temperate forest ecosystems in the Western Himalayan region of Kashmir.

Precise tree inventory plays a critical role in sustainable forest planting, restoration, and management. LiDAR-based individual tree detection algorithms often focus on finding individual treetops to discern tree positions. However, deliquescent tree forms (broad, flattened crowns) in deciduous forests can make these algorithms ineffective. In this study, we propose a stepwise tree detection approach, by first identifying individual trees using horizontal point density and then analyzing their vertical structure profiles. We first project LiDAR data onto a 2D horizontal plane and apply mean shift clustering to generate candidate tree clusters. Next, we apply a series of structure analyses on the vertical phase, to overcome local variations in crown size and tree density. This study demonstrates that the horizontal point density of LiDAR data provides critical information to locate and isolate individual trees in temperate hardwood plantations with varied densities, while vertical structure profiles can identify spreading branches and reconstruct deliquescent crowns. One challenge of applying mean shift clustering is training a dynamic search kernel to identify trees of different sizes, which usually requires a large number of field measurements. The stepwise approach proposed in this study demonstrated robustness when using a constant kernel in clustering, making it an efficient tool for large-scale analysis. This stepwise approach was designed for quantifying temperate hardwood plantation inventories using relatively low-density airborne LiDAR, and it has potential applications for monitoring large-scale plantation forests. Further research is needed to adapt this method to natural stands with diverse tree ages and structures.

Ongoing rapid climatic changes are expected to modify the structure, composition, and functioning of forest ecosystems. Studying the influence of such changes on biogeochemical processes is thus crucial for a fuller understanding of forest response to climate change. In a temperate forest of Quebec, Canada, we emulated climate change by warming the acidic, nutrient-poor, and dry soils of two mixedwoods by 3 to 4 °C using heating cables. Leaf-litter mass loss of the local red maple, sugar maple, large-tooth aspen, and American beech were monitored to assess the ability of these tree species to condition boreal soils in the context of their northward migration under climate change. We hypothesized that decomposition rates of all leaf-litter types would be decreased equally by warming due to a drying effect of the soil and its surface, which is detrimental to microbial biomass and activity. Our results suggest differences in decomposition rates between tree species as follows: sugar maple > red maple ≥ American beech = large-tooth aspen. There was no indication of a slower turnover in these marginal soils compared to other studies conducted on typical hardwood soils. Moreover, no difference in litter mass loss was detected between treatments, likely due to a drying effect of the soil warming treatment. Results imply that climate change has a marginal influence on leaf-litter dynamics of temperate tree species on soils that are typical of the boreal forest. However, some variables that could play an important role on litter decomposition in the context of climate change were not measured (e.g., plant phenology, understory composition and density, microbes) and thus, uncertainties remain. The soil drying effect by warming also needs to be further documented and modeled. The study year was characterized by significant periods of water stress but was not considered an exceptional year in that regard. It would be relevant to test for leaf-litter dynamics during dry and wet summers and verify again our initial hypothesis of decreased leaf-litter decomposition rates due to soil warming/drying.

Investigating the response of soil microbial communities to nitrogen (N) deposition is critical to understanding biogeochemical processes and the sustainable development of forests. However, whether and to what extent different forms of N deposition affect soil microbial communities in temperate forests is not fully clear. In this work, a field experiment with three years of simulated nitrogen deposition was conducted in temperate forests. The glycine and urea were chosen as organic nitrogen (ON) source, while NH4NO3 was chosen as inorganic nitrogen (IN) source. Different ratios of ON to IN (CK = 0:0, Mix-1 = 10:0, Mix-2 = 7:3, Mix-3 = 5:5, Mix-4 = 3:7, Mix-5 = 0:10) were mixed and then used with equal total amounts of 10 kg·N·ha−1·a−1. We determined soil microbial diversity and community composition for bacteria and fungi (16S rRNA and ITS), and soil parameters. Different forms of N addition significantly changed the soil bacterial and fungal communities. Mixed N sources had a positive effect on soil bacterial diversity and a negative effect on fungal diversity. Bacterial and fungal community structures were significantly separated under different forms of N addition. Soil pH was the main factor affecting the change in fungal community structure, while bacterial community structure was mainly controlled by STN. We also found that Proteobacteria, Acidobacteriota, Basidiomycota and Ascomycota were the most abundant phyla, regardless of the form of N addition. RDA showed that C/P and NH4+ were the main factors driving the change in bacterial community composition, and C/P, pH and C/N were the main factors driving the change in fungal community composition. Our results indicate that different components of N deposition need to be considered when studying the effects of N deposition on soil microorganisms in terrestrial ecosystems.

The structure of forests in temperate climates has been changing to ensure the resilience of trees. This change affects the local water balance. Knowledge of soil hydraulic properties (SHP) is essential to assess the water cycle in ecosystems. There is little knowledge about the impact of tree species on SHP and the water balance. Based on a compilation of 539 related studies we aimed at identifying the effects of tree species and age on SHP in temperate climates. However, most studies concentrated on soil biogeochemical properties, whereas only 256 studies focused on SHP. The literature presents no standard methods for assessing SHP and there is no knowledge of their variations in forests. We present a systematic overview of the current state of knowledge on variations in SHP based on forest type in temperate climates. We identify the gaps and weaknesses in the literature and the difficulties of evaluating the reviewed studies. More studies following standardised methodologies are needed to create a robust database for each forest type and soil texture. It would improve the assessment of the forest water balance through calibrated plot/site-scale process models. Such a database does not yet exist, but it would greatly improve the management and development of future forest ecosystems.

Forest soils represent a large carbon pool and already small changes in this pool may have an important effect on the global carbon cycle. To predict the future development of the soil organic carbon (SOC) pool, well-validated models are needed. We applied the litter and soil carbon model Yasso15 to 1838 plots of the German national forest soil inventory (NFSI) for the period between 1985 and 2014 to enables a direct comparison to the NFSI measurements. In addition, to provide data for the German Greenhouse Gas Inventory, we simulated the development of SOC with Yasso15 applying a climate projection based on the RCP8.5 scenario. The initial model-calculated SOC stocks were adjusted to the measured ones in the NFSI. On average, there were no significant differences between the simulated SOC changes (0.25 ± 0.10 Mg C ha−1 a−1) and the NFSI data (0.39 ± 0.11 Mg C ha−1 a−1). Comparing regional soil-unit-specific aggregates of the SOC changes, the correlation between both methods was significant (r2 = 0.49) although the NFSI values had a wider range and more negative values. In the majority of forest types, representing 75% of plots, both methods produced similar estimates of the SOC balance. Opposite trends were found in mountainous coniferous forests on acidic soils. These soils had lost carbon according to the NFSI (−0.89 ± 0.30 Mg C ha−1 a−1) whereas they had gained it according to Yasso15 (0.21 ± 0.10 Mg C ha−1 a−1). In oligotrophic pine forests, the NFSI indicated high SOC gains (1.36 ± 0.17 Mg C ha−1 a−1) and Yasso15 much smaller (0.29 ± 0.10 Mg C ha−1 a−1). According to our results, German forest soils are a large carbon sink. The application of the Yasso15 model supports the results of the NFSI. The sink strength differs between forest types possibly because of differences in organic matter stabilisation.

