The net primary productivity(NPP)of forest ecosystems plays a crucial role in regulating the terrestrial carbon cycle under global climate change.While the temporal effect driven by ecosystem processes on NPP variatio...The net primary productivity(NPP)of forest ecosystems plays a crucial role in regulating the terrestrial carbon cycle under global climate change.While the temporal effect driven by ecosystem processes on NPP variations is well-documented,spatial variations(from local to regional scales)remain inadequately understood.To evaluate the scale-dependent effects of productivity,predictions from the Biome-BGC model were compared with moderate-resolution imaging spectroradiometer(MODIS)and biometric NPP data in a large temperate forest region at both local and regional levels.Linear mixed-effect models and variance partitioning analysis were used to quantify the effects of environmental heterogeneity and trait variation on simulated NPP at varying spatial scales.Results show that NPP had considerable predictability at the local scale,with a coefficient of determination(R^(2))of 0.37,but this predictability declined significantly to 0.02 at the regional scale.Environmental heterogeneity and photosynthetic traits collectively explained 94.8%of the local variation in NPP,which decreased to 86.7%regionally due to the reduced common effects among these variables.Locally,the leaf area index(LAI)predominated(34.6%),while at regional scales,the stomatal conductance and maximum carboxylation rate were more influential(41.1%).Our study suggests that environmental heterogeneity drives the photosynthetic processes that mediate NPP variations across spatial scales.Incorporating heterogeneous local conditions and trait variations into analyses could enhance future research on the relationship between climate and carbon cycles at larger scales.展开更多
Warm-wet climatic conditions are widely regarded as conducive to remarkable tree growth,alleviating climatic pressures.However,the notable decline in tree growth observed in the southern edge of boreal forests has hei...Warm-wet climatic conditions are widely regarded as conducive to remarkable tree growth,alleviating climatic pressures.However,the notable decline in tree growth observed in the southern edge of boreal forests has heightened concerns over the spatial-temporal dynamics of forest decline.Currently,attaining a comprehensive grasp of the underlying patterns and their propelling factors remains a formidable challenge.We collected tree ring samples from a network of 50 sites across the Greater Xing'an Mountains.These samples were subsequently grouped into two distinct clusters,designated as Groups A and B.The percentage change of growth(GC,%)and the proportion of declining sites were utilized to assess forest decline.The decline in tree growth within Larix gmelinii forests exhibits significant regional variation,accompanied by temporal fluctuations even within a given region.Group A exhibited a pronounced increase in frequency(59.26%)of occurrences and encountered more severe declines(21.65%)in tree growth subsequent to the 1990s,contrasting sharply with Group B,which observed lower frequencies(20.00%)and relatively less severe declines(21.02%)prior to the 1980s.The primary impetus underlying the opposite radial growth increments observed in Larix gmelinii trees from the interplay between their differential response to temperatures and wetter climatic conditions,which is significantly influenced by varying stand densities.In cold-dry conditions,low-density forests may experience soil water freezing,exacerbating drought conditions and thereby inhibiting tree growth,in Group B.Trees growth in high-density stands is restrained by warm-wet conditions,in Group A.These results provide new insights into the variability at the southern edge of the boreal forest biome with different responses to density and climate.展开更多
Understanding competition between trees is essential for sustainable forest management as interactions between trees in uneven-aged mixed forests play a key role in growth dynamics. This study investigated nine compet...Understanding competition between trees is essential for sustainable forest management as interactions between trees in uneven-aged mixed forests play a key role in growth dynamics. This study investigated nine competition indices(CIs) for their suitability to model the effects of neighboring trees on silver fir(Abies alba) growth in Dinaric silver fir-European beech(Fagus sylvatica) forests. Although numerous competition indices have been developed, there is still limited consensus on their applicability in different forest types, especially in mature, structurally complex forest stands. The indices were evaluated using the adjusted coefficient of determination in a linear model wherein the volume growth of the last five years for 60 dominant silver fir trees was modeled as a function of tree volume and competition index. The results demonstrated that distance-dependent indices(e.g., the Hegyi height-distance competition and Rouvinen-Kuuluvainen diameter-distance competition indices), which consider the distance to competitors and their size, perform better than distance-independent indices. Using the optimization procedure in calculating the competition indices, only neighboring trees at a distance of up to 26-fold the diameter at breast height(DBH) of the selected tree(optimal search radius) and with a DBH of at least 20% of that of the target tree(optimal DBH) were considered competitors. Therefore, competition significantly influences the growth of dominant silver firs even in older age classes. The model based solely on tree volume explained 32.5% of the variability in volume growth, while the model that accounted for competition explained 64%. Optimizing the optimal search radius had a greater impact on model performance than optimizing the DBH threshold. This emphasizes the importance of balancing stand density and competition in silvicultural practice.展开更多
Evergreen broad-leaved forests(EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various discipli...Evergreen broad-leaved forests(EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various disciplines. In this study, we explored the occurrence of East Asian EBLFs from a paleobotanical perspective. By collecting plant fossils from four regions in East Asia, we have established the evolutionary history of EBLFs. Through floral similarity analysis and paleoclimatic reconstruction, we have revealed a diverse spatio-temporal pattern for the occurrence of EBLFs in East Asia. The earliest occurrence of EBLFs in southern China can be traced back to the middle Eocene, followed by southwestern China during the late Eocene-early Oligocene. Subsequently, EBLFs emerged in Japan during the early Oligocene and eventually appeared in central-eastern China around the Miocene. Paleoclimate simulation results suggest that the precipitation of wettest quarter(PWet Q, mm) exceeding 600 mm is crucial for the occurrence of EBLFs. Furthermore, the heterogeneous occurrence of EBLFs in East Asia is closely associated with the evolution of the Asian Monsoon. This study provides new insights into the occurrence of EBLFs in East Asia.展开更多
The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical ...The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical forest ecosystems in different ecological zones,which are being affected by climate change to a level that they are becoming carbon sources instead of sinks.Stratified sampling technique was used to categorize tropical forests into rain,moist deciduous and dry zone forests depending on the average annual rainfall received.Simple random sampling technique was used to select three tropical forests in each category.Modified consistent sampling technique was used to develop 10 main 20 m×100 m plots in each forest,with 202 m×50 m sub-plots in each plot.Systematic random sampling technique was used in selecting 10 sub-plots from each main plot for inventory study.Non-destructive approach based on allometric equations using trees’diameter at breast height(DBH),total height and species’wood specific gravity were used in estimating tree carbon stock in each forest.Soil organic carbon(SOC)and litter nutrient concentration(total phosphorus and nitrogen)were determined in each forest based on standard laboratory procedures.The results indicated that,whilst trees in rain forests recorded a significantly higher(p<0.001)DBH(20.36 cm)and total tree height(12.1 m),trees in dry zone forests recorded a significantly higher(p<0.001)specific gravity(0.67 kg m^(−3)).Dry zone tropical forests stored a significantly lower amount of total tree carbon of 73 Mg ha^(−1),compared to tropical rain forests(439.5 Mg ha^(−1))and moist deciduous tropical forests(449 Mg ha^(−1)).The SOC content was significantly higher in tropical rainforests(3.9%),compared to soils from moist deciduous(2.9%)and dry zone forests(1.8%).While litter from tropical rain forests recorded a significantly higher amount of total nitrogen(3.4%),litter from dry zone forests recorded a significantly higher concentration of total phosphorus(0.27%).In conclusion,ecological gradient that is dictated by the prevailing temperatures and precipitation affects the tropical forests carbon stock potential and litter nutrient concentration.This implies that,the changing climate is having a serious implication on the ecosystem services such as carbon stock and nutrients cycling in tropical forests.展开更多
