High-altitude peatlands(HAPs;defined as>1,500 m)provide important ecosystem services including soil carbon(C)storage.However,temperatures in high-altitude regions have been rising rapidly in recent decades,while HA...High-altitude peatlands(HAPs;defined as>1,500 m)provide important ecosystem services including soil carbon(C)storage.However,temperatures in high-altitude regions have been rising rapidly in recent decades,while HAPs are increasingly affected by human activities such as intensive drainage and grazing.Collectively,climate change and land management may strongly affect the HAP C cycle.Here,we synthesise current global progress on the HAP C cycle,focussing on the impacts of climate change and land management.Warming increased both ecosystem respiration(ER)and methane(CH_(4))emissions(26%–86%),while impacts on net ecosystem exchange(NEE)of CO_(2)were still unclear.However,short-term drought decreased ER and CH_(4)emissions(7%–96%),along with NEE(12%–52%).Snow,permafrost,and glacier decline may also impact the C cycle in HAPs,although a limited number of studies have been conducted.Grazing and vegetation degradation impacts on HAP C cycling were related to grazing and degradation intensity,while generally decreasing soil organic C stocks(3%–51%).Moving from shallower to deeper WTLs stimulated ER(9%–812%),while reducing CH_(4)emissions(13%–100%),with variable effects on NEE(-53%–700%).Restoration by rewetting began to reverse the trend of drainage.We highlight several knowledge gaps,including limited understanding of climate change and land-management effects on gross primary productivity and dissolved organic carbon,while there is still limited knowledge of regional differences in HAP C cycling.Future research should focus on the interaction of land-use and climate change in HAPs,including HAP restoration,which may help future conservation of these valuable ecosystems.展开更多
A new form of producing and sharing knowledge has emerged as an international(United States of America,Asia,and Europe) research collaboration,known as the Long-Term Ecological Research(LTER) Network.Although Africa b...A new form of producing and sharing knowledge has emerged as an international(United States of America,Asia,and Europe) research collaboration,known as the Long-Term Ecological Research(LTER) Network.Although Africa boasts rich biodiversity,including endemic species,it lacks the long-term initiatives to underpin sustainable biodiversity managements.At present,climate change may exacerbate hunger and poverty concerns in addition to resulting in ecosystem degradation,land use change,and other threats in Africa.Therefore,ecosystem monitoring was suggested to understanding the effects of climate change and setting strategies to mitigate these changes.This paper aimed to investigate ecosystem monitoring ground sites and address their coverage gaps in Africa to provide a foundation for optimizing the African Ecosystem Research Network(AERN) ground sites.The geographic coordinates and characteristics of ground sites-based ecosystem monitoring were collected from various networks aligned with the LTER implementation in Africa.Additionally,climatic data and biodiversity distribution maps were retrieved from various sources.These data were used to assess the size of existing ground sites and the gaps in description,ecosystems and biomes.The results reveal that there were 1089 sites established by various networks.Among these sites,30.5%,27.5%,and 28.8% had no information of area,year of establishment,current status,respectively.However,68.0% of them had an area equal to or greater than 1 km2.Sites were created progressively over the course of the years,with 68.9% being created from 2000 to 2005.To date,only 41.5% of the sites were operational.The sites were scattered across Africa,but they were concentrated in Eastern and Southern Africa.The unbalanced distribution pattern of the sites left Central and Northern Africa hardly covered,and many unique ecosystems in Central Africa were not included.To sustain these sites,the AERN should be based on operational sites,seeking secure funding by establishing multiple partnerships.展开更多
In order to enhance and restore the ecosystems of natural capital in African arid regions,the Global Dryland Ecosystem Programme(G-DEP)consultative meeting was hosted in Dakar,Senegal,from 23 to 25 September 2019.This...In order to enhance and restore the ecosystems of natural capital in African arid regions,the Global Dryland Ecosystem Programme(G-DEP)consultative meeting was hosted in Dakar,Senegal,from 23 to 25 September 2019.This paper details the first African meeting of the G-DEP.Consultative meeting reviewed preceding dryland ecosystems case studies,identified vulnerable arid and semi-arid regions,and proposed sustainable solutions to problems.It also identified the successes and failures of previous attempts to improve vulnerable ecosystems and ultimately formed an action plan to improve these attempts.Climate,ecosystems,and livelihoods for Sustainable Development Goals(SDGs),Great Green Wall Initiative(GGWI)for Sahara and Sahel,and China-Africa cooperation on science,technology,and innovation are three extra main sections concerned of the meeting.Separately,more specific topics as the complicated relationship between these natural processes and human activity,including pastoralism,soil restoration,and vegetation regenerate techniques,were fully discussed.Consultative meeting also identified the positive effects international collaboration can have on dryland regions,specifically in the capacity of sharing information,technology,and innovation on purpose to develop a joint proposal for long-term research programs in African arid and semi-arid areas.Moreover,meetings that review the progress made on ecosystem management for the sustainable livelihoods in Africa,identification of priority areas,and the development and implementation of ecosystem programs for proper research and collaboration in African arid and semi-arid zones,have been proposed as strategic recommendations to enhance the global partnership for sustainable development.Furthermore,as the outcomes of the workshop,there are three steps proposed to handle African dryland climate changes,several aspects suggested to solve current dilemmas of the GGWI,and a series of actions recommended for G-DEP related activities in Africa.展开更多
The steppe in the region of Ain Skhouna (Department of Saida) includes three major vegetation types: Stipa tenacissima, Artemisia herba alba and Lygeum spartum. They have a very important ecological and socio-economic...The steppe in the region of Ain Skhouna (Department of Saida) includes three major vegetation types: Stipa tenacissima, Artemisia herba alba and Lygeum spartum. They have a very important ecological and socio-economic role. Nevertheless, they are exposed to a threat of deterioration due essentially to a combination of adverse climate circumstances and human impact. In the field, we found three physiognomic stages for each type of vegetation: degraded, moderately degraded and well growing. For a better comprehension of the process of each facies, we considered that the dynamic of the above-ground biomass is an interesting indicator for quantifying the degree of degradation of the steppic ecosystems. For that, we have adopted a combined method: linear transects and vegetation harvests over a one-square meter surface. This approach allowed us to identify the chosen site taxa on the one hand and quantify the above-ground biomass of each plot on the other hand. The obtained results reveal a significant regression of the above-ground biomass when moving from one site to another. The values about the Stipa formations present an average biomass oscillating between 1024 and 271.7 kg DM/ha for perennial species and between 367 and 68.8 kg DM/ha for annuals. Those about Artemisia formations fluctuate between 3584 and 805 kg DM/ha for perennials and between 524 and 66 kg DM/ha for annuals. Those about Lygeum formations oscillate between 274.4 and 87.9 kg DM/ha for perennial species accompanying Lygeum spartum and between 162.3 and 31.6 kg DM/ha for annuals.展开更多
Use of synthetic pesticides to manage crop pests has had a toll on human health, environmental safety and farmer’s income creating a need for alternative crop protection strategies. Botanical pesticides have been rep...Use of synthetic pesticides to manage crop pests has had a toll on human health, environmental safety and farmer’s income creating a need for alternative crop protection strategies. Botanical pesticides have been reported to be effective in managing crop pests, and a number of them have been formulated and commercialized. This study was conducted in North-Eastern Tanzania to establish the pesticidal and medicinal value of turmeric (Curcuma longa) and ginger (Zingiber officinale). Purposive sampling was adopted to select and interview 167 respondents drawn from farmers, traders, pharmaceutical shops, agro-shop operators and consumers of turmeric and ginger. Ginger and turmeric rhizomes were also collected for extraction, antifungal assay and biochemical analysis. Results showed that majority of the respondents were aware of the medicinal value of ginger and turmeric, with 59.5% having used the plants to treat respiratory related infections and healing skin surface and internal wounds. About 14% of farmers were aware of and had used aqueous botanical preparations from neem, moringa and Tephrosia to manage insect pests. Only 2.7% of farmers had used ginger powder as a protective insecticide on stored grains. Ginger and turmeric rhizome extracts showed high antifungal activity against Pythium (83% - 95%), Fusarium oxysporum f. sp. lycopersici (34% - 52%) and Alternaria solani (38% - 53%). A GC-MS analysis of ginger and turmeric extracts showed presence of α-zingiberene, β-sesquiphellandrene, α-farnesene, ar-curcumene, α-copaene, ar-tumerone and curlone. This study recommends that ginger and turmeric extracts be considered for development of a botanical pesticide and especially for management of damping off diseases.展开更多
Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold ecosystems.Larch is a widely distributed tree spec...Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold ecosystems.Larch is a widely distributed tree species in boreal Eurasia,calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water physiology.Here,we conducted a short-term rainfall(−60% ambient rainfall;three-year)and snowfall(−73% ambient snowfall;two-year)exclusions experiment in Larix gmelinii forest in northeastern China,and aimed to explore the responses of hydraulic(leaf pressure-volume traits,leaf and branch hydraulic conductivity and embolism resistance),stomatal(stomatal closure point and stomatal safety margin),and economic(photosynthetic rate,nutrient and non-structural carbohydrates contents)traits to rainfall and snowfall reductions.Despite the weak alternation of leaf and branch hydraulic traits,both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins(the difference between stomatal closure point and xylem embolism threshold,describing drought resistance by merging both hydraulic and stomatal strategies).Reductions in rainfall and snowfall induced water or/and low-temperature stress,resulting in more conservative leaf economic traits,including a reduced photosynthetic rate,lower leaf nitrogen concentration,and higher leaf density.In addition,larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem,which helps repair embolism or lower the freezing point acting as osmolytes.Overall,our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing,at the cost of carbon assimilation.展开更多
Root tips are the main components of absorptive fine roots,but their seasonal dynamics and relationship to environmental factors remain unclear due to the difficulties in methodology.In this study,we explored the temp...Root tips are the main components of absorptive fine roots,but their seasonal dynamics and relationship to environmental factors remain unclear due to the difficulties in methodology.In this study,we explored the temporal patterns of root-tip production and mortality in monoculture plantations of five temperate tree species at a common site in northeastern China,and identified the general environmental controls on such processes.We made monthly in-situ assessments of root tip length(RTL)production and mortality in two hardwood and three coniferous species with a minirhizotron(MR)method during the growing seasons of 2008 and 2009.Air temperature,rainfall,soil temperature and water content at 10 cm depth were determined concurrently.RTL production in all species exhibited consistent peaks in summer(June–August)in two growing seasons.RTL mortality showed substantial interannual and interspecific variability,with peaks in autumn and winter in 2008,but various patterns in 2009.RTL production positively correlated with monthly soil and air temperature across all species,and with monthly rainfall in three coniferous species.However,there was no significant correlation between RTL production and soil water content.By contrast,RTL mortality was weakly related to environmental factors,showing positive correlations with soil temperature in Korean spruce,and with rainfall in Korean pine and Korean spruce.Our findings suggest that the seasonal patterns of RTL production are convergent across the five temperate tree species due to the overlapped distribution of heat and rainfall,which can conduce roots to maximizing the acquisition of nutrient resources in the soil.展开更多
Forest inventory is increasingly producing infor-mation on the locations and sizes of individual trees.This information can be acquired by airborne or terrestrial laser scanning or analyzing photogrammetric data.Howev...Forest inventory is increasingly producing infor-mation on the locations and sizes of individual trees.This information can be acquired by airborne or terrestrial laser scanning or analyzing photogrammetric data.However,all trees are seldom detected,especially in young,dense,or multi-layered stands.On the other hand,the complete size distributions of trees can be predicted with various methods,for instance,kNN data imputation in an area-based LiDAR inventory,predicting the parameters of a distribution func-tion from remote sensing data,field sampling,or using his-togram matching and calibration methods.The predicted distribution can be used to estimate the number and sizes of the non-detected trees.The study’s objective was to develop a method for forest planning that efficiently uses the avail-able tree-level data in management optimization.The study developed a two-stage hierarchical method for tree-level management optimization for cases where only part of the trees is detected or measured individually.Cutting years and harvest rate curves for the non-detected trees are optimized at the higher level,and the cutting events of the detected trees are optimized at the lower level.The study used differ-ential evolution at the higher level and simulated annealing at the lower level.The method was tested and demonstrated in even-aged Larix olgensis plantations in the Heilongjiang province of China.The optimizations showed that optimiz-ing the harvest decisions at the tree level improves the profit-ability of management compared to optimizations in which only the dependence of thinning intensity on tree diameter is optimized.The approach demonstrated in this study pro-vides feasible options for tree-level forest planning based on LiDAR inventories.The method is immediately applicable to forestry practice,especially in plantations.展开更多
Understanding the complex relationship between vegetation change and both natural and anthropogenic factors is a subject of global importance.However,comprehensive explanations of vegetation cover trends across China...Understanding the complex relationship between vegetation change and both natural and anthropogenic factors is a subject of global importance.However,comprehensive explanations of vegetation cover trends across China’s different regions and the dynamic roles of their drivers remain limited.This study analyzed national and regional vegetation change trends from 2000 to 2020 and evaluated the evolving impacts of natural and anthropogenic factors.Results indicate that 44.14%of China’s land experienced significant increase(P<0.05)in vegetation coverage.The Northeast(A1),Southwest(A5),and South China(A8)regions showed extremely significant increases in vegetation cover,with over 65%of vegetation exhibiting extremely significant growth(P<0.01).In contrast,less than 25%of vegetation in Inner Mongolia(A2),Northwest(A3),and the Qinghai-Tibetan Plateau(A4)subregions demonstrated an extremely significant increasing trend(P<0.01).Precipitation(q=0.766)and land use type(q=0.636)were the most influential natural and anthropogenic factors,respectively,with their interaction(q=0.838)dominating national vegetation patterns.On the west side of the Hu Line,vegetation dynamics were mainly limited by arid and semi-arid climates,with precipitation as the dominant factor,though land use measures have contributed to some vegetation improvement.Between 2000 and 2020,the influence of precipitation on vegetation cover increased in regions A3 and A4,with q-values rising by 26.73%and 101.13%,respectively.Additionally,soil type exerted a significant effect(P<0.001)on vegetation cover across all regions,being most pronounced in A2(q=0.692).On the east side of the Hu Line,vegetation growth benefited generally from warm and humid conditions,while local decline in urbanized areas was largely attributable to land use change and economic expansion.Concurrently anthropogenic factors such as land use and population density increasingly influenced vegetation dynamics in eastern urban areas of the Hu Line.Population density and GDP were the most influential factors affecting vegetation cover in region A8,with q-values of 0.443 and 0.380,respectively(P<0.001).Future efforts should maintain the benefits of large-scale ecological projects and harmonize the relationship between urban vegetation and anthropogenic influences.展开更多
