Residential segregation is a dual process of socio-spatial differentiation in residents and spatio-temporal heterogeneity in dwelling.However,most of the existing studies are established from the single perspective of...Residential segregation is a dual process of socio-spatial differentiation in residents and spatio-temporal heterogeneity in dwelling.However,most of the existing studies are established from the single perspective of urban residents based on demographic data,which is difficult to reveal the dynamics and complex spatial reconstruction within and between cities.With the characteristics of both stability and timeliness,the rapidly changing housing market is one of the processes and results of socio-spatial reconfiguration,and it is undoubtedly a better lens to observe residential segregation.This paper adopts methods such as multi-group segregation index,multi-scalar segregation profiles,and decomposition of segregation index,with Nanjing and Hangzhou as case cities,and establishes multi-scalar segregation profiles and comparative models based on three geographical scales of census tract,block and grid,and different residential types.A quantitative study was conducted on the degree and pattern of multi-scalar residential segregation in Nanjing and Hangzhou from 2009 to 2018.The paper found that the spatial segregation index is an improvement of the non-spatial segregation index.There are differences between Nanjing and Hangzhou in the evolution process of residential segregation.Nanjing has a higher degree of spatial differentiation as a whole,among which spatial components have a more significant impact.展开更多
Knowledge of sex ratio and spatial distribution of males and females of dioecious species is both of evolutionary interest and of crucial importance for biological conservation. Eurycorymbus cavaleriei, the only speci...Knowledge of sex ratio and spatial distribution of males and females of dioecious species is both of evolutionary interest and of crucial importance for biological conservation. Eurycorymbus cavaleriei, the only species in the genus Eurycorymbus （Sapindaceae）, is a dioecious tree endemic to subtropical montane forest in South China. Sex ratios were investigated in 15 natural populations for the two defined ages （young and old）. Spatial distribution of males and females was further studied in six large populations occurring in different habitats （fragmented and continuous）. The study revealed a slight trend of male- biased sex ratio in both ages of E. cavaleriei, but sex ratio of most populations （13 out of 15） did not display statistically significant deviation from equality. All of the four significantly male-biased populations in the young class shifted to equality or even female-biased, The Ripley＇s K analysis of the distribution of males with respect to females suggested that individuals of the opposite sexes were more randomly distributed rather than spatially structured. These results suggest that the male-biased sex ratio in E. cavaleriei may result from the precocity of males and habitat heterogeneity. The sex ratio and the sex spatial distribution pattern are unlikely to constitute a serious threat to the survival of the species.展开更多
Background:There is increasing interest in evaluating home-range overlap(or,otherwise,segregation)between bird species,and between or within bird populations,to inform spatial planning.So far,studies of home-range ove...Background:There is increasing interest in evaluating home-range overlap(or,otherwise,segregation)between bird species,and between or within bird populations,to inform spatial planning.So far,studies of home-range overlap typically make use of comparisons between pairs of individuals,populations or species,and return a matrix of pairwise overlaps(e.g.,percent overlaps).However,when the number of individuals,populations or species to be compared is elevated,an overlarge overlap matrix is difficult to interpret from an ecological viewpoint.Methods:We propose here a new,conceptually simple and computationally efficient index(general overlap index;GOI)for the ready computation within GIS of home range overlap of an arbitrarily large number(i.e.,n≥2)of individuals,populations or species.Whatever the number of home ranges to be compared,GOI always returns a single score between 0 and 100.As a case study,we applied our index to 24,074 GPS points of 10 Lesser Kestrels(Falco naumanni)in order to estimate within-colony and between-colony overlaps in two neighboring colonies in Southern Italy.Results:Within-colony overlap was elevated for both colonies(96.41%at Cassano delle Murge,n=5 individuals;81.38%at Santeramo in Colle,n=5 individuals),while between-colony overlap was low(19.12%;n=2 colonies)and,after a randomization procedure,more spatially-segregated than expected by chance.Conclusions:Modern biotelemetry offers huge amounts of data describing the space use of animal species.The use of intuitive and straightforward indices,like GOI,can be useful to promptly extract ecological information from such an amount of data(e.g.detecting change in space use over successive years,evaluating the reliability of various home-range estimators).展开更多