Old-growth forests are of major importance for biodiversity conservation and climate change mitigation,as well as being a benchmark for the implementation of sustainable forest management.Although dedicated studies ha...Old-growth forests are of major importance for biodiversity conservation and climate change mitigation,as well as being a benchmark for the implementation of sustainable forest management.Although dedicated studies have significantly increased in the last decades,there is still limited knowledge of Mediterranean forests,especially those dominated by Quercus pubescens and related taxa.To fill this knowledge gap,we primarily studied in the field two downy oak forests possessing old-growth traits,localized in Sicily(Mediterranean,Italy).Second,we used a structural heterogeneity index(SHI)to assess their old-growthness level,in comparison with the downy oak stands surveyed in the Regional Forest Inventory(RFI)of Sicily.Third,we tested the effect of different sets of structural parameters on SHI scores,thus assessing whether their choice could affect the final score and the stand assessment.SHI was well proven to discriminate these two stands from the others,both showing,on average,a SHI score just higher than 80,whilst SHI in RFI plots was just under 50,a significantly lower value.The methodological approach used in our study highlights the need to standardize the parameters used to characterize the old-growthness level of Mediterranean forests in order to allow more reliable comparisons.Most of the structural parameters were higher in the two selected stands,except for the attributes related to standing deadwood,suggesting a still limited contribution of standing dead trees and snags in the potential old-growth stands under investigation.The application of a structural index has proven effective for the purpose it was tested for,demonstrating its usefulness in discriminating between two potential old-growth stands from ordinary stands of the same forest type.We believe that both forests deserve primary attention and tailored management measures,as well as inclusion in the recently established Italian Network of old-growth forests.展开更多
Over the past decades,the expansion of natu-ral secondary forests has played a crucial role in offsetting the loss of primary forests and combating climate change.Despite this,there is a gap in our understanding of ho...Over the past decades,the expansion of natu-ral secondary forests has played a crucial role in offsetting the loss of primary forests and combating climate change.Despite this,there is a gap in our understanding of how tree species’growth and mortality patterns vary with eleva-tion in these secondary forests.In this study,we analyzed data from two censuses(spanning a five-year interval)conducted in both evergreen broadleaved forests(EBF)and temperate coniferous forests(TCF),which have been recovering for half a century,across elevation gradients in a subtropical mountain region,Mount Wuyi,China.The results indicated that the relative growth rate(RGR)of EBF(0.028±0.001 cm·cm^(-1)·a^(-1))and the mortality rate(MR)(20.03%±1.70%)were 27.3%and 16.4%higher,respec-tively,than those of TCF.Interestingly,the trade-off between RGR and MR in EBF weakened as elevation increased,a trend not observed in TCF.Conversely,TCF consistently showed a stronger trade-off between RGR and MR compared to EBF.Generalized linear mixed models revealed that ele-vation influences RGR both directly and indirectly through its interactions with slope,crown competition index(CCI),and tree canopy height(CH).However,tree mortality did not show a significant correlation with elevation.Additionally,DBH significantly influenced both tree growth and mortal-ity,whereas and CH and CCI had opposite effects on tree growth between EBF and TCF.Our study underscores the importance of elevation in shaping the population dynamics and the biomass carbon sink balance of mountain forests.These insights enhance our understanding of tree species’life strategies,enabling more accurate predictions of forest dynamics and their response to environmental changes.展开更多
With the rapid economic development and continuous expansion of human activities,forest degradation—characterized by reduced forest stock within the forest including declining carbon storage—poses significant threat...With the rapid economic development and continuous expansion of human activities,forest degradation—characterized by reduced forest stock within the forest including declining carbon storage—poses significant threats to ecosystem stability.Understanding the current status of forest degradation and assessing potential carbon stocks in China are of strategic importance for making forest restoration efforts and enhancing carbon sequestration capacity.In this study,we used the national forest inventory data from 2009 to 2018 to develop a set of standard measures for assessing degraded forests across China,based on five key indicators:forest accumulation growth rate(FAGR),forest recruitment rate(FRR),tree species reduction rate(TSRR),forest canopy cover reduction rate(FCCRR),and forest disaster level(FDL).Additionally,we estimated standing carbon stock,potential carbon stock,and theoretical space to grow by developing a stand growth model,which accounts for stand density across different site classes,to evaluate the restoration potential of degraded forests.The results indicate that degraded forest area in China is 36.15 million hectares,accounting for 20.10% of a total forest area.Standing carbon stock and potential carbon stock of degraded forests in China are 23.93 million tons and 61.90 million tons,respectively.Overall,degraded forest varies significantly across different regions.The results highlight the important trade-offs among environmental factors,policy decisions,and forest conditions,providing a robust foundation for developing measures to enhance forest quality.展开更多
Forests play a vital role in mitigating climate change through their physiological functions and metabolic processes,including their ability to convert solar energy into biomolecules.However,further research is necess...Forests play a vital role in mitigating climate change through their physiological functions and metabolic processes,including their ability to convert solar energy into biomolecules.However,further research is necessary to elucidate how structural characteristics of a forest and topographic settings influence energy conversion and surface temperature of a forest.In this study,we investigated a beech forest in central Germany using airborne laser scanning(ALS)point cloud data and land surface temperature(LST)data derived from Landsat 9 satellite imagery.We constructed 30 m×30 m plots across the study area(approximately 17 km2)to align the spatial resolution of the satellite imagery with the ALS data.We analyzed topographic variables(surface elevation,aspect and slope),forest attributes(canopy cover,canopy height,and woody area index),as well as forest structural complexity,quantified by the box-dimension(Db).Our analysis revealed that LST is significantly influenced by both forest attributes and topographic variables.A multiple linear regression model demonstrated an inverse relationship(R^(2)=0.38,AIC=8105)between LST and a combination of Db,elevation,slope,and aspect.However,the model residuals exhibited significant spatial dependency,as indicated by Moran’s I test.To address this,we applied a spatial autoregressive model,which effectively accounted for spatial autocorrelation and improved the model fit(AIC=746).Our findings indicate that elevation exerts the most substantial influence on LST,followed by forest structural complexity,slope,and aspect.We conclude that forest management practices that enhance structural complexity can effectively reduce land surface temperatures in forested landscapes.展开更多
Rapid urbanization has caused significant changes along the urban-rural gradient,leading to a variety of landscapes that are mainly shaped by human activities.This dynamic interplay also influences the distribution an...Rapid urbanization has caused significant changes along the urban-rural gradient,leading to a variety of landscapes that are mainly shaped by human activities.This dynamic interplay also influences the distribution and characteristics of trees outside forests(TOF).Understanding the pattern of these trees will support informed decision-making in urban planning,in conservation strategies,and altogether in sustainable land management practices in the urban context.In this study,we employed a deep learning-based object detection model and high resolution satellite imagery to identify 1.3 million trees with bounding boxes within a 250 km^(2)research transect spanning the urban-rural gradient of Bengaluru,a megacity in Southern India.Additionally,we developed an allometric equation to estimate diameter at breast height(DBH)from the tree crown diameter(CD)derived from the detected bounding boxes.Our study focused on analyzing variations in tree density and tree size along this gradient.The findings revealed distinct patterns:the urban domain displayed larger tree crown diameters(mean:8.87 m)and DBH(mean:43.78 cm)but having relatively low tree density(32 trees per hectare).Furthermore,with increasing distance from the city center,tree density increased,while the mean tree crown diameter and mean tree basal area decreased,showing clear differences of tree density and size between the urban and rural domains in Bengaluru.This study offers an efficient methodology that helps generating instructive insights into the dynamics of TOF along the urban-rural gradient.This may inform urban planning and management strategies for enhancing green infrastructure and biodiversity conservation in rapidly urbanizing cities like Bengaluru.展开更多