Chemicals that modify pest behavior are developed to reduce crop damage by altering pest behavior, using specific genes within the olfactory system as molecular targets. The identification of these molecular targets i...Chemicals that modify pest behavior are developed to reduce crop damage by altering pest behavior, using specific genes within the olfactory system as molecular targets. The identification of these molecular targets in Bactrocera dorsalis, also known as the functional study of key olfactory genes, relies on CRISPR/Cas9-mediated gene knockout techniques. However, these techniques face limitations when applied to lethal genes. Transgenic technology offers a solution since it enables precise manipulation of gene expression in specific tissues or during certain developmental stages. Consequently, this study developed a piggyBac-mediated transgenic system in B. dorsalis to investigate reporter gene expression in olfactory organs, and assessed the olfactory behavior andantennal electrophysiological responses in transgenic lines. The goal was to assess the potential of this approach for future research on olfactory gene function. A universally expressed housekeeping gene from the BdorActin family was identified using the developmental transcriptome dataset. Its candidate promoter region(BdorActinA3a-1^(P–2k)) was then cloned into the piggyBac plasmid. We subsequently established two stable transgenic lines with specific TTAA insertion sites on chromosomes 4 and 5, consistent with the characteristics of piggyBac transposition. The transgenic strains exhibited essentially normal survival, with hatchability and adult lifespan unaffected, althoughthere were slight reductions in the emergence rate and oviposition capacity. The fluorescent reporter has been successfully expressed in olfactory-related organs, such as the antennae, proboscis, maxillary palp, legs, external genitalia, and brain. The antennal electrophysiological responses to representative chemicals in the transgenic lines were consistent with those of the wild type. However, some olfactory-related behaviors, such as pheromone response and mating, were significantly affected in the transgenic lines. These findings suggest that our system could potentially be applied in future olfactory research, such as driving the expression of exogenous elements that are effective in olfactory organs. However, caution is advised regarding its impact when applied to some olfactoryrelated behavioral phenotypes.展开更多
While the fire protection function of tree bark has been extensively documented,other critical functions,including storage and mechanical support,have received less attention.In this study we examined:(1)the allometry...While the fire protection function of tree bark has been extensively documented,other critical functions,including storage and mechanical support,have received less attention.In this study we examined:(1)the allometry of bark thickness(and biomass)against wood radius(and biomass)at a disc level,(2)differences in bark allocation between the ratio and the regression approaches,(3)differences between bark thickness and biomass as metrics of bark allocation,and(4)how bark allocation is associated with the evolution of wood from non-porous to diffuse-porous and ring-porous types.Thickness and biomass of bark and wood were measured using trunk discs of 88 individual trees of 36 species in a temperate forest characterized by a long fire interval.Allometric relationships of bark thickness(and biomass)against wood radius(and biomass)explained why both relative bark thickness and biomass decreased with increasing stem diameter.Variations in both among species varied by factors of 3.5 to 7.5 depending on the measurement methods.The ratio approach produced higher estimates of both relative bark thickness and biomass compared to the regression approach,while relative bark thickness was significantly lower than relative bark biomass.Ring-porous species exhibited higher bark thickness based on the ratio approach,which might reflect evolutionary adaptations where ring-porous species have developed thicker bark as protection:thermal insulation against freeze-thaw embolism coupled with carbohydrate reservoirs for hydraulic repair.The regression slope of bark allocation against wood density increased along the wood porosity gradient,demonstrating evolutionary biomechanical coordination between bark and wood.These findings highlight systematic coupling between bark and xylem multifunctionality.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
The restoration of severely fragmented forests requires urgent guidance from succession theory.New theories and methods in plant functional ecology offer novel perspectives on the mechanisms that drive forest successi...The restoration of severely fragmented forests requires urgent guidance from succession theory.New theories and methods in plant functional ecology offer novel perspectives on the mechanisms that drive forest succession and productivity.Here,we established a restoration gradient of seven forest logging periods in temperate forests in China,and conducted systematic surveys on the leaf functional traits of all observed plant species,plant community structure,and soil properties.Inspired by the new concept of two-dimensional plant community traits(i.e.,efficiency and quantity traits)and plant trait networks(PTNs),we explored the adaptation mechanisms of forest communities along a restoration succession and their relationship to productivity.Efficiency and quantity traits initially increased and then stabilized,whereas multi-trait relationships(MR)exhibited fluctuations,with community resource utilization efficiency increasing initially before stabilization.As expected,productivity is poorly explained by either efficiency or quantity traits alone but is substantially better explained by their joint consideration as two-dimensional community traits.Among these,the efficiency and quantity traits of leaf area and leaf dry weight can explain up to 43%of productivity.Furthermore,MR exhibit a time-lag effect on productivity.A structural equation model(SEM)with time-lag analysis showed that efficiency traits,quantity traits,MR,and soil properties explained 64%of the spatial variation in productivity during forest succession.Efficiency and quantity traits directly regulated productivity,whereas soil properties and MR indirectly regulated productivity.Our findings are the first to demonstrate the regulation mechanisms between forest succession and productivity from the framework of efficiency traits-quantity traits-MR,providing theoretical guidance and a reference for ecological restoration,and predicting the spatial variation of forest productivity,especially at small scale.展开更多
Forests play a critical role in mitigating cli-mate change by sequestering carbon,yet their responses to environmental shifts remain complex and multifaceted.This special issue,“Tree Rings,Forest Carbon Sink,and Clim...Forests play a critical role in mitigating cli-mate change by sequestering carbon,yet their responses to environmental shifts remain complex and multifaceted.This special issue,“Tree Rings,Forest Carbon Sink,and Climate Change,”compiles 41 interdisciplinary studies exploring forest-climate interactions through dendrochro-nological and ecological approaches.It addresses climate reconstruction(e.g.,temperature,precipitation,isotopes)using tree-ring proxies,species-specific and age-dependent growth responses to warming and drought,anatomical adap-tations,and methodological innovations in isotope analysis and multi-proxy integration.Key findings reveal ENSO/AMO modulation of historical climates,elevation-and latitude-driven variability in tree resilience,contrasting carbon dynamics under stress,and projected habitat shifts for vulnerable species.The issue underscores forests’dual role as climate archives and carbon regulators,offering insights for adaptive management and nature-based climate solutions.Contributions bridge micro-scale physiological processes to macro-scale ecological modeling,advancing sustainable strategies amid global environmental challenges.展开更多
Osyris lanceolata is heavily and illegally exploited in East Africa for its essential oils, yet little is known about its population status and ecological requirements. This study examined its population structure and...Osyris lanceolata is heavily and illegally exploited in East Africa for its essential oils, yet little is known about its population status and ecological requirements. This study examined its population structure and environmental factors influencing its distribution in the semi-arid Karamoja sub-region, Uganda. We surveyed 388 plots (5 m radius) at different altitudes, recording life stages, stem diameters, and regeneration patterns, and analyzed soil samples. Multivariate analyses, including Canonical Correspondence Analysis (CCA), Detrended Correspondence Analysis (DCA), Non-metric Multidimensional Scaling (NMDS), and Multiple Regression Modeling (MRM), identified key environmental factors affecting its distribution. Findings show that O. lanceolata populations in Moroto, Nakapiripirit, and Amudat districts are severely degraded due to overexploitation. The species is primarily regenerating through coppicing rather than seedlings, with an exploitation intensity of 56.6%. Population densities are low, distribution is irregular, and sustainable harvesting is not viable. Soil properties, particularly Ca2+, N, P, K+, Na+, and organic matter, significantly influence its abundance. Conservation efforts should focus on identifying suitable provenances for genetic preservation and plantation establishment. Areas with at least 9 trees per hectare in Moroto, Nakapiripirit, and Amudat could serve as potential sites for ex-situ plantations. Further research should explore how biotic interactions, genetic diversity, and morphology affect oil yield and quality to support restoration, breeding, and domestication initiatives.展开更多
