The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems （GIS） and multi-criteria decision analysis （MCDA） have been inc...The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems （GIS） and multi-criteria decision analysis （MCDA） have been increasingly used to improve the management of vulnerable ecosystems to prevent further degradation and increase the sustainability of land use. This study presents a methodology to assess land suitability using remote sensing （RS） to obtain wall-to-wall data for the calculations, GIS to analyze the data, and MCDA to rank alternative land uses. The criteria and subcriteria affecting the suitability of land for different uses were identified and weighted using an analytic hierarchy process. Variables used as subcriteria were assessed using satellite data and other sources of information such as existing maps and field surveys. Numerical values for the subcriteria were classified, and each class was given a priority rating according to expert judgments. Based on the ratings and weights of the subcriteria, a priority map was created for each land use using the weighted linear combination method. The priority maps for different land uses were overlaid to obtain a preliminary land use map, which often indicated several simultaneous land uses for the same location. The preliminary map was further edited by removing unrealistic, mutually exclusive land-use combinations. The study tested and demonstrated the potential of integrating RS, G1S and MCDA techniques for solving complicated land allocation problems in forested regions using a scientifically sound and practical approach for efficient and sustainable allocation of forestland for different uses.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
In this paper,we show that an ideal generated by matching Rota-Baxter equations is a bideal of a Hopf algebra on decorated rooted forests.We then get a bialgebraic structure on the space of decorated rooted forests mo...In this paper,we show that an ideal generated by matching Rota-Baxter equations is a bideal of a Hopf algebra on decorated rooted forests.We then get a bialgebraic structure on the space of decorated rooted forests modulo this biideal.As an application,a connected graded bialgebra and so a graded Hopf algebra on matching Rota-Baxter algebras are constructed,which simplifies the Hopf algebraic structure proposed by[Pacific J.Math.,2022,317(2):441-475].展开更多
Conservation and enhancement of old-growth forests are key in forest planning and policies.In order to do so,more knowledge is needed on how the attributes traditionally associated with old-growth forests are distribu...Conservation and enhancement of old-growth forests are key in forest planning and policies.In order to do so,more knowledge is needed on how the attributes traditionally associated with old-growth forests are distributed in space,what differences exist across distinct forest types and what natural or anthropic conditions are affecting the distribution of these old-growthness attributes.Using data from the Third Spanish National Forest Inventory(1997–2007),we calculated six indicators commonly associated with forest old-growthness for the plots in the territory of Peninsular Spain and Balearic Islands,and then combined them into an aggregated index.We then assessed their spatial distribution and the differences across five forest functional types,as well as the effects of ten climate,topographic,landscape,and anthropic variables in their distribution.Relevant geographical patterns were apparent,with climate factors,namely temperature and precipitation,playing a crucial role in the distribution of these attributes.The distribution of the indicators also varied across different forest types,while the effects of recent anthropic impacts were weaker but still relevant.Aridity seemed to be one of the main impediments for the development of old-growthness attributes,coupled with a negative impact of recent human pressure.However,these effects seemed to be mediated by other factors,specially the legacies imposed by the complex history of forest management practices,land use changes and natural disturbances that have shaped the forests of Spain.The results of this exploratory analysis highlight on one hand the importance of climate in the dynamic of forests towards old-growthness,which is relevant in a context of Climate Change,and on the other hand,the need for more insights on the history of our forests in order to understand their present and future.展开更多
Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon...Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon stocks in the sacred forests of Bandrefam and Batoufam (western Cameroon). The floristic inventory and the stand structures were carried out in 25 m × 25 m plots for individuals with diameters greater than 10 cm;5 m × 5 m for individuals with diameters less than 10 cm. Carbon stocks were estimated using the non-destructive method and allometric equations. The floristic inventory identified 65 species divided into 57 genera and 30 families in the Bandrefam sacred forest and 45 species divided into 42 genera and 27 families in the Batoufam sacred forest. In the Bandrefam, the most important families are Phyllanthaceae (53.98%), Moraceae (21.69%), Lamiaceae (20.15%). At Batoufam, the most important families are Phyllanthaceae (39.73%), Fabaceae (28.47%), Araliaceae (23.77%). Malacantha alnifolia (55.14%), Vitex grandifolia (18.43%), Bosqueia angolensis (15.06%) were the most important species in Bandrefam. Otherwise, Malacantha alnifolia (28%), Polyscias fulva (22.73%), Psychotria sp. (21.28%) were the most important in Batoufam. The Bandrefam sacred forest has the highest tree density (2669 stems/ha). Total carbon stock is 484.88 ± 2.28 tC/ha at Batoufam and 313.95 ± 0.93 tC/ha at Bandrefam. The economic value varies between 5858.04 ± 27.62 USD/ha in Batoufam sacred forest and 3788.51 ± 11.26 USD/ha in Bandrefam sacred forest. The number of individuals and small-diameter trees has little influence on the carbon stocks in the trees. Medium-diameter trees store the most carbon, and very large-diameter trees, which are very poorly represented, store less carbon. In another way, wood density and the basal areas influence the carbon storage of the trees.展开更多
Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richnes...Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests.We,there-fore,aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels.Based on decision tree modelling,our results showed that the density of trees larger than 30 cm DBH was an overall important variable,indi-cating that large-diameter trees were essential to provide diverse bird communities.The total abundance of birds,the foliage-gleaners,primary and secondary cavity nest-ers,residents,and five specific bird species were related to the density of high trunk diameter trees.The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH.The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners,secondary cavity nesters and residents.Analysis of the co-dominant tree species showed that the presence of linden,beech,and hornbeam was important in influencing the abundance of various bird species,e.g.,Eur-asian Treecreeper(Certhia familiaris),Marsh Tit(Poecile palustris)and Wood Warbler(Phylloscopus sibilatrix).Our results indicated that large trees,high tree diversity,and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.展开更多