In this study,we used an extensive sampling network established in central Romania to develop tree height and crown length models.Our analysis included more than 18,000 tree measurements from five different species.In...In this study,we used an extensive sampling network established in central Romania to develop tree height and crown length models.Our analysis included more than 18,000 tree measurements from five different species.Instead of building univariate models for each response variable,we employed a multivariate approach using seemingly unrelated mixed-effects models.These models incorporated variables related to species mixture,tree and stand size,competition,and stand structure.With the inclusion of additional variables in the multivariate seemingly unrelated mixed-effects models,the accuracy of the height prediction models improved by over 10% for all species,whereas the improvement in the crown length models was considerably smaller.Our findings indicate that trees in mixed stands tend to have shorter heights but longer crowns than those in pure stands.We also observed that trees in homogeneous stand structures have shorter crown lengths than those in heterogeneous stands.By employing a multivariate mixed-effects modelling framework,we were able to perform cross-model random-effect predictions,leading to a significant increase in accuracy when both responses were used to calibrate the model.In contrast,the improvement in accuracy was marginal when only height was used for calibration.We demonstrate how multivariate mixed-effects models can be effectively used to develop multi-response allometric models that can be easily calibrated with a limited number of observations while simultaneously achieving better-aligned projections.展开更多
Prescribed burning is commonly used to maintain forest ecosystem functions and reduce the risk of future wildfires.Although many studies have investigated the response of microbial community to wildfires in forest eco...Prescribed burning is commonly used to maintain forest ecosystem functions and reduce the risk of future wildfires.Although many studies have investigated the response of microbial community to wildfires in forest ecosystems,the effects of prescribed burnings on soil microbial community structure are less studied.It is also unclear that how post-fire soil physiochemical properties changes affected soil microbial communities.Here,we studied the impacts of prescribed burning on soil microbiome in three typical temperate forests of northern China by collecting soil physicochemical and high-throughput sequencing for 16S rRNA and 18S rRNA was applied to analyze the diversity and community composition of soil microbes(bacteria and fungi).Compared with pre-fire condition,prescribed burning significantly decreased Chaol index and altered soil bacterial communities(P<0.05),whereas it had no significant effect on fungal diversity and community structure of the(P>0.05).Planctomycetes and Actinobacteria made the greatest contributions to the bacterial community dissimilarity between the pre-fire and post-fire conditions.The main variables influencing the post-fire soil microbial community structure are soil pH,available phosphorus,total nitrogen,and the ratio of soil total carbon to soil total nitrogen,which could account for 73.5% of the variation in the microbial community structure in these stands.Our findings demonstrated a great discrepancy in the responses of bacteria and fungi to prescribed burning.Prescribed burning altered the soil microbial structure by modifying the physicochemical properties.Our results pointed that it is essential to evaluate the impact of prescribed burnings on forest ecosystem functions.These findings provide an important baseline for assessing post-fire microbial recovery in the region and offer critical guidance for restoration efforts.展开更多
Fine roots play a crucial role in the biogeochemical cycles of terrestrial ecosystems.Patterns of fine roots biomass formation for broad geographical areas are still unclear.We use published estimates of characteristi...Fine roots play a crucial role in the biogeochemical cycles of terrestrial ecosystems.Patterns of fine roots biomass formation for broad geographical areas are still unclear.We use published estimates of characteristics of European pine and spruce stands to determine their productivity and calculate the needle biomass.Then,the relationship between the fine-root:needle biomass ratio of European pine and spruce forests and the stand quality index,which is a proxy of soil fertility,was determined.We show that a rise in soil fertility is accompanied by a decrease in this ratio.Moving from the northern edge of the boreal zone southwards,with the related rise in air and soil temperatures,we see a decline in the mass ratio of fine roots and needle.The change in the fine-root:needle biomass ratio is controlled by the change in specific water uptake by roots,which is related to the osmotic pressure of the solution in the absorbing root's central vascular cylinder.The fine-root:needle ratio does not vary among stands of the same age if the stand quality index and the geographical latitude(a proxy of air and soil temperatures)are constant.These findings may be useful for further in-depth analysis of forest ecosystem functioning in Europe.展开更多
Extreme disturbance activity is a signature of anthropogenic environmental change. Empirical information describing the historical normative limits of disturbance regimes provides baseline data that facilitates the de...Extreme disturbance activity is a signature of anthropogenic environmental change. Empirical information describing the historical normative limits of disturbance regimes provides baseline data that facilitates the detection of contemporary trends in both disturbances and community-level responses. Quantifying the attributes of historical disturbances is challenging due to their transient episodic nature, with decades-to centurieslong intervals between recurrences. Unmanaged primary forests that support centuries-old trees therefore serve as unique reference systems for quantifying past disturbance regimes. We surveyed relict stands of primary beech-dominated forests over wide environmental gradients in the Carpathian Mountains of Europe. We collected core samples from 3,026 trees in 208 field survey plots distributed across 13 forest stands in two countries. We used dendrochronological methods to analyze time-series of annually-resolved ring-width variation and to identify anomalous growth patterns diagnostic of past forest canopy removal. A 180-year record(1810–1990) of spatially and temporally explicit disturbance events(n =333) was compiled and used to derive s tatistical attributes of the disturbance regime. We quantified disturbance severity(canopy area lost), patch size, and return intervals. Our analyses describe a complex regime where a background of relatively frequent, smallscale, low-to intermediate-severity disturbance was punctuated by episodic large-scale high-severity events. Even the most severe events were non-catastrophic at a stand level, leaving significant residual tree cover that supported a continuity of ecological function. We did not detect evidence for an expected climate-induced intensification of disturbance with time, but methodological limitations precluded an assessment of disturbance activity in the decades since 1990.展开更多
Texas experienced the worst drought in its 100-year history in 2011,resulting in the death of approximately 300 million trees.The high number of sudden deaths had a significant impact on forest ecosystems.This study a...Texas experienced the worst drought in its 100-year history in 2011,resulting in the death of approximately 300 million trees.The high number of sudden deaths had a significant impact on forest ecosystems.This study aimed to gain insight into the long-term and combined impacts of drought-induced forest tree deaths and their effects on biomass.This study used data obtained from 1797 National Forest Inventory(NFI)plots to analyze trends and major causes of changes in tree biomass at the sample plot level in East Texas forests over the past 20 years(2000-2019).In this study,forest trees in East Texas were divided into diameter at breast height(dbh),height,stand types,latitude,elevation,ecological zones,and FIA Unit.Principal component analysis(PCA)was also performed using drought intensity,drought duration,the four competing factor indicators,and the biomass loss rate of forest trees to better understand r drought impacts on forest trees.The results showed the lowest biomass loss rate of Pine species.Similarly,trees with shorter height and smaller dbh experienced a higher biomass loss rate.A higher biomass loss rate was observed in natural forests,West Gulf Coastal Plain and Plain and Southern East Texas ecoregion experienced higher biomass loss.Principal component analyses of drought intensity,drought duration,and the four competing metrics revealed that overall drought was the main contributor to biomass loss rates,and that drought intensity and drought duration had comparable effects on biomass loss rates.展开更多