Although the bioconversion of lignocellulosic residues is essential for nutrient storage in forest floors, little is known about the mechanisms behind wood decay and its interactions with site-specific belowground microbial community composition and chemical properties. This study examined the components of white-rot vs. brown-rot woody debris, closely contacted soil chemical properties and microbial community composition using high-throughput Illumina MiSeq sequencing in coniferous and deciduous temperate forests. The lignin concentrations were higher in the brown-rot than in the white-rot woody debris of the coniferous forest. However, lower cellulose concentrations were observed in the brown-rot sets than in the white-rot sets of both coniferous and deciduous forest stands. Furthermore, the woody debris had higher concentrations of nonstructural compounds and ash in the brown-rot than in the white-rot sets of the coniferous and deciduous forests, respectively. Surprisingly, nearly 90% of the variation in the woody debris components was explained by the belowground fungal and bacterial phylum-level compositions. Of these major phyla, Basidiomycota was closely related to the lignin concentration and accounted for 26.62% of the variation in woody debris components, while Ascomycota was related to the hemicellulose concentration and accounted for 17.7% of the variance in the woody debris components. Furthermore, soil total carbon, available phosphorus, and available potassium were 131%, 138%, and 91% higher in the brown-rot than white-rot sets of the coniferous (but not deciduous) forest stand. In addition, Basidiomycota fungi presented an oligotrophic life strategy and were significantly negatively correlated with the soil total carbon, total nitrogen, alkali-hydrolysable nitrogen, and available phosphorus contents. In contrast, Ascomycota fungi were characterized by a copiotrophic strategy and were positively correlated with the contents of soil total carbon, total nitrogen, and total phosphorus. These findings indicate that wood decay processes are strongly determined by site-specific microbial community structure and nutrient status in temperate forests.

Although much is known about the ecology and functional importance of canopy arthropods in temperate forests, few studies have tried to assess the overall diversity and investigate the composition and dynamics of tree-specific communities. This has impeded a deeper understanding of the functioning of forests, and of how to maintain system services. Here, we present the first comprehensive data of whole arthropod communities, collected by insecticidal knockdown (fogging) from 1159 trees in 18 study areas in Central Europe during the last 25 years. The data includes 3,253,591 arthropods from 32 taxa (order, suborder, family) collected on 24 tree species from 18 genera. Fogging collects free-living, ectophytic arthropods in approximately the same number as they occur in the trees. To our knowledge, these are the most comprehensive data available today on the taxonomic composition of arboreal fauna. Assigning all arthropods to their feeding guild provided a proxy of their functional importance. The data showed that the canopy communities were regularly structured, with a clear dominance hierarchy comprised of eight ‘major taxa’ that represented 87% of all arthropods. Despite significant differences in the proportions of taxa on deciduous and coniferous trees, the composition of the guilds was very similar. The individual tree genera, on the other hand, showed significant differences in guild composition, especially when different study areas and years were compared, whereas tree-specific traits, such as tree height, girth in breast height or leaf cover, explained little of the overall variance. On the ordinal level, guild composition also differed significantly between managed and primary forests, with a simultaneous low within-group variability, indicating that management is a key factor determining the distribution of biodiversity and guild composition.

Many woody and herbaceous plants in temperate forests cannot establish and survive in the absence of mycorrhizal associations. Most temperate forests are dominated by ectomycorrhizal woody plant species, which implies that the carrying capacity of the habitat for arbuscular mycorrhizal fungi (AMF) is relatively low and AMF could in some cases experience a limitation of propagules. Here we address how the AMF community composition varied in a small temperate forest site in Germany in relation to time, space, two plant host species, and also with regard to the degree to which plots were covered with AMF-associating woody species. The AMF communities in our study were non-random. We observed that space had a greater impact on fungal community composition than either time, mycorrhizal state of the close-by woody species, or the identity of the host plant. The identity of the host plant was the only parameter that modified AMF richness in the roots. The set of parameters which we addressed has rarely been studied together, and the resulting ranking could ease prioritizing some of them to be included in future surveys. AMF are crucial for the establishment of understory plants in temperate forests, making it desirable to further explore how they vary in time and space. Supplementary information The online version contains supplementary material available at 10.1007/s00572-021-01041-6.

This work describes the development and analysis of a spatially explicit environmental model to estimate the current, ecological, condition class of a managed forest landscape in the southern United States. The model could be extendable to other similar temperate forest landscapes, yet is characterized as a problem-specific, hierarchical, binary process model given the explicit relationships it recognizes between the management of southern United States pine-dominated natural forests and historical ecological conditions. The model is theoretical, based on informed proposals of the landscape processes that influence the ecological condition, and their relationship to perceived ecological condition. The modeling effort is based on spatial data that describe the historical forest community classes, forest plan provisions, fire history, silvicultural treatments, and current vegetation conditions, and six potential ecological condition classes (ECC) are assigned to lands. A case study was provided involving a large national forest, and validation of the outcomes of the modelling effort suggested that the overall accuracy when predicting the exact ecological condition class was about 46%, while the overall accuracy ±1 class was about 81%. For large, heterogeneous forest areas, issues remain in estimating the input variables relatively accurately, particularly the pine basal area.

Background An ethnomycological study was conducted to describe the fungus concept and the traditional fungus classification system for the Nahuas of San Isidro Buensuceso, in central Mexico. The study which provides information on the co-existence of various forms of classification, based on both cultural and biological characteristics. Methods The research included conducting community interviews and forest forays in the company of mushroom pickers. The triad technique, pile sorting, and fresh mushroom sampling methods were used. Traditional names were analyzed to describe the Nahua classification system for fungi. Results and conclusion The triad technique with non-utilitarian stimuli allowed the fungi to be identified as an independent group of plants and animals. The Nahua people of San Isidro classify fungi primarily based on their use, where they grow, and by humoral characteristics. The analysis of the names revealed a classification based on the criteria proposed by Brent Berlin. This study identified the detailed knowledge of fungi in this Nahua community. The criteria used for the recognition of the species are very reliable, since they use organoleptic, ecological, phenological, and morphological characteristics.

