Understanding the ecogeographic mechanisms driving morphological variation is pivotal in biogeographic studies. However, patterns and determinants of such variation remain contentious, particularly in amphibians. Alth...Understanding the ecogeographic mechanisms driving morphological variation is pivotal in biogeographic studies. However, patterns and determinants of such variation remain contentious, particularly in amphibians. Although several hypotheses have been formulated and investigated in amphibians, their validity remains disputed with mixed support. Using the Sichuan spiny frog(Nanorana sichuanensis) as an indicator, we investigated the morphological variations across geographic and environmental gradients to explore the underlying ecogeographic mechanisms. We found that both the body size and limb characteristics of N.sichuanensis were not significantly related to latitude or elevation, suggesting that it did not follow Bergmann's or Allen's rules. Eye diameter decreased linearly with increasing elevation and latitude, whereas snout length increased with increasing elevation and latitude. Heat balance, endurance, seasonality, water availability, and primary productivity collectively explain body size variation. Hierarchical partitioning identified primary productivity and thermal excursion as the most influential factors, explaining significant variability in body size and other morphological features. Specifically, primary productivity accounted for 52.40% of the variation in body size, whereas thermal excursion had the greatest impact on eye diameter(36.23%) and snout length(72.17%). Based on body size and dimensionally reduced morphological features, our results identified ecogeographic patterns, assessed the validity of different hypotheses, and examined how environmental factors influence these morphological variations. More generally, our study offers comprehensive insights into the ecogeographic variation observed in mountain amphibians,provides a critical evaluation of existing ecogeographic hypotheses, and infers possible morphological adaptations in response to environmental change.展开更多
Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protect...Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protection and restoration of natural wetlands. In this study, the spatial patterns of wetland plants and the environmental gradient of wetland habitats were assessed in the Honghe National Nature Reserve （HNNR） in Northeast China, a wetland of international importance on the Ramsar list. Biophysical parameters’ values of wetland plants were obtained by field sampling methods, and wetland mapping at the community scale was completed using remote sensing techniques. Digital delineation of the surface water system, hydrological zoning and wetness index were produced by spatial analysis methods in Geographic Information System. An ecological ordination method and two clustering methods were used to quantify the relationship between the spatial distribution patterns of wetland plants and the corresponding environmental gradients. Such quantitative analyses also present the specific diversity of different types of wetland plants based on the environmental attributes of their habitats. With the support from modern geo-information techniques, the experimental results indicate how four ecotypes of wetland plants spatially transit from forest swamp, shrub wetland and meadow into marsh wetland with increasing wetness index and water table. And they also show how wetland spatial distribution patterns are controlled by an environmental gradient of wetness. Another key finding of this research work is that our results present the exact fundamental differences between marsh and non-marsh plants of 11 wetland plant communities within the core study area. Hence, this case study gives a good sample for better understanding of the complex correlation between the spatial patterns of wetland plants and their environmental attributes using advanced digital analysis methods. It is also useful to show how to integrate geoinformatic techniques with statistical analysis methods based on the field data base.展开更多
Dry evergreen montane forests in Ethiopia are severely threatened.The status of species composition and structure of forest vegetation are important indicators to understand the trends of threats on local plant commun...Dry evergreen montane forests in Ethiopia are severely threatened.The status of species composition and structure of forest vegetation are important indicators to understand the trends of threats on local plant communities.In the present study,we examined the floristic composition and structure of the Kibate Forest,Wonchi Highland,Ethiopia along environmental gradients.Sixty-six(30 m×30 m)plots were established every 100 m interval along altitudinal gradients(2811‒3073 m a.s.l.)in five transect lines for vegetation and environmental data collection.In total,125 vascular plant species belonging to 104 genera and 52 families were identified.Eighteen species(14%)were endemic to Ethiopia and Eritrea.The two most dominant families,Asteraceae(29 species)and Lamiaceae(eight species)accounted for 30%of the total number of species.The highest number of species(54%)was herbs.Four major community types(viz.,Olinia rochetiana-Myrsine melanophloeos,Ilex mitis-Galiniera saxifraga,Erica arborea-Protea gaguedi,and Hagenia abyssinica-Juniperus procera)were identified.The highest species richness,evenness,diversity,and importance value index were in community types 2 and 4.About 82%of the species and all endemic taxa except five were recorded in these two community types.The most dominant woody species were O.rochetiana,E.arborea,Olea europaea subsp.cuspidata,Myrica salicifolia,I.mitis var.mitis,and H.abyssinica with different patterns of population structure.The results show that there was a weak correlation between species richness and altitude.Our findings confirm that environmental variables both with interactions(such as altitude)and without interactions(such as livestock grazing)significantly(p<0.05)affect species richness.Anthropogenic activities and overgrazing by livestock appear to be the main threat in community types 2 and 3.Urgent management practices and conservation measures such as prohibiting forest clearing and overgrazing and planting indigenous trees through community participation should be considered in community types that are rich in endemic species but are highly threatened.展开更多
Phytoplankton communities can response immediately and directly to environmental changes,and thus have been applied as reliable biotic indicators in aquatic systems.This study provided insights into the relationships ...Phytoplankton communities can response immediately and directly to environmental changes,and thus have been applied as reliable biotic indicators in aquatic systems.This study provided insights into the relationships concerning ecological thresholds of phytoplankton communities and individual taxon in response to environmental changes in coastal waters of northern Zhejiang Province,East China Sea.Results demonstrated that there existed seasonal variations of phytoplankton community ecological thresholds of which spring being higher than those in summer.As for individual species,Prorocentrum donghaiense and Noctiluca scintillans were identified as the most tolerant and sensitive indicator species in spring and summer,respectively.They exhibited strong indications in response to environmental changes.These findings highlighted that phytoplankton community structure in this region was stable when environmental gradients were below the thresholds of sensitive species,whereas potential harmful algal blooms may occur when environmental gradients exceeded the thresholds of tolerant species.展开更多