Anthropogenic activities have significantly contributed to the loss and fragmentation of primary forests across the globe,which has accelerated biodiversity decline,particularly among highly specialised species depend...Anthropogenic activities have significantly contributed to the loss and fragmentation of primary forests across the globe,which has accelerated biodiversity decline,particularly among highly specialised species dependent on unique forest structures.Nevertheless,comparative studies between primary and managed forests are scarce,despite their importance for effective monitoring and conservation planning.To address this knowledge gap,we conducted a comparative study using a unique dataset of permanent study plots established across some of the best-preserved,mixed-beech primary forests and their adjacent managed counterparts in the Western Carpathian Mountains.We assessed the effects of forest structure and tree age—determined through extensive dendrochronological reconstructions—on contemporary lichen communities.Lichen species richness and the richness of red-listed species were 26%and 50%higher in primary forests than in managed forests,respectively,highlighting the outstanding conservation importance of primary forests.Generalised least squares(GLS)modelling demonstrated that in managed forests,lichen species richness was strongly associated with structural attributes:It increased with maximum tree age and the diameter of standing deadwood,and decreased with higher basal area(BA)of living trees,likely due to reduced understory light.In contrast,no structural variables significantly explained richness in primary forests,likely due to structural saturation and widespread microhabitat availability.Elevation emerged as the sole variable with significant explanatory strength.These findings underscore the critical role of structural complexity in supporting lichen diversity under different management regimes and provide a robust evidence base for promoting elements such as old trees,deadwood—especially large standing deadwood—and reduced canopy density.At the same time,they reaffirm the irreplaceable value of primary forests as biodiversity refuges and highlight the need for landscape-level conservation strategies that integrate both intact primary and structurally enriched managed forests.展开更多
A key property of the boreal forest is that it stores huge amounts of carbon(C),especially belowground in the soil.Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to...A key property of the boreal forest is that it stores huge amounts of carbon(C),especially belowground in the soil.Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to an interplay between several variables facilitating or preventing C accumulation.In this study,we split C stocks into the organic layer and charcoal C due to their difference in origin,stability,and ecological properties.We compared organic layer C and charcoal C stocks in two regions of south-central Norway(Trillemarka and Varaldskogen),characterized by Scots pine and Norway spruce forests with varying fire histories.We used structural equation modeling to investigate how vegetation composition,hydrotopography,and soil properties interplay to shape organic layer C and charcoal C stocks.Pine forests consistently contained larger organic layer C stocks than spruce forests.Charcoal stocks,in contrast,were less consistent across both forest types and study regions as pine forests had higher charcoal C stocks than spruce forests in Trillemarka,while the two forest types contained equal charcoal C stocks in Varaldskogen.Charcoal and soil organic layer C stocks increased with higher fire frequencies(number of fire events over the last 600 years),but not with a shorter time since last fire(TSF).Additionally,vegetation composition,terrain slope,and soil moisture were the most important drivers of the organic layer C stocks,while charcoal C stocks were mainly controlled by the depth of the organic layer.Also,microtopography was of importance for organic layer C and charcoal C,since depressions in the forest floor had more charcoal C than well-drained minor hills.展开更多
The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European b...The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas.Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems'resistance and resilience mechanisms.Process-based models(PBMs)can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches.In this study,we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes.We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon(C)and water(H_(2)O)fluxes in two sites of the Italian peninsula,Cansiglio in the north and Mongiana in the south,under managed vs.unmanaged scenarios and under current climate and different climatic scenarios(RCP4.5 and RCP8.5).To ensure confidence in the models’results,we preliminary evaluated their performance in simulating C and H_(2)O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy.The 3D-CMCC-FEM model achieved R^(2)values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H_(2)O fluxes,respectively.MEDFATE showed R^(2)values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01.At the Cansiglio site in northern Italy,both models simulated a general increase in C and H_(2)O fluxes under the RCP8.5 climate scenario compared to the current climate.Still,no benefit in managed plots compared to unmanaged ones,as the site does not have water availability limitations,and thus,competition for water is low.At the Mongiana site in southern Italy,both models predict a decrease in C and H_(2)O fluxes and sensitivity to the different climatic forcing compared to the current climate;and an increase in C and H_(2)O fluxes when considering specific management regimes compared to unmanaged scenarios.Conversely,under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress(MEDFATE)and carbon starvation(3D-CMCC-FEM)scenarios.In conclusion,while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio,in drier sites like Mongiana conservation may not lie in management interventions alone.展开更多
Soil organic carbon(SOC)decomposition in high-latitude boreal forests exhibits heightened sensitivity to climate change.However,a comprehensive understanding of the underlying drivers governing soil microbial decompos...Soil organic carbon(SOC)decomposition in high-latitude boreal forests exhibits heightened sensitivity to climate change.However,a comprehensive understanding of the underlying drivers governing soil microbial decomposition responses to warming in these ecosystems remains elusive,especially regarding the roles of mineral protection and microbial genomic traits.In this study,we examined the temperature sensitivity(Q_(10))and minimum temperature(Tmin)of soil microbial respiration across a latitudinal gradient in China's boreal forests.The potential regulators,including climatic factors,soil physicochemical properties,substrate quality,mineral protection,and microbial genomic traits,were also synchronously measured.The results showed a positive correlation between Q_(10) and Tmin,i.e.,greater microbial adaptability to low temperatures is associated with lower microbial sensitivity to increasing temperatures.Boreal forest soil with stronger mineral protection exhibited a higher Q10.In addition,microbial communities characterized by a higher abundance of coding genes demonstrated significantly lower Q_(10) and reduced Tmin.These results collectively highlight the pivotal roles of mineral protection and microbial genomic traits in shaping the biogeographic pattern of Q_(10) across boreal forests.展开更多
基金supported by the National Key R&D Program of China(No.2023YFF1304001-01)the Science and Technology Project of the Department of Transportation of Heilongjiang Province(No.HJK2023B024-3)the Program of National Natural Science Foundation of China(No.32371870).
文摘The net primary productivity(NPP)of forest ecosystems plays a crucial role in regulating the terrestrial carbon cycle under global climate change.While the temporal effect driven by ecosystem processes on NPP variations is well-documented,spatial variations(from local to regional scales)remain inadequately understood.To evaluate the scale-dependent effects of productivity,predictions from the Biome-BGC model were compared with moderate-resolution imaging spectroradiometer(MODIS)and biometric NPP data in a large temperate forest region at both local and regional levels.Linear mixed-effect models and variance partitioning analysis were used to quantify the effects of environmental heterogeneity and trait variation on simulated NPP at varying spatial scales.Results show that NPP had considerable predictability at the local scale,with a coefficient of determination(R^(2))of 0.37,but this predictability declined significantly to 0.02 at the regional scale.Environmental heterogeneity and photosynthetic traits collectively explained 94.8%of the local variation in NPP,which decreased to 86.7%regionally due to the reduced common effects among these variables.Locally,the leaf area index(LAI)predominated(34.6%),while at regional scales,the stomatal conductance and maximum carboxylation rate were more influential(41.1%).Our study suggests that environmental heterogeneity drives the photosynthetic processes that mediate NPP variations across spatial scales.Incorporating heterogeneous local conditions and trait variations into analyses could enhance future research on the relationship between climate and carbon cycles at larger scales.