Premise A key question in plant dispersal via animal vectors is where and why fruit colors vary between species and how color relates to other fruit traits. To better understand the factors shaping the evolution of fruit color diversity, we tested for the existence of syndromes of traits (color, morphology, and nutrition) in the fruits of Viburnum. We placed these results in a larger phylogenetic context and reconstructed ancestral states to assess how Viburnum fruit traits have evolved across the clade. Results We find that blue Viburnum fruits are not very juicy, and have high lipid content and large, round endocarps surrounded by a small quantity of pulp. Red fruits display the opposite suite of traits: they are very juicy with low lipid content and smaller, flatter endocarps. The ancestral Viburnum fruit may have gone through a sequence of color changes before maturation (green to yellow to red to black), though our reconstructions are equivocal. In one major clade of Viburnum (Nectarotinus), fruits mature synchronously with reduced intermediate color stages. Most transitions between fruit colors occurred in this synchronously fruiting clade. Conclusions It is widely accepted that fruit trait diversity has primarily been driven by the differing perceptual abilities of bird versus mammal frugivores. Yet within a clade of largely bird-dispersed fruits, we find clear correlations between color, morphology, and nutrition. These correlations are likely driven by a shift from sequential to synchronous development, followed by diversification in color, nutrition, and morphology. A deeper understanding of fruit evolution within clades will elucidate the degree to which such syndromes structure extant fruit diversity.

Selection harvesting is a common silvicultural practice in uneven-aged natural forests. Understanding the complex response of individual trees to forest harvesting is of great importance to clearly assess how forest ecosystems respond to future management. While tree growth dynamics following forest harvesting have been well documented at the stand level, at the individual level, how neighborhood interaction affects tree growth after forest harvesting has received little attention. Based on the data from four1-ha permanent forest plots with mapped trees and different harvesting intensities in Northeastern China, the effects of neighborhood interaction on tree growth of 1,108 focal trees were analyzed four years after forest harvesting. Neighborhood interaction was quantified by several indices, considering both crowding and biological dissimilarity (based on taxonomy, phylogeny, and functional traits) between neighboring trees. Additionally, we tested whether the effects of the neighborhood interaction on tree growth might differ across harvesting intensities. Our results found that selection harvesting significantly increased tree growth and biological dissimilarity but decreased crowding at the individual tree level. Focal tree growth decreased by 12.9%, 9.7%, and 7.9% as a result of neighborhood interaction based on taxonomic, phylogenetic, and multi-trait dissimilarity, respectively. Neighborhood interaction based on maximum height appeared to be the most important determinant of tree growth among the four traits examined (i.e., leaf dry mass per area; leaf nitrogen concentration; wood density; and maximum height), and its effect was much stronger than that of the multi-trait dissimilarity index. Moreover, among the neighborhood interaction indices, increasing neighborhood crowding reduced tree growth and there was a significant negative crowding effect at medium to high harvesting intensities (40%∼60% basal area removed) on tree growth. Our study expands our understanding of the relationship between neighborhood interaction and tree growth by identifying crowding and biological dissimilarity as important neighborhood indices for post-harvest tree growth.

Social associations within mixed-species bird flocks can promote information flow about food availability and provide predator avoidance benefits. The relationship between flocking propensity, foraging habitat quality, and interspecific competition can be altered by human-induced habitat degradation. Here we take a close look at sociality within two ecologically important flock-leader (core) species, the Carolina chickadee (Poecile carolinensis) and tufted titmouse (Baeolophus bicolor), to better understand how degradation of foraging habitat quality affects mixed-species flocking dynamics. We compared interactions of free ranging wild birds across a gradient of foraging habitat quality in three managed forest remnants. Specifically, we examined aspects of the social network at each site, including network density, modularity, and species assortativity. Differences in the social networks between each end of our habitat gradient suggest that elevated levels of interspecific association are more valuable in the habitat with low quality foraging conditions. This conclusion is supported by two additional findings: First, foraging height for the subordinate Carolina chickadee relative to the tufted titmouse decreased with an increase in the number of satellite species in the most disturbed site but not in the other two sites. Second, the chickadee gargle call rate, an acoustic signal emitted during agonistic encounters between conspecifics, was relatively higher at the high-quality site. Collectively, these results suggest an increase in heterospecific associations increases the value of cross-species information flow in degraded habitats.

While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above‐ and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation. The work was partly funded by the DFG Priority Program 1374 ‘Infrastructure-Biodiversity-Exploratories’ (DFG-Refno. Po362/18-3). SSo was supported by the Spanish Government under a Ramón y Cajal contract (RYC-2016-20604).

Root lifespan, often is estimated in landscape- and ecosystem-level carbon models using linear approximations. In water manipulation experiments, fine root lifespan can vary with soil water content. Soil water content is generally structured by complex topography, which is largely unaccounted for in landscape- and ecosystem-scale carbon models. Topography governs the range of soil water content experienced by roots which may impact their lifespan. We hypothesized that root lifespan varied nonlinearly across a temperate, mesic, forested catchment due to differences in soil water content associated with topographic position. We expected regions of the landscape that were too wet or too dry would have soils that were not optimal for roots and thus result in shorter root lifespans. Specifically, we hypothesized that root lifespan would be longest in areas that consistently had soil water content in the middle of the soil water content spectrum, while in soils at either very low or very high soil water content, root lifespan would be relatively short. We tested this hypothesis by collecting and analyzing two years of minirhizotron and soil moisture data in plots widely distributed in the Shale Hills catchment of the Susquehanna-Shale Hills Critical Zone Observatory in Pennsylvania. We found that fine root lifespans were longer in traditionally wetter topographic regions, but detected no short term (biweekly) effect of soil moisture on root lifespan. Additionally, depth in soil, soil series, slope face orientation, and season of birth strongly affected root lifespans across the catchment. In contrast, lifespan was unaffected by root diameter or mycorrhizal association. Failure to account for these variables could result in erroneous estimates of fine root lifespan and, consequentially, carbon flux in temperate forested regions.

Research Highlights: Carpathian forests hold high ecological and economic value while generating conservation concerns, with some of these forests being among the few remaining temperate virgin forests in Europe. Carpathian forests partially lost their original integrity due to their management. Climate change has also gradually contributed to forest changes due to its modification of the environmental conditions. Background and Objectives: Understanding trees’ responses to past climates and forms of management is critical in foreseeing the responses of forests to future conditions. This study aims (1) to determine the sensitivity of Carpathian forests to past climates using dendrochronological records and (2) to describe the effects that climate change and management will have on the attributes of Carpathian forests, with a particular focus on the different response of pure and mixed forests. Materials and Methods: To this end, we first analysed the past climate-induced growth change in a dendrochronological reference series generated for virgin forests in the Romanian Curvature Carpathians and then used the obtained information to calibrate spatially explicit forest Landis-II models for the same region. The model was used to project forest change under four climate change scenarios, from mild to extreme. Results: The dendrochronological analysis revealed a climate-driven increase in forest growth over time. Landis-II model simulations also indicate that the amount of aboveground forest biomass will tend to increase with climate change. Conclusions: There are differences in the response of pure and mixed forests. Therefore, suitable forest management is required when forests change with the climate.