Background Bacteria,Archaea,and Microeukaryotes comprise taxonomic domains that interact in mediating biogeochemical cycles in coastal waters.Many studies have revealed contrasting biogeographic patterns of community ...Background Bacteria,Archaea,and Microeukaryotes comprise taxonomic domains that interact in mediating biogeochemical cycles in coastal waters.Many studies have revealed contrasting biogeographic patterns of community structure and assembly mechanisms in microbial communities from diferent domains in coastal ecosystems;however,knowledge of specifc biogeographic patterns on microbial co-occurrence relationships across complex coastal environmental gradients remains limited.Using a dense sampling scheme at the regional scale,SSU rRNA gene amplicon sequencing,and network analysis,we investigated intra-and inter-domain co-occurrence relationships and network topology-based biogeographic patterns from three microbial domains in coastal waters that show environmental gradients across the inshore-nearshore-ofshore continuum in the East China Sea.Results Overall,we found the highest complexity and connectivity in the bacterial network,the highest modularity in the archaeal network,and the lowest complexity,connectivity,and modularity in the microeukaryotic network.Although microbial co-occurrence networks from the three domains showed distinct topological features,they exhibited a consistent biogeographic pattern across the inshore-nearshore-ofshore continuum.Specifcally,the nearshore zones with intermediate levels of terrestrial impacts refected by multiple environmental factors(including water temperature,salinity,pH,dissolved oxygen,and nutrient-related parameters)had a higher intensity of microbial co-occurrence for all three domains.In contrast,the intensity of microbial co-occurrence was weaker in both the inshore and the ofshore zones at the two ends of the environmental gradients.Archaea occupied a central position in the microbial inter-domain co-occurrence network.In particular,members of the Thaumarchaeota Marine Group I(MGI,now placed within the Family Nitrosopumilaceae of the Phylum Thermoproteota)appeared to be the hubs in the biogeographic shift between inter-domain network modules across environmental gradients.Conclusions Our work ofers new insights into microbial biogeography by integrating network features into biogeographic patterns,towards a better understanding of the potential of microbial interactions in shaping biogeographic patterns of coastal marine microbiota.展开更多
Aims Environmental gradients are drivers of species diversity;however,we know relatively little about the evolutionary processes underlying these relationships.A potentially powerful approach to studying diversity gra...Aims Environmental gradients are drivers of species diversity;however,we know relatively little about the evolutionary processes underlying these relationships.A potentially powerful approach to studying diversity gradients is to quantify the phylogenetic structure within and between assemblages arrayed along broad spatial and environmental gradients.Here,we evaluate the phylogenetic structure of plant assemblages along an environmental gradient with the expectation that the habitat specialization of entire lineages is an important evolutionary pattern influencing the structure of tree communities along environmental gradients.Methods We evaluated the effect of several environmental variables on the phylogenetic structure of plant assemblages in 145 plots distributed in northwestern South America that cover a broad environmental gradient.The phylogenetic alpha diversity was quantified for each plot and the phylogenetic beta diversity between each pair of plots was also quantified.Both the alpha and beta diversity measures were then related to spatial and environmental gradients in the study system.Important Findings We found that gradients in temperature and potential evapotranspiration have a strong relationship with the phylogenetic alpha diversity in our study system,with phylogenetic overdispersion in low temperatures and phylogenetic clustering at higher temperatures.Further,the phylogenetic beta diversity between two plots increases with an increasing difference in temperature,whereas annual precipitation was not a significant predictor of community phylogenetic turnover.We also found that the phylogenetic structure of the plots in our study system was related to the degree of seasonal flooding and seasonality in precipitation.In particular,more stressful environments such as dry forests and flooded forests showed phylogenetic clustering.Finally,in contrast with previous studies,we find that phylogenetic beta diversity was not strongly related to the spatial distance separating two forest plots,which may be the result of the importance of the three independent mountain ranges in our study system,which generate a high degree of environmental variation over very short distances.In conclusion,we found that environmental gradients are important drivers of both phylogenetic alpha and phylogenetic beta diversities in these forests over spatial distance.展开更多
Twenty-three secondary forest communities with different structure were selected in Mao＇er Mountain National Park of Heilongjiang Province, China to study the relationship between diversity of forest plant species an...Twenty-three secondary forest communities with different structure were selected in Mao＇er Mountain National Park of Heilongjiang Province, China to study the relationship between diversity of forest plant species and environmental gradient. The forest plant species diversity was analyzed by the diversity index, and the environmental factors was quantified by the method of Whittaker＇s quantification of environmental gradient. Meanwhile, β-diversity indexes of communities were calculated with similar measurements. The results showed that the Shannon-wiener diversity index of forest plant species increased with the increase of the environmental gradient, and the β-diversity indexes of communities showed a liner increase along with the change of environmental gradient.展开更多
Leaf nitrogen(N)and phosphorus(P)levels provide critical strategies for plant adaptions to changing environments.However,it is unclear whether leaf N and P levels of different plant functional groups(e.g.,monocots and...Leaf nitrogen(N)and phosphorus(P)levels provide critical strategies for plant adaptions to changing environments.However,it is unclear whether leaf N and P levels of different plant functional groups(e.g.,monocots and dicots)respond to environmental gradients in a generalizable pattern.Here,we used a global database of leaf N and P to determine whether monocots and dicots might have evolved contrasting strategies to balance N and P in response to changes in climate and soil nutrient availability.Specifically,we characterized global patterns of leaf N,P and N/P ratio in monocots and dicots,and explored the sensitivity of stoichiometry to environment factors in these plants.Our results indicate that leaf N and P levels responded to environmental factors differently in monocots than in dicots.In dicots,variations of leaf N,P and N/P ratio were significantly correlated to temperature and precipitation.In monocots,leaf N/P ratio was not significantly affected by temperature or precipitation.This indicates that leaf N,P and N/P ratio are less sensitive to environmental dynamics in monocots.We also found that in both monocots and dicots N/P ratios are associated with the availability of soil total P rather than soil total N,indicating that P limitation on plant growth is pervasive globally.In addition,there were significant phylogenetic signals for leaf N(λ=0.65),P(λ=0.57)and N/P ratio(λ=0.46)in dicots,however,only significant phylogenetic signals for leaf P in monocots.Taken together,our findings indicate that monocots exhibit a“conservative”strategy(high stoichiometric homeostasis and weak phylogenetic signals in stoichiometry)to maintain their growth in stressful conditions with lower water and soil nutrients.In contrast,dicots exhibit lower stoichiometric homeostasis in changing environments because of their wide climate-soil niches and significant phylogenetic signals in stoichiometry.展开更多
Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmen...Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale.展开更多
Plant community composition typically undergoes progressive changes along environmental gradients.However,most experimental studies have focused on individual communities,so it remains unclear how exogenous nutrient i...Plant community composition typically undergoes progressive changes along environmental gradients.However,most experimental studies have focused on individual communities,so it remains unclear how exogenous nutrient inputs affect the stability of plant communities along environmental gradients.Along a rainfall gradient on the northern Tibetan Plateau,we conducted an 8-year nitrogen(N)addition experiment in four alpine grasslands:alpine desert steppe(ADS),alpine steppe(AS),alpine meadow steppe(AMS),alpine meadow(AM),and we used twoway ANOVA to examine the effects of N addition on the temporal stability of these different alpine grasslands.We found that community aboveground biomass showed saturation trends in AM and AMS with increasing N gradients,while there was no change in AS and a gradual increase in ADS.The temporal stability showed different patterns of gradual decreases in ADS and AM,and a unimodal trend in AMS with increasing N gradients.However,N addition had no effect on the temporal stability of AS.Dominant species stability was the controlling factor for alpine grasslands along the transect,while the effect of asynchrony gradually increased with decreasing precipitation.These findings highlight that community composition,especially the dominant species,along the environmental gradient can mediate the effects of N inputs on community temporal stability.Thus,the conservation and restoration of the dominant species are particularly important under future scenarios of increased atmospheric N deposition.展开更多
Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil ...Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil quality of some vegetable fields was characterized along an urban-rural gradient in Shaoxing County, Zhejiang Province. Fifteen soil physical and chemical properties were evaluated by using principal component analysis.Results showed that there was a great variation in the soil quality along the gradient. From rural to urban zones, soil organic matter, water-stable aggregates, cation exchangeable capacity (CEC), total N and P, and available K increased, whereas soil pH value decreased. In addition, Pb, Cu, Ni, Co, Zn and Cr in the soils tended to be accumulated toward the urban zone. Sequential chemical extraction showed that mobility of all the heavy metals in the soils tended to increase from the rural to the urban zones. The variation of soil properties accounted for by the first principal component was significantly explained by the difference in application rates of municipal wastes.展开更多
Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still la...Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales （1, 10, 100 and 1,000 m2） at three different dune stabilization stages （mobile dune, semi-fixed dune and fixed dune） in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis （CCA） showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon （SOC）, total nitrogen （TN）, carbon/nitrogen （C/N）, pH, electrical conductivity （EC）, soil water content （SWC）, fine sand （FS）, very fine sand （VFS）, silt and clay （SC）, and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.展开更多
Unraveling the factors that determine variation of diversity in tropical mountain systems is a topic for debate in plant ecology.This is especially true in areas where topography is complex due to volcano elevational ...Unraveling the factors that determine variation of diversity in tropical mountain systems is a topic for debate in plant ecology.This is especially true in areas where topography is complex due to volcano elevational gradients and where forests are vulnerable to human activity.In this study we used a set of climatic(temperature,rainfall,and radiation solar),topographic(elevation,slope aspect,and slope orientation)and human disturbance variables to determine their effect on diversity and composition patterns of a tree community,considering three slope aspects of a tropical volcano in southeastern Mexico.We sampled trees in seventy 0.1-ha plots distributed on three slope aspects of the Tacanávolcano along an elevational gradient of 1500 to 2500 m.We determined diversity patterns(general tree richness,exponential of Shannon index,and pioneer species richness)with linear regression models,and for beta diversity,we used a dissimilarity index(within and between elevational bands 100 m wide).The effect of a set of environmental and human disturbance variables on tree diversity and community composition was analyzed with general linear models and multivariate analyses,respectively.We registered 2,949 individual trees belonging to 176 species and 58families.The average species richness and alpha diversity per plot were 13(standard deviation±6)and 9(±5),respectively.General tree richness and alpha diversity increased in the middle part(unimodal patterns)of the elevational gradient,but pioneer species richness decreased linearly with elevation.The variance explained by general linear models was greater in richness(32%)than in alpha diversity(25.3%).The most important predictor variables were temperature(elevational gradient),which explained the unimodal pattern(richness and alpha diversity increase at intermediate levels of temperature),and slope orientation,which explained the increase in richness and alpha diversity toward the geographic north.Only temperature had a significant effect on pioneer species diversity(22%).For community composition,all the predictor variables evaluated had a significant effect,but the most important were slope aspect and temperature.Assemblages were almost completely different in plots that were farther apart along the elevation gradient and had different slope aspects.Finally,the forests at lower elevations(1500–1900 m)were those that had the most human disturbance.Our study reveals the importance of considering a set of environmental variables related to climate,topography(e.g.,slope aspect),and human disturbance to understand variation in diversity and composition of a tree community on a tropical volcano.With this information,we believe that it is important to implement conservation and restoration measures in the forests of the lower parts of the Tacanávolcano,complemented by studies that contribute to designing better conservation strategies.展开更多
The present study was undertaken in moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to understand the regeneration dynamics of the dominant tr...The present study was undertaken in moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to understand the regeneration dynamics of the dominant tree species along an altitudinal gradient in naturally regen- erating, restricted access forest. The overall regeneration status was fairly high in the study area. Most of the native canopy and undercanopy domi- nants had frequent reproduction and expanding populations, which sug- gests the stability of forest structure/composition and further expansion of dominant species. The overall regeneration of trees in the forest had a greater contribution of middle and understurey species. Because of infre- quent rep＇roduction and declining populations of some of the dominant native species viz., Abies pindrow, Alnus nepalensis and Betula alnoides, structural/compositional changes in the future are expected in respective forests dominated by them..4bies pindrow and Taxus baccata need im- mediate attention by forest managers for their survival in the area. Seed- lings were found to be more prone to competition from herb and shrubs than saplings.展开更多
Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored...Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored. Here, we investigate the geographic variation of such environmental factors, more precisely the quality and quantity of nest resources （bivalve shells） along a salinity gradient in the Baltic Sea Area （Baltic Sea, Sounds and Belts, and Kattegat）. We further test whether we find any salinity-associated morphological differences in body size between populations of common gobies Pomatoschistus microps, a small marine fish with a resource-based mat- ing system. In a geographically expansive field study, we sampled 5 populations of P. microps occurring along the salinity gradient （decreasing from West to East） in the Baltic Sea Area over 3 consecutive years. Nest resource quantity and quality decreased from West to East, and a correla- tion between mussel size and male body size was detected. Population density, sex ratios, mating- and reproductive success as well as brood characteristics also differed between populations but with a less clear relation to salinity. With this field study we shed light on geographic variation of distinct environmental parameters possibly acting on population differentiation. We provide insights on relevant ecological variation, and draw attention to its importance in the framework of context-dependent plasticity of sexual selection.展开更多
