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
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
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
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
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
Access to off-farm employment has been expected to be a critical approach to ending hunger and all forms of malnutrition,two important targets of achieving Zero Hunger.This study aims to investigate the role of off-fa...Access to off-farm employment has been expected to be a critical approach to ending hunger and all forms of malnutrition,two important targets of achieving Zero Hunger.This study aims to investigate the role of off-farm employment in improving dietary diversity through substitution effect and complementary effect with agricultural production activities and income effect.This study adopts Poisson/Tobit/Probit/OLS regressions and the instrument variable method based on the primary survey data collected among 1,282 households at 12 sites in environmentally and economically vulnerable areas of China,Nepal,Cambodia,Thailand,and Myanmar in 2019.The results show that off-farm employment is positively associated with household dietary diversity and the consumption of flesh meat,fish and other aquatic animals,fruits,and milk and dairy products,which are rich in protein and micronutrients.The results of mechanism analysis show that off-farm employment contributes to household dietary diversity by improving crop diversity,especially for poor households,boosting the probability of livestock raising for households with the middle one-third disposal income,and increasing household income.The positive association between off-farm employment and household dietary diversity is much higher for households with the bottom one-third disposal income,low illiteracy,and from upper-middle income countries.These findings imply that off-farm employment does play a vital role in achieving multiple benefits of poverty alleviation,malnutrition reduction,and agrobiodiversity conservation in environmentally and economically vulnerable areas.However,it may enlarge the gaps in dietary diversity between households with low human capital and from low and lower-middle income countries and those with high human capital and from middle-high countries.展开更多
Plant stoichiometry and nutrient allocation may reflect adaptation strategies to environmental nutrient changes.Fire,as a major disturbance in forests,mediates soil nutrient availability that may influence plant nutri...Plant stoichiometry and nutrient allocation may reflect adaptation strategies to environmental nutrient changes.Fire,as a major disturbance in forests,mediates soil nutrient availability that may influence plant nutrient dynamics.However,plant–soil stoichiometric allocation strategies during different post-fire periods and the effects of soil,enzymes,and microbial biomass on plant stoichiom-etry are largely unknown.The pioneer tree species Betula platyphylla in burnt forests of northern China was the object of this study,and severely burned areas selected with dif-ferent fire years.Nearby unburned areas acted as a control.Carbon(C),nitrogen(N),and phosphorus(P)contents in leaves,branches,and fine roots and rhizosphere soil,C-,N-and P-acquiring enzyme activities were examined.Microbial biomass C,N,and P were measured,and factors influenc-ing C:N:P stoichiometry of plants during the burned area restoration were explored.Our results show that C and N contents in leaves increased with time since fire,while C and P in branches and C,N and P in fine roots decreased.Activities of C-,N-,and P-acquiring enzymes and microbial biomass N increased with time since fire.Redundancy analy-sis showed that changes in soil N-acquiring enzyme activity,microbial biomass C,and N had significant effects on plant ecological stoichiometry.These results show a significant flexibility in plant nutrient element allocation strategies and C:N:P stoichiometric characteristics.Soil extracellular enzyme activity drives the changes in stoichiometry during the process of post-fire restoration.展开更多
Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of pl...Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of plantings on soil microbial diversity.The results showed that the overall effect of afforestation on soil microbial diversity was positive across the country.Random forest algorithm suggested that soil carbon was the most important factor regulating microbial diversity and the positive response was only found with new plantings on low-carbon bare lands but not on high-carbon farmlands and grasslands.In addition,afforestation with broadleaved species increased microbial diversity,whereas planting with conifers had no effect on microbial diversity.This study clarified the effects of plantings on soil microbial diversity,which has an important implication for establishing appropriate policies and practices to improve the multiple functionalities(e.g.,biodiversity conservation and climate change mitigation)during plantation establishment.展开更多