The naturally fermented Inner Mongolian cheese’s flavor and nutritional value make it a popular choice among customers.In this work,to create multi-functional peptides that have taste and biological activity,peptidom...The naturally fermented Inner Mongolian cheese’s flavor and nutritional value make it a popular choice among customers.In this work,to create multi-functional peptides that have taste and biological activity,peptidomics and bioinformatics were used to screen flavor peptides from Inner Mongolian cheese and further assess their antioxidant and angiotensin I-converting enzyme(ACE)inhibitory properties.According to sensory data,YH8 and IL7 had detectable bitter tastes with low thresholds of 0.03 and 0.06 mmol/L,respectively.With an umami threshold range of 0.24‒0.81 mmol/L,VQ6,FK13,HP13 and QT14 exhibited a range of flavors dominated by umami,including sweet,bitter,salty,sour and kokumi.Antioxidant activity wise,YH8,VQ6,HP13 and QT14 were well represented.The above-mentioned peptides all had some ACE inhibitory effect.The bitter peptide IL7(IC_(50)=0.08 mmol/L)had the highest level of ACE inhibitory activity,followed by YH8(IC_(50)=0.33 mmol/L).These multi-functional peptides,which have been assessed for bioactive and taste features in Inner Mongolian cheese,may have positive impacts on health and harmonize the cheese’s overall flavor.These results suggest that some flavor peptides produced in fermented foods might be with bioactivities while providing a basis for the exploration and application of multi-functional peptides.展开更多
Tree growth synchrony serves as a valuable ecological indicator of forest resilience to climate stress and disturbances.However,our understanding of how increasing temperature affects tree growth synchrony during rapi...Tree growth synchrony serves as a valuable ecological indicator of forest resilience to climate stress and disturbances.However,our understanding of how increasing temperature affects tree growth synchrony during rapidly and slowly warming periods in ecosystems with varying climatic conditions remains limited.By using tree-ring data from temperate broadleaf(Fraxinus mandshurica,Phellodendron amurense,Quercus mongolica,and Juglans mandshurica)and Korean pine(Pinus koraiensis)mixed forests in northeast China,we investigated the effects of climate change,particularly warming,on the growth synchrony of five dominant temperate tree species across contrasting warm-dry and cool-wet climate conditions.Results show that temperature over water availability was the primary factor driving the growth and growth synchrony of the five species.Growth synchrony was significantly higher in warm-dry than in cool-wet areas,primarily due to more uniform climate conditions and higher climate sensitivity in the former.Rapid warming from the 1960s to the 1990s significantly enhanced tree growth synchrony in both areas,followed by a marked reversal as temperatures exceeded a certain threshold or warming slowed down,particularly in the warm-dry area.The growth synchrony variation patterns of the five species were highly consistent over time,although broadleaves exhibited higher synchrony than conifers,suggesting potential risks to forest resilience and stability under future climate change scenarios.Growing season temperatures and non-growing season temperatures and precipitation had a stronger positive effect on tree growth in the cool-wet area compared to the warm-dry area.High relative humidity hindered growth in the cool-wet area but enhanced it in the warm-dry area.Overall,our study highlights that the diversity and sensitivity of climate-growth relationships directly determine spatiotemporal growth synchrony.Temperature,along with water availability,shape long-term forest dynamics by affecting tree growth and synchrony.These results provide crucial insights for forest management practice to enhance structural diversity and resilience capacity against climate changeinduced synchrony shifts.展开更多
1.In recent years,climate change has led to drought and severe bark beetle infestations,affecting Norway spruce(Picea abies)across Europe,with detrimental consequences for forest owners,the forestry sector and associa...1.In recent years,climate change has led to drought and severe bark beetle infestations,affecting Norway spruce(Picea abies)across Europe,with detrimental consequences for forest owners,the forestry sector and associated industries.As a result,silviculture now faces the challenge of identifying tree species more resilient to these stressors to mitigate the impacts on forest management,forest-dependent economies and rural livelihoods.The North American Douglas-fir(Pseudotsuga menziesii)has emerged as a promising conifer species,better suited to future climate conditions and capable of producing high timber yields.2.Non-native tree species may affect native biodiversity,yet the impacts of Douglas-fir on native forest biodiversity are not clear.A comprehensive review evaluating the impact of Douglas-fir on faunal and floral biodiversity in European forests is lacking.3.Here,we present the results of a systematic literature review on Douglas-fir effects on native biodiversity,focusing on studies conducted in Europe.For arthropods,sufficient studies were found to do more detailed quantitative assessments.For fungi,birds,plants and soil fauna some studies existed,but only qualitative evaluations could be made.Other taxa were not investigated.4.In the present literature,the effects of Douglas-fir inclusion in stands on native biodiversity,compared to stands of solely native tree species,were mostly non-significant(78.6%,based on 32 studies).Positive effects were noted in 12%of cases,while negative effects were observed in 9.4%(total of 1,936 effects).Above-ground fauna was more extensively studied than below-ground fauna.Mechanisms proposed to explain taxa responses were often discussed but not always formally tested.For arthropods,there were varying effects on diversity between studies evaluating different scales(i.e.,tree-scale vs.stand-scale).In general,differences in effects depended on a range of factors,including stand composition and structure,season,and sampling site and period.5.Our review indicates limited evidence of adverse effects of Douglas-fir on biodiversity in European forests,highlighting a significant knowledge gap due to the scarcity of studies.Douglas-fir's impact on biodiversity likely varies depending on the forest type and management practices.Further research in diverse contexts is crucial to determine optimal levels of admixture and guide forest management.展开更多
Figure 6(a)in the paper[Chin.Phys.B 33074203(2024)]was incorrect due to editorial oversight.The correct figure is provided.This modification does not affect the result presented in the paper.