Adaptive vegetation management is time-consuming and requires long-term colony monitoring to obtain reliable results. Although vegetation management has been widely adopted, the only method existing at present for eva...Adaptive vegetation management is time-consuming and requires long-term colony monitoring to obtain reliable results. Although vegetation management has been widely adopted, the only method existing at present for evaluating the habitat conditions under management involves observations over a long period of time. The presence of reactive oxygen species （ROS） has long been used as an indicator of environmen- tal stress in plants, and has recently been intensely studied. Among such ROS, hydrogen peroxide （H202） is relatively stable, and can be conveniently and accurately quantified. Thus, the quantification of plant H202 could be applied as a stress indicator for riparian and aquatic vegetation management approaches while evaluating the conditions of a plant species within a habitat. This study presents an approach for elucidating the applicability of H202 as a quantitative indicator of environmental stresses on plants, particularly for vegetation management. Submerged macrophytes and riparian species were studied under laboratory and field conditions （Lake Shinji, Saba River, Eno River, and Hii River in Japan） for H202 formation under various stress conditions. The results suggest that H202 can be conveniently applied as a stress indicator in environmental management.展开更多
Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradi...Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradient. Motivated by observations of alpine treeline ecotones, we suggest that this switch in interaction could operate along a gradient of relative size of individual plants. We propose that as neighbors increase in size relative to a focal plant they improve the environment for that plant up to a critical point. After this critical point is surpassed, however, increasing relative size of neighbors will degrade the environment such that the net interaction intensity becomes negative. We developed a conceptual(not site or species specific) individual based model to simulate a single species with recruitment, growth, and mortality dependent on the environment mediated by the relative size of neighbors. Growth and size form a feedback. Simulation results show that the size gradient model produces metrics similar to that of a stress gradient model. Visualizations reveal that the size gradient model produces spatial patterns that are similar to the complex ones observed at alpine treelines. Size-mediated interaction could be a mechanism of the stress gradient hypothesis or it could operate independent of abiotic stress.展开更多
Phylogenetic niche conservatism posits that species tend to retain ancestral ecological traits and distributions,which has been broadly tested for lineages originating in tropical climates but has been rarely tested f...Phylogenetic niche conservatism posits that species tend to retain ancestral ecological traits and distributions,which has been broadly tested for lineages originating in tropical climates but has been rarely tested for lineages that originated and diversified in temperate climates.Liverworts are thought to originate in temperate climates.Mean lineage age reflects evolutionary history of biological communities.Here,using regional liverwort floras across a long latitudinal gradient from tropical to arctic climates in North America,we test the age-component of the temperate niche conservatism hypothesis.Mean genus age(MGA)was estimated for each of 76 regional floras of liverworts.We related MGA to climatic variables for North America as a whole and for its eastern and western parts separately,and used variation partitioning analysis to assess the relative importance of temperature-versus precipitationrelated variables and of climate extremes versus seasonality on MGA.We found that older genera of liverworts tend to concentrate in humid regions of intermediate temperatures in the range of 10℃-20℃,from which liverworts have adapted to and diversified into more arid,colder,and hotter regions,supporting the temperate niche conservatism hypothesis.We also found that across North America the MGA of liverwort assemblages is more strongly affected by precipitation-related variables than by temperature-related variables,and is more strongly affected by climate extremes than by climate seasonality.Geographic patterns of the MGA of liverworts are consistent with the temperate niche conservatism hypothesis,rather than the tropical niche conservatism hypothesis,the latter of which is broadly supported by angiosperms.展开更多
The mechanisms of plant adaptation to environmental gradients have been the focus of ecological research,with environmental stresses driving coordinated or differentiated regulation of plant functional traits.Plant re...The mechanisms of plant adaptation to environmental gradients have been the focus of ecological research,with environmental stresses driving coordinated or differentiated regulation of plant functional traits.Plant resource acquisition involves root trait plasticity and mycorrhizal symbiosis.However,root trait plasticity along precipitation gradients and root-mycorrhizal trade-offs remain unclear.We conducted community surveys along a west-east precipitation gradient in four natural grassland communities(alpine desert steppe,alpine steppe,alpine meadow steppe and alpine meadow)on the plateau in northern Xizang Plateau.Six key root traits(root diameter,RD;root dry matter content,RDMC;root tissue density,RTD;specific root length,SRL;root branching intensity,RBI;and root length colonization percentage,RLC)were measured in 18 alpine plant species to investigate the coordination and trade-offs between root traits and mycorrhizal fungi along the precipitation gradient.Our results showed community-level declines in RDMC,RD,RTD and RLC with increasing precipitation,contrasting with elevated RBI and SRL.Functional groups exhibited distinct patterns:grasses and legumes demonstrated root-mycorrhizal trade-offs,sedges displayed synergy and forbs showed inconsistent responses.Divergent trends in plant root traits and mycorrhizal fungi were observed at the species level.Alpine plants in humid eastern meadows favored root elongation,while those in arid western desert steppe relied on radial growth and mycorrhizal fungal cooperation for resource acquisition.These findings highlight varied root absorption strategies among alpine plants along environmental gradients,supporting the importance of ecological niche diversification in maintaining alpine ecosystem diversity and stability.展开更多
基金supported by the National Natural Science Foundation of China (32071544, 32271737)the Interdisciplinary Innovation Team of the Chinese Academy of Sciences (CAS) “Light of West China” Program (xbzg-zdsys-202207)。
文摘Understanding the ecogeographic mechanisms driving morphological variation is pivotal in biogeographic studies. However, patterns and determinants of such variation remain contentious, particularly in amphibians. Although several hypotheses have been formulated and investigated in amphibians, their validity remains disputed with mixed support. Using the Sichuan spiny frog(Nanorana sichuanensis) as an indicator, we investigated the morphological variations across geographic and environmental gradients to explore the underlying ecogeographic mechanisms. We found that both the body size and limb characteristics of N.sichuanensis were not significantly related to latitude or elevation, suggesting that it did not follow Bergmann's or Allen's rules. Eye diameter decreased linearly with increasing elevation and latitude, whereas snout length increased with increasing elevation and latitude. Heat balance, endurance, seasonality, water availability, and primary productivity collectively explain body size variation. Hierarchical partitioning identified primary productivity and thermal excursion as the most influential factors, explaining significant variability in body size and other morphological features. Specifically, primary productivity accounted for 52.40% of the variation in body size, whereas thermal excursion had the greatest impact on eye diameter(36.23%) and snout length(72.17%). Based on body size and dimensionally reduced morphological features, our results identified ecogeographic patterns, assessed the validity of different hypotheses, and examined how environmental factors influence these morphological variations. More generally, our study offers comprehensive insights into the ecogeographic variation observed in mountain amphibians,provides a critical evaluation of existing ecogeographic hypotheses, and infers possible morphological adaptations in response to environmental change.