Betula platyphylla and Betula costata are important species in mixed broadleaved-Korean pine(Pinus koraiensis)forests.However,the specific ways in which their growth is affected by warm temperatures and drought remain...Betula platyphylla and Betula costata are important species in mixed broadleaved-Korean pine(Pinus koraiensis)forests.However,the specific ways in which their growth is affected by warm temperatures and drought remain unclear.To address this issue,60 and 62 tree-ring cores of B.platyphylla and B.costata were collected in Yichun,China.Using dendrochronological methods,the response and adaptation of these species to climate change were examined.A“hysteresis effect”was found in the rings of both species,linked to May–September moisture conditions of the previous year.Radial growth of B.costata was positively correlated with the standardized precipitation-evapotranspiration index(SPEI),the precipitation from September to October of the previous year,and the relative humidity in October of the previous year.Growth of B.costata is primarily restricted by moisture conditions from September to October.In contrast,B.platyphylla growth is mainly limited by minimum temperatures in May–June of both the previous and current years.After droughts,B.platyphylla had a faster recovery rate compared to B.costata.In the context of rising temperatures since 1980,the correlation between B.platyphylla growth and monthly SPEI became positive and strengthened over time,while the growth of B.costata showed no conspicuous change.Our findings suggest that the growth of B.platyphylla is already affected by warming temperatures,whereas B.costata may become limited if warming continues or intensifies.Climate change could disrupt the succession of these species,possibly accelerating the succession of pioneer species.The results of this research are of great significance for understanding how the growth changes of birch species under warming and drying conditions,and contribute to understanding the structural adaptation of mixed broadleaved-Korean pine(Pinus koraiensis)forests under climate change.展开更多
Forest productivity is closely linked to seasonal variations and vertical differentiation in leaf traits.However,leaf structural and chemical traits variation among co-existing species,and plant functional types withi...Forest productivity is closely linked to seasonal variations and vertical differentiation in leaf traits.However,leaf structural and chemical traits variation among co-existing species,and plant functional types within the canopy are poorly quantified.In this study,the seasonality of leaf chlorophyll,nitrogen(N),and phosphorus(P)were quantified vertically along the canopy of four major tree species and two types of herbs in a temperate deciduous forest.The role of shade tolerance in shaping the seasonal variation and vertical differentiation was examined.During the entire season,chlorophyll content showed a distinct asymmetric unimodal pattern for all species,with greater chlorophyll levels in autumn than in spring,and the timing of peak chlorophyll per leaf area gradually decreased as shade tolerance increased.Chlorophyll a:b ratios gradually decreased with increasing shade tolerance.Leaf N and P contents sharply declined during leaf expansion,remained steady in the mature stage and decreased again during leaf senescence.Over the seasons,the lower canopy layer had significantly higher chlorophyll per leaf mass but not chlorophyll per leaf area than the upper canopy layer regardless of degree of shade tolerance.However,N and P per leaf area of intermediate shade-tolerant and fully shade-tolerant tree species were significantly higher in the upper canopy than in the lower.Seasonal variations in N:P ratios suggest changes in N or P limitation.These findings indicate that shade tolerance is a key feature shaping inter-specific differences in leaf chlorophyll,N,and P contents as well as their seasonality in temperate deciduous forests,which have significant implications for modeling leaf photosynthesis and ecosystem production.展开更多
Pinus sylvestris var.mongolica(P.sylvestris)plantations are extensively established in the boreal zone.Increasing stand biomass of these plantations can effectively enhance carbon stock,which is crucial for mitigating...Pinus sylvestris var.mongolica(P.sylvestris)plantations are extensively established in the boreal zone.Increasing stand biomass of these plantations can effectively enhance carbon stock,which is crucial for mitigating climate change.However,the current understanding of optimizing plantation strategies to maximize stand biomass is primarily derived from experiments in tropical and subtropical zones,which is difficult to extend to the boreal due to substantial climatic differences.Based on a comprehensive dataset from 1,076 sample plots of P.sylvestris plantations in the boreal zone of China,we evaluated the effects of tree species richness and stand density on tree height,diameter at breast height(DBH),and stand biomass to investigate the optimal plantation strategy.Furthermore,we examined how these effects changed with stand age and investigated their relative importance.We found that monocultures at a high stand density of 2,000–2,500ha^(−1) were the optimal plantation strategy to maximize stand biomass(107.5Mg·ha^(−1)),and this held true at almost all stand ages.Unfortunately,this strategy resulted in low species richness and small individual trees(10.6m height and 9.8cm DBH),thus presenting a trade-off.In addition,as stand age increased,the effect of tree species richness on stand biomass shifted from positive to negative,but the effect of stand density was always positive.Overall,stand age had the greatest effect on stand biomass,followed by stand density and then tree species richness.Our findings reveal a distinct plantation strategy for optimizing stand biomass of P.sylvestris plantations in the boreal zone.More importantly,this study highlights that(1)maximizing stand biomass in the boreal zone may compromise tree species richness;(2)net effects of tree species richness on stand biomass are not always positive,as negative selection effects offset positive complementary effects.展开更多