According to the contemporary ecosystem approach, the linkages of human actions with their environment have to be assessed in an integrative manner. The Driver-Pressure-State-Impact-Response （DPSIR） model is applied...According to the contemporary ecosystem approach, the linkages of human actions with their environment have to be assessed in an integrative manner. The Driver-Pressure-State-Impact-Response （DPSIR） model is applied to identify and describe processes and interactions in human-environmental systems. An example application from a research project dealing with the development of sustainable management strategies for the agriculture in Jiangsu, China, illustrates the potentials and limitations of its sustainable development. The concept and indicators of ecological integrity are used to assess the indicators in the dimensions of DPSIR between 2003 and 2006. The main drivers included population growth which caused increasing demand for food, growing environmental demands, and rapidly decreasing of land and other natural resources. The main environmental problem was water pollution. The results show that in the dimension of driver, total grain output and agricultural land productivity both increased. Labor intensive agriculture has been promoted to increase agricultural land productivity. In the dimension of pressure, on the positive side, infrastructure got greatly improved, the input level such as total power of machinery, and level of fertilizer use increased, and level of pesticides use decreased, but on the negative side, cultivated land per capita and irrigation rate decreased, natural resources keep decreased. Environmental pollution indicators such as industrial wastewater discharge and acid rain rate increased in Jiangsu Province. In the aspect of state, ecosystem state was improved, plant coverage index increased, biological abundance index increased, fertilizer productivity increased, eco-environmental quality index increased, but land degradation index also increased. In the aspect of impact, output level increased, output efficiency enhanced, farmer＇s social economic benefit improved. In the aspect of response, social support was greatly improved, input for environmental governance increased. To assess the effects of environmental governance, Jiangsu government was successful to increase compliance rate of sulfur dioxide emissions, but not so efficient in compliance rate of industrial wastewater discharge.展开更多
Quantifying fi ne root(≤ 2.0 mm in diameter) distribution and turnover is essential for accurately estimating forest carbon budgets. However, fi ne root dynamics are poorly understood, possibly because of their inacc...Quantifying fi ne root(≤ 2.0 mm in diameter) distribution and turnover is essential for accurately estimating forest carbon budgets. However, fi ne root dynamics are poorly understood, possibly because of their inaccessibility. This study quantifi es fi ne root distribution and turnover rates for fi ve representative Chinese temperate forests types. Fine root number, diameter, biomass, necromass, production, mortality, and turnover rates were measured using a minirhizotron over a 12-month period. More than 90% of the fi ne roots were < 0.5 mm in diameter, with thin fi ne roots at shallow layers, and thicker ones in deeper soil layers. The fi ne root dynamics were signifi cantly diff erent among the forest types. Coniferous plantations had fewer fi ne roots, less biomass, necromass, production and mortality but greater average diameters than fi ne roots of broadleaved forests. All traits, except for diameter, decreased along the soil profi le. Fine root numbers and production exhibited a unimodal seasonal pattern with peaks occurring in summer, whereas biomass, necromass and mortality progressivelyincreased over the growing season. The turnover rates of roots < 0.5 mm varied from 0.4 to 1.0 a-1 for the fi ve forest types, 0.5–1.0 a-1 for the soil layers and 0.2–1.1 a-1 for the seasons, with the largest turnover rate at the 0–10 cm depth in summer. The patterns of fi ne root numbers, biomass, necromass, production, mortality, and turnover rates varied with forest types, soil depths, growing season and diameter classes. This study highlights the importance of forest types and diameters in quantifying fi ne root turnover rates.展开更多
The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） Wha...The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） What is the ecological niche of the different epiphytic orchid species？ （2） What are the ecological factors that threaten epiphytic orchid＇s population under anthropogenic disturbances？ Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis （PCA）. The correlations between the different site factors were statistically significant. Spearman＇s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height （dbh） of host had the highest significant positive correlation coefficient （0.67 and 0.64 respectively）. On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient （-0.80 and -0.61, respectively）. Different epiphytic orchid species interact differently with the given set of environmental factors： for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees （species and size） and increasing air pollution, resulting in increasing host bark pH.展开更多
Sand and dust storms （SDS） are common phenomena in arid and semi-arid areas. In recent years, SDS frequencies and intensities have increased significantly in Iran. A research on SDS sources is important for understa...Sand and dust storms （SDS） are common phenomena in arid and semi-arid areas. In recent years, SDS frequencies and intensities have increased significantly in Iran. A research on SDS sources is important for understanding the mechanisms of dust generation and assessing its socio-economic and environmental impacts. In this paper, we developed a new approach to identify SDS source areas in Iran using a combination of nine related datasets, namely drought events, temperature, precipitation, location of sandy soils, SDS frequency, hu- man-induced soil degradation （HISD）, human influence index （HII）, rain use efficiency （RUE） and net primary pro- ductivity （NPP） loss. To identify SDS source areas, we firstly normalized these datasets under uniform criteria in- cluding layer reprojection using Lambert conformal conic projection, data conversion from shapefile to raster, Min-Max Normalization with data range from 0 to 1, and data interpolation by Kriging and images resampling （resolution of 1 km）. After that, a score map for the possibility of SDS sources was generated through overlaying multiple datasets under average weight allocation criterion, in which each item obtained weight equally. In the score map, the higher the score, the more possible a specific area could be regarded as SDS source area. Exceptions mostly came from large cities, like Tehran and Isfahan. As a result, final SDS source areas were mapped out, and Al-Howizeh/Al-Azim marshes and Sistan Basin were identified as main SDS source areas in Iran. The SDS source area in Al-Howizeh/Al-Azim marshes still keeps expanding. In addition, Al-Howizeh/Al-Azim marshes are now suf- fering rapid land degradation due to natural and human-induced factors and might totally vanish in the near future. Sistan Basin also demonstrates the impacts of soil degradation and wind erosion. With appropriate intensity, dura- tion, wind speed and altitude of the dust storms, sand particles uplifting from this area might have developed into extreme dust storms, especially during the summer.展开更多
As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared w...As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.展开更多
基金supported by the National Natural Science Foundation of China(Grants No.U2243226 and 42250410326)the Research Start-up Fund of the Institute of Geographic Sciences and Natural Resources Research(Chinese Academy of Sciences)。
文摘High-altitude peatlands(HAPs;defined as>1,500 m)provide important ecosystem services including soil carbon(C)storage.However,temperatures in high-altitude regions have been rising rapidly in recent decades,while HAPs are increasingly affected by human activities such as intensive drainage and grazing.Collectively,climate change and land management may strongly affect the HAP C cycle.Here,we synthesise current global progress on the HAP C cycle,focussing on the impacts of climate change and land management.Warming increased both ecosystem respiration(ER)and methane(CH_(4))emissions(26%–86%),while impacts on net ecosystem exchange(NEE)of CO_(2)were still unclear.However,short-term drought decreased ER and CH_(4)emissions(7%–96%),along with NEE(12%–52%).Snow,permafrost,and glacier decline may also impact the C cycle in HAPs,although a limited number of studies have been conducted.Grazing and vegetation degradation impacts on HAP C cycling were related to grazing and degradation intensity,while generally decreasing soil organic C stocks(3%–51%).Moving from shallower to deeper WTLs stimulated ER(9%–812%),while reducing CH_(4)emissions(13%–100%),with variable effects on NEE(-53%–700%).Restoration by rewetting began to reverse the trend of drainage.We highlight several knowledge gaps,including limited understanding of climate change and land-management effects on gross primary productivity and dissolved organic carbon,while there is still limited knowledge of regional differences in HAP C cycling.Future research should focus on the interaction of land-use and climate change in HAPs,including HAP restoration,which may help future conservation of these valuable ecosystems.