基金Knowledge Innovation Program of the Chinese Academy of Sciences,No.KZCX2-YW-Q06-03 National Natural Science Foundation of China,No.40871241
文摘Quantifying correlation between the spatial patterns of natural wetland plants and environmental gradient gives better understanding of wetland habitats, which is the fundamental for the strategy making on the protection and restoration of natural wetlands. In this study, the spatial patterns of wetland plants and the environmental gradient of wetland habitats were assessed in the Honghe National Nature Reserve （HNNR） in Northeast China, a wetland of international importance on the Ramsar list. Biophysical parameters’ values of wetland plants were obtained by field sampling methods, and wetland mapping at the community scale was completed using remote sensing techniques. Digital delineation of the surface water system, hydrological zoning and wetness index were produced by spatial analysis methods in Geographic Information System. An ecological ordination method and two clustering methods were used to quantify the relationship between the spatial distribution patterns of wetland plants and the corresponding environmental gradients. Such quantitative analyses also present the specific diversity of different types of wetland plants based on the environmental attributes of their habitats. With the support from modern geo-information techniques, the experimental results indicate how four ecotypes of wetland plants spatially transit from forest swamp, shrub wetland and meadow into marsh wetland with increasing wetness index and water table. And they also show how wetland spatial distribution patterns are controlled by an environmental gradient of wetness. Another key finding of this research work is that our results present the exact fundamental differences between marsh and non-marsh plants of 11 wetland plant communities within the core study area. Hence, this case study gives a good sample for better understanding of the complex correlation between the spatial patterns of wetland plants and their environmental attributes using advanced digital analysis methods. It is also useful to show how to integrate geoinformatic techniques with statistical analysis methods based on the field data base.
基金The work was supported by the Regional Capacity Building for Sustainable Natural Resource Management and Agricultural Improvement under Climate Change(CAPSNAC)Project of the Norwegian Program for Capacity Building in Higher Education and Research for Development(NORHED).
文摘Dry evergreen montane forests in Ethiopia are severely threatened.The status of species composition and structure of forest vegetation are important indicators to understand the trends of threats on local plant communities.In the present study,we examined the floristic composition and structure of the Kibate Forest,Wonchi Highland,Ethiopia along environmental gradients.Sixty-six(30 m×30 m)plots were established every 100 m interval along altitudinal gradients(2811‒3073 m a.s.l.)in five transect lines for vegetation and environmental data collection.In total,125 vascular plant species belonging to 104 genera and 52 families were identified.Eighteen species(14%)were endemic to Ethiopia and Eritrea.The two most dominant families,Asteraceae(29 species)and Lamiaceae(eight species)accounted for 30%of the total number of species.The highest number of species(54%)was herbs.Four major community types(viz.,Olinia rochetiana-Myrsine melanophloeos,Ilex mitis-Galiniera saxifraga,Erica arborea-Protea gaguedi,and Hagenia abyssinica-Juniperus procera)were identified.The highest species richness,evenness,diversity,and importance value index were in community types 2 and 4.About 82%of the species and all endemic taxa except five were recorded in these two community types.The most dominant woody species were O.rochetiana,E.arborea,Olea europaea subsp.cuspidata,Myrica salicifolia,I.mitis var.mitis,and H.abyssinica with different patterns of population structure.The results show that there was a weak correlation between species richness and altitude.Our findings confirm that environmental variables both with interactions(such as altitude)and without interactions(such as livestock grazing)significantly(p<0.05)affect species richness.Anthropogenic activities and overgrazing by livestock appear to be the main threat in community types 2 and 3.Urgent management practices and conservation measures such as prohibiting forest clearing and overgrazing and planting indigenous trees through community participation should be considered in community types that are rich in endemic species but are highly threatened.
基金The Quantitative Analysis of Distribution Pattern of Water Quality and Design of Monitoring Networks in Xiangshan Bay and its Adjacent Waters,Northern Coastal Zhejiang under contract No.15130401。
文摘Phytoplankton communities can response immediately and directly to environmental changes,and thus have been applied as reliable biotic indicators in aquatic systems.This study provided insights into the relationships concerning ecological thresholds of phytoplankton communities and individual taxon in response to environmental changes in coastal waters of northern Zhejiang Province,East China Sea.Results demonstrated that there existed seasonal variations of phytoplankton community ecological thresholds of which spring being higher than those in summer.As for individual species,Prorocentrum donghaiense and Noctiluca scintillans were identified as the most tolerant and sensitive indicator species in spring and summer,respectively.They exhibited strong indications in response to environmental changes.These findings highlighted that phytoplankton community structure in this region was stable when environmental gradients were below the thresholds of sensitive species,whereas potential harmful algal blooms may occur when environmental gradients exceeded the thresholds of tolerant species.
基金supported by the National Natural Science Foundation of China(41977192)Zhejiang Provincial Natural Science Foundation of China(LY21D060004)+2 种基金Natural Science Foundation of Ningbo(2021J060 and 2019A610449)Fundamental Research Funds for the Provincial Universities of Zhejiang(SJLY2022001)K.C.Wong Magna Fund in Ningbo University
文摘Background Bacteria,Archaea,and Microeukaryotes comprise taxonomic domains that interact in mediating biogeochemical cycles in coastal waters.Many studies have revealed contrasting biogeographic patterns of community structure and assembly mechanisms in microbial communities from diferent domains in coastal ecosystems;however,knowledge of specifc biogeographic patterns on microbial co-occurrence relationships across complex coastal environmental gradients remains limited.Using a dense sampling scheme at the regional scale,SSU rRNA gene amplicon sequencing,and network analysis,we investigated intra-and inter-domain co-occurrence relationships and network topology-based biogeographic patterns from three microbial domains in coastal waters that show environmental gradients across the inshore-nearshore-ofshore continuum in the East China Sea.Results Overall,we found the highest complexity and connectivity in the bacterial network,the highest modularity in the archaeal network,and the lowest complexity,connectivity,and modularity in the microeukaryotic network.Although microbial co-occurrence networks from the three domains showed distinct topological features,they exhibited a consistent biogeographic pattern across the inshore-nearshore-ofshore continuum.Specifcally,the nearshore zones with intermediate levels of terrestrial impacts refected by multiple environmental factors(including water temperature,salinity,pH,dissolved oxygen,and nutrient-related parameters)had a higher intensity of microbial co-occurrence for all three domains.In contrast,the intensity of microbial co-occurrence was weaker in both the inshore and the ofshore zones at the two ends of the environmental gradients.Archaea occupied a central position in the microbial inter-domain co-occurrence network.In particular,members of the Thaumarchaeota Marine Group I(MGI,now placed within the Family Nitrosopumilaceae of the Phylum Thermoproteota)appeared to be the hubs in the biogeographic shift between inter-domain network modules across environmental gradients.Conclusions Our work ofers new insights into microbial biogeography by integrating network features into biogeographic patterns,towards a better understanding of the potential of microbial interactions in shaping biogeographic patterns of coastal marine microbiota.