Plant carbon(C)concentration is a fundamental trait for estimating C storage and nutrient utilization.However,the mechanisms of C concentration variations among different tree tissues and across species remains poorly...Plant carbon(C)concentration is a fundamental trait for estimating C storage and nutrient utilization.However,the mechanisms of C concentration variations among different tree tissues and across species remains poorly understood.In this study,we explored the variations and determinants of C concentration of nine tissues from 216 individuals of 32 tree species,with particular attention on the effect of wood porosity(i.e.,non-porous wood,diffuse-porous wood,and ring-porous wood).The inter-tissue pattern of C concentration diverged across the three porosity types;metabolically active tissues(foliage and fine roots,except for the foliage of ring-porous species)generally had higher C levels compared with inactive wood.The poor inter-correlations between tissue C concentrations indicated a necessity of measuring tissue-and specific-C concentrations.Carbon concentration for almost all tissues generally decreased from non-porous,to diffuse-porous and to ring-porous.Tissue C was often positively correlated with tissue(foliage and wood)density and tree size,while negatively correlated with growth rate,depending on wood porosity.Our results highlight the mediating effect of type of wood porosity on the variation in tissue C among temperate species.The variations among tissues were more important than that among species.These findings provided insights on tissue C concentration variability of temperate forest species.展开更多
From 20 January to 20 July 2023, a study was carried out on the Lobé Creek, a waterway subject to considerable natural and man-made pressures, with a negative impact on its biodiversity and habitats. The aim was ...From 20 January to 20 July 2023, a study was carried out on the Lobé Creek, a waterway subject to considerable natural and man-made pressures, with a negative impact on its biodiversity and habitats. The aim was to evaluate the growth rate of invasive aquatic macrophytes and their contribution to the use of organic fertilisers: a case of Eicchornia crassipes (Mart.) Solms, 1883 in the Lobé Creek (Littoral-Cameroon) with a view to its appropriate use in agronomy. The specific objective was to examine the impact of anthropogenic actions on Lobé Creek, characterise physico-chemical environment of the study area, and evaluate the growth rate of E. crassipes and its chemical composition with a view to producing an organic biofertiliser. The results show that E. crassipes represents a considerable threat to the populations of these localities. As for the physico-chemical parameters, the temperature values vary from 24 ± 1.41˚C to 26.5 ± 1.13˚C;pH from 6.3 ± 0.1 to 7.2 ± 0.07;conductivity and dissolved oxygen vary respectively from 40.7 ± 1.83 µS/cm to 19.6 ± 3.11 µS/cm and from 7.3 ± 0.14 mg/l to 5.8 ± 1.55 mg/l. Its average growth rate varies from 0.69 feet/day to 0.63 feet/day. With regard to the nitrogen, phosphorus and potassium content of water hyacinth plants, the results show that the average total nitrogen content ranges from 6.11 ± 1.59 g/kg to 5.2 ± 2.03 g/kg;total phosphorus, from 0.52 ± 0.54 g/kg to 0.88 ± 0.38 g/kg;and potassium, from 1.43 ± 0.45 g/kg to 2.61 ± 0.89 g/kg.展开更多
In Côte d’Ivoire, maize (Zea mays L) is the second most cultivated cereal after rice. Since the first report of Spodoptera frugiperda in Côte d’Ivoire, maize production in the northern regions has been aff...In Côte d’Ivoire, maize (Zea mays L) is the second most cultivated cereal after rice. Since the first report of Spodoptera frugiperda in Côte d’Ivoire, maize production in the northern regions has been affected resulting in maize production losses. This study aims to study the seasonal dynamic of Spodoptera frugiperda in maize fields in the sub-Sudanese zone, main zone of maize cultivation in Côte d’Ivoire. The study was done using pheromone trap lures. The results revealed a variation in the moth population at various growth stages during rainy and dry seasons. Notably, the highest numbers of moths were consistently trapped during the whorl stage with counts ranging from 131 ± 35.7 during the rainy season to 70.6 ± 15.01 in the dry season. The lowest numbers of moths were observed during pod maturation, with counts ranging from 30.3 ± 13.05 during the rainy season to 11.7 ± 3.05 in the dry season. Between the 7<sup>th</sup> and 21<sup>st</sup> days after sowing, the count of moths displayed a consistent upward trajectory, reaching 188 moths during the rainy season. The damages were particularly observed at whorl stage. The relationship between the numbers of moths and some climatic variables revealed a negative correlation between moths numbers and rainfall (r= −0.44) and relative humidity (r= −0.684). In contrast, there were positive relationships with temperature (r = 0.16), highlighting the significant impact of temperature changes on moth population dynamics. The research highlights the need for integrated pest management strategies that consider climatic factors and growth stages of maize to mitigate the impact of this insect pest on maize.展开更多
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 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.