基金Under the auspices of National Natural Science Foundation of China(No.31161140355)
文摘A new form of producing and sharing knowledge has emerged as an international(United States of America,Asia,and Europe) research collaboration,known as the Long-Term Ecological Research(LTER) Network.Although Africa boasts rich biodiversity,including endemic species,it lacks the long-term initiatives to underpin sustainable biodiversity managements.At present,climate change may exacerbate hunger and poverty concerns in addition to resulting in ecosystem degradation,land use change,and other threats in Africa.Therefore,ecosystem monitoring was suggested to understanding the effects of climate change and setting strategies to mitigate these changes.This paper aimed to investigate ecosystem monitoring ground sites and address their coverage gaps in Africa to provide a foundation for optimizing the African Ecosystem Research Network(AERN) ground sites.The geographic coordinates and characteristics of ground sites-based ecosystem monitoring were collected from various networks aligned with the LTER implementation in Africa.Additionally,climatic data and biodiversity distribution maps were retrieved from various sources.These data were used to assess the size of existing ground sites and the gaps in description,ecosystems and biomes.The results reveal that there were 1089 sites established by various networks.Among these sites,30.5%,27.5%,and 28.8% had no information of area,year of establishment,current status,respectively.However,68.0% of them had an area equal to or greater than 1 km2.Sites were created progressively over the course of the years,with 68.9% being created from 2000 to 2005.To date,only 41.5% of the sites were operational.The sites were scattered across Africa,but they were concentrated in Eastern and Southern Africa.The unbalanced distribution pattern of the sites left Central and Northern Africa hardly covered,and many unique ecosystems in Central Africa were not included.To sustain these sites,the AERN should be based on operational sites,seeking secure funding by establishing multiple partnerships.
基金Funding to support this consultative meeting was provided by the National Natural Science Foundation of China(41761144053,41661144022)the International Partnership Program of Chinese Academy of Sciences(121311KYSB201700).
文摘In order to enhance and restore the ecosystems of natural capital in African arid regions,the Global Dryland Ecosystem Programme(G-DEP)consultative meeting was hosted in Dakar,Senegal,from 23 to 25 September 2019.This paper details the first African meeting of the G-DEP.Consultative meeting reviewed preceding dryland ecosystems case studies,identified vulnerable arid and semi-arid regions,and proposed sustainable solutions to problems.It also identified the successes and failures of previous attempts to improve vulnerable ecosystems and ultimately formed an action plan to improve these attempts.Climate,ecosystems,and livelihoods for Sustainable Development Goals(SDGs),Great Green Wall Initiative(GGWI)for Sahara and Sahel,and China-Africa cooperation on science,technology,and innovation are three extra main sections concerned of the meeting.Separately,more specific topics as the complicated relationship between these natural processes and human activity,including pastoralism,soil restoration,and vegetation regenerate techniques,were fully discussed.Consultative meeting also identified the positive effects international collaboration can have on dryland regions,specifically in the capacity of sharing information,technology,and innovation on purpose to develop a joint proposal for long-term research programs in African arid and semi-arid areas.Moreover,meetings that review the progress made on ecosystem management for the sustainable livelihoods in Africa,identification of priority areas,and the development and implementation of ecosystem programs for proper research and collaboration in African arid and semi-arid zones,have been proposed as strategic recommendations to enhance the global partnership for sustainable development.Furthermore,as the outcomes of the workshop,there are three steps proposed to handle African dryland climate changes,several aspects suggested to solve current dilemmas of the GGWI,and a series of actions recommended for G-DEP related activities in Africa.
文摘The steppe in the region of Ain Skhouna (Department of Saida) includes three major vegetation types: Stipa tenacissima, Artemisia herba alba and Lygeum spartum. They have a very important ecological and socio-economic role. Nevertheless, they are exposed to a threat of deterioration due essentially to a combination of adverse climate circumstances and human impact. In the field, we found three physiognomic stages for each type of vegetation: degraded, moderately degraded and well growing. For a better comprehension of the process of each facies, we considered that the dynamic of the above-ground biomass is an interesting indicator for quantifying the degree of degradation of the steppic ecosystems. For that, we have adopted a combined method: linear transects and vegetation harvests over a one-square meter surface. This approach allowed us to identify the chosen site taxa on the one hand and quantify the above-ground biomass of each plot on the other hand. The obtained results reveal a significant regression of the above-ground biomass when moving from one site to another. The values about the Stipa formations present an average biomass oscillating between 1024 and 271.7 kg DM/ha for perennial species and between 367 and 68.8 kg DM/ha for annuals. Those about Artemisia formations fluctuate between 3584 and 805 kg DM/ha for perennials and between 524 and 66 kg DM/ha for annuals. Those about Lygeum formations oscillate between 274.4 and 87.9 kg DM/ha for perennial species accompanying Lygeum spartum and between 162.3 and 31.6 kg DM/ha for annuals.
文摘Use of synthetic pesticides to manage crop pests has had a toll on human health, environmental safety and farmer’s income creating a need for alternative crop protection strategies. Botanical pesticides have been reported to be effective in managing crop pests, and a number of them have been formulated and commercialized. This study was conducted in North-Eastern Tanzania to establish the pesticidal and medicinal value of turmeric (Curcuma longa) and ginger (Zingiber officinale). Purposive sampling was adopted to select and interview 167 respondents drawn from farmers, traders, pharmaceutical shops, agro-shop operators and consumers of turmeric and ginger. Ginger and turmeric rhizomes were also collected for extraction, antifungal assay and biochemical analysis. Results showed that majority of the respondents were aware of the medicinal value of ginger and turmeric, with 59.5% having used the plants to treat respiratory related infections and healing skin surface and internal wounds. About 14% of farmers were aware of and had used aqueous botanical preparations from neem, moringa and Tephrosia to manage insect pests. Only 2.7% of farmers had used ginger powder as a protective insecticide on stored grains. Ginger and turmeric rhizome extracts showed high antifungal activity against Pythium (83% - 95%), Fusarium oxysporum f. sp. lycopersici (34% - 52%) and Alternaria solani (38% - 53%). A GC-MS analysis of ginger and turmeric extracts showed presence of α-zingiberene, β-sesquiphellandrene, α-farnesene, ar-curcumene, α-copaene, ar-tumerone and curlone. This study recommends that ginger and turmeric extracts be considered for development of a botanical pesticide and especially for management of damping off diseases.