基金National Nature Science Foundation of China(No.32371871)。
文摘Warm-wet climatic conditions are widely regarded as conducive to remarkable tree growth,alleviating climatic pressures.However,the notable decline in tree growth observed in the southern edge of boreal forests has heightened concerns over the spatial-temporal dynamics of forest decline.Currently,attaining a comprehensive grasp of the underlying patterns and their propelling factors remains a formidable challenge.We collected tree ring samples from a network of 50 sites across the Greater Xing'an Mountains.These samples were subsequently grouped into two distinct clusters,designated as Groups A and B.The percentage change of growth(GC,%)and the proportion of declining sites were utilized to assess forest decline.The decline in tree growth within Larix gmelinii forests exhibits significant regional variation,accompanied by temporal fluctuations even within a given region.Group A exhibited a pronounced increase in frequency(59.26%)of occurrences and encountered more severe declines(21.65%)in tree growth subsequent to the 1990s,contrasting sharply with Group B,which observed lower frequencies(20.00%)and relatively less severe declines(21.02%)prior to the 1980s.The primary impetus underlying the opposite radial growth increments observed in Larix gmelinii trees from the interplay between their differential response to temperatures and wetter climatic conditions,which is significantly influenced by varying stand densities.In cold-dry conditions,low-density forests may experience soil water freezing,exacerbating drought conditions and thereby inhibiting tree growth,in Group B.Trees growth in high-density stands is restrained by warm-wet conditions,in Group A.These results provide new insights into the variability at the southern edge of the boreal forest biome with different responses to density and climate.
基金funded by the Slovenian Research and Innovation Agency(https://www.aris-rs.si/sl/)ProgramResearch Core Fund-ing No.P4-0107(TL)and No.P4-0059(MK)+1 种基金Young Researcher Program Grant(MK)funded by the Slovenian Forestry Institute(P4-0107).
文摘Understanding competition between trees is essential for sustainable forest management as interactions between trees in uneven-aged mixed forests play a key role in growth dynamics. This study investigated nine competition indices(CIs) for their suitability to model the effects of neighboring trees on silver fir(Abies alba) growth in Dinaric silver fir-European beech(Fagus sylvatica) forests. Although numerous competition indices have been developed, there is still limited consensus on their applicability in different forest types, especially in mature, structurally complex forest stands. The indices were evaluated using the adjusted coefficient of determination in a linear model wherein the volume growth of the last five years for 60 dominant silver fir trees was modeled as a function of tree volume and competition index. The results demonstrated that distance-dependent indices(e.g., the Hegyi height-distance competition and Rouvinen-Kuuluvainen diameter-distance competition indices), which consider the distance to competitors and their size, perform better than distance-independent indices. Using the optimization procedure in calculating the competition indices, only neighboring trees at a distance of up to 26-fold the diameter at breast height(DBH) of the selected tree(optimal search radius) and with a DBH of at least 20% of that of the target tree(optimal DBH) were considered competitors. Therefore, competition significantly influences the growth of dominant silver firs even in older age classes. The model based solely on tree volume explained 32.5% of the variability in volume growth, while the model that accounted for competition explained 64%. Optimizing the optimal search radius had a greater impact on model performance than optimizing the DBH threshold. This emphasizes the importance of balancing stand density and competition in silvicultural practice.
基金supported by National Key R&D Program of China(No.2022YFF0800800)National Science Fund for Distinguished Young Scholars(No.32225005)+3 种基金National Natural Science Foundation of China(NSFC)(Nos.42072024,42320104005,42372033)the Young and Middle-aged Academic and Technical Leaders of Yunnan(No.202305AC160051)Basic Research Project of Yunnan Province(No.202401AT070222)the 14th Five-Year Plan of the Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences(Nos.XTBG-1450101,E3ZKFF7B).
文摘Evergreen broad-leaved forests(EBLFs) are widely distributed in East Asia and play a vital role in ecosystem stability. The occurrence of these forests in East Asia has been a subject of debate across various disciplines. In this study, we explored the occurrence of East Asian EBLFs from a paleobotanical perspective. By collecting plant fossils from four regions in East Asia, we have established the evolutionary history of EBLFs. Through floral similarity analysis and paleoclimatic reconstruction, we have revealed a diverse spatio-temporal pattern for the occurrence of EBLFs in East Asia. The earliest occurrence of EBLFs in southern China can be traced back to the middle Eocene, followed by southwestern China during the late Eocene-early Oligocene. Subsequently, EBLFs emerged in Japan during the early Oligocene and eventually appeared in central-eastern China around the Miocene. Paleoclimate simulation results suggest that the precipitation of wettest quarter(PWet Q, mm) exceeding 600 mm is crucial for the occurrence of EBLFs. Furthermore, the heterogeneous occurrence of EBLFs in East Asia is closely associated with the evolution of the Asian Monsoon. This study provides new insights into the occurrence of EBLFs in East Asia.
基金funded by the Kenya National Research Fund(NRF-Kenya,2018).
文摘The study determined the carbon stocks and litter nutrient concentration in tropical forests along the ecological gradient in Kenya.This could help understand the potential of mitigating climate change using tropical forest ecosystems in different ecological zones,which are being affected by climate change to a level that they are becoming carbon sources instead of sinks.Stratified sampling technique was used to categorize tropical forests into rain,moist deciduous and dry zone forests depending on the average annual rainfall received.Simple random sampling technique was used to select three tropical forests in each category.Modified consistent sampling technique was used to develop 10 main 20 m×100 m plots in each forest,with 202 m×50 m sub-plots in each plot.Systematic random sampling technique was used in selecting 10 sub-plots from each main plot for inventory study.Non-destructive approach based on allometric equations using trees’diameter at breast height(DBH),total height and species’wood specific gravity were used in estimating tree carbon stock in each forest.Soil organic carbon(SOC)and litter nutrient concentration(total phosphorus and nitrogen)were determined in each forest based on standard laboratory procedures.The results indicated that,whilst trees in rain forests recorded a significantly higher(p<0.001)DBH(20.36 cm)and total tree height(12.1 m),trees in dry zone forests recorded a significantly higher(p<0.001)specific gravity(0.67 kg m^(−3)).Dry zone tropical forests stored a significantly lower amount of total tree carbon of 73 Mg ha^(−1),compared to tropical rain forests(439.5 Mg ha^(−1))and moist deciduous tropical forests(449 Mg ha^(−1)).The SOC content was significantly higher in tropical rainforests(3.9%),compared to soils from moist deciduous(2.9%)and dry zone forests(1.8%).While litter from tropical rain forests recorded a significantly higher amount of total nitrogen(3.4%),litter from dry zone forests recorded a significantly higher concentration of total phosphorus(0.27%).In conclusion,ecological gradient that is dictated by the prevailing temperatures and precipitation affects the tropical forests carbon stock potential and litter nutrient concentration.This implies that,the changing climate is having a serious implication on the ecosystem services such as carbon stock and nutrients cycling in tropical forests.
基金Field surveys were carried out within the forest monitoring activities of Action A1.3 of the Project LIFE4OAKFORESTS(LIFE16NAT/IT/000245),in collaboration with“Ente di Gestione per i Parchi e la Biodiversità-Romagna”.
文摘Old-growth forests are of major importance for biodiversity conservation and climate change mitigation,as well as being a benchmark for the implementation of sustainable forest management.Although dedicated studies have significantly increased in the last decades,there is still limited knowledge of Mediterranean forests,especially those dominated by Quercus pubescens and related taxa.To fill this knowledge gap,we primarily studied in the field two downy oak forests possessing old-growth traits,localized in Sicily(Mediterranean,Italy).Second,we used a structural heterogeneity index(SHI)to assess their old-growthness level,in comparison with the downy oak stands surveyed in the Regional Forest Inventory(RFI)of Sicily.Third,we tested the effect of different sets of structural parameters on SHI scores,thus assessing whether their choice could affect the final score and the stand assessment.SHI was well proven to discriminate these two stands from the others,both showing,on average,a SHI score just higher than 80,whilst SHI in RFI plots was just under 50,a significantly lower value.The methodological approach used in our study highlights the need to standardize the parameters used to characterize the old-growthness level of Mediterranean forests in order to allow more reliable comparisons.Most of the structural parameters were higher in the two selected stands,except for the attributes related to standing deadwood,suggesting a still limited contribution of standing dead trees and snags in the potential old-growth stands under investigation.The application of a structural index has proven effective for the purpose it was tested for,demonstrating its usefulness in discriminating between two potential old-growth stands from ordinary stands of the same forest type.We believe that both forests deserve primary attention and tailored management measures,as well as inclusion in the recently established Italian Network of old-growth forests.