Temperate forest ecosystems are important habitats for many bat species. However, these habitats are increasingly affected by anthropogenic disturbances, particularly urban development, leading to landscapes with vary...Temperate forest ecosystems are important habitats for many bat species. However, these habitats are increasingly affected by anthropogenic disturbances, particularly urban development, leading to landscapes with varying land cover composition and configuration. Limited research has examined how forest and urban landscape composition and configuration influence bat activity and diversity. Using a multi-year statewide bat acoustic monitoring dataset from North Carolina, USA, we investigated the effects of forest and urban composition and configuration at multiple spatial scales on bat activity and diversity. First, we constructed single-variable landscape index regression models and found that both the composition and configuration of forests and urban developments influenced bat activity and diversity in a species-specific manner. Next, we applied a hierarchical partitioning approach to compare the relative contributions of composition and configuration indices in explaining variance in bat activity. For big brown bats and hoary bats, evergreen forest and urban development composition indices contributed the most to explaining activity variance. In contrast, for eastern red bats, evening bats, and tricolored bats, deciduous forest fragmentation indices describing landscape configuration were the most influential factors. Silver-haired bat activity variance was primarily explained by an evergreen forest fragmentation index. Lastly, urban development configuration indices were the strongest predictors of Mexican free-tailed bat activity and total bat activity. These results suggest that forest and urban landscape configuration should be considered in conservation and management planning for North American temperate forest ecosystems, particularly in regions that have not experienced drastic deforestation in recent decades.展开更多
This paper explores the synergistic effect of a model combining Elastic Net and Random Forest in online fraud detection.The study selects a public network dataset containing 1781 data records,divides the dataset by 70...This paper explores the synergistic effect of a model combining Elastic Net and Random Forest in online fraud detection.The study selects a public network dataset containing 1781 data records,divides the dataset by 70%for training and 30%for validation,and analyses the correlation between features using a correlation matrix.The experimental results show that the Elastic Net feature selection method generally outperforms PCA in all models,especially when combined with the Random Forest and XGBoost models,and the ElasticNet+Random Forest model achieves the highest accuracy of 0.968 and AUC value of 0.983,while the Kappa and MCC also reached 0.839 and 0.844 respectively,showing extremely high consistency and correlation.This indicates that combining Elastic Net feature selection and Random Forest model has significant performance advantages in online fraud detection.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
Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant co...Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.展开更多
Gabon,located on the west coast of Central Africa,is one of the most forested countries.This small but richly biodiverse country is covered by rainforests,which make up approximately 85%of its land area.These forests ...Gabon,located on the west coast of Central Africa,is one of the most forested countries.This small but richly biodiverse country is covered by rainforests,which make up approximately 85%of its land area.These forests are home to a wide variety of wildlife,including elephants and numerous bird species,making Gabon a crucial area for conservation efforts.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
Natural forests are the primary carbon sinks within terrestrial ecosystems,playing a crucial role in mitigating global climate change.China has successfully restored its natural forest area through extensive protectiv...Natural forests are the primary carbon sinks within terrestrial ecosystems,playing a crucial role in mitigating global climate change.China has successfully restored its natural forest area through extensive protective measures.However,the aboveground carbon(AGC)stock potential of China's natural forests remains considerably uncertain in spatial and temporal dynamics.In this study,we provide a spatially detailed estimation of the maximum AGC stock potential for China's natural forests by integrating high-resolution multi-source remote sensing and field survey data.The analysis reveals that China's natural forests could sequester up to 9.880.10 Pg C by 2030,potentially increasing to 10.460.11 Pg C by 2060.Despite this,the AGC sequestration rate would decline from 0.190.001 to 0.080.001 Pg C·yr^(-1)over the period.Spatially,the future AGC accumulation rates exhibit marked heterogeneity.The warm temperate deciduous broadleaf forest region with predominantly young natural forests,is expected to exhibit the most significant increase of 26.36%by 2060,while the Qinghai-Tibet Plateau Alpine region comprising mainly mature natural forests would exhibit only a 0.74%increase.To sustain the high carbon sequestration capacity of China's natural forests,it is essential to prioritize protecting mature forests alongside preserving and restoring young natural forest areas.展开更多