Arbuscular mycorrhiza represents a ubiquitous nutritional symbiosis between the roots of most terrestrial plant species and fungi of the subphylum Glomeromycotina (Spatafora et al., 2016). Terrestrial habitats are unlikely to be limited in propagules of arbuscular mycorrhizal fungi (AMF), because AMF propagule densities build up fast in vegetated soil (e.g. Gould et al., 1996). We start to appreciate, however, that shortages in AMF propagules are common in some habitats, such as agricultural fields subject to intensive farming (Schnoor et al., 2011; Manoharan et al., 2017). Forest habitats in the temperate region might also be occasionally AMF propagule limited (Veresoglou et al., 2017), but to the best of our understanding this has not been shown with empirical data.

Slow growing oomycete isolates with morphological resemblance toPhytophthorawere obtained from forest streams during routine monitoring for the EU quarantine forest pathogenPhytophthora ramorumin Ireland and Northern Ireland. Internal Transcribed Spacer (ITS) sequence analysis indicated that they belonged to two previously unknown species ofNothophytophthora, a recently erected sister genus ofPhytophthora. Morphological and temperature-growth studies were carried out to characterise both new species. In addition, Bayesian and Maximum-Likelihood analyses of nuclear 5-loci and mitochondrial 3-loci datasets were performed to resolve the phylogenetic positions of the two new species. Both species were sterile, formed chlamydospores and partially caducous nonpapillate sporangia, and showed slower growth than any of the six knownNothophytophthoraspecies. In all phylogenetic analyses both species formed distinct, strongly supported clades, closely related toN.chlamydosporaandN.valdivianafrom Chile. Based on their unique combination of morphological and physiological characters and their distinct phylogenetic positions the two new species are described asNothophytophthora irlandicasp. nov. andN.liriisp. nov. Their potential lifestyle and geographic origin are discussed.

The aim of this study was to review the most important results from the last 40 years of intense ornithological research conducted in the Białowieża Forest. Furthermore, we discuss the threats that may destroy the unique ecology and characteristics of this forest. Studying the avifauna of the Białowieża Forest provides us with a good general knowledge about natural ecological conditions and relationships, which prevailed in temperate European forests in the past. The avifauna of the Białowieża Forest is characterized by features associated with primeval habitats such as the stability of communities over time, high species richness, relatively low densities, high proportion of hole-nesting birds, very high predation pressure and weak, insignificant competition interactions. This emphasizes the importance of predation, excess of nesting sites for cavity nesting birds, high abundance of food, especially for insectivorous species and fluctuation of bird population size due to rodent outbreaks (pulsed resources). The most severe threats for the avifauna of the Białowieża Forest are: rejuvenation of tree stands, removal of dead wood, fragmentation of old-growth stands, change of tree stand composition (reducing the proportion of some tree species). In order to expand our ecological knowledge about birds, we should keep the Białowieża Forest fully protected for years to come. The main priority should be the maintenance of natural processes changing the forest’s species composition.

This study aimed at estimating temporal (1989-2018) change in forest cover, carbon stock and trend in corresponding CO2 emissions/sequestration of a sub-tropical pine forest (STPF) in AJK, Pakistan. Our field inventory estimation shows an average above ground biomass (AAGB) accumulation of 0.145 Kt/ha with average carbon stock (ACS) value of 0.072 Kt/ha. Landsat TM, ETM+ and OLI images of 1989, 1993, 1999, 2005, 2010, 2015 and 2018 were used to extract vegetation fractions through Linear Spectral Mixture Analysis (LSMA) and forest area was calculated for respective years. Based on the forest area and estimated ACS value, the biomass carbon stock with corresponding CO2 emissions/sequestration was worked out for each time and change in forest carbon stock was determined for different time periods from 1989 to 2018. Our analysis shows net increase of 561 ha in forest cover and 40.39 Kt of ACS along with increase in corresponding CO2 sequestrations of 147.83 Kt over the study period. The results based on combination of remote sensing and field inventory provide valuable information and scientific basis to plan and ensure sustainable forest management (SFM) through reforestation, protection and conservation to enhance and maintain adequate forest cover and reduce CO2 emissions.

Forest management mimicking natural processes represents an approach to maintain mixed, uneven-aged stands at small spatial scales. The reliance on natural processes, especially on natural regeneration leads to the use of gap-based regeneration as a fundamental silvicultural technique. As a baseline for such management, we investigated mixed forest in unmanaged National Nature Reserve Sitno in the Western Carpathians, which harbours extraordinary diversity on a rather small scale. To quantify the impact of gaps on gap-filling processes and to assess the role they play in recently observed changes in tree species composition we established a large (2.5 ha) permanent research plot and surveyed the status of natural regeneration, forest structure, tree species composition, and disturbance regime. Our research highlights the long-term and contemporary difficulties in the establishment of Quercus petraea (Matt.) Liebl and Fagus sylvatica (L.). Based on the provided evidence, the native tree species diversity in one of the few preserved old-growth multi-species beech-oak forest remnants is not likely to persist, what could have many implications for future ecosystem functioning. Our results suggest that variation in gap size is an important factor contributing to composition of tree species composition of natural regeneration. The recent intermediate-scale disturbance pattern dominating the old-growth beech-oak forest is beneficial to canopy recruitment of species less shade-tolerant than Fagus sylvatica, as Acer pseudoplatanus (L.), Acer platanoides (L.), and Fraxinus excelsior (L.). We discuss possible factors behind observed shifts in tree species composition and limitations for application of gap dynamics to forest practice in managed beech-oak forest systems. Overall, results of this study may help to design silvicultural measures promoting mixed-species forests to deliver a range of desired ecosystem services.

Wildfire-altered soil may be an important source of polycyclic aromatic hydrocarbons (PAHs) in the environment. With projected increase of wildfire frequency and intensity due to changing global climate, understanding the quantity and speciation of PAHs, including halogenated PAHs (XPAHs), resulting from different burn intensities has important ramifications for environmental quality concerns and global soil carbon dynamics. Here, we quantified levels of 16 U.S. Environmental Protection Agency regulated PAHs, 3 chlorinated PAHs, and 6 brominated PAHs in nonburned forest soils and burned ash/soil samples covered with black ash (B-Ash; moderate burn intensity) or white ash (W-Ash; severe burn intensity) from the 2013 Rim Fire (1,041 km 2 ) in California. The - 16 PAH concentrations follow (mean ± standard deviation; μg/kg) B-Ash (893 ± 285) > W-Ash (515 ± 333) ≈ nonburned soils (247 ± 58). Moreover, the - 16 PAH profiles were altered by both moderate and severe burn conditions with the size of aromatic structures following B-Ash > W-Ash > nonburned soils. Neither chlorinated nor brominated PAH concentration was significantly elevated by moderate or severe wildfire. Overall, fire intensity is critical in regulating soil PAH concentrations and profiles. Given the high erodibility of wildfire ash, these PAHs can be easily transported to rivers and reservoirs where they could impact the aquatic food web and drinking source water.