文摘Aims Environmental gradients are drivers of species diversity;however,we know relatively little about the evolutionary processes underlying these relationships.A potentially powerful approach to studying diversity gradients is to quantify the phylogenetic structure within and between assemblages arrayed along broad spatial and environmental gradients.Here,we evaluate the phylogenetic structure of plant assemblages along an environmental gradient with the expectation that the habitat specialization of entire lineages is an important evolutionary pattern influencing the structure of tree communities along environmental gradients.Methods We evaluated the effect of several environmental variables on the phylogenetic structure of plant assemblages in 145 plots distributed in northwestern South America that cover a broad environmental gradient.The phylogenetic alpha diversity was quantified for each plot and the phylogenetic beta diversity between each pair of plots was also quantified.Both the alpha and beta diversity measures were then related to spatial and environmental gradients in the study system.Important Findings We found that gradients in temperature and potential evapotranspiration have a strong relationship with the phylogenetic alpha diversity in our study system,with phylogenetic overdispersion in low temperatures and phylogenetic clustering at higher temperatures.Further,the phylogenetic beta diversity between two plots increases with an increasing difference in temperature,whereas annual precipitation was not a significant predictor of community phylogenetic turnover.We also found that the phylogenetic structure of the plots in our study system was related to the degree of seasonal flooding and seasonality in precipitation.In particular,more stressful environments such as dry forests and flooded forests showed phylogenetic clustering.Finally,in contrast with previous studies,we find that phylogenetic beta diversity was not strongly related to the spatial distance separating two forest plots,which may be the result of the importance of the three independent mountain ranges in our study system,which generate a high degree of environmental variation over very short distances.In conclusion,we found that environmental gradients are important drivers of both phylogenetic alpha and phylogenetic beta diversities in these forests over spatial distance.
基金Foundation project： The paper was supported by National Natural Science Foundation of China （39899370）.
文摘Twenty-three secondary forest communities with different structure were selected in Mao＇er Mountain National Park of Heilongjiang Province, China to study the relationship between diversity of forest plant species and environmental gradient. The forest plant species diversity was analyzed by the diversity index, and the environmental factors was quantified by the method of Whittaker＇s quantification of environmental gradient. Meanwhile, β-diversity indexes of communities were calculated with similar measurements. The results showed that the Shannon-wiener diversity index of forest plant species increased with the increase of the environmental gradient, and the β-diversity indexes of communities showed a liner increase along with the change of environmental gradient.
基金supported by the National Science Foundation of China(Grant No.32271774,42301071)the China Postdoctoral Science Foundation(Grant No.2023M743633).
文摘Leaf nitrogen(N)and phosphorus(P)levels provide critical strategies for plant adaptions to changing environments.However,it is unclear whether leaf N and P levels of different plant functional groups(e.g.,monocots and dicots)respond to environmental gradients in a generalizable pattern.Here,we used a global database of leaf N and P to determine whether monocots and dicots might have evolved contrasting strategies to balance N and P in response to changes in climate and soil nutrient availability.Specifically,we characterized global patterns of leaf N,P and N/P ratio in monocots and dicots,and explored the sensitivity of stoichiometry to environment factors in these plants.Our results indicate that leaf N and P levels responded to environmental factors differently in monocots than in dicots.In dicots,variations of leaf N,P and N/P ratio were significantly correlated to temperature and precipitation.In monocots,leaf N/P ratio was not significantly affected by temperature or precipitation.This indicates that leaf N,P and N/P ratio are less sensitive to environmental dynamics in monocots.We also found that in both monocots and dicots N/P ratios are associated with the availability of soil total P rather than soil total N,indicating that P limitation on plant growth is pervasive globally.In addition,there were significant phylogenetic signals for leaf N(λ=0.65),P(λ=0.57)and N/P ratio(λ=0.46)in dicots,however,only significant phylogenetic signals for leaf P in monocots.Taken together,our findings indicate that monocots exhibit a“conservative”strategy(high stoichiometric homeostasis and weak phylogenetic signals in stoichiometry)to maintain their growth in stressful conditions with lower water and soil nutrients.In contrast,dicots exhibit lower stoichiometric homeostasis in changing environments because of their wide climate-soil niches and significant phylogenetic signals in stoichiometry.
基金supported by the National Key Research and Development Program of China(2023YFF0805602)National Natural Science Foundation of China(32225032,32001192,32271597)+1 种基金the Innovation Base Project of Gansu Province(2021YFF0703904)the Science and Technology Program of Gansu Province(24JRRA515,22JR5RA525,23JRRA1157).
文摘Studies on plant diversity are usually based on the total number of species in a community.However,few studies have examined species richness(SR)of different plant life forms in a community along largescale environmental gradients.Particularly,the relative importance(RIV)of different plant life forms in a community and how they vary with environmental variables are still unclear.To fill these gaps,we determined plant diversity of ephemeral plants,annual herbs,perennial herbs,and woody plants from 187 sites across drylands in China.The SR patterns of herbaceous plants,especially perennial herbs,and their RIV in plant communities increased with increasing precipitation and soil nutrient content;however,the RIV of annual herbs was not altered along these gradients.The SR and RIV of ephemeral plants were affected mainly by precipitation seasonality.The SR of woody plants had a unimodal relationship with air temperature and exhibited the highest RIV and SR percentage in plant communities under the harshest environments.An obvious shift emerged in plant community composition,SR and their critical impact factors at 238.5 mm of mean annual precipitation(MAP).In mesic regions(>238.5 mm),herbs were the dominant species,and the SR displayed a relatively slow decreasing rate with increasing aridity,which was mediated mainly by MAP and soil nutrients.In arid regions(<238.5 mm),woody plants were the dominant species,and the SR displayed a relatively fast decreasing rate with increasing aridity,which was mediated mainly by climate variables,especially precipitation.Our findings highlight the importance of comparative life form studies in community structure and biodiversity,as their responses to gradients differed substantially on a large scale.