European beech(Fagus sylvatica L.)forests can have a high variability in plant species richness and abundance,from monospecific stands to highly species-rich communities.To understand what causes the low plant diversi...European beech(Fagus sylvatica L.)forests can have a high variability in plant species richness and abundance,from monospecific stands to highly species-rich communities.To understand what causes the low plant diversity observed in some beech forests,we analyzed the drivers of plant community completeness in 155 vegetation plots.Data were collected in mature,closed-canopy beech forests in Tuscany,central Italy.Site-specific species pools were estimated based on species co-occurrences.We used Generalized Least Squares linear modeling to assess the effects of anthropogenic and environmental drivers on the community completeness of whole communities and on the set of specialist species of beech forests.We also tested the response of the total cover of the herb layer to the selected predictors and related both the predictive and response variables to species composition in a Non-metric Multidimensional Scaling ordination.The community completeness of whole communities and that of beech forest specialists were negatively affected by total beech cover and positively influenced by slope.Moreover,the community completeness of whole communities was negatively impacted by elevation and positively influenced by disturbance frequency.The cover of the herb layer decreased with increasing beech cover,elevation,and precipitation.High community completeness and high cover of the herb layer were associated with the presence of thermophilic species of mixed deciduous woods in low-elevation beech forests.Our results suggest that a low plant community completeness and a low cover of the herb layer are mainly due to the competition by beech itself when it forms pure forests in its ecological optimum.Such competition is better exerted at upper elevations and in sites with low slopes,where beech litter accumulation is a limiting factor for understory species.Such evidence suggests that species absence in mature beech forests is mainly due to natural drivers and should therefore not be considered an indicator of ecological degradation of the forest.展开更多
The distance from the river is a crucial factor that affects the structure and function of desert riparian forests,impeding their regeneration and biodiversity due to water conditions.However,few studies have confirme...The distance from the river is a crucial factor that affects the structure and function of desert riparian forests,impeding their regeneration and biodiversity due to water conditions.However,few studies have confirmed the long-term variation in structure and function of this azonal riparian forest type caused by water stress.We hypothesize that a complex and diverse stand structure is associated with the distance from the river,and tree size plays a crucial role in establishing random frameworks for stability in forest stands.Our investigation was conducted in the lower Trim River.Based on long-term observation from 2005 to 2023,both stand structure parameters and diversity index were used.The variation in stand structure was analyzed using the least significant difference,and stand stability was assessed using Gaussian distribution and bivariate regression methods.Our study indicated that there were no significant differences in the response of size differentiation and crowding to distance from the river.However,a significant divergence in spatial pattern was observed at greater distances from the river,which became more pronounced over time.Regardless of the distance from the river or time-scale,there were significant differences in DBH,crown diameter and length.Furthermore,structural diversity exhibited varying trends with distance from the river and time-scale,indicating a diverse and complex pattern in stand structure due to water stress.The proportion of random frameworks for stability is influenced by the distance from the river,and tree size,especially crown diameter and length,plays an important role.Our research examines the multiple relationships among water conditions,forest structure,and function in an arid region,highlighting the significance of water conditions in the natural restoration of desert riparian forest ecosystems.The findings provide new insights for further exploration of the relationship between stand structure and stability,enhancing our understanding of the theory of random frameworks-stability.Overall,the study provides scientific guidance for sustainable forest management and conservation in the context of a changing climate,particularly regarding water stress.展开更多
文摘The Zagros forests are a treasure of valuable oak forests, but they have been severely degraded from long-term misuse. Geographic information systems （GIS） and multi-criteria decision analysis （MCDA） have been increasingly used to improve the management of vulnerable ecosystems to prevent further degradation and increase the sustainability of land use. This study presents a methodology to assess land suitability using remote sensing （RS） to obtain wall-to-wall data for the calculations, GIS to analyze the data, and MCDA to rank alternative land uses. The criteria and subcriteria affecting the suitability of land for different uses were identified and weighted using an analytic hierarchy process. Variables used as subcriteria were assessed using satellite data and other sources of information such as existing maps and field surveys. Numerical values for the subcriteria were classified, and each class was given a priority rating according to expert judgments. Based on the ratings and weights of the subcriteria, a priority map was created for each land use using the weighted linear combination method. The priority maps for different land uses were overlaid to obtain a preliminary land use map, which often indicated several simultaneous land uses for the same location. The preliminary map was further edited by removing unrealistic, mutually exclusive land-use combinations. The study tested and demonstrated the potential of integrating RS, G1S and MCDA techniques for solving complicated land allocation problems in forested regions using a scientifically sound and practical approach for efficient and sustainable allocation of forestland for different uses.
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.