基金supported by the National Key R&D Program of China(2022YFE0127900,2021YFD2200401)the National Natural Science Foundation of China(31901278).
文摘Ongoing climate change has a considerable influence on the seasonality,timing,and intensity of rainfall worldwide,and is also predicted to decrease snow cover in cold ecosystems.Larch is a widely distributed tree species in boreal Eurasia,calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water physiology.Here,we conducted a short-term rainfall(−60% ambient rainfall;three-year)and snowfall(−73% ambient snowfall;two-year)exclusions experiment in Larix gmelinii forest in northeastern China,and aimed to explore the responses of hydraulic(leaf pressure-volume traits,leaf and branch hydraulic conductivity and embolism resistance),stomatal(stomatal closure point and stomatal safety margin),and economic(photosynthetic rate,nutrient and non-structural carbohydrates contents)traits to rainfall and snowfall reductions.Despite the weak alternation of leaf and branch hydraulic traits,both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins(the difference between stomatal closure point and xylem embolism threshold,describing drought resistance by merging both hydraulic and stomatal strategies).Reductions in rainfall and snowfall induced water or/and low-temperature stress,resulting in more conservative leaf economic traits,including a reduced photosynthetic rate,lower leaf nitrogen concentration,and higher leaf density.In addition,larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem,which helps repair embolism or lower the freezing point acting as osmolytes.Overall,our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing,at the cost of carbon assimilation.
基金supported by the National Natural Science Foundation of China(32071749)。
文摘Root tips are the main components of absorptive fine roots,but their seasonal dynamics and relationship to environmental factors remain unclear due to the difficulties in methodology.In this study,we explored the temporal patterns of root-tip production and mortality in monoculture plantations of five temperate tree species at a common site in northeastern China,and identified the general environmental controls on such processes.We made monthly in-situ assessments of root tip length(RTL)production and mortality in two hardwood and three coniferous species with a minirhizotron(MR)method during the growing seasons of 2008 and 2009.Air temperature,rainfall,soil temperature and water content at 10 cm depth were determined concurrently.RTL production in all species exhibited consistent peaks in summer(June–August)in two growing seasons.RTL mortality showed substantial interannual and interspecific variability,with peaks in autumn and winter in 2008,but various patterns in 2009.RTL production positively correlated with monthly soil and air temperature across all species,and with monthly rainfall in three coniferous species.However,there was no significant correlation between RTL production and soil water content.By contrast,RTL mortality was weakly related to environmental factors,showing positive correlations with soil temperature in Korean spruce,and with rainfall in Korean pine and Korean spruce.Our findings suggest that the seasonal patterns of RTL production are convergent across the five temperate tree species due to the overlapped distribution of heat and rainfall,which can conduce roots to maximizing the acquisition of nutrient resources in the soil.
基金supported by the Natural Science Foundation of China (U21A20244 and 32071758)funding provided by University of Eastern Finland (including Kuopio University Hospital)
文摘Forest inventory is increasingly producing infor-mation on the locations and sizes of individual trees.This information can be acquired by airborne or terrestrial laser scanning or analyzing photogrammetric data.However,all trees are seldom detected,especially in young,dense,or multi-layered stands.On the other hand,the complete size distributions of trees can be predicted with various methods,for instance,kNN data imputation in an area-based LiDAR inventory,predicting the parameters of a distribution func-tion from remote sensing data,field sampling,or using his-togram matching and calibration methods.The predicted distribution can be used to estimate the number and sizes of the non-detected trees.The study’s objective was to develop a method for forest planning that efficiently uses the avail-able tree-level data in management optimization.The study developed a two-stage hierarchical method for tree-level management optimization for cases where only part of the trees is detected or measured individually.Cutting years and harvest rate curves for the non-detected trees are optimized at the higher level,and the cutting events of the detected trees are optimized at the lower level.The study used differ-ential evolution at the higher level and simulated annealing at the lower level.The method was tested and demonstrated in even-aged Larix olgensis plantations in the Heilongjiang province of China.The optimizations showed that optimiz-ing the harvest decisions at the tree level improves the profit-ability of management compared to optimizations in which only the dependence of thinning intensity on tree diameter is optimized.The approach demonstrated in this study pro-vides feasible options for tree-level forest planning based on LiDAR inventories.The method is immediately applicable to forestry practice,especially in plantations.
基金Under the auspices of the National Natural Science Foundation of China(No.32371863)Fundamental Research Funds for the Central Universities(No.2572025AW39)。
文摘Understanding the complex relationship between vegetation change and both natural and anthropogenic factors is a subject of global importance.However,comprehensive explanations of vegetation cover trends across China’s different regions and the dynamic roles of their drivers remain limited.This study analyzed national and regional vegetation change trends from 2000 to 2020 and evaluated the evolving impacts of natural and anthropogenic factors.Results indicate that 44.14%of China’s land experienced significant increase(P<0.05)in vegetation coverage.The Northeast(A1),Southwest(A5),and South China(A8)regions showed extremely significant increases in vegetation cover,with over 65%of vegetation exhibiting extremely significant growth(P<0.01).In contrast,less than 25%of vegetation in Inner Mongolia(A2),Northwest(A3),and the Qinghai-Tibetan Plateau(A4)subregions demonstrated an extremely significant increasing trend(P<0.01).Precipitation(q=0.766)and land use type(q=0.636)were the most influential natural and anthropogenic factors,respectively,with their interaction(q=0.838)dominating national vegetation patterns.On the west side of the Hu Line,vegetation dynamics were mainly limited by arid and semi-arid climates,with precipitation as the dominant factor,though land use measures have contributed to some vegetation improvement.Between 2000 and 2020,the influence of precipitation on vegetation cover increased in regions A3 and A4,with q-values rising by 26.73%and 101.13%,respectively.Additionally,soil type exerted a significant effect(P<0.001)on vegetation cover across all regions,being most pronounced in A2(q=0.692).On the east side of the Hu Line,vegetation growth benefited generally from warm and humid conditions,while local decline in urbanized areas was largely attributable to land use change and economic expansion.Concurrently anthropogenic factors such as land use and population density increasingly influenced vegetation dynamics in eastern urban areas of the Hu Line.Population density and GDP were the most influential factors affecting vegetation cover in region A8,with q-values of 0.443 and 0.380,respectively(P<0.001).Future efforts should maintain the benefits of large-scale ecological projects and harmonize the relationship between urban vegetation and anthropogenic influences.