New methods in landscape ecology to study the link between landscape heterogeneity and landscape functionality are needed. Heterogeneity is a basic characteristic of landscape, and landscape function is the capacity t...New methods in landscape ecology to study the link between landscape heterogeneity and landscape functionality are needed. Heterogeneity is a basic characteristic of landscape, and landscape function is the capacity to change the structural heterogeneity of a landscape system. In most developed countries the industrialisation of agriculture has in general resulted in a change of agricultural landscapes from a small-grained heterogeneous pattern towards more monotonous and monofunctional landscapes. During the 1990's this trends seems to have changed due to a diversification of rural land use and new trends in urbanisation. Weather these phases of landscape development should be expected in developing countries is a totally open question. Dealing with the study of multifunctionality of landscapes it is proposed to distinguish between ecological functionality of landscape ecosystems, functionality pertaining to land use and social functionality. Further, the relation between function, space and scale is important by the determination of spatial and time segregation as well as spatial and time integration of multifunctionality in landscapes.展开更多
Reintroduction of captive-bred Chinese giant salamanders is a primary approach for restoring wild populations.Despite previous studies have investigated the habitat preferences of reintroduced Chinese giant salamander...Reintroduction of captive-bred Chinese giant salamanders is a primary approach for restoring wild populations.Despite previous studies have investigated the habitat preferences of reintroduced Chinese giant salamanders,the intraspecific variation in their habitat selection has been neglected.In the present study,30 captive-bred Chinese giant salamanders belonging to 3 groups(i.e.,10 males,10 females,and 10 juveniles)were released into a montane stream to explore whether intraspecific variation in habitat selection occurred in this species using radiotelemetry.Our results indicated that linear home range and daily movement of males were significantly higher than those of females and juveniles.Male sedentariness was significantly lower than that of females and juveniles.No significant differences were detected between females and juveniles in these measures.Importantly,we found that males preferred microhabitats with low water conductivity and deep water depth.Females preferred microhabitats with high water conductivity,low dissolved oxygen and ammonium-nitrogen,and slow current velocity,while juveniles occupied microhabitats with low ammonium-nitrogen.In addition,males and juveniles exhibited higher niche breadth than females.Niche overlap was high between adults and juveniles but low between males and females.Our study revealed the presence of spatial segregation in reintroduced Chinese giant salamanders.Males,females,and juveniles exhibited variation in microhabitat selection.These results provide important information for use when planning strategies for conservation of Chinese giant salamanders.展开更多
This article is concerned with a strongly coupled elliptic system modeling the steady state of two or more populations that compete in some regions. We prove the uniqueness of the limiting configuration as the competi...This article is concerned with a strongly coupled elliptic system modeling the steady state of two or more populations that compete in some regions. We prove the uniqueness of the limiting configuration as the competing rate tends to infinity, under suitable conditions. The proof relies on properties of limiting solution and Maximum principle.展开更多
Aims The spatial segregation hypothesis and the low-frequency hypothesis are two important proposed mechanisms that delay or prevent competitive exclusion in ecosystems.Because tree species interact with their neighbo...Aims The spatial segregation hypothesis and the low-frequency hypothesis are two important proposed mechanisms that delay or prevent competitive exclusion in ecosystems.Because tree species interact with their neighbors,the importance of these potential processes can be investigated by analyzing the spatial structures of tree species.Methods The distribution of the adults of 27 common tree species in a fully mapped 5-ha subtropical forest plot in Baishanzu,eastern China,was analyzed to investigate the community-level intra-and interspecific spatial association