基金Supported by NSFC(No.12101316)Belt and Road Innovative Talents Exchange Foreign Experts project(No.DL2023014002L)。
文摘In this paper,we show that an ideal generated by matching Rota-Baxter equations is a bideal of a Hopf algebra on decorated rooted forests.We then get a bialgebraic structure on the space of decorated rooted forests modulo this biideal.As an application,a connected graded bialgebra and so a graded Hopf algebra on matching Rota-Baxter algebras are constructed,which simplifies the Hopf algebraic structure proposed by[Pacific J.Math.,2022,317(2):441-475].
基金supported by the Spanish Ministry of Science and Innovation project GREEN-RISK(Evaluation of past changes in ecosystem services and biodiversity in forests and restoration priorities under global change impacts-PID2020-119933RB-C21)A.C.received a pre-doctoral fellowship funded by the Spanish Ministry of Science and Innovation(PRE2021-099642).
文摘Conservation and enhancement of old-growth forests are key in forest planning and policies.In order to do so,more knowledge is needed on how the attributes traditionally associated with old-growth forests are distributed in space,what differences exist across distinct forest types and what natural or anthropic conditions are affecting the distribution of these old-growthness attributes.Using data from the Third Spanish National Forest Inventory(1997–2007),we calculated six indicators commonly associated with forest old-growthness for the plots in the territory of Peninsular Spain and Balearic Islands,and then combined them into an aggregated index.We then assessed their spatial distribution and the differences across five forest functional types,as well as the effects of ten climate,topographic,landscape,and anthropic variables in their distribution.Relevant geographical patterns were apparent,with climate factors,namely temperature and precipitation,playing a crucial role in the distribution of these attributes.The distribution of the indicators also varied across different forest types,while the effects of recent anthropic impacts were weaker but still relevant.Aridity seemed to be one of the main impediments for the development of old-growthness attributes,coupled with a negative impact of recent human pressure.However,these effects seemed to be mediated by other factors,specially the legacies imposed by the complex history of forest management practices,land use changes and natural disturbances that have shaped the forests of Spain.The results of this exploratory analysis highlight on one hand the importance of climate in the dynamic of forests towards old-growthness,which is relevant in a context of Climate Change,and on the other hand,the need for more insights on the history of our forests in order to understand their present and future.
文摘Sacred forests play a valuable role in the conservation of local biodiversity and provide numerous ecosystem services in Cameroon. The aim of this study was to estimate floristic diversity, stand structures and carbon stocks in the sacred forests of Bandrefam and Batoufam (western Cameroon). The floristic inventory and the stand structures were carried out in 25 m × 25 m plots for individuals with diameters greater than 10 cm;5 m × 5 m for individuals with diameters less than 10 cm. Carbon stocks were estimated using the non-destructive method and allometric equations. The floristic inventory identified 65 species divided into 57 genera and 30 families in the Bandrefam sacred forest and 45 species divided into 42 genera and 27 families in the Batoufam sacred forest. In the Bandrefam, the most important families are Phyllanthaceae (53.98%), Moraceae (21.69%), Lamiaceae (20.15%). At Batoufam, the most important families are Phyllanthaceae (39.73%), Fabaceae (28.47%), Araliaceae (23.77%). Malacantha alnifolia (55.14%), Vitex grandifolia (18.43%), Bosqueia angolensis (15.06%) were the most important species in Bandrefam. Otherwise, Malacantha alnifolia (28%), Polyscias fulva (22.73%), Psychotria sp. (21.28%) were the most important in Batoufam. The Bandrefam sacred forest has the highest tree density (2669 stems/ha). Total carbon stock is 484.88 ± 2.28 tC/ha at Batoufam and 313.95 ± 0.93 tC/ha at Bandrefam. The economic value varies between 5858.04 ± 27.62 USD/ha in Batoufam sacred forest and 3788.51 ± 11.26 USD/ha in Bandrefam sacred forest. The number of individuals and small-diameter trees has little influence on the carbon stocks in the trees. Medium-diameter trees store the most carbon, and very large-diameter trees, which are very poorly represented, store less carbon. In another way, wood density and the basal areas influence the carbon storage of the trees.
基金supported part ia l l y by LIFE4Oak Forests Project LIFE16NAT/IT/000245)the RRF 2.3.121202200008 projectthe MERLiN project funded under the European Commission H2020 Programme(101036337 MERLiN H2020 LC GD 2020)。
文摘Increasing human activity is altering the struc-ture of forests,which affects the composition of communi-ties,including birds.However,little is known about the key forest structure variables that determine the richness of bird communities in European temperate oak forests.We,there-fore,aimed to identify key variables in these habitats that could contribute to the design of management strategies for forest conservation by surveying 11 oak-dominated forest sites throughout the mid-mountain range of Hungary at 86 survey points to reveal the role of different compositional and structural variables for forest stands that influence the breeding bird assemblages in the forests at the functional group and individual species levels.Based on decision tree modelling,our results showed that the density of trees larger than 30 cm DBH was an overall important variable,indi-cating that large-diameter trees were essential to provide diverse bird communities.The total abundance of birds,the foliage-gleaners,primary and secondary cavity nest-ers,residents,and five specific bird species were related to the density of high trunk diameter trees.The abundance of shrub nesters was negatively influenced by a high density of trees over 10 cm DBH.The density of the shrub layer positively affected total bird abundance and the abundance of foliage gleaners,secondary cavity nesters and residents.Analysis of the co-dominant tree species showed that the presence of linden,beech,and hornbeam was important in influencing the abundance of various bird species,e.g.,Eur-asian Treecreeper(Certhia familiaris),Marsh Tit(Poecile palustris)and Wood Warbler(Phylloscopus sibilatrix).Our results indicated that large trees,high tree diversity,and dense shrub layer were essential for forest bird communities and are critical targets for protection to maintain diverse and abundant bird communities in oak-dominated forest habitats.