基金We acknowledge the financial support from the National Natural Science Foundation of China(72373140 and 42061144004)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20010303).
文摘Access to off-farm employment has been expected to be a critical approach to ending hunger and all forms of malnutrition,two important targets of achieving Zero Hunger.This study aims to investigate the role of off-farm employment in improving dietary diversity through substitution effect and complementary effect with agricultural production activities and income effect.This study adopts Poisson/Tobit/Probit/OLS regressions and the instrument variable method based on the primary survey data collected among 1,282 households at 12 sites in environmentally and economically vulnerable areas of China,Nepal,Cambodia,Thailand,and Myanmar in 2019.The results show that off-farm employment is positively associated with household dietary diversity and the consumption of flesh meat,fish and other aquatic animals,fruits,and milk and dairy products,which are rich in protein and micronutrients.The results of mechanism analysis show that off-farm employment contributes to household dietary diversity by improving crop diversity,especially for poor households,boosting the probability of livestock raising for households with the middle one-third disposal income,and increasing household income.The positive association between off-farm employment and household dietary diversity is much higher for households with the bottom one-third disposal income,low illiteracy,and from upper-middle income countries.These findings imply that off-farm employment does play a vital role in achieving multiple benefits of poverty alleviation,malnutrition reduction,and agrobiodiversity conservation in environmentally and economically vulnerable areas.However,it may enlarge the gaps in dietary diversity between households with low human capital and from low and lower-middle income countries and those with high human capital and from middle-high countries.
基金supported by National Natural Science Foundation of China(No.32071777)the Fundamental Research Funds for the Central Universities(2572021BA04).
文摘Plant stoichiometry and nutrient allocation may reflect adaptation strategies to environmental nutrient changes.Fire,as a major disturbance in forests,mediates soil nutrient availability that may influence plant nutrient dynamics.However,plant–soil stoichiometric allocation strategies during different post-fire periods and the effects of soil,enzymes,and microbial biomass on plant stoichiom-etry are largely unknown.The pioneer tree species Betula platyphylla in burnt forests of northern China was the object of this study,and severely burned areas selected with dif-ferent fire years.Nearby unburned areas acted as a control.Carbon(C),nitrogen(N),and phosphorus(P)contents in leaves,branches,and fine roots and rhizosphere soil,C-,N-and P-acquiring enzyme activities were examined.Microbial biomass C,N,and P were measured,and factors influenc-ing C:N:P stoichiometry of plants during the burned area restoration were explored.Our results show that C and N contents in leaves increased with time since fire,while C and P in branches and C,N and P in fine roots decreased.Activities of C-,N-,and P-acquiring enzymes and microbial biomass N increased with time since fire.Redundancy analy-sis showed that changes in soil N-acquiring enzyme activity,microbial biomass C,and N had significant effects on plant ecological stoichiometry.These results show a significant flexibility in plant nutrient element allocation strategies and C:N:P stoichiometric characteristics.Soil extracellular enzyme activity drives the changes in stoichiometry during the process of post-fire restoration.
基金supported by the National Key Research and Development Program of China(2021YFD2200401)the National Natural Science Foundation of China(31901293)。
文摘Afforestation has an important role in biodiversity conservation and ecosystem function improvement.A meta-analysis was carried out in China,which has the largest plantation area globally,to quantify the effects of plantings on soil microbial diversity.The results showed that the overall effect of afforestation on soil microbial diversity was positive across the country.Random forest algorithm suggested that soil carbon was the most important factor regulating microbial diversity and the positive response was only found with new plantings on low-carbon bare lands but not on high-carbon farmlands and grasslands.In addition,afforestation with broadleaved species increased microbial diversity,whereas planting with conifers had no effect on microbial diversity.This study clarified the effects of plantings on soil microbial diversity,which has an important implication for establishing appropriate policies and practices to improve the multiple functionalities(e.g.,biodiversity conservation and climate change mitigation)during plantation establishment.