International audience; Why can hosts coexist with conspecifics or phylogenetically proximate neighbours despite sharingspecialist enemies? Do the hosts evolve increased enemy resistance? If so, does this have costs interms of climatic-stress resistance, or in such neighbourhoods, does climatic-stress select for resis-tances that are multifunctional against climate and enemies? We studied oak (Quercus petraea)descendants from provenances of contrasting phylogenetic neighbourhoods and climates in a 25-year-old common garden. We found that descendants from conspecific or phylogenetically proxi-mate neighbourhoods had the toughest leaves and fewest leaf miners, but no reduction in cli-matic-stress resistance. Descendants from such neighbourhoods under cold or dry climates hadthe highest flavonol and anthocyanin levels and the thickest leaves. Overall, populations facingphylogenetically proximate neighbours can rapidly evolve herbivore resistance, without cost to cli-matic-stress resistance, but possibly facilitating resistance against cold and drought via multifunc-tional traits. Microevolution might hence facilitate ecological coexistence of close relatives andthereby macroevolutionary conservatism of niches.

We analysed the flora of 46 forest inventory plots (25 m x 100 m) in old growth forests from the Amazonian region to identify the role of environmental (topographic) and spatial variables (obtained using PCNM, Principal Coordinates of Neighbourhood Matrix analysis) for common and rare species. For the analyses, we used multiple partial regression to partition the specific effects of the topographic and spatial variables on the univariate data (standardised richness, total abundance and total biomass) and partial RDA (Redundancy Analysis) to partition these effects on composition (multivariate data) based on incidence, abundance and biomass. The different attributes (richness, abundance, biomass and composition based on incidence, abundance and biomass) used to study this metacommunity responded differently to environmental and spatial processes. Considering standardised richness, total abundance (univariate) and composition based on biomass, the results for common species differed from those obtained for all species. On the other hand, for total biomass (univariate) and for compositions based on incidence and abundance, there was a correspondence between the data obtained for the total community and for common species. Our data also show that in general, environmental and/or spatial components are important to explain the variability in tree communities for total and common species. However, with the exception of the total abundance, the environmental and spatial variables measured were insufficient to explain the attributes of the communities of rare species. These results indicate that predicting the attributes of rare tree species communities based on environmental and spatial variables is a substantial challenge. As the spatial component was relevant for several community attributes, our results demonstrate the importance of using a metacommunities approach when attempting to understand the main ecological processes underlying the diversity of tropical forest communities.

Atmospheric deposition of nitrogen (N) influences forest demographics and carbon (C) uptake through multiple mechanisms that vary among tree species. Prior studies have estimated the effects of atmospheric N deposition on temperate forests by leveraging forest inventory measurements across regional gradients in deposition. However, in the United States (U.S.), these previous studies were limited in the number of species and the spatial scale of analysis, and did not include sulfur (S) deposition as a potential covariate. Here, we present a comprehensive analysis of how tree growth and survival for 71 species vary with N and S deposition across the conterminous U.S. Our analysis of 1,423,455 trees from forest plots inventoried between 2000 and 2016 reveals that the growth and/or survival of the vast majority of species in the analysis (n = 66, or 93%) were significantly affected by atmospheric deposition. Species co-occurred across the conterminous U.S. that had decreasing and increasing relationships between growth (or survival) and N deposition, with just over half of species responding negatively in either growth or survival to increased N deposition somewhere in their range (42 out of 71). Averaged across species and conterminous U.S., however, we found that an increase in deposition above current rates of N deposition would coincide with a small net increase in tree growth (1.7% per Δ kg N ha-1 yr-1), and a small net decrease in tree survival (-0.22% per Δ kg N ha-1 yr-1), with substantial regional and among-species variation. Adding S as a predictor improved the overall model performance for 70% of the species in the analysis. Our findings have potential to help inform ecosystem management and air pollution policy across the conterminous U.S., and suggest that N and S deposition have likely altered forest demographics in the U.S.

Ferns are an important component of ecosystems around the world. Studies of the impacts that global changes may have on ferns are scarce, yet emerging studies indicate that some species may be particularly sensitive to climate change. The lack of research in this subject is much more aggravated in the case of epiphytes, and especially those that live under temperate climates. A mathematical model was developed for two temperate epiphytic ferns in order to predict potential impacts on spore germination kinetics, in response to different scenarios of global change, coming from increasing temperature and forest fragmentation. Our results show that an increasing temperature will have a negative impact over the populations of these temperate epiphytic ferns. Under unfragmented forests the germination percentage was comparatively less influenced than in fragmented patches. This study highlight that, in the long term, populations of the studied epiphytic temperate ferns may decline due to climate change. Overall, epiphytic fern communities will suffer changes in diversity, richness and dominance. Our study draws attention to the role of ferns in epiphytic communities of temperate forests, emphasizing the importance of considering these plants in any conservation strategy, specifically forest conservation. From a methodological point of view, the model we propose could be easily used to dynamically monitor the status of ecosystems, allowing the quick prediction of possible future scenarios, which is a crucial issue in biodiversity conservation decision-making.

The fire ecology of European beech (Fagus sylvatica L.) is poorly understood. We analyzed beech recruitment after a mast year in recently burnt and unburnt stands to answer to the questions: (i) Does post-fire mast seed production and recruitment in beech depend on fire severity, and (ii) which are the processes by which fire and the environment affect beech seed production, germination and seedling emergence and establishment in the first year after masting? We selected three beech stands in the Southwestern Alps, burnt in either the winter of 2012 or 2013 but before the 2013 beech mast year. In the summer of 2013, at each stand, we established 30 sampling plots stratified by fire severity based on the percent basal area loss of beech (low; intermediate; high). Another 10 plots per stand were assigned to a control (unburnt) group. In the spring of 2014, we counted cupules, seeds, germinated seeds, and emergent seedlings (i.e., rooted in mineral soil) in four squares (0.4 × 0.4 m) at each plot. In the summer of 2014, at each plot, we measured stand characteristics (i.e., a circular area of 12-m in a planar radius) and counted established seedlings in 12 squares (1 × 1 m). Control stands had 448 ± 38 cupules m−2 and 489 ± 44 seeds m−2 with a germination rate of 11%. In comparison to the control, production of cupules and seeds was significantly lower only under high fire severity (−75% and −63%, respectively). At intermediate and low severity sites, cupule and seed production were similar to unburnt sites, while seed germination and seedling emergence were higher. At intermediate severity sites established seedlings (86,000 ± 10,574 seedlings ha−1) were significantly more frequent than the control. Generalized linear and additive models demonstrated that intermediate disturbance of litter and canopy cover favored beech regeneration. Mixed severity fires are an important ecological factor for the natural regeneration of beech. Such insights in beech disturbance ecology can help improve silviculture and post-fire restoration of Alpine forests. The synergy between fire and masting raises new questions concerning the role of fire in temperate beech forests.