基金supported by the central government and guides local funds for science and technology development(2022ZY0109).
文摘The naturally fermented Inner Mongolian cheese’s flavor and nutritional value make it a popular choice among customers.In this work,to create multi-functional peptides that have taste and biological activity,peptidomics and bioinformatics were used to screen flavor peptides from Inner Mongolian cheese and further assess their antioxidant and angiotensin I-converting enzyme(ACE)inhibitory properties.According to sensory data,YH8 and IL7 had detectable bitter tastes with low thresholds of 0.03 and 0.06 mmol/L,respectively.With an umami threshold range of 0.24‒0.81 mmol/L,VQ6,FK13,HP13 and QT14 exhibited a range of flavors dominated by umami,including sweet,bitter,salty,sour and kokumi.Antioxidant activity wise,YH8,VQ6,HP13 and QT14 were well represented.The above-mentioned peptides all had some ACE inhibitory effect.The bitter peptide IL7(IC_(50)=0.08 mmol/L)had the highest level of ACE inhibitory activity,followed by YH8(IC_(50)=0.33 mmol/L).These multi-functional peptides,which have been assessed for bioactive and taste features in Inner Mongolian cheese,may have positive impacts on health and harmonize the cheese’s overall flavor.These results suggest that some flavor peptides produced in fermented foods might be with bioactivities while providing a basis for the exploration and application of multi-functional peptides.
基金supported by the National Natural Science Foundation of China(Nos.42107476 and 42177421)the China Postdoctoral International Exchange Fellowship Program(No.PC2021099)+1 种基金the Science and Technology Innovation Program of Hunan Province(No.2020RC2058)the China Scholarship Council(CSC,No.202206600004,to D.Yuan).
文摘Tree growth synchrony serves as a valuable ecological indicator of forest resilience to climate stress and disturbances.However,our understanding of how increasing temperature affects tree growth synchrony during rapidly and slowly warming periods in ecosystems with varying climatic conditions remains limited.By using tree-ring data from temperate broadleaf(Fraxinus mandshurica,Phellodendron amurense,Quercus mongolica,and Juglans mandshurica)and Korean pine(Pinus koraiensis)mixed forests in northeast China,we investigated the effects of climate change,particularly warming,on the growth synchrony of five dominant temperate tree species across contrasting warm-dry and cool-wet climate conditions.Results show that temperature over water availability was the primary factor driving the growth and growth synchrony of the five species.Growth synchrony was significantly higher in warm-dry than in cool-wet areas,primarily due to more uniform climate conditions and higher climate sensitivity in the former.Rapid warming from the 1960s to the 1990s significantly enhanced tree growth synchrony in both areas,followed by a marked reversal as temperatures exceeded a certain threshold or warming slowed down,particularly in the warm-dry area.The growth synchrony variation patterns of the five species were highly consistent over time,although broadleaves exhibited higher synchrony than conifers,suggesting potential risks to forest resilience and stability under future climate change scenarios.Growing season temperatures and non-growing season temperatures and precipitation had a stronger positive effect on tree growth in the cool-wet area compared to the warm-dry area.High relative humidity hindered growth in the cool-wet area but enhanced it in the warm-dry area.Overall,our study highlights that the diversity and sensitivity of climate-growth relationships directly determine spatiotemporal growth synchrony.Temperature,along with water availability,shape long-term forest dynamics by affecting tree growth and synchrony.These results provide crucial insights for forest management practice to enhance structural diversity and resilience capacity against climate changeinduced synchrony shifts.
基金supported by grant klifW018 of the Bavarian State Ministry for Food,Agriculture and Forestry for funding.
文摘1.In recent years,climate change has led to drought and severe bark beetle infestations,affecting Norway spruce(Picea abies)across Europe,with detrimental consequences for forest owners,the forestry sector and associated industries.As a result,silviculture now faces the challenge of identifying tree species more resilient to these stressors to mitigate the impacts on forest management,forest-dependent economies and rural livelihoods.The North American Douglas-fir(Pseudotsuga menziesii)has emerged as a promising conifer species,better suited to future climate conditions and capable of producing high timber yields.2.Non-native tree species may affect native biodiversity,yet the impacts of Douglas-fir on native forest biodiversity are not clear.A comprehensive review evaluating the impact of Douglas-fir on faunal and floral biodiversity in European forests is lacking.3.Here,we present the results of a systematic literature review on Douglas-fir effects on native biodiversity,focusing on studies conducted in Europe.For arthropods,sufficient studies were found to do more detailed quantitative assessments.For fungi,birds,plants and soil fauna some studies existed,but only qualitative evaluations could be made.Other taxa were not investigated.4.In the present literature,the effects of Douglas-fir inclusion in stands on native biodiversity,compared to stands of solely native tree species,were mostly non-significant(78.6%,based on 32 studies).Positive effects were noted in 12%of cases,while negative effects were observed in 9.4%(total of 1,936 effects).Above-ground fauna was more extensively studied than below-ground fauna.Mechanisms proposed to explain taxa responses were often discussed but not always formally tested.For arthropods,there were varying effects on diversity between studies evaluating different scales(i.e.,tree-scale vs.stand-scale).In general,differences in effects depended on a range of factors,including stand composition and structure,season,and sampling site and period.5.Our review indicates limited evidence of adverse effects of Douglas-fir on biodiversity in European forests,highlighting a significant knowledge gap due to the scarcity of studies.Douglas-fir's impact on biodiversity likely varies depending on the forest type and management practices.Further research in diverse contexts is crucial to determine optimal levels of admixture and guide forest management.
