Plant roots have been recognized to be modu- lar, and a third order root cluster has been proposed to be the basic root module unit based upon the life cycle. This experiment examines root modularity of the nutrient-u...Plant roots have been recognized to be modu- lar, and a third order root cluster has been proposed to be the basic root module unit based upon the life cycle. This experiment examines root modularity of the nutrient-up- take function using stable isotope 15N. Solidago canadensis root clusters of second or third orders--from the same third or fourth order roots, respectively--were treated with 15NH15NO3, NH4NO3, and de-ionized water for 15 and 180 min. The δ15N values of the root clusters were then analyzed and compared. The 15N values of 15N-treated root clusters of both second and third orders were hundreds of times higher than that of the 15N untreated root clusters. However, the differences of the δ15N values among 15N untreated root clusters （though expressed some significant variations）, did not indicate the 15N shared by the sister root clusters came from a common higher-order root. These results demonstrated functional modularity of root nutrient uptake, revealed a second order root, perhaps even a first order root to be a base module unit in terms of root nutrient uptake. The results also suggested that the concept of root modularity is function-specific. This experiment further revealed the importance of treatment timing in stabilizing the internal 15N/14N ratio in roots and avoiding top-down transportation of 15N back into roots to secure unbiased measurements.展开更多
Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their struc...Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.展开更多
As an apex predator the Amur tiger(Panthera tigris altaica)could play a pivotal role in maintaining the integrity of forest ecosystems in Northeast Asia.Due to habitat loss and harvest over the past century,tige...As an apex predator the Amur tiger(Panthera tigris altaica)could play a pivotal role in maintaining the integrity of forest ecosystems in Northeast Asia.Due to habitat loss and harvest over the past century,tigers rapidly declined in China and are now restricted to the Russian Far East and bordering habitat in nearby China.To facilitate restoration of the tiger in its historical range,reliable estimates of population size are essential to assess effectiveness of conservation interventions.Here we used camera trap data collected in Hunchun National Nature Reserve from April to June 2013 and 2014 to estimate tiger density and abundance using both maximum likelihood and Bayesian spatially explicit capture-recapture(SECR)methods.A minimum of 8 individuals were detected in both sample periods and the documentation of marking behavior and reproduction suggests the presence of a resident population.Using Bayesian SECR modeling within the 11400 km2 state space,density estimates were 0.33 and 0.40 individuals/100 km^(2) in 2013 and 2014,respectively,corresponding to an estimated abundance of 38 and 45 animals for this transboundary Sino-Russian population.In a maximum likelihood framework,we estimated densities of 0.30 and 0.24 individuals/100 km^(2) corresponding to abundances of 34 and 27,in 2013 and 2014,respectively.These density estimates are comparable to other published estimates for resident Amur tiger populations in the Russian Far East.This study reveals promising signs of tiger recovery in Northeast China,and demonstrates the importance of connectivity between the Russian and Chinese populations for recovering tigers in Northeast China.展开更多
The North Chinese leopard(Panthera pardus japonensis),the least-known big cat,disappeared in most historical range for decades,following the development of modern civilization.Unfortunately,we have scarce knowledge ab...The North Chinese leopard(Panthera pardus japonensis),the least-known big cat,disappeared in most historical range for decades,following the development of modern civilization.Unfortunately,we have scarce knowledge about the status of this big cat so far,apart from anecdotal reports.In this study,we investigated density,distribution,and habitat use of the leopard,the apex predator,in a complex forest landscape in the Loess Plateau.We used a camera-trapping network to obtain population estimates for leopards over 2 years through spatially explicit capture-recapture models.Our results,based on maximum likelihood and Bayesian/MCMC methods,reveal that the largest wild population of the leopard was found widely distributed in remnant forests in central Loess plateau.The population is increasing in our study area,and the density of leopards(1.70(SE=0.48)−2.40(SE=0.67)/100 km^(2))is higher than other areas of China.According to the analysis of 2 seasonal occupancy models,prey species drive partially the leopard habitat use,predicting that the big cat thrives from the recovery of prey community.However,human disturbances,especially oil wells,seem to have negative impacts on the habitat use of leopards.Specifically,it is necessary to have joint efforts by the government and researchers to improve human disturbances management and prey species population density,as well as strengthen the investment in research on the North Chinese leopard,which could all further strengthen protection ability and ensure the long-term survival of this species.展开更多