基金funded by the National Natural Science Foundation of China(Grant No.32271872).
文摘Over the past decades,the expansion of natu-ral secondary forests has played a crucial role in offsetting the loss of primary forests and combating climate change.Despite this,there is a gap in our understanding of how tree species’growth and mortality patterns vary with eleva-tion in these secondary forests.In this study,we analyzed data from two censuses(spanning a five-year interval)conducted in both evergreen broadleaved forests(EBF)and temperate coniferous forests(TCF),which have been recovering for half a century,across elevation gradients in a subtropical mountain region,Mount Wuyi,China.The results indicated that the relative growth rate(RGR)of EBF(0.028±0.001 cm·cm^(-1)·a^(-1))and the mortality rate(MR)(20.03%±1.70%)were 27.3%and 16.4%higher,respec-tively,than those of TCF.Interestingly,the trade-off between RGR and MR in EBF weakened as elevation increased,a trend not observed in TCF.Conversely,TCF consistently showed a stronger trade-off between RGR and MR compared to EBF.Generalized linear mixed models revealed that ele-vation influences RGR both directly and indirectly through its interactions with slope,crown competition index(CCI),and tree canopy height(CH).However,tree mortality did not show a significant correlation with elevation.Additionally,DBH significantly influenced both tree growth and mortal-ity,whereas and CH and CCI had opposite effects on tree growth between EBF and TCF.Our study underscores the importance of elevation in shaping the population dynamics and the biomass carbon sink balance of mountain forests.These insights enhance our understanding of tree species’life strategies,enabling more accurate predictions of forest dynamics and their response to environmental changes.
基金supported by National Key Research and Development Program of China(No.2021YFD2200405(S.R.L.))Natural Science Foundation of China(Grant No.31971653).
文摘With the rapid economic development and continuous expansion of human activities,forest degradation—characterized by reduced forest stock within the forest including declining carbon storage—poses significant threats to ecosystem stability.Understanding the current status of forest degradation and assessing potential carbon stocks in China are of strategic importance for making forest restoration efforts and enhancing carbon sequestration capacity.In this study,we used the national forest inventory data from 2009 to 2018 to develop a set of standard measures for assessing degraded forests across China,based on five key indicators:forest accumulation growth rate(FAGR),forest recruitment rate(FRR),tree species reduction rate(TSRR),forest canopy cover reduction rate(FCCRR),and forest disaster level(FDL).Additionally,we estimated standing carbon stock,potential carbon stock,and theoretical space to grow by developing a stand growth model,which accounts for stand density across different site classes,to evaluate the restoration potential of degraded forests.The results indicate that degraded forest area in China is 36.15 million hectares,accounting for 20.10% of a total forest area.Standing carbon stock and potential carbon stock of degraded forests in China are 23.93 million tons and 61.90 million tons,respectively.Overall,degraded forest varies significantly across different regions.The results highlight the important trade-offs among environmental factors,policy decisions,and forest conditions,providing a robust foundation for developing measures to enhance forest quality.
文摘Forests play a vital role in mitigating climate change through their physiological functions and metabolic processes,including their ability to convert solar energy into biomolecules.However,further research is necessary to elucidate how structural characteristics of a forest and topographic settings influence energy conversion and surface temperature of a forest.In this study,we investigated a beech forest in central Germany using airborne laser scanning(ALS)point cloud data and land surface temperature(LST)data derived from Landsat 9 satellite imagery.We constructed 30 m×30 m plots across the study area(approximately 17 km2)to align the spatial resolution of the satellite imagery with the ALS data.We analyzed topographic variables(surface elevation,aspect and slope),forest attributes(canopy cover,canopy height,and woody area index),as well as forest structural complexity,quantified by the box-dimension(Db).Our analysis revealed that LST is significantly influenced by both forest attributes and topographic variables.A multiple linear regression model demonstrated an inverse relationship(R^(2)=0.38,AIC=8105)between LST and a combination of Db,elevation,slope,and aspect.However,the model residuals exhibited significant spatial dependency,as indicated by Moran’s I test.To address this,we applied a spatial autoregressive model,which effectively accounted for spatial autocorrelation and improved the model fit(AIC=746).Our findings indicate that elevation exerts the most substantial influence on LST,followed by forest structural complexity,slope,and aspect.We conclude that forest management practices that enhance structural complexity can effectively reduce land surface temperatures in forested landscapes.
基金financial support provided by the German Research Foundation,DFG,through grant number KL894/23-2 and NO 1444/1-2 as part of the Research Unit FOR2432/2the China Scholarship Council(CSC)that supports the first author with a Ph D scholarshipsupport provided by Indian partners at the Institute of Wood Science and Technology(IWST),Bengaluru。
文摘Rapid urbanization has caused significant changes along the urban-rural gradient,leading to a variety of landscapes that are mainly shaped by human activities.This dynamic interplay also influences the distribution and characteristics of trees outside forests(TOF).Understanding the pattern of these trees will support informed decision-making in urban planning,in conservation strategies,and altogether in sustainable land management practices in the urban context.In this study,we employed a deep learning-based object detection model and high resolution satellite imagery to identify 1.3 million trees with bounding boxes within a 250 km^(2)research transect spanning the urban-rural gradient of Bengaluru,a megacity in Southern India.Additionally,we developed an allometric equation to estimate diameter at breast height(DBH)from the tree crown diameter(CD)derived from the detected bounding boxes.Our study focused on analyzing variations in tree density and tree size along this gradient.The findings revealed distinct patterns:the urban domain displayed larger tree crown diameters(mean:8.87 m)and DBH(mean:43.78 cm)but having relatively low tree density(32 trees per hectare).Furthermore,with increasing distance from the city center,tree density increased,while the mean tree crown diameter and mean tree basal area decreased,showing clear differences of tree density and size between the urban and rural domains in Bengaluru.This study offers an efficient methodology that helps generating instructive insights into the dynamics of TOF along the urban-rural gradient.This may inform urban planning and management strategies for enhancing green infrastructure and biodiversity conservation in rapidly urbanizing cities like Bengaluru.