Summary Local adaptation in tree species has been documented through a long history of common garden experiments where functional traits (height, bud phenology) are used as proxies for fitness. However, the ability to identify genes or genomic regions related to adaptation to climate requires the evaluation of traits that precisely reflect how and when climate exerts selective constraints.We combine dendroecology with association genetics to establish a link between genotypes, phenotypes and interannual climatic fluctuations. We illustrate this approach by examining individual tree responses embedded in the annual rings of 233 Pinus strobus trees growing in a common garden experiment representing 38 populations from the majority of its range.We found that interannual variability in growth was affected by low temperatures during spring and autumn, and by summer heat and drought. Among‐population variation in climatic sensitivity was significantly correlated with the mean annual temperature of the provenance, suggesting local adaptation. Genotype–phenotype associations using these new tree‐ring phenotypes validated nine candidate genes identified in a previous genetic–environment association study.Combining dendroecology with association genetics allowed us to assess tree vulnerability to past climate at fine temporal scales and provides avenues for future genomic studies on functional adaptation in forest trees., See also the Commentary on this article by https://doi.org/10.1111/nph.15094.

Protected areas are key to preserving biodiversity and maintaining ecosystem services. However, their ability to ensure long-term survival of threatened andendangered species varies across countries, regions and landscapes. Distribution surveys can beparticularly important for assessing the value of protected areas, and gauging their efficacy incatering to species-specific requirements. We assessed the conservation value of one such reserve for a charismatic yet globally endangered species, the red panda Ailurus fulgens,in the light of on-going land-use transformation in Nepal. We conducted field surveys forindirect signs of red pandas along forest trails in 25-km2 sampling grid cells (n = 54) of Dhorpatan Hunting Reserve, and confronted a set of ecological hypotheses to the data using hierarchical occupancy models. We estimated overall occupancy at Ψ(SE) = 0.41 (0.007), with relatively high site-level detectability [p = 0.93 (SE = 0.001)]. Our results show that despitebeing a subsistence form of small-scale resource use, extraction of bamboo and livestock grazing negatively affected panda occurrence, albeit at different intensities. The amount of bamboo cover,rather than the overall proportion of forest cover, had greater influence on the panda occurrence. Despite availability of bamboo cover, areas with bamboo extraction and anthropogenic disturbances were less likely to be occupied by pandas. Together, these results suggest that long-term persistence of red pandas in this reserve and elsewhere across the species’ range will require preventing commercial extractionof bamboo, coupled with case-specific regulation of anthropogenic exploitation of red panda habitats.

International audience; Tree populations at the low-altitudinal or -latitudinal limits of species' distributional ranges are predicted to retreat toward higher altitudes and latitudes to track the ongoing changes in climate. Studies have focused on the climatic sensitivity of the retreating species, whereas little is known about the potential replacements. Competition between tree species in forest ecotones will likely be strongly influenced by the ecophysiological responses to heat and drought. We used tree-ring widths and δ13 C and δ18 O chronologies to compare the growth rates and long-term ecophysiological responses to climate in the temperate-Mediterranean ecotone formed by the deciduous Fagus sylvatica and the evergreen Quercus ilex at the low altitudinal and southern latitudinal limit of F. sylvatica (NE Iberian Peninsula). F. sylvatica growth rates were similar to those of other southern populations and were surprisingly not higher than those of Q. ilex, which were an order of magnitude higher than those in nearby drier sites. Higher Q. ilex growth rates were associated with high temperatures, which have increased carbon discrimination rates in the last 25 years. In contrast, stomatal regulation in F. sylvatica was proportional to the increase in atmospheric CO2 . Tree-ring δ18 O for both species were mostly correlated with δ18 O in the source water. In contrast to many previous studies, relative humidity was not negatively correlated with tree-ring δ18 O but had a positive effect on Q. ilex tree-ring δ18 O. Furthermore, tree-ring δ18 O decreased in Q. ilex over time. The sensitivity of Q. ilex to climate likely reflects the uptake of deep water that allowed it to benefit from the effect of CO2 fertilization, in contrast to the water-limited F. sylvatica. Consequently, Q. ilex is a strong competitor at sites currently dominated by F. sylvatica and could be favored by increasingly warmer conditions.

Climate change and habitat fragmentation are considered key pressures on biodiversity, and mammalian carnivores with a limited geographical distribution are particularly vulnerable. The kodkod Leopardus guigna, a small felid endemic to the temperate forests of southern Chile and Argentina, has the smallest geographical range of any New World felid. Although the species occurs in protected areas in both countries, it is not known how well these areas protect the kodkod either currently or under climate change scenarios. We used species distribution models and spatial analyses to assess the distribution of the kodkod, examining the effects of changes in human land use and future climate change. We also assessed the species’ present representation in protected areas and in light of climate change scenarios. We found that the kodkod has already lost 5.5% of its range as a result of human land use, particularly in central areas of its distribution with intermediate habitat suitability. Climate change, together with human land use, will affect 40% of the kodkod's present potential distribution by the year 2050. Currently, 12.5% of the species’ potential distribution lies in protected areas and this will increase to 14% in the future. This increase does not, however, mean an increase in protected habitat but rather a reduction of the species' total potential range; a relatively larger percentage will be protected in Argentina than in Chile but the species is more susceptible to extinction in Argentina and the Chilean Matorral. Fil: Cuyckens, Griet An Erica. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Morales, Miriam Mariana. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tognelli, Marcelo Fabio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; Argentina

Changing forest cover is a key driver of local climate change worldwide, as it affects both albedo and evapotranspiration (ET). Deforestation and forestation are predicted to have opposing influences on surface albedo and ET rates, and thus impact local surface temperatures differently. Relationships between forest change, albedo, ET, and local temperatures may further vary regionally, as the strengths of warming by albedo effects and cooling by ET effects vary with latitude. Despite these important relationships, the magnitude of forest cover effects on local surface temperature across the globe remains unclear. Using recently-released global forest change data, we first show that forestation and deforestation have pervasive and opposite effects on LST, ET and albedo worldwide. Deforestation from 2000 to 2010 caused consistent warming of 0.38 ± 0.02 (mean ± SE) and 0.16 ± 0.01°C in tropical and temperate regions respectively, while forestation caused cooling in those regions of -0.18 ± 0.02 and -0.19 ± 0.02°C. Tropical forests were particularly sensitive to the climate effects of forest change, with forest cover losses of ~50% associated with increased LST of 1.08 ± 0.25°C, whereas similar forest cover gains decreased LST by -1.11 ± 0.26°C. Secondly, based on a new structural equation model, we show that these changes on LST were largely mediated by changes in albedo and ET. Finally, based on this model, we show that predicted forest changes in Brazil associated with a business-as-usual land use scenario through 2050 may increase LST up to 1.45°C. Our results contribute to a better understanding of the mechanistic inter-relationships between forest change and changes in albedo, ET and LST, and provide additional evidence that forestation has the potential to reverse deforestation impacts on local climate, especially in tropical and temperate regions.