基金the Key Project of the China National Key Research and Development Program(2021YFD2200401)the National Natural Science Foundation of China(42177421 and 41877426)。
文摘Betula platyphylla and Betula costata are important species in mixed broadleaved-Korean pine(Pinus koraiensis)forests.However,the specific ways in which their growth is affected by warm temperatures and drought remain unclear.To address this issue,60 and 62 tree-ring cores of B.platyphylla and B.costata were collected in Yichun,China.Using dendrochronological methods,the response and adaptation of these species to climate change were examined.A“hysteresis effect”was found in the rings of both species,linked to May–September moisture conditions of the previous year.Radial growth of B.costata was positively correlated with the standardized precipitation-evapotranspiration index(SPEI),the precipitation from September to October of the previous year,and the relative humidity in October of the previous year.Growth of B.costata is primarily restricted by moisture conditions from September to October.In contrast,B.platyphylla growth is mainly limited by minimum temperatures in May–June of both the previous and current years.After droughts,B.platyphylla had a faster recovery rate compared to B.costata.In the context of rising temperatures since 1980,the correlation between B.platyphylla growth and monthly SPEI became positive and strengthened over time,while the growth of B.costata showed no conspicuous change.Our findings suggest that the growth of B.platyphylla is already affected by warming temperatures,whereas B.costata may become limited if warming continues or intensifies.Climate change could disrupt the succession of these species,possibly accelerating the succession of pioneer species.The results of this research are of great significance for understanding how the growth changes of birch species under warming and drying conditions,and contribute to understanding the structural adaptation of mixed broadleaved-Korean pine(Pinus koraiensis)forests under climate change.
基金This work was supported by the National Natural Science Foundation of China(32171765).
文摘Forest productivity is closely linked to seasonal variations and vertical differentiation in leaf traits.However,leaf structural and chemical traits variation among co-existing species,and plant functional types within the canopy are poorly quantified.In this study,the seasonality of leaf chlorophyll,nitrogen(N),and phosphorus(P)were quantified vertically along the canopy of four major tree species and two types of herbs in a temperate deciduous forest.The role of shade tolerance in shaping the seasonal variation and vertical differentiation was examined.During the entire season,chlorophyll content showed a distinct asymmetric unimodal pattern for all species,with greater chlorophyll levels in autumn than in spring,and the timing of peak chlorophyll per leaf area gradually decreased as shade tolerance increased.Chlorophyll a:b ratios gradually decreased with increasing shade tolerance.Leaf N and P contents sharply declined during leaf expansion,remained steady in the mature stage and decreased again during leaf senescence.Over the seasons,the lower canopy layer had significantly higher chlorophyll per leaf mass but not chlorophyll per leaf area than the upper canopy layer regardless of degree of shade tolerance.However,N and P per leaf area of intermediate shade-tolerant and fully shade-tolerant tree species were significantly higher in the upper canopy than in the lower.Seasonal variations in N:P ratios suggest changes in N or P limitation.These findings indicate that shade tolerance is a key feature shaping inter-specific differences in leaf chlorophyll,N,and P contents as well as their seasonality in temperate deciduous forests,which have significant implications for modeling leaf photosynthesis and ecosystem production.
基金supported by the National Key Research and Development Program of China(No.2022YFF1300500)the Youth Innovation Promotion Association of CAS(No.2022195).
文摘Pinus sylvestris var.mongolica(P.sylvestris)plantations are extensively established in the boreal zone.Increasing stand biomass of these plantations can effectively enhance carbon stock,which is crucial for mitigating climate change.However,the current understanding of optimizing plantation strategies to maximize stand biomass is primarily derived from experiments in tropical and subtropical zones,which is difficult to extend to the boreal due to substantial climatic differences.Based on a comprehensive dataset from 1,076 sample plots of P.sylvestris plantations in the boreal zone of China,we evaluated the effects of tree species richness and stand density on tree height,diameter at breast height(DBH),and stand biomass to investigate the optimal plantation strategy.Furthermore,we examined how these effects changed with stand age and investigated their relative importance.We found that monocultures at a high stand density of 2,000–2,500ha^(−1) were the optimal plantation strategy to maximize stand biomass(107.5Mg·ha^(−1)),and this held true at almost all stand ages.Unfortunately,this strategy resulted in low species richness and small individual trees(10.6m height and 9.8cm DBH),thus presenting a trade-off.In addition,as stand age increased,the effect of tree species richness on stand biomass shifted from positive to negative,but the effect of stand density was always positive.Overall,stand age had the greatest effect on stand biomass,followed by stand density and then tree species richness.Our findings reveal a distinct plantation strategy for optimizing stand biomass of P.sylvestris plantations in the boreal zone.More importantly,this study highlights that(1)maximizing stand biomass in the boreal zone may compromise tree species richness;(2)net effects of tree species richness on stand biomass are not always positive,as negative selection effects offset positive complementary effects.