基金financially supported by the National Natural Science Foundation of China(42071066)the West Light Foundation of the Chinese Academy of Sciences(2021)+1 种基金the National Key Research and Development Program of China(2023YFF1304304)the Natural Science Foundation of XizangAutonomous Region,China(XZ202201ZR0026G)。
文摘Plant community composition typically undergoes progressive changes along environmental gradients.However,most experimental studies have focused on individual communities,so it remains unclear how exogenous nutrient inputs affect the stability of plant communities along environmental gradients.Along a rainfall gradient on the northern Tibetan Plateau,we conducted an 8-year nitrogen(N)addition experiment in four alpine grasslands:alpine desert steppe(ADS),alpine steppe(AS),alpine meadow steppe(AMS),alpine meadow(AM),and we used twoway ANOVA to examine the effects of N addition on the temporal stability of these different alpine grasslands.We found that community aboveground biomass showed saturation trends in AM and AMS with increasing N gradients,while there was no change in AS and a gradual increase in ADS.The temporal stability showed different patterns of gradual decreases in ADS and AM,and a unimodal trend in AMS with increasing N gradients.However,N addition had no effect on the temporal stability of AS.Dominant species stability was the controlling factor for alpine grasslands along the transect,while the effect of asynchrony gradually increased with decreasing precipitation.These findings highlight that community composition,especially the dominant species,along the environmental gradient can mediate the effects of N inputs on community temporal stability.Thus,the conservation and restoration of the dominant species are particularly important under future scenarios of increased atmospheric N deposition.
基金Project supported by the National Key Basic Research Support Foundation (NKBRSF) of China (No. 1999011809).
文摘Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil quality of some vegetable fields was characterized along an urban-rural gradient in Shaoxing County, Zhejiang Province. Fifteen soil physical and chemical properties were evaluated by using principal component analysis.Results showed that there was a great variation in the soil quality along the gradient. From rural to urban zones, soil organic matter, water-stable aggregates, cation exchangeable capacity (CEC), total N and P, and available K increased, whereas soil pH value decreased. In addition, Pb, Cu, Ni, Co, Zn and Cr in the soils tended to be accumulated toward the urban zone. Sequential chemical extraction showed that mobility of all the heavy metals in the soils tended to increase from the rural to the urban zones. The variation of soil properties accounted for by the first principal component was significantly explained by the difference in application rates of municipal wastes.
基金financially supported by the National Natural Science Foundation of China (41171414)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-QN313)+1 种基金the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (2011T2Z36)the Key Project of Scientific and Technical Supporting Programs (2011BAC07B02-09), and the National Basic Research Program of China (2009CB421303)
文摘Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales （1, 10, 100 and 1,000 m2） at three different dune stabilization stages （mobile dune, semi-fixed dune and fixed dune） in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis （CCA） showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon （SOC）, total nitrogen （TN）, carbon/nitrogen （C/N）, pH, electrical conductivity （EC）, soil water content （SWC）, fine sand （FS）, very fine sand （VFS）, silt and clay （SC）, and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.
基金funded by the Comisión Nacional deáreas Naturales Protegidas(CONANP)-Reserva de la Biosfera Volcán Tacaná(CONANP/PROCODES/6799/2017)through a grant to Manuel Martínez Meléndez。
文摘Unraveling the factors that determine variation of diversity in tropical mountain systems is a topic for debate in plant ecology.This is especially true in areas where topography is complex due to volcano elevational gradients and where forests are vulnerable to human activity.In this study we used a set of climatic(temperature,rainfall,and radiation solar),topographic(elevation,slope aspect,and slope orientation)and human disturbance variables to determine their effect on diversity and composition patterns of a tree community,considering three slope aspects of a tropical volcano in southeastern Mexico.We sampled trees in seventy 0.1-ha plots distributed on three slope aspects of the Tacanávolcano along an elevational gradient of 1500 to 2500 m.We determined diversity patterns(general tree richness,exponential of Shannon index,and pioneer species richness)with linear regression models,and for beta diversity,we used a dissimilarity index(within and between elevational bands 100 m wide).The effect of a set of environmental and human disturbance variables on tree diversity and community composition was analyzed with general linear models and multivariate analyses,respectively.We registered 2,949 individual trees belonging to 176 species and 58families.The average species richness and alpha diversity per plot were 13(standard deviation±6)and 9(±5),respectively.General tree richness and alpha diversity increased in the middle part(unimodal patterns)of the elevational gradient,but pioneer species richness decreased linearly with elevation.The variance explained by general linear models was greater in richness(32%)than in alpha diversity(25.3%).The most important predictor variables were temperature(elevational gradient),which explained the unimodal pattern(richness and alpha diversity increase at intermediate levels of temperature),and slope orientation,which explained the increase in richness and alpha diversity toward the geographic north.Only temperature had a significant effect on pioneer species diversity(22%).For community composition,all the predictor variables evaluated had a significant effect,but the most important were slope aspect and temperature.Assemblages were almost completely different in plots that were farther apart along the elevation gradient and had different slope aspects.Finally,the forests at lower elevations(1500–1900 m)were those that had the most human disturbance.Our study reveals the importance of considering a set of environmental variables related to climate,topography(e.g.,slope aspect),and human disturbance to understand variation in diversity and composition of a tree community on a tropical volcano.With this information,we believe that it is important to implement conservation and restoration measures in the forests of the lower parts of the Tacanávolcano,complemented by studies that contribute to designing better conservation strategies.
基金supported by the Department of Science and Technology, Government of India, New Delhi, vide its Project No. SP/SO/PS-52/2004
文摘The present study was undertaken in moist temperate forest of Mandal-Chopta area in the Garhwal region of Uttarakhand, India. The aim of the present study was to understand the regeneration dynamics of the dominant tree species along an altitudinal gradient in naturally regen- erating, restricted access forest. The overall regeneration status was fairly high in the study area. Most of the native canopy and undercanopy domi- nants had frequent reproduction and expanding populations, which sug- gests the stability of forest structure/composition and further expansion of dominant species. The overall regeneration of trees in the forest had a greater contribution of middle and understurey species. Because of infre- quent rep＇roduction and declining populations of some of the dominant native species viz., Abies pindrow, Alnus nepalensis and Betula alnoides, structural/compositional changes in the future are expected in respective forests dominated by them..4bies pindrow and Taxus baccata need im- mediate attention by forest managers for their survival in the area. Seed- lings were found to be more prone to competition from herb and shrubs than saplings.