patterns.We first tested for the overall spatial pattern in the 5-to 40-m neighborhoods and classified first-order bivariate associations with a diametric scheme based on Ripley’s K and nearest-neighbor statistic(G-function).Then heterogeneous Poisson null models were used to distinguish second-order interactions from overall spatial associations(including first-order effects).Finally,we analyzed correlations between the existence of species interactions and some attributes of the species involved.Important Findings Partial overlap and segregation increased with scale,whereas mixing decreased.Nearly 70%of the species pairs occurred less than expected at random,and only 3.4%of the species pairs were well mixed;11.0%of all species pairs showed significant small-scale interactions,which was a greater frequency than expected by chance if species are abundant or prefer the same habitat,but less frequent than expected if species are highly aggregated.This suggests that both spatial segregation and low frequency of species facilitate species coexistence by reducing the opportunity that trees of two species encounter each other.The study also revealed that positive interactions were more prevalent than negative interactions in the forest,which indicates that positive interactions may have important effects on forest species assemblies.展开更多
Dioecious plants exhibit sexual dimorphism in both sexual features(reproductive organs)and secondary sex characteristics(vegetative traits).Sexual differences in secondary traits,including morphological,physiological ...Dioecious plants exhibit sexual dimorphism in both sexual features(reproductive organs)and secondary sex characteristics(vegetative traits).Sexual differences in secondary traits,including morphological,physiological and ecological characters,have been commonly associated with trade-offs between the cost of reproduction and other plant functions.Such trade-offs may be modified by environmental stressors,although there is evidence that sexually dimorphic responses to stress do not always exist in all plant species.When sexual dimorphism exists,sexually different responses appear to depend on the species and stress types.Yet,further studies on dioecious plant species are needed to allow the generalization of stress effects on males and females.Additionally,sexual dimorphism may influence the frequency and distribution of the sexes along environmental gradients,likely causing niche differentiation and spatial segregation of sexes.At the present,the causes and mechanisms governing sex ratio biases are poorly understood.This review aims to discuss sex-specific responses and sex ratio biases occurring under adverse conditions,which will advance our knowledge of sexually dimorphic responses to environmental stressors.展开更多
For the strongly coupled system of M ≥ 3 competing species：-△[（di＋∑j=1^Mβijuj）ui]=（ai-bi）ui-kui∑j≠iui,i=1,…,M,we prove the uniqueness of the limiting configuration as k →∞ under suitable conditions. Mor...For the strongly coupled system of M ≥ 3 competing species：-△[（di＋∑j=1^Mβijuj）ui]=（ai-bi）ui-kui∑j≠iui,i=1,…,M,we prove the uniqueness of the limiting configuration as k →∞ under suitable conditions. Moreover, we prove that the limiting configuration minimizes a variational problem associated to the strongly coupled system among the segregated states with the same boundary conditions.展开更多
基金National Natural Science Foundation of China,No.41771184,No.42171234。
文摘Residential segregation is a dual process of socio-spatial differentiation in residents and spatio-temporal heterogeneity in dwelling.However,most of the existing studies are established from the single perspective of urban residents based on demographic data,which is difficult to reveal the dynamics and complex spatial reconstruction within and between cities.With the characteristics of both stability and timeliness,the rapidly changing housing market is one of the processes and results of socio-spatial reconfiguration,and it is undoubtedly a better lens to observe residential segregation.This paper adopts methods such as multi-group segregation index,multi-scalar segregation profiles,and decomposition of segregation index,with Nanjing and Hangzhou as case cities,and establishes multi-scalar segregation profiles and comparative models based on three geographical scales of census tract,block and grid,and different residential types.A quantitative study was conducted on the degree and pattern of multi-scalar residential segregation in Nanjing and Hangzhou from 2009 to 2018.The paper found that the spatial segregation index is an improvement of the non-spatial segregation index.There are differences between Nanjing and Hangzhou in the evolution process of residential segregation.Nanjing has a higher degree of spatial differentiation as a whole,among which spatial components have a more significant impact.