基金supported by the European Union and the Romanian Government through the Competitiveness Operational Programme 2014–2020, under the project“Increasing the economic competitiveness of the forestry sector and the quality of life through knowledge transfer,technology and CDI skills”(CRESFORLIFE),ID P 40 380/105506, subsidiary contract no. 17/2020partially by the FORCLIMSOC Nucleu Programme (Contract 12N/2023)+2 种基金project PN 23090101CresPerfInst project (Contract 34PFE/December 30, 2021)“Increasing the institutional capacity and performance of INCDS ‘Marin Drǎcea’in RDI activities-CresPer”LM was financially supported by the Research Council of Finland's flagship ecosystem for Forest-Human-Machine Interplay–Building Resilience, Redefining Value Networks and Enabling Meaningful Experiences (UNITE)(decision number 357909)
文摘In this study,we used an extensive sampling network established in central Romania to develop tree height and crown length models.Our analysis included more than 18,000 tree measurements from five different species.Instead of building univariate models for each response variable,we employed a multivariate approach using seemingly unrelated mixed-effects models.These models incorporated variables related to species mixture,tree and stand size,competition,and stand structure.With the inclusion of additional variables in the multivariate seemingly unrelated mixed-effects models,the accuracy of the height prediction models improved by over 10% for all species,whereas the improvement in the crown length models was considerably smaller.Our findings indicate that trees in mixed stands tend to have shorter heights but longer crowns than those in pure stands.We also observed that trees in homogeneous stand structures have shorter crown lengths than those in heterogeneous stands.By employing a multivariate mixed-effects modelling framework,we were able to perform cross-model random-effect predictions,leading to a significant increase in accuracy when both responses were used to calibrate the model.In contrast,the improvement in accuracy was marginal when only height was used for calibration.We demonstrate how multivariate mixed-effects models can be effectively used to develop multi-response allometric models that can be easily calibrated with a limited number of observations while simultaneously achieving better-aligned projections.
基金financially supported by the National Natural Science Foundation(No.32471868,No.32001324)Youth Lift Project of China Association for Science and Technology(No.YESS20210370)+1 种基金Fundamental Research Funds for the Central Universities(2572023CT01)We thank the Grassland Bureau and the National Innovation Alliance of Wildland Fire Prevention and Control Technology of China for supporting this research.
文摘Prescribed burning is commonly used to maintain forest ecosystem functions and reduce the risk of future wildfires.Although many studies have investigated the response of microbial community to wildfires in forest ecosystems,the effects of prescribed burnings on soil microbial community structure are less studied.It is also unclear that how post-fire soil physiochemical properties changes affected soil microbial communities.Here,we studied the impacts of prescribed burning on soil microbiome in three typical temperate forests of northern China by collecting soil physicochemical and high-throughput sequencing for 16S rRNA and 18S rRNA was applied to analyze the diversity and community composition of soil microbes(bacteria and fungi).Compared with pre-fire condition,prescribed burning significantly decreased Chaol index and altered soil bacterial communities(P<0.05),whereas it had no significant effect on fungal diversity and community structure of the(P>0.05).Planctomycetes and Actinobacteria made the greatest contributions to the bacterial community dissimilarity between the pre-fire and post-fire conditions.The main variables influencing the post-fire soil microbial community structure are soil pH,available phosphorus,total nitrogen,and the ratio of soil total carbon to soil total nitrogen,which could account for 73.5% of the variation in the microbial community structure in these stands.Our findings demonstrated a great discrepancy in the responses of bacteria and fungi to prescribed burning.Prescribed burning altered the soil microbial structure by modifying the physicochemical properties.Our results pointed that it is essential to evaluate the impact of prescribed burnings on forest ecosystem functions.These findings provide an important baseline for assessing post-fire microbial recovery in the region and offer critical guidance for restoration efforts.
基金funded by state order to the Karelian Research Centre of the Russian Academy of Sciences(Forest Research Institute of KarRC RAS)。
文摘Fine roots play a crucial role in the biogeochemical cycles of terrestrial ecosystems.Patterns of fine roots biomass formation for broad geographical areas are still unclear.We use published estimates of characteristics of European pine and spruce stands to determine their productivity and calculate the needle biomass.Then,the relationship between the fine-root:needle biomass ratio of European pine and spruce forests and the stand quality index,which is a proxy of soil fertility,was determined.We show that a rise in soil fertility is accompanied by a decrease in this ratio.Moving from the northern edge of the boreal zone southwards,with the related rise in air and soil temperatures,we see a decline in the mass ratio of fine roots and needle.The change in the fine-root:needle biomass ratio is controlled by the change in specific water uptake by roots,which is related to the osmotic pressure of the solution in the absorbing root's central vascular cylinder.The fine-root:needle ratio does not vary among stands of the same age if the stand quality index and the geographical latitude(a proxy of air and soil temperatures)are constant.These findings may be useful for further in-depth analysis of forest ecosystem functioning in Europe.
基金supported by the Czech Science Foundation project GACR21-27454STechnology Agency of the Czech Republic(project Center for Landscape and Biodiversity,SS02030018).
文摘Extreme disturbance activity is a signature of anthropogenic environmental change. Empirical information describing the historical normative limits of disturbance regimes provides baseline data that facilitates the detection of contemporary trends in both disturbances and community-level responses. Quantifying the attributes of historical disturbances is challenging due to their transient episodic nature, with decades-to centurieslong intervals between recurrences. Unmanaged primary forests that support centuries-old trees therefore serve as unique reference systems for quantifying past disturbance regimes. We surveyed relict stands of primary beech-dominated forests over wide environmental gradients in the Carpathian Mountains of Europe. We collected core samples from 3,026 trees in 208 field survey plots distributed across 13 forest stands in two countries. We used dendrochronological methods to analyze time-series of annually-resolved ring-width variation and to identify anomalous growth patterns diagnostic of past forest canopy removal. A 180-year record(1810–1990) of spatially and temporally explicit disturbance events(n =333) was compiled and used to derive s tatistical attributes of the disturbance regime. We quantified disturbance severity(canopy area lost), patch size, and return intervals. Our analyses describe a complex regime where a background of relatively frequent, smallscale, low-to intermediate-severity disturbance was punctuated by episodic large-scale high-severity events. Even the most severe events were non-catastrophic at a stand level, leaving significant residual tree cover that supported a continuity of ecological function. We did not detect evidence for an expected climate-induced intensification of disturbance with time, but methodological limitations precluded an assessment of disturbance activity in the decades since 1990.
基金supported by a Forest Health Monitoring(FHM)award from the USDA Forest Service(Grant No.:19-DG-11083150-030)to Dr.Weimin Xi。
文摘Texas experienced the worst drought in its 100-year history in 2011,resulting in the death of approximately 300 million trees.The high number of sudden deaths had a significant impact on forest ecosystems.This study aimed to gain insight into the long-term and combined impacts of drought-induced forest tree deaths and their effects on biomass.This study used data obtained from 1797 National Forest Inventory(NFI)plots to analyze trends and major causes of changes in tree biomass at the sample plot level in East Texas forests over the past 20 years(2000-2019).In this study,forest trees in East Texas were divided into diameter at breast height(dbh),height,stand types,latitude,elevation,ecological zones,and FIA Unit.Principal component analysis(PCA)was also performed using drought intensity,drought duration,the four competing factor indicators,and the biomass loss rate of forest trees to better understand r drought impacts on forest trees.The results showed the lowest biomass loss rate of Pine species.Similarly,trees with shorter height and smaller dbh experienced a higher biomass loss rate.A higher biomass loss rate was observed in natural forests,West Gulf Coastal Plain and Plain and Southern East Texas ecoregion experienced higher biomass loss.Principal component analyses of drought intensity,drought duration,and the four competing metrics revealed that overall drought was the main contributor to biomass loss rates,and that drought intensity and drought duration had comparable effects on biomass loss rates.
基金Funding for this research was provided by the TAČR SS06010420the Czech University of Life Sciences Prague(grant no.IGA A_13_23).