Research Highlights: Excess N from atmospheric deposition has been shown to decrease plant biodiversity of impacted forests, especially in its effects on herbaceous layer communities. This work demonstrates that one of the mechanisms of such response is in N-mediated changes in the response of herb communities to soil resources and light availability. Background and Objectives: Numerous studies in a variety of forest types have shown that excess N can cause loss of biodiversity of herb layer communities, which are typically responsive to spatial patterns of soil resource and light availability. The objectives of this study were to examine (1) gradients of temporal change in herb composition over a quarter century, and (2) spatial patterns of herb cover and diversity and how they are influenced by soil resources and canopy structure. Materials and Methods: This study used two watersheds (WS) at the Fernow Experimental Forest, West Virginia, USA: WS4 as an untreated reference and WS3 as treatment, receiving 35 kg N/ha/yr via aerial application. Herb cover and composition was measured in seven permanent plots/WS from 1991 to 2014. In 2011, soil moisture and several metrics of soil N availability were measured in each plot, along with measurement of several canopy structural variables. Backwards stepwise regression was used to determine relationships between herb cover/diversity and soil/canopy measurements. Results: Herb diversity and composition varied only slightly over time on reference WS4, in contrast to substantial change on N-treated WS3. Herb layer diversity appeared to respond to neither soil nor canopy variables on either watershed. Herb cover varied spatially with soil resources on WS4, whereas cover varied spatially with canopy structure on WS3. Conclusions: Results support work in many forest types that excess N can decrease plant diversity in impacted stands. Much of this response is likely related to N-mediated changes in the response of the herb layer to soil N and light availability.

In Andean Patagonia, Argentina, severe wildfires produce high mortality in Austrocedrus chilensis forests. Owing to its high timber quality, A. chilensis trees are generally salvage logged right after wildfires. Post-logged areas result in open, denuded stands with low herbaceous or shrub cover, which precludes natural A. chilensis regeneration. In severely burned A. chilensis stands, we determined how different site conditions (salvage logging, SL, and without logging, WL), and the combination of different methods of control of above-and belowground competition and micro-environmental factors (incident radiation, soil temperature and soil moisture) affected survival, growth and hydric status of planted A seedlings. Two growing seasons after plantation, seedling survival was lower than 10% at SL sites, whereas it was near 90% at WL sites. Four seasons after establishment, and regardless of competition treatments, no seedlings survived at SL sites, whereas over 75% survived at WL sites. Radiation attenuation by canopy of WL sites benefitted A. chilensis seedling survival, and no additional control of early successional herbaceous species should be necessary to attain high seedling survival 4 years after restoration. Selective logging, by leaving ∼50% of burned snags, and active restoration practices, may help reconcile economic needs of society and ecological requirements of A. chilensis for recovering former structure and functions. Fil: Urretavizcaya, María Florencia. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Ministerio de la Producción; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Defossé, Guillermo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; Argentina

Analyzing how climate change affects vegetation distribution is one of the central issues of global change ecology as this has important implications for the carbon budget of terrestrial vegetation. Mapping vegetation distribution under historical climate scenarios is essential for understanding the response of vegetation distribution to future climatic changes. The reconstructions of palaeovegetation based on pollen data provide a useful method to understand the relationship between climate and vegetation distribution. However, this method is limited in time and space. Here, using species distribution model (SDM) approaches, we explored the climatic determinants of contemporary vegetation distribution and reconstructed the distribution of Chinese vegetation during the Last Glacial Maximum (LGM, 18,000 14C yr BP) and Middle-Holocene (MH, 6000 14C yr BP). The dynamics of vegetation distribution since the LGM reconstructed by SDMs were largely consistent with those based on pollen data, suggesting that the SDM approach is a useful tool for studying historical vegetation dynamics and its response to climate change across time and space. Comparison between the modeled contemporary potential natural vegetation distribution and the observed contemporary distribution suggests that temperate deciduous forests, subtropical evergreen broadleaf forests, temperate deciduous shrublands and temperate steppe have low range fillings and are strongly influenced by human activities. In general, the Tibetan Plateau, North and Northeast China, and the areas near the 30°N in Central and Southeast China appeared to have experienced the highest turnover in vegetation due to climate change from the LGM to the present.

While various relationships between productivity and biodiversity are found in forests, the processes underlying these relationships remain unclear and theory struggles to coherently explain them. In this work, we analyse diversity–productivity relationships through an examination of forest structure (described by basal area and tree height heterogeneity). We use a new modelling approach, called ‘forest factory’, which generates various forest stands and calculates their annual productivity (above-ground wood increment). Analysing approximately 300 000 forest stands, we find that mean forest productivity does not increase with species diversity. Instead forest structure emerges as the key variable. Similar patterns can be observed by analysing 5054 forest plots of the German National Forest Inventory. Furthermore, we group the forest stands into nine forest structure classes, in which we find increasing, decreasing, invariant and even bell-shaped relationships between productivity and diversity. In addition, we introduce a new index, called optimal species distribution, which describes the ratio of realized to the maximal possible productivity (by shuffling species identities). The optimal species distribution and forest structure indices explain the obtained productivity values quite well ( R 2 between 0.7 and 0.95), whereby the influence of these attributes varies within the nine forest structure classes.

Harsh environmental conditions in xeric sites of Andean Patagonia, affect the emergence, survival, and growth of either naturally grown or planted Austrocedrus seedlings. We evaluated the effects of nurse shrubs and tree shelters on the survival and growth of Austrocedrus seedlings as compared to unprotected (control) areas and how differently produced seedling types perform under these treatments. In 2006, two Austrocedrus seedling types (1 + 2 = S1 and Plug 2 + 1 = S2) were planted under shrub cover (C1), tree shelter (C2), and control (C3). Soil surface temperature and moisture were measured for each treatment during the first growing season, while seedling survival and height were recorded during 5 years. Survival was not affected by cover type the first year, but it was affected by seedling type (S1 > S2). After an extremely dry second growing season, seedling survival significantly decreased in relation to either cover or seedling type. Five years after plantation, survival was significantly higher for C1 and C2 (40–60 %) as compared to C3-S2 (18 %). Seedling height was significantly affected by cover, but not by seedling type. The use of nurse shrubs and/or tree shelters is useful in Austrocedrus seedling restoration trials. Seedling morphology appears as relevant for survival in semiarid environments.