文摘Figure 6(a)in the paper[Chin.Phys.B 33074203(2024)]was incorrect due to editorial oversight.The correct figure is provided.This modification does not affect the result presented in the paper.
基金funding support from the United States Fish and Wildlife Service,the North Carolina Wildlife Resources Commission,and the University of North Carolina at Greensboro,as part of a collective effort for the North American Bat Monitoring Program(NABat).
文摘Temperate forest ecosystems are important habitats for many bat species. However, these habitats are increasingly affected by anthropogenic disturbances, particularly urban development, leading to landscapes with varying land cover composition and configuration. Limited research has examined how forest and urban landscape composition and configuration influence bat activity and diversity. Using a multi-year statewide bat acoustic monitoring dataset from North Carolina, USA, we investigated the effects of forest and urban composition and configuration at multiple spatial scales on bat activity and diversity. First, we constructed single-variable landscape index regression models and found that both the composition and configuration of forests and urban developments influenced bat activity and diversity in a species-specific manner. Next, we applied a hierarchical partitioning approach to compare the relative contributions of composition and configuration indices in explaining variance in bat activity. For big brown bats and hoary bats, evergreen forest and urban development composition indices contributed the most to explaining activity variance. In contrast, for eastern red bats, evening bats, and tricolored bats, deciduous forest fragmentation indices describing landscape configuration were the most influential factors. Silver-haired bat activity variance was primarily explained by an evergreen forest fragmentation index. Lastly, urban development configuration indices were the strongest predictors of Mexican free-tailed bat activity and total bat activity. These results suggest that forest and urban landscape configuration should be considered in conservation and management planning for North American temperate forest ecosystems, particularly in regions that have not experienced drastic deforestation in recent decades.
基金Guangdong Innovation and Entrepreneurship Training Programme for Undergraduates“Automatic Classification and Identification of Fraudulent Websites Based on Machine Learning”(Project No.:DC2023125)。
文摘This paper explores the synergistic effect of a model combining Elastic Net and Random Forest in online fraud detection.The study selects a public network dataset containing 1781 data records,divides the dataset by 70%for training and 30%for validation,and analyses the correlation between features using a correlation matrix.The experimental results show that the Elastic Net feature selection method generally outperforms PCA in all models,especially when combined with the Random Forest and XGBoost models,and the ElasticNet+Random Forest model achieves the highest accuracy of 0.968 and AUC value of 0.983,while the Kappa and MCC also reached 0.839 and 0.844 respectively,showing extremely high consistency and correlation.This indicates that combining Elastic Net feature selection and Random Forest model has significant performance advantages in online fraud detection.
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supported by the National Natural Science Foundation of China(No.32201426,No.31988102)the Major Program for Basic Research Project of Yunnan Province(No.202101BC070002)the Key Research and Development Program of Yunnan Provin ce(No.202303AC100009).
文摘Ecological stoichiometry plays an important role in revealing the mechanisms underlying biogeochemical cycles and ecosystem functions.Abiotic factors have strong effects on N-P stoichiometry,yet the impact of plant community structure,especially in forests,has not been fully elucidated.We investigated 68 plots in larch forests in northern China to explore how plant community structure and environmental factors affect the N-P stoichiometry of soil and leaves.The results showed significant differences in soil and leaf N-P stoichiometry among the three larch forests,P concentration and N:P ratio of leaves were significantly related to those of soil.Except for larch forest type,N-P stoichiometry was also regulated by elevation,climatic factors,and community structure.With increasing age(from 25 to 236 years),soil N and N:P ratio significantly increased,especially in the topsoil.With increasing mean DBH,leaf N concentration and N:P ratio also increased,indicating a shift in nutrient limitations with stand growth.These findings provide evidence that plant community structure and environmental factors regulate soil and leaf N-P stoichiometry,which is critically important for understanding biogeochemical cycles and forest management undergoing natural succession.
文摘Gabon,located on the west coast of Central Africa,is one of the most forested countries.This small but richly biodiverse country is covered by rainforests,which make up approximately 85%of its land area.These forests are home to a wide variety of wildlife,including elephants and numerous bird species,making Gabon a crucial area for conservation efforts.
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 the National Key Research and Development Program of China(Grant No.2022YFF1300203)the National Natural Science Foundation of China(Grant No.42371329s).