基金the support from the Shenzhen Science and Technology Program, China (KQTD2018041 1143628272)the special funds for Science Technology Innovation and Industrial Development of Shenzhen Dapeng New District, China (PT202101-02)the National Key Research and Development Program of China (2022YFD1700201)。
文摘Chemicals that modify pest behavior are developed to reduce crop damage by altering pest behavior, using specific genes within the olfactory system as molecular targets. The identification of these molecular targets in Bactrocera dorsalis, also known as the functional study of key olfactory genes, relies on CRISPR/Cas9-mediated gene knockout techniques. However, these techniques face limitations when applied to lethal genes. Transgenic technology offers a solution since it enables precise manipulation of gene expression in specific tissues or during certain developmental stages. Consequently, this study developed a piggyBac-mediated transgenic system in B. dorsalis to investigate reporter gene expression in olfactory organs, and assessed the olfactory behavior andantennal electrophysiological responses in transgenic lines. The goal was to assess the potential of this approach for future research on olfactory gene function. A universally expressed housekeeping gene from the BdorActin family was identified using the developmental transcriptome dataset. Its candidate promoter region(BdorActinA3a-1^(P–2k)) was then cloned into the piggyBac plasmid. We subsequently established two stable transgenic lines with specific TTAA insertion sites on chromosomes 4 and 5, consistent with the characteristics of piggyBac transposition. The transgenic strains exhibited essentially normal survival, with hatchability and adult lifespan unaffected, althoughthere were slight reductions in the emergence rate and oviposition capacity. The fluorescent reporter has been successfully expressed in olfactory-related organs, such as the antennae, proboscis, maxillary palp, legs, external genitalia, and brain. The antennal electrophysiological responses to representative chemicals in the transgenic lines were consistent with those of the wild type. However, some olfactory-related behaviors, such as pheromone response and mating, were significantly affected in the transgenic lines. These findings suggest that our system could potentially be applied in future olfactory research, such as driving the expression of exogenous elements that are effective in olfactory organs. However, caution is advised regarding its impact when applied to some olfactoryrelated behavioral phenotypes.
基金supported by the National Natural Science Foundation of China(32171765)。
文摘While the fire protection function of tree bark has been extensively documented,other critical functions,including storage and mechanical support,have received less attention.In this study we examined:(1)the allometry of bark thickness(and biomass)against wood radius(and biomass)at a disc level,(2)differences in bark allocation between the ratio and the regression approaches,(3)differences between bark thickness and biomass as metrics of bark allocation,and(4)how bark allocation is associated with the evolution of wood from non-porous to diffuse-porous and ring-porous types.Thickness and biomass of bark and wood were measured using trunk discs of 88 individual trees of 36 species in a temperate forest characterized by a long fire interval.Allometric relationships of bark thickness(and biomass)against wood radius(and biomass)explained why both relative bark thickness and biomass decreased with increasing stem diameter.Variations in both among species varied by factors of 3.5 to 7.5 depending on the measurement methods.The ratio approach produced higher estimates of both relative bark thickness and biomass compared to the regression approach,while relative bark thickness was significantly lower than relative bark biomass.Ring-porous species exhibited higher bark thickness based on the ratio approach,which might reflect evolutionary adaptations where ring-porous species have developed thicker bark as protection:thermal insulation against freeze-thaw embolism coupled with carbohydrate reservoirs for hydraulic repair.The regression slope of bark allocation against wood density increased along the wood porosity gradient,demonstrating evolutionary biomechanical coordination between bark and wood.These findings highlight systematic coupling between bark and xylem multifunctionality.
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(32301362,42301544,32430067)。
文摘The restoration of severely fragmented forests requires urgent guidance from succession theory.New theories and methods in plant functional ecology offer novel perspectives on the mechanisms that drive forest succession and productivity.Here,we established a restoration gradient of seven forest logging periods in temperate forests in China,and conducted systematic surveys on the leaf functional traits of all observed plant species,plant community structure,and soil properties.Inspired by the new concept of two-dimensional plant community traits(i.e.,efficiency and quantity traits)and plant trait networks(PTNs),we explored the adaptation mechanisms of forest communities along a restoration succession and their relationship to productivity.Efficiency and quantity traits initially increased and then stabilized,whereas multi-trait relationships(MR)exhibited fluctuations,with community resource utilization efficiency increasing initially before stabilization.As expected,productivity is poorly explained by either efficiency or quantity traits alone but is substantially better explained by their joint consideration as two-dimensional community traits.Among these,the efficiency and quantity traits of leaf area and leaf dry weight can explain up to 43%of productivity.Furthermore,MR exhibit a time-lag effect on productivity.A structural equation model(SEM)with time-lag analysis showed that efficiency traits,quantity traits,MR,and soil properties explained 64%of the spatial variation in productivity during forest succession.Efficiency and quantity traits directly regulated productivity,whereas soil properties and MR indirectly regulated productivity.Our findings are the first to demonstrate the regulation mechanisms between forest succession and productivity from the framework of efficiency traits-quantity traits-MR,providing theoretical guidance and a reference for ecological restoration,and predicting the spatial variation of forest productivity,especially at small scale.
基金supported by the Outstanding Action Plan of Chinese Sci-tech Journals(Grant No.OAP-C-077).
文摘Forests play a critical role in mitigating cli-mate change by sequestering carbon,yet their responses to environmental shifts remain complex and multifaceted.This special issue,“Tree Rings,Forest Carbon Sink,and Climate Change,”compiles 41 interdisciplinary studies exploring forest-climate interactions through dendrochro-nological and ecological approaches.It addresses climate reconstruction(e.g.,temperature,precipitation,isotopes)using tree-ring proxies,species-specific and age-dependent growth responses to warming and drought,anatomical adap-tations,and methodological innovations in isotope analysis and multi-proxy integration.Key findings reveal ENSO/AMO modulation of historical climates,elevation-and latitude-driven variability in tree resilience,contrasting carbon dynamics under stress,and projected habitat shifts for vulnerable species.The issue underscores forests’dual role as climate archives and carbon regulators,offering insights for adaptive management and nature-based climate solutions.Contributions bridge micro-scale physiological processes to macro-scale ecological modeling,advancing sustainable strategies amid global environmental challenges.
文摘Osyris lanceolata is heavily and illegally exploited in East Africa for its essential oils, yet little is known about its population status and ecological requirements. This study examined its population structure and environmental factors influencing its distribution in the semi-arid Karamoja sub-region, Uganda. We surveyed 388 plots (5 m radius) at different altitudes, recording life stages, stem diameters, and regeneration patterns, and analyzed soil samples. Multivariate analyses, including Canonical Correspondence Analysis (CCA), Detrended Correspondence Analysis (DCA), Non-metric Multidimensional Scaling (NMDS), and Multiple Regression Modeling (MRM), identified key environmental factors affecting its distribution. Findings show that O. lanceolata populations in Moroto, Nakapiripirit, and Amudat districts are severely degraded due to overexploitation. The species is primarily regenerating through coppicing rather than seedlings, with an exploitation intensity of 56.6%. Population densities are low, distribution is irregular, and sustainable harvesting is not viable. Soil properties, particularly Ca2+, N, P, K+, Na+, and organic matter, significantly influence its abundance. Conservation efforts should focus on identifying suitable provenances for genetic preservation and plantation establishment. Areas with at least 9 trees per hectare in Moroto, Nakapiripirit, and Amudat could serve as potential sites for ex-situ plantations. Further research should explore how biotic interactions, genetic diversity, and morphology affect oil yield and quality to support restoration, breeding, and domestication initiatives.