We modelled the combined effects of past and expected future changes in climate and nitrogen deposition on tree carbon sequestration by European forests for the period 1900–2050. Two scenarios for deposition (current legislation and maximum technically feasible reductions) and two climate scenarios (no change and SRES A1 scenario) were used. Furthermore, the possible limitation of forest growth by calcium, magnesium, potassium and phosphorus is investigated. The area and age structure of the forests was assumed to stay constant to observations during the period 1970–1990. Under these assumptions, the simulations show that the change in forest growth and carbon sequestration in the past is dominated by changes in nitrogen deposition, while climate change is the major driver for future carbon sequestration. However, its impact is reduced by nitrogen availability. Furthermore, limitations in base cations, especially magnesium, and in phosphorus may significantly affect predicted growth in the future. A modelling exercise indicates that nitrogen deposition mainly enhanced tree carbon sequestration in Europe in the past, while climate change will do so in the future

Forest vegetation is a key factor in the maintenance of global carbon cycle balance under the present climate change conditions. Forest ecosystems are both buffers against extreme climatic events accompanying climate change and carbon sinks diminishing the environmental impact of anthropogenic greenhouse gas emissions. We investigated the influence of stand structure and site characteristics on the productivity and carbon storage capacity of temperate forest types. Predictors of species productivity were parameters such as stand density, age, height, average diameter and wood density. Morus alba (L.) was more productive than average both in terms of annual volume increment and annual biomass gain, while Quercus sessiliflora (Matt.) Lieb. and Quercus frainetto (Ten.) were significantly less productive than average. Differences in stand productivity were explained by stand density, age, height, altitude, type of regeneration and species composition. Statistically significant differences were measured between the productivity of stands dominated by different woody species, with low productive stands dominated by slow growing species with high wood density like Quercus or Fagus, and highly productive stands rich in fast growing species with low wood density like Populus or Salix. Stands with different plant communities in the underlying herbaceous layer also tended to have different levels of productivity.

China harbors diversified forest types, from tropical rainforest to boreal coniferous forest, and has implemented large-scale reforestation/afforestation programs over the past several decades. However, little information is available on changes in China's forest area and the causes. In this study, we used the classified forest distribution thematic map derived from Normalized Difference Vegetation Index (NDVI) datasets and a revised IPAT model to examine China's forest area change and the possible driving factors from 1982 to 2006. Overall, NDVI-derived forest areas were numerically consistent with those reported in the 3rd, 4th, 5th, and 6th National Forest Inventories, respectively. Over the past 25 years, China's forest area was estimated to have an average of 169.18 million hectares with an annual increase of 0.15 million hectares (c.a. a total net increment of 3.60 million hectares), which is equivalent to 0.089% of the relative annual change rate. However, a large difference in the changing rate and direction of forest area at the province level was found; for instance, forest area has declined in 10 provinces, mainly in Northeastern and Southern China, while 21 provinces showed an increase. The changes were most likely attributed to the policy regarding the import and export of timber and affluence (per capita gross domestic product), and both contributed more than 80% of the total contribution of the six factors of the revised IPAT model.

Partitioning the components of soil respiration is crucial to understand and model carbon cycling in forest ecosystems. In this study, total soil respiration (RS), autotrophic respiration (RA), heterotrophic respiration (RH), litter respiration (RL), litterfall input and environmental factors were synchronously monitored for 2 years in a subtropical Michelia wilsonii forest of southwestern China. RH rates were often higher than RA rates during the two years except for the middle growing season (from July to September). The mean rate of Rs, RA, RH and RL was 1.94 μmol m-1 s-1, 0.85 μmol m-1 s-1, 1.09 μmol m-1 s-1 and 0.65 μmol m-1 s-1, respectively, during the 2-year experiment. Annual CO2 emission derived from RA, RH and RL was 3.26 Mg C ha-1 a-1, 4.67 Mg C ha-1 a-1 and 2.61 Mg C ha-1 a-1, respectively, which accounted for 41.4%, 58.6% and 32.9% of RS. Over the experimental period, the ratio of RA/RS increased with soil temperature but the opposite was true for RH/RS and RL/RS. The Q10 value was 2.01, 4.01, 1.34 and 1.30, respectively, for RS, RA, RH and RL. Path analysis indicated that environmental variables and litterfall production together explained 82.0%, 86.8%, 42.9% and 34.7% variations of monthly fluxes of RS, RA, RH and RL, respectively. Taken together, our results highlight the differential responses of the components of RS to environmental variables.

The Chinese pine (Pinus tabulaeformis Carr.) is an ecologically and economically important evergreen coniferous tree which dominates warm temperate forests throughout northern China. We established two permanent plots within the Chinese pine forest in the Jiulong Mountains, Beijing, China. To understand the structural characteristics and dynamics of these plots, we analyzed the spatial structural characteristics within nearest-neighbor relationships using the bivariate distributions of the stand spatial structural parameters: uniform angle index, W; mingling index, M; dominance index, U; and crowding index, C. Results revealed that most trees in the forest were randomly distributed. The predominant individuals and randomly arranged trees were in very dense areas and surrounded by the same species. In addition, both plots exhibited a uniform size differentiation pattern. The two plots differed mainly in the level of species mixture and dominance. The majority of reference trees in the pure Chinese pine forest (plot 1) exhibited poor species mingling and low dominance, whereas trees in the mixed Chinese pine forest (plot 2) were evenly distributed in each mingling class and most trees were of intermediate dominance. The study results are useful for optimizing forest management activities in the studied stands, promoting tree growth, regeneration and habitat diversity, and improving forest quality at a fine scale.

Increasing temperature and nitrogen (N) deposition are two large-scale changes projected to occur over the coming decades. The effects of these changes on dissolved organic matter (DOM) are largely unknown. This study aimed to assess the effects of warming and N addition on the quantity and quality of DOM from a subtropical Cunninghamia lanceolata plantation. Between 2014 and 2016, soil solutions were collected from 0-15, 15-30, and 30-60 cm depths by using a negative pressure sampling method. The quantity and quality of DOM were measured under six different treatments. The spectra showed that the DOM of the forest soil solution mainly consisted of aromatic protein-like components, microbial degradation products, and negligible amounts of humic-like substances. Warming, N addition, and warming + N addition significantly inhibited the concentration of dissolved organic carbon (DOC) in the surface (0-15 cm) soil solution. Our results suggested that warming reduced the amount of DOM originating from microbes. The decrease in protein and carboxylic acid contents was mostly attributed to the reduction of DOC following N addition. The warming + N addition treatment showed an interactive effect rather than an additive effect. Thus, short-term warming and warming + N addition decreased the quantity of DOM and facilitated the migration of nutrients to deeper soils. Further, N addition increased the complexity of the DOM structure. Hence, the loss of soil nutrients and the rational application of N need to be considered in order to prevent the accumulation of N compounds in soil.