基金the National Natural Science Foundation of China (30470185)KIP Pilot Project of the Chinese Academy of Sciences (KSCX2-YW-N-061)
文摘Knowledge of sex ratio and spatial distribution of males and females of dioecious species is both of evolutionary interest and of crucial importance for biological conservation. Eurycorymbus cavaleriei, the only species in the genus Eurycorymbus （Sapindaceae）, is a dioecious tree endemic to subtropical montane forest in South China. Sex ratios were investigated in 15 natural populations for the two defined ages （young and old）. Spatial distribution of males and females was further studied in six large populations occurring in different habitats （fragmented and continuous）. The study revealed a slight trend of male- biased sex ratio in both ages of E. cavaleriei, but sex ratio of most populations （13 out of 15） did not display statistically significant deviation from equality. All of the four significantly male-biased populations in the young class shifted to equality or even female-biased, The Ripley＇s K analysis of the distribution of males with respect to females suggested that individuals of the opposite sexes were more randomly distributed rather than spatially structured. These results suggest that the male-biased sex ratio in E. cavaleriei may result from the precocity of males and habitat heterogeneity. The sex ratio and the sex spatial distribution pattern are unlikely to constitute a serious threat to the survival of the species.
基金supported by LIPU-UK(GIS and modelling work)by the Alta Murgia National Park(biotelemetry and field work)。
文摘Background:There is increasing interest in evaluating home-range overlap(or,otherwise,segregation)between bird species,and between or within bird populations,to inform spatial planning.So far,studies of home-range overlap typically make use of comparisons between pairs of individuals,populations or species,and return a matrix of pairwise overlaps(e.g.,percent overlaps).However,when the number of individuals,populations or species to be compared is elevated,an overlarge overlap matrix is difficult to interpret from an ecological viewpoint.Methods:We propose here a new,conceptually simple and computationally efficient index(general overlap index;GOI)for the ready computation within GIS of home range overlap of an arbitrarily large number(i.e.,n≥2)of individuals,populations or species.Whatever the number of home ranges to be compared,GOI always returns a single score between 0 and 100.As a case study,we applied our index to 24,074 GPS points of 10 Lesser Kestrels(Falco naumanni)in order to estimate within-colony and between-colony overlaps in two neighboring colonies in Southern Italy.Results:Within-colony overlap was elevated for both colonies(96.41%at Cassano delle Murge,n=5 individuals;81.38%at Santeramo in Colle,n=5 individuals),while between-colony overlap was low(19.12%;n=2 colonies)and,after a randomization procedure,more spatially-segregated than expected by chance.Conclusions:Modern biotelemetry offers huge amounts of data describing the space use of animal species.The use of intuitive and straightforward indices,like GOI,can be useful to promptly extract ecological information from such an amount of data(e.g.detecting change in space use over successive years,evaluating the reliability of various home-range estimators).
文摘New methods in landscape ecology to study the link between landscape heterogeneity and landscape functionality are needed. Heterogeneity is a basic characteristic of landscape, and landscape function is the capacity to change the structural heterogeneity of a landscape system. In most developed countries the industrialisation of agriculture has in general resulted in a change of agricultural landscapes from a small-grained heterogeneous pattern towards more monotonous and monofunctional landscapes. During the 1990's this trends seems to have changed due to a diversification of rural land use and new trends in urbanisation. Weather these phases of landscape development should be expected in developing countries is a totally open question. Dealing with the study of multifunctionality of landscapes it is proposed to distinguish between ecological functionality of landscape ecosystems, functionality pertaining to land use and social functionality. Further, the relation between function, space and scale is important by the determination of spatial and time segregation as well as spatial and time integration of multifunctionality in landscapes.
基金supported by the National Key Programme of Research and'Development,Ministry of Science and Technology(2016YFC0503200)the Biodiversity Survey and Assessment Project of the Ministry of Ecology and Environment,China(2019HJ2096001006)+1 种基金the Construction of Basic Conditions Platform of Sichuan Science and TechnologyDepartment(2019JDPT0020)China Biodiversity Observation Networks(Sino BON).
文摘Reintroduction of captive-bred Chinese giant salamanders is a primary approach for restoring wild populations.Despite previous studies have investigated the habitat preferences of reintroduced Chinese giant salamanders,the intraspecific variation in their habitat selection has been neglected.In the present study,30 captive-bred Chinese giant salamanders belonging to 3 groups(i.e.,10 males,10 females,and 10 juveniles)were released into a montane stream to explore whether intraspecific variation in habitat selection occurred in this species using radiotelemetry.Our results indicated that linear home range and daily movement of males were significantly higher than those of females and juveniles.Male sedentariness was significantly lower than that of females and juveniles.No significant differences were detected between females and juveniles in these measures.Importantly,we found that males preferred microhabitats with low water conductivity and deep water depth.Females preferred microhabitats with high water conductivity,low dissolved oxygen and ammonium-nitrogen,and slow current velocity,while juveniles occupied microhabitats with low ammonium-nitrogen.In addition,males and juveniles exhibited higher niche breadth than females.Niche overlap was high between adults and juveniles but low between males and females.Our study revealed the presence of spatial segregation in reintroduced Chinese giant salamanders.Males,females,and juveniles exhibited variation in microhabitat selection.These results provide important information for use when planning strategies for conservation of Chinese giant salamanders.