Aims Slash removal is a common practice to prepare recently harvested sites for replanting.However,little is known about its impact on soil carbon(C)dynamics in subtropical plantations.This study evaluates the effects...Aims Slash removal is a common practice to prepare recently harvested sites for replanting.However,little is known about its impact on soil carbon(C)dynamics in subtropical plantations.This study evaluates the effects of burning versus manual slash removal site preparation treatments on soil organic carbon(SOC),soil respiration and soil microbial community structure in a Pinus massoniana plantation in southern China.Methods Three areas within a mature P.massoniana plantation were clearcut.Two months following harvesting,slash on one-half of each area was burned(BURN),whereas slash was manually removed(MANR)on the other portion.Slash removal treatments were also compared with adjacent uncut plantation areas(UNCUT).Soil samples,and soil respiration measurements were used to characterize soil properties and microbial communities following slash removal treatments.Important Findings Mean soil respiration rates from the MANR and BURN treatments were 26%and 17%lower,respectively,than the UNCUT treatment over 1 year.The MANR and BURN treatment resulted in soils with 27%and 9%reduction in total phospholipid fatty acids(PLFAs)and 18%and 10%reduction in bacterial PLFAs,respectively,compared with the UNCUT treatment.However,no significant differences existed between slash removal treatments with respect to soil chemical properties,SOC chemical compositions,soil respiration and microbial communities;although PLFA patterns were notably different for the burned plots.Most factors affecting C dynamics and microbial communities were not sensitive to the differences imparted to the ecosystem due to manual slash removal or burning.Our results suggested that low-intensity burning after clear-cutting might have no significant effect on soil C pool and its dynamics compared with manual slash removal in subtropical plantations.展开更多
基金financially supported by the National Science Foundation of China(grants 30830024 and 30770330)
文摘Plant roots have been recognized to be modu- lar, and a third order root cluster has been proposed to be the basic root module unit based upon the life cycle. This experiment examines root modularity of the nutrient-up- take function using stable isotope 15N. Solidago canadensis root clusters of second or third orders--from the same third or fourth order roots, respectively--were treated with 15NH15NO3, NH4NO3, and de-ionized water for 15 and 180 min. The δ15N values of the root clusters were then analyzed and compared. The 15N values of 15N-treated root clusters of both second and third orders were hundreds of times higher than that of the 15N untreated root clusters. However, the differences of the δ15N values among 15N untreated root clusters （though expressed some significant variations）, did not indicate the 15N shared by the sister root clusters came from a common higher-order root. These results demonstrated functional modularity of root nutrient uptake, revealed a second order root, perhaps even a first order root to be a base module unit in terms of root nutrient uptake. The results also suggested that the concept of root modularity is function-specific. This experiment further revealed the importance of treatment timing in stabilizing the internal 15N/14N ratio in roots and avoiding top-down transportation of 15N back into roots to secure unbiased measurements.
基金supported by National Natural Science Foundation of China(30830024)
文摘Ectomycorrhizal(EM)networks provide a variety of services to plants and ecosystems include nutrient uptake and transfer,seedling survival,internal cycling of nutrients,plant competition,and so on.To deeply their structure and function in ecosystems,we investigated the spatial patterns and nitrogen(N)transfer of EM networks usingN labelling technique in a Mongolian scotch pine(Pinus sylvestris var.mongolica Litv.)plantation in Northeastern China.In August 2011,four plots(20 × 20 m)were set up in the plantation.125 ml 5 at.%0.15 mol/LNHNOsolution was injected into soil at the center of each plot.Before and 2,6,30 and 215 days after theN application,needles(current year)of each pine were sampled along four 12 m sampling lines.Needle total N andN concentrations were analyzed.We observed needle N andN concentrations increased significantly over time afterN application,up to 31 and0.42%,respectively.There was no correlation between needle N concentration andN/N ratio(R2=0.40,n=5,P=0.156),while excess needle N concentration and excess needleN/N ratio were positively correlated across different time intervals(R~2=0.89,n=4,P\0.05),but deceased with time interval lengthening.NeedleN/N ratio increased with time,but it was not correlated with distance.NeedleN/N ratio was negative with distance before and 6th day and 30th day,positive with distance at 2nd day,but the trend was considerably weaker,their slop were close to zero.These results demonstrated that EM networks were ubiquitous and uniformly distributed in the Mongolian scotch pine plantation and a random network.We found N transfer efficiency was very high,absorbed N by EM network was transferred as wide as possible,we observed N uptake of plant had strong bias forN andN,namely N fractionation.Understanding the structure and function of EM networks in ecosystems may lead to a deeper understanding of ecological stability and evolution,and thus provide new theoretical approaches to improve conservation practices for the management of the Earth’s ecosystems.