基金supported by the National Natural Science Foundation of China(32171765).
文摘Plant carbon(C)concentration is a fundamental trait for estimating C storage and nutrient utilization.However,the mechanisms of C concentration variations among different tree tissues and across species remains poorly understood.In this study,we explored the variations and determinants of C concentration of nine tissues from 216 individuals of 32 tree species,with particular attention on the effect of wood porosity(i.e.,non-porous wood,diffuse-porous wood,and ring-porous wood).The inter-tissue pattern of C concentration diverged across the three porosity types;metabolically active tissues(foliage and fine roots,except for the foliage of ring-porous species)generally had higher C levels compared with inactive wood.The poor inter-correlations between tissue C concentrations indicated a necessity of measuring tissue-and specific-C concentrations.Carbon concentration for almost all tissues generally decreased from non-porous,to diffuse-porous and to ring-porous.Tissue C was often positively correlated with tissue(foliage and wood)density and tree size,while negatively correlated with growth rate,depending on wood porosity.Our results highlight the mediating effect of type of wood porosity on the variation in tissue C among temperate species.The variations among tissues were more important than that among species.These findings provided insights on tissue C concentration variability of temperate forest species.
文摘From 20 January to 20 July 2023, a study was carried out on the Lobé Creek, a waterway subject to considerable natural and man-made pressures, with a negative impact on its biodiversity and habitats. The aim was to evaluate the growth rate of invasive aquatic macrophytes and their contribution to the use of organic fertilisers: a case of Eicchornia crassipes (Mart.) Solms, 1883 in the Lobé Creek (Littoral-Cameroon) with a view to its appropriate use in agronomy. The specific objective was to examine the impact of anthropogenic actions on Lobé Creek, characterise physico-chemical environment of the study area, and evaluate the growth rate of E. crassipes and its chemical composition with a view to producing an organic biofertiliser. The results show that E. crassipes represents a considerable threat to the populations of these localities. As for the physico-chemical parameters, the temperature values vary from 24 ± 1.41˚C to 26.5 ± 1.13˚C;pH from 6.3 ± 0.1 to 7.2 ± 0.07;conductivity and dissolved oxygen vary respectively from 40.7 ± 1.83 µS/cm to 19.6 ± 3.11 µS/cm and from 7.3 ± 0.14 mg/l to 5.8 ± 1.55 mg/l. Its average growth rate varies from 0.69 feet/day to 0.63 feet/day. With regard to the nitrogen, phosphorus and potassium content of water hyacinth plants, the results show that the average total nitrogen content ranges from 6.11 ± 1.59 g/kg to 5.2 ± 2.03 g/kg;total phosphorus, from 0.52 ± 0.54 g/kg to 0.88 ± 0.38 g/kg;and potassium, from 1.43 ± 0.45 g/kg to 2.61 ± 0.89 g/kg.
文摘In Côte d’Ivoire, maize (Zea mays L) is the second most cultivated cereal after rice. Since the first report of Spodoptera frugiperda in Côte d’Ivoire, maize production in the northern regions has been affected resulting in maize production losses. This study aims to study the seasonal dynamic of Spodoptera frugiperda in maize fields in the sub-Sudanese zone, main zone of maize cultivation in Côte d’Ivoire. The study was done using pheromone trap lures. The results revealed a variation in the moth population at various growth stages during rainy and dry seasons. Notably, the highest numbers of moths were consistently trapped during the whorl stage with counts ranging from 131 ± 35.7 during the rainy season to 70.6 ± 15.01 in the dry season. The lowest numbers of moths were observed during pod maturation, with counts ranging from 30.3 ± 13.05 during the rainy season to 11.7 ± 3.05 in the dry season. Between the 7<sup>th</sup> and 21<sup>st</sup> days after sowing, the count of moths displayed a consistent upward trajectory, reaching 188 moths during the rainy season. The damages were particularly observed at whorl stage. The relationship between the numbers of moths and some climatic variables revealed a negative correlation between moths numbers and rainfall (r= −0.44) and relative humidity (r= −0.684). In contrast, there were positive relationships with temperature (r = 0.16), highlighting the significant impact of temperature changes on moth population dynamics. The research highlights the need for integrated pest management strategies that consider climatic factors and growth stages of maize to mitigate the impact of this insect pest on maize.