文摘Natural forests are the primary carbon sinks within terrestrial ecosystems,playing a crucial role in mitigating global climate change.China has successfully restored its natural forest area through extensive protective measures.However,the aboveground carbon(AGC)stock potential of China's natural forests remains considerably uncertain in spatial and temporal dynamics.In this study,we provide a spatially detailed estimation of the maximum AGC stock potential for China's natural forests by integrating high-resolution multi-source remote sensing and field survey data.The analysis reveals that China's natural forests could sequester up to 9.880.10 Pg C by 2030,potentially increasing to 10.460.11 Pg C by 2060.Despite this,the AGC sequestration rate would decline from 0.190.001 to 0.080.001 Pg C·yr^(-1)over the period.Spatially,the future AGC accumulation rates exhibit marked heterogeneity.The warm temperate deciduous broadleaf forest region with predominantly young natural forests,is expected to exhibit the most significant increase of 26.36%by 2060,while the Qinghai-Tibet Plateau Alpine region comprising mainly mature natural forests would exhibit only a 0.74%increase.To sustain the high carbon sequestration capacity of China's natural forests,it is essential to prioritize protecting mature forests alongside preserving and restoring young natural forest areas.
基金funded by the Tuscany region(project Nat-NET)Project funded under the National Recovery and Resilience Plan(NRRP),Mission 4 Component 2 Investment 1.4-Call for tender No.3138 of 16 December 2021,rectified by Decree n.3175 of 18 December 2021 of Italian Ministry of University and Research funded by the European Union-NextGenerationEUProject code CN_00000033,Concession Decree No.1034 of 17 June 2022 adopted by the Italian Ministry of University and Research,CUP B63C22000650007,Project title“National Biodiversity Future Center-NBFC”.
文摘European beech(Fagus sylvatica L.)forests can have a high variability in plant species richness and abundance,from monospecific stands to highly species-rich communities.To understand what causes the low plant diversity observed in some beech forests,we analyzed the drivers of plant community completeness in 155 vegetation plots.Data were collected in mature,closed-canopy beech forests in Tuscany,central Italy.Site-specific species pools were estimated based on species co-occurrences.We used Generalized Least Squares linear modeling to assess the effects of anthropogenic and environmental drivers on the community completeness of whole communities and on the set of specialist species of beech forests.We also tested the response of the total cover of the herb layer to the selected predictors and related both the predictive and response variables to species composition in a Non-metric Multidimensional Scaling ordination.The community completeness of whole communities and that of beech forest specialists were negatively affected by total beech cover and positively influenced by slope.Moreover,the community completeness of whole communities was negatively impacted by elevation and positively influenced by disturbance frequency.The cover of the herb layer decreased with increasing beech cover,elevation,and precipitation.High community completeness and high cover of the herb layer were associated with the presence of thermophilic species of mixed deciduous woods in low-elevation beech forests.Our results suggest that a low plant community completeness and a low cover of the herb layer are mainly due to the competition by beech itself when it forms pure forests in its ecological optimum.Such competition is better exerted at upper elevations and in sites with low slopes,where beech litter accumulation is a limiting factor for understory species.Such evidence suggests that species absence in mature beech forests is mainly due to natural drivers and should therefore not be considered an indicator of ecological degradation of the forest.
基金supported by the Third Xinjiang Scientific Expedition and Research Program of the Ministry of Science&Technology of China(Grant No:2022xjkk0300)National Science Foundation of China(Grant No:32260285)+1 种基金Graduate Research Innovation Project of the Xinjiang Uygur Autonomous Region(Grant No:XJ2024G049)Excellent Doctoral Innovation Program of Xinjiang University(Grant No:XJU2024BS121).
文摘The distance from the river is a crucial factor that affects the structure and function of desert riparian forests,impeding their regeneration and biodiversity due to water conditions.However,few studies have confirmed the long-term variation in structure and function of this azonal riparian forest type caused by water stress.We hypothesize that a complex and diverse stand structure is associated with the distance from the river,and tree size plays a crucial role in establishing random frameworks for stability in forest stands.Our investigation was conducted in the lower Trim River.Based on long-term observation from 2005 to 2023,both stand structure parameters and diversity index were used.The variation in stand structure was analyzed using the least significant difference,and stand stability was assessed using Gaussian distribution and bivariate regression methods.Our study indicated that there were no significant differences in the response of size differentiation and crowding to distance from the river.However,a significant divergence in spatial pattern was observed at greater distances from the river,which became more pronounced over time.Regardless of the distance from the river or time-scale,there were significant differences in DBH,crown diameter and length.Furthermore,structural diversity exhibited varying trends with distance from the river and time-scale,indicating a diverse and complex pattern in stand structure due to water stress.The proportion of random frameworks for stability is influenced by the distance from the river,and tree size,especially crown diameter and length,plays an important role.Our research examines the multiple relationships among water conditions,forest structure,and function in an arid region,highlighting the significance of water conditions in the natural restoration of desert riparian forest ecosystems.The findings provide new insights for further exploration of the relationship between stand structure and stability,enhancing our understanding of the theory of random frameworks-stability.Overall,the study provides scientific guidance for sustainable forest management and conservation in the context of a changing climate,particularly regarding water stress.