基金supported by the Key Projects of National Philosophy and Social Science Foundation of China(11&ZD046)The Key Projects of National Natural Science Foundation of China (70833001)+2 种基金China Agricultural Research System (CARS-14-10B)Doctoral Fund of Ministry of Education of China (20120097110034)the Fundamental Research Funds for the Central Universities of China(6J0546)
文摘According to the contemporary ecosystem approach, the linkages of human actions with their environment have to be assessed in an integrative manner. The Driver-Pressure-State-Impact-Response （DPSIR） model is applied to identify and describe processes and interactions in human-environmental systems. An example application from a research project dealing with the development of sustainable management strategies for the agriculture in Jiangsu, China, illustrates the potentials and limitations of its sustainable development. The concept and indicators of ecological integrity are used to assess the indicators in the dimensions of DPSIR between 2003 and 2006. The main drivers included population growth which caused increasing demand for food, growing environmental demands, and rapidly decreasing of land and other natural resources. The main environmental problem was water pollution. The results show that in the dimension of driver, total grain output and agricultural land productivity both increased. Labor intensive agriculture has been promoted to increase agricultural land productivity. In the dimension of pressure, on the positive side, infrastructure got greatly improved, the input level such as total power of machinery, and level of fertilizer use increased, and level of pesticides use decreased, but on the negative side, cultivated land per capita and irrigation rate decreased, natural resources keep decreased. Environmental pollution indicators such as industrial wastewater discharge and acid rain rate increased in Jiangsu Province. In the aspect of state, ecosystem state was improved, plant coverage index increased, biological abundance index increased, fertilizer productivity increased, eco-environmental quality index increased, but land degradation index also increased. In the aspect of impact, output level increased, output efficiency enhanced, farmer＇s social economic benefit improved. In the aspect of response, social support was greatly improved, input for environmental governance increased. To assess the effects of environmental governance, Jiangsu government was successful to increase compliance rate of sulfur dioxide emissions, but not so efficient in compliance rate of industrial wastewater discharge.
基金supported by the National Key Technology Research and Development Program of China(2011BAD37B01)the program for Changjiang Scholars and Innovative Research Team in University(IRT1054)。
文摘Quantifying fi ne root(≤ 2.0 mm in diameter) distribution and turnover is essential for accurately estimating forest carbon budgets. However, fi ne root dynamics are poorly understood, possibly because of their inaccessibility. This study quantifi es fi ne root distribution and turnover rates for fi ve representative Chinese temperate forests types. Fine root number, diameter, biomass, necromass, production, mortality, and turnover rates were measured using a minirhizotron over a 12-month period. More than 90% of the fi ne roots were < 0.5 mm in diameter, with thin fi ne roots at shallow layers, and thicker ones in deeper soil layers. The fi ne root dynamics were signifi cantly diff erent among the forest types. Coniferous plantations had fewer fi ne roots, less biomass, necromass, production and mortality but greater average diameters than fi ne roots of broadleaved forests. All traits, except for diameter, decreased along the soil profi le. Fine root numbers and production exhibited a unimodal seasonal pattern with peaks occurring in summer, whereas biomass, necromass and mortality progressivelyincreased over the growing season. The turnover rates of roots < 0.5 mm varied from 0.4 to 1.0 a-1 for the fi ve forest types, 0.5–1.0 a-1 for the soil layers and 0.2–1.1 a-1 for the seasons, with the largest turnover rate at the 0–10 cm depth in summer. The patterns of fi ne root numbers, biomass, necromass, production, mortality, and turnover rates varied with forest types, soil depths, growing season and diameter classes. This study highlights the importance of forest types and diameters in quantifying fi ne root turnover rates.
文摘The survival chance of epiphytie orchids today not only depends on the natural site conditions required by the orchids but also on anthropogenic changes in site conditions. This study answers two questions： （1） What is the ecological niche of the different epiphytic orchid species？ （2） What are the ecological factors that threaten epiphytic orchid＇s population under anthropogenic disturbances？ Our study area was the Kathmandu valley, Nepal, with its subtropical forest. We established 156 systematically selected sampling points in the Kathmandu area covering different types of ecosystems under human impacts such as densely populated area, agricultural land, mixed agricultural and settled area, old tree patches, and a natural forest in a national park. The ecological niche of the orchid species was analyzed with a principal component analysis （PCA）. The correlations between the different site factors were statistically significant. Spearman＇s rank correlation matrices showed that the variables land-use intensities with altitude, and height with diameter in breast height （dbh） of host had the highest significant positive correlation coefficient （0.67 and 0.64 respectively）. On the other hand, host bark pH and altitude as well as land use had a significantly strong negative correlation coefficient （-0.80 and -0.61, respectively）. Different epiphytic orchid species interact differently with the given set of environmental factors： for occurrence of Vanda cristata there is no single environmental factor of special influence, while for Rhynehostylis retusa high bark pH and high light availability are important. First two axis of the PCA explained more than 50% of the total variance. Most orchid species occupy a specific, narrow niche in this ecological space. The main causes of anthropogenie influence of orchid population in the Kathmandu Valley are loss of adequate host trees （species and size） and increasing air pollution, resulting in increasing host bark pH.
基金funded by the Small Scale Funding Agreement (UNEP/ROWA)
文摘Sand and dust storms （SDS） are common phenomena in arid and semi-arid areas. In recent years, SDS frequencies and intensities have increased significantly in Iran. A research on SDS sources is important for understanding the mechanisms of dust generation and assessing its socio-economic and environmental impacts. In this paper, we developed a new approach to identify SDS source areas in Iran using a combination of nine related datasets, namely drought events, temperature, precipitation, location of sandy soils, SDS frequency, hu- man-induced soil degradation （HISD）, human influence index （HII）, rain use efficiency （RUE） and net primary pro- ductivity （NPP） loss. To identify SDS source areas, we firstly normalized these datasets under uniform criteria in- cluding layer reprojection using Lambert conformal conic projection, data conversion from shapefile to raster, Min-Max Normalization with data range from 0 to 1, and data interpolation by Kriging and images resampling （resolution of 1 km）. After that, a score map for the possibility of SDS sources was generated through overlaying multiple datasets under average weight allocation criterion, in which each item obtained weight equally. In the score map, the higher the score, the more possible a specific area could be regarded as SDS source area. Exceptions mostly came from large cities, like Tehran and Isfahan. As a result, final SDS source areas were mapped out, and Al-Howizeh/Al-Azim marshes and Sistan Basin were identified as main SDS source areas in Iran. The SDS source area in Al-Howizeh/Al-Azim marshes still keeps expanding. In addition, Al-Howizeh/Al-Azim marshes are now suf- fering rapid land degradation due to natural and human-induced factors and might totally vanish in the near future. Sistan Basin also demonstrates the impacts of soil degradation and wind erosion. With appropriate intensity, dura- tion, wind speed and altitude of the dust storms, sand particles uplifting from this area might have developed into extreme dust storms, especially during the summer.
基金supported by the Fundamental Research Funds for the Central Universities (572017PZ03,2572020DR04 and 2572019CP16)。
文摘As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.