文摘Although it has become clear that sexual selection may shape mating systems and drive speciation, the potential constraints of environmental factors on processes and outcomes of sexual selection are largely unexplored. Here, we investigate the geographic variation of such environmental factors, more precisely the quality and quantity of nest resources （bivalve shells） along a salinity gradient in the Baltic Sea Area （Baltic Sea, Sounds and Belts, and Kattegat）. We further test whether we find any salinity-associated morphological differences in body size between populations of common gobies Pomatoschistus microps, a small marine fish with a resource-based mat- ing system. In a geographically expansive field study, we sampled 5 populations of P. microps occurring along the salinity gradient （decreasing from West to East） in the Baltic Sea Area over 3 consecutive years. Nest resource quantity and quality decreased from West to East, and a correla- tion between mussel size and male body size was detected. Population density, sex ratios, mating- and reproductive success as well as brood characteristics also differed between populations but with a less clear relation to salinity. With this field study we shed light on geographic variation of distinct environmental parameters possibly acting on population differentiation. We provide insights on relevant ecological variation, and draw attention to its importance in the framework of context-dependent plasticity of sexual selection.
基金financially supported by grant-in-aid from the Japan Society for the Promotion of Science Scientific Research (15H04045)+5 种基金Development Grant for River Management Technology from the Ministry of Land Infrastructure Transportation and Tourism JapanRiver Fund from the River Foundation of Japan and Watershed Ecology Research Group of WEC
文摘Adaptive vegetation management is time-consuming and requires long-term colony monitoring to obtain reliable results. Although vegetation management has been widely adopted, the only method existing at present for evaluating the habitat conditions under management involves observations over a long period of time. The presence of reactive oxygen species （ROS） has long been used as an indicator of environmen- tal stress in plants, and has recently been intensely studied. Among such ROS, hydrogen peroxide （H202） is relatively stable, and can be conveniently and accurately quantified. Thus, the quantification of plant H202 could be applied as a stress indicator for riparian and aquatic vegetation management approaches while evaluating the conditions of a plant species within a habitat. This study presents an approach for elucidating the applicability of H202 as a quantitative indicator of environmental stresses on plants, particularly for vegetation management. Submerged macrophytes and riparian species were studied under laboratory and field conditions （Lake Shinji, Saba River, Eno River, and Hii River in Japan） for H202 formation under various stress conditions. The results suggest that H202 can be conveniently applied as a stress indicator in environmental management.
基金based upon work while an author served at the National Science Foundation(USA)
文摘Research on the stress gradient hypothesis recognizes that positive(i.e. facilitative) and negative(i.e. competitive) plant interactions change in intensity and effect relative to abiotic stress experienced on a gradient. Motivated by observations of alpine treeline ecotones, we suggest that this switch in interaction could operate along a gradient of relative size of individual plants. We propose that as neighbors increase in size relative to a focal plant they improve the environment for that plant up to a critical point. After this critical point is surpassed, however, increasing relative size of neighbors will degrade the environment such that the net interaction intensity becomes negative. We developed a conceptual(not site or species specific) individual based model to simulate a single species with recruitment, growth, and mortality dependent on the environment mediated by the relative size of neighbors. Growth and size form a feedback. Simulation results show that the size gradient model produces metrics similar to that of a stress gradient model. Visualizations reveal that the size gradient model produces spatial patterns that are similar to the complex ones observed at alpine treelines. Size-mediated interaction could be a mechanism of the stress gradient hypothesis or it could operate independent of abiotic stress.
文摘Phylogenetic niche conservatism posits that species tend to retain ancestral ecological traits and distributions,which has been broadly tested for lineages originating in tropical climates but has been rarely tested for lineages that originated and diversified in temperate climates.Liverworts are thought to originate in temperate climates.Mean lineage age reflects evolutionary history of biological communities.Here,using regional liverwort floras across a long latitudinal gradient from tropical to arctic climates in North America,we test the age-component of the temperate niche conservatism hypothesis.Mean genus age(MGA)was estimated for each of 76 regional floras of liverworts.We related MGA to climatic variables for North America as a whole and for its eastern and western parts separately,and used variation partitioning analysis to assess the relative importance of temperature-versus precipitationrelated variables and of climate extremes versus seasonality on MGA.We found that older genera of liverworts tend to concentrate in humid regions of intermediate temperatures in the range of 10℃-20℃,from which liverworts have adapted to and diversified into more arid,colder,and hotter regions,supporting the temperate niche conservatism hypothesis.We also found that across North America the MGA of liverwort assemblages is more strongly affected by precipitation-related variables than by temperature-related variables,and is more strongly affected by climate extremes than by climate seasonality.Geographic patterns of the MGA of liverworts are consistent with the temperate niche conservatism hypothesis,rather than the tropical niche conservatism hypothesis,the latter of which is broadly supported by angiosperms.
基金supported by the National Natural Science Foundation of China(42071066)the National Key Research and Development Program of China(2023YFF1304304)the West Light Foundation of the Chinese Academy of Sciences(2021).
文摘The mechanisms of plant adaptation to environmental gradients have been the focus of ecological research,with environmental stresses driving coordinated or differentiated regulation of plant functional traits.Plant resource acquisition involves root trait plasticity and mycorrhizal symbiosis.However,root trait plasticity along precipitation gradients and root-mycorrhizal trade-offs remain unclear.We conducted community surveys along a west-east precipitation gradient in four natural grassland communities(alpine desert steppe,alpine steppe,alpine meadow steppe and alpine meadow)on the plateau in northern Xizang Plateau.Six key root traits(root diameter,RD;root dry matter content,RDMC;root tissue density,RTD;specific root length,SRL;root branching intensity,RBI;and root length colonization percentage,RLC)were measured in 18 alpine plant species to investigate the coordination and trade-offs between root traits and mycorrhizal fungi along the precipitation gradient.Our results showed community-level declines in RDMC,RD,RTD and RLC with increasing precipitation,contrasting with elevated RBI and SRL.Functional groups exhibited distinct patterns:grasses and legumes demonstrated root-mycorrhizal trade-offs,sedges displayed synergy and forbs showed inconsistent responses.Divergent trends in plant root traits and mycorrhizal fungi were observed at the species level.Alpine plants in humid eastern meadows favored root elongation,while those in arid western desert steppe relied on radial growth and mycorrhizal fungal cooperation for resource acquisition.These findings highlight varied root absorption strategies among alpine plants along environmental gradients,supporting the importance of ecological niche diversification in maintaining alpine ecosystem diversity and stability.