文摘This article is concerned with a strongly coupled elliptic system modeling the steady state of two or more populations that compete in some regions. We prove the uniqueness of the limiting configuration as the competing rate tends to infinity, under suitable conditions. The proof relies on properties of limiting solution and Maximum principle.
基金Appropriative Foundation of Ecology and Environment Protection of Zhejiang Province(ZCJ200317)China National Program for R&D Infrastructure and Facility Development(2008BAC39B02).
文摘Aims The spatial segregation hypothesis and the low-frequency hypothesis are two important proposed mechanisms that delay or prevent competitive exclusion in ecosystems.Because tree species interact with their neighbors,the importance of these potential processes can be investigated by analyzing the spatial structures of tree species.Methods The distribution of the adults of 27 common tree species in a fully mapped 5-ha subtropical forest plot in Baishanzu,eastern China,was analyzed to investigate the community-level intra-and interspecific spatial association patterns.We first tested for the overall spatial pattern in the 5-to 40-m neighborhoods and classified first-order bivariate associations with a diametric scheme based on Ripley’s K and nearest-neighbor statistic(G-function).Then heterogeneous Poisson null models were used to distinguish second-order interactions from overall spatial associations(including first-order effects).Finally,we analyzed correlations between the existence of species interactions and some attributes of the species involved.Important Findings Partial overlap and segregation increased with scale,whereas mixing decreased.Nearly 70%of the species pairs occurred less than expected at random,and only 3.4%of the species pairs were well mixed;11.0%of all species pairs showed significant small-scale interactions,which was a greater frequency than expected by chance if species are abundant or prefer the same habitat,but less frequent than expected if species are highly aggregated.This suggests that both spatial segregation and low frequency of species facilitate species coexistence by reducing the opportunity that trees of two species encounter each other.The study also revealed that positive interactions were more prevalent than negative interactions in the forest,which indicates that positive interactions may have important effects on forest species assemblies.
基金This work was supported by the Natural Science Foundation of China(U1803231)the Talent Program ofthe Hangzhou Normal University(2016QDLO20).
文摘Dioecious plants exhibit sexual dimorphism in both sexual features(reproductive organs)and secondary sex characteristics(vegetative traits).Sexual differences in secondary traits,including morphological,physiological and ecological characters,have been commonly associated with trade-offs between the cost of reproduction and other plant functions.Such trade-offs may be modified by environmental stressors,although there is evidence that sexually dimorphic responses to stress do not always exist in all plant species.When sexual dimorphism exists,sexually different responses appear to depend on the species and stress types.Yet,further studies on dioecious plant species are needed to allow the generalization of stress effects on males and females.Additionally,sexual dimorphism may influence the frequency and distribution of the sexes along environmental gradients,likely causing niche differentiation and spatial segregation of sexes.At the present,the causes and mechanisms governing sex ratio biases are poorly understood.This review aims to discuss sex-specific responses and sex ratio biases occurring under adverse conditions,which will advance our knowledge of sexually dimorphic responses to environmental stressors.
基金Supported by PRC grant NSFC(Grant Nos.11371310,11401515)
文摘For the strongly coupled system of M ≥ 3 competing species：-△[（di＋∑j=1^Mβijuj）ui]=（ai-bi）ui-kui∑j≠iui,i=1,…,M,we prove the uniqueness of the limiting configuration as k →∞ under suitable conditions. Moreover, we prove that the limiting configuration minimizes a variational problem associated to the strongly coupled system among the segregated states with the same boundary conditions.