文摘Anthropogenic activities have significantly contributed to the loss and fragmentation of primary forests across the globe,which has accelerated biodiversity decline,particularly among highly specialised species dependent on unique forest structures.Nevertheless,comparative studies between primary and managed forests are scarce,despite their importance for effective monitoring and conservation planning.To address this knowledge gap,we conducted a comparative study using a unique dataset of permanent study plots established across some of the best-preserved,mixed-beech primary forests and their adjacent managed counterparts in the Western Carpathian Mountains.We assessed the effects of forest structure and tree age—determined through extensive dendrochronological reconstructions—on contemporary lichen communities.Lichen species richness and the richness of red-listed species were 26%and 50%higher in primary forests than in managed forests,respectively,highlighting the outstanding conservation importance of primary forests.Generalised least squares(GLS)modelling demonstrated that in managed forests,lichen species richness was strongly associated with structural attributes:It increased with maximum tree age and the diameter of standing deadwood,and decreased with higher basal area(BA)of living trees,likely due to reduced understory light.In contrast,no structural variables significantly explained richness in primary forests,likely due to structural saturation and widespread microhabitat availability.Elevation emerged as the sole variable with significant explanatory strength.These findings underscore the critical role of structural complexity in supporting lichen diversity under different management regimes and provide a robust evidence base for promoting elements such as old trees,deadwood—especially large standing deadwood—and reduced canopy density.At the same time,they reaffirm the irreplaceable value of primary forests as biodiversity refuges and highlight the need for landscape-level conservation strategies that integrate both intact primary and structurally enriched managed forests.
基金funded by the Norwegian University of Life Sciences(NMBU)a strategic institutional research program at the Norwegian Institute of Bioeconomy Research(NIBIO).
文摘A key property of the boreal forest is that it stores huge amounts of carbon(C),especially belowground in the soil.Amounts of C stored in the uppermost organic layer of boreal forest soils vary greatly in space due to an interplay between several variables facilitating or preventing C accumulation.In this study,we split C stocks into the organic layer and charcoal C due to their difference in origin,stability,and ecological properties.We compared organic layer C and charcoal C stocks in two regions of south-central Norway(Trillemarka and Varaldskogen),characterized by Scots pine and Norway spruce forests with varying fire histories.We used structural equation modeling to investigate how vegetation composition,hydrotopography,and soil properties interplay to shape organic layer C and charcoal C stocks.Pine forests consistently contained larger organic layer C stocks than spruce forests.Charcoal stocks,in contrast,were less consistent across both forest types and study regions as pine forests had higher charcoal C stocks than spruce forests in Trillemarka,while the two forest types contained equal charcoal C stocks in Varaldskogen.Charcoal and soil organic layer C stocks increased with higher fire frequencies(number of fire events over the last 600 years),but not with a shorter time since last fire(TSF).Additionally,vegetation composition,terrain slope,and soil moisture were the most important drivers of the organic layer C stocks,while charcoal C stocks were mainly controlled by the depth of the organic layer.Also,microtopography was of importance for organic layer C and charcoal C,since depressions in the forest floor had more charcoal C than well-drained minor hills.
基金the Institute Research Centre for Ecological and Forestry Applications (CREAF) of Barcelona that supported the research by the Spanish “Ministerio de Ciencia e Innovacio'n”(MCIN/AEI/ 10.13039/501100011033) (grant agreement No. PID 2021-126679OBI00)partially supported by MIUR Project (PRIN 2020) between WATER and carbon cycles during droug“Unraveling interactionsht and their impact on water resources and forest and grassland ecosySTEMs in the Mediterranean climate (WATERSTEM)”(Project number: 20202WF53Z),“WAFER”at CNR (Consiglio Nazionale delle Ricerche)+3 种基金Priwitzer et al. (2014) (cod. 2020E52THS)-Research Projects of National Relevance funded by the Italian Ministry of University and Research entitled: “Multi-scale observations to predict Forest response to pollution and climate change”(MULTIFOR, project number: 2020E52THS)funding by the project OptForEU Horizon Europe research and innovation programme under grant agreement No. 101060554the project funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4-Call for tender No. 3138 of December 16, 2021, rectified by Decree n.3175 of December 18, 2021 of Italian Ministry of UniversityResearch funded by the European UnionationEU under award Number: Project code CN_00000033–Next Gener, Concession Decree No. 1034 of June 17, 2022 adopted by the Italian Ministry of University and Research, CUP B83C22002930006, Project title“National Biodiversity Future Centre-NBFC”
文摘The consequences of climate change continue to threaten European forests,particularly for species located at the edges of their latitudinal and altitudinal ranges.While extensively studied in Central Europe,European beech forests require further investigation to understand how climate change will affect these ecosystems in Mediterranean areas.Proposed silvicultural options increasingly aim at sustainable management to reduce biotic and abiotic stresses and enhance these forest ecosystems'resistance and resilience mechanisms.Process-based models(PBMs)can help us to simulate such phenomena and capture early stress signals while considering the effect of different management approaches.In this study,we focus on estimating sensitivity of two state-of-the-art PBMs forest models by simulating carbon and water fluxes at the stand level to assess productivity changes and feedback resulting from different climatic forcings as well as different management regimes.We applied the 3D-CMCC-FEM and MEDFATE forest models for carbon(C)and water(H_(2)O)fluxes in two sites of the Italian peninsula,Cansiglio in the north and Mongiana in the south,under managed vs.unmanaged scenarios and under current climate and different climatic scenarios(RCP4.5 and RCP8.5).To ensure confidence in the models’results,we preliminary evaluated their performance in simulating C and H_(2)O flux in three additional beech forests of the FLUXNET network along a latitudinal gradient spanning from Denmark to central Italy.The 3D-CMCC-FEM model achieved R^(2)values of 0.83 and 0.86 with RMSEs of 2.53 and 2.05 for C and H_(2)O fluxes,respectively.MEDFATE showed R^(2)values of 0.76 and 0.69 with RMSEs of 2.54 and 3.01.At the Cansiglio site in northern Italy,both models simulated a general increase in C and H_(2)O fluxes under the RCP8.5 climate scenario compared to the current climate.Still,no benefit in managed plots compared to unmanaged ones,as the site does not have water availability limitations,and thus,competition for water is low.At the Mongiana site in southern Italy,both models predict a decrease in C and H_(2)O fluxes and sensitivity to the different climatic forcing compared to the current climate;and an increase in C and H_(2)O fluxes when considering specific management regimes compared to unmanaged scenarios.Conversely,under unmanaged scenarios plots are simulated to experience first signals of mortality prematurely due to water stress(MEDFATE)and carbon starvation(3D-CMCC-FEM)scenarios.In conclusion,while management interventions may be considered a viable solution for the conservation of beech forests under future climate conditions at moister sites like Cansiglio,in drier sites like Mongiana conservation may not lie in management interventions alone.
基金financially supported by the National Key R&D Program of China(No.2022YFE0127900).
文摘Soil organic carbon(SOC)decomposition in high-latitude boreal forests exhibits heightened sensitivity to climate change.However,a comprehensive understanding of the underlying drivers governing soil microbial decomposition responses to warming in these ecosystems remains elusive,especially regarding the roles of mineral protection and microbial genomic traits.In this study,we examined the temperature sensitivity(Q_(10))and minimum temperature(Tmin)of soil microbial respiration across a latitudinal gradient in China's boreal forests.The potential regulators,including climatic factors,soil physicochemical properties,substrate quality,mineral protection,and microbial genomic traits,were also synchronously measured.The results showed a positive correlation between Q_(10) and Tmin,i.e.,greater microbial adaptability to low temperatures is associated with lower microbial sensitivity to increasing temperatures.Boreal forest soil with stronger mineral protection exhibited a higher Q10.In addition,microbial communities characterized by a higher abundance of coding genes demonstrated significantly lower Q_(10) and reduced Tmin.These results collectively highlight the pivotal roles of mineral protection and microbial genomic traits in shaping the biogeographic pattern of Q_(10) across boreal forests.