基金supported by grants from the Natural Science Foundation of China(31270567,31210103911,31421063,31200410 and 31470566)the National Scientific and Technical Foundation Project of China(2012FY112000).
文摘As an apex predator the Amur tiger(Panthera tigris altaica)could play a pivotal role in maintaining the integrity of forest ecosystems in Northeast Asia.Due to habitat loss and harvest over the past century,tigers rapidly declined in China and are now restricted to the Russian Far East and bordering habitat in nearby China.To facilitate restoration of the tiger in its historical range,reliable estimates of population size are essential to assess effectiveness of conservation interventions.Here we used camera trap data collected in Hunchun National Nature Reserve from April to June 2013 and 2014 to estimate tiger density and abundance using both maximum likelihood and Bayesian spatially explicit capture-recapture(SECR)methods.A minimum of 8 individuals were detected in both sample periods and the documentation of marking behavior and reproduction suggests the presence of a resident population.Using Bayesian SECR modeling within the 11400 km2 state space,density estimates were 0.33 and 0.40 individuals/100 km^(2) in 2013 and 2014,respectively,corresponding to an estimated abundance of 38 and 45 animals for this transboundary Sino-Russian population.In a maximum likelihood framework,we estimated densities of 0.30 and 0.24 individuals/100 km^(2) corresponding to abundances of 34 and 27,in 2013 and 2014,respectively.These density estimates are comparable to other published estimates for resident Amur tiger populations in the Russian Far East.This study reveals promising signs of tiger recovery in Northeast China,and demonstrates the importance of connectivity between the Russian and Chinese populations for recovering tigers in Northeast China.
基金supported by grant from the National Natural Sci-ence Foundation of China(31670537,31200410)the National Scientific and Technical Foundation Project of China(2012FY112000)Cyrus Tang Foundation(2016),and the Doctoral Fund of Ministry of Education of China(2019M653714).
文摘The North Chinese leopard(Panthera pardus japonensis),the least-known big cat,disappeared in most historical range for decades,following the development of modern civilization.Unfortunately,we have scarce knowledge about the status of this big cat so far,apart from anecdotal reports.In this study,we investigated density,distribution,and habitat use of the leopard,the apex predator,in a complex forest landscape in the Loess Plateau.We used a camera-trapping network to obtain population estimates for leopards over 2 years through spatially explicit capture-recapture models.Our results,based on maximum likelihood and Bayesian/MCMC methods,reveal that the largest wild population of the leopard was found widely distributed in remnant forests in central Loess plateau.The population is increasing in our study area,and the density of leopards(1.70(SE=0.48)−2.40(SE=0.67)/100 km^(2))is higher than other areas of China.According to the analysis of 2 seasonal occupancy models,prey species drive partially the leopard habitat use,predicting that the big cat thrives from the recovery of prey community.However,human disturbances,especially oil wells,seem to have negative impacts on the habitat use of leopards.Specifically,it is necessary to have joint efforts by the government and researchers to improve human disturbances management and prey species population density,as well as strengthen the investment in research on the North Chinese leopard,which could all further strengthen protection ability and ensure the long-term survival of this species.
基金Ministry of Science and Technology(2012BAD22B01 and 2015DFA31440)China’s National Natural Science Foundation(31290223)+1 种基金the Ministry of Finance(200804001 and 201104006)the Lecture and Study Program for Outstanding Scholars from Home and Abroad(CAFYBB2011007)。
文摘Aims Slash removal is a common practice to prepare recently harvested sites for replanting.However,little is known about its impact on soil carbon(C)dynamics in subtropical plantations.This study evaluates the effects of burning versus manual slash removal site preparation treatments on soil organic carbon(SOC),soil respiration and soil microbial community structure in a Pinus massoniana plantation in southern China.Methods Three areas within a mature P.massoniana plantation were clearcut.Two months following harvesting,slash on one-half of each area was burned(BURN),whereas slash was manually removed(MANR)on the other portion.Slash removal treatments were also compared with adjacent uncut plantation areas(UNCUT).Soil samples,and soil respiration measurements were used to characterize soil properties and microbial communities following slash removal treatments.Important Findings Mean soil respiration rates from the MANR and BURN treatments were 26%and 17%lower,respectively,than the UNCUT treatment over 1 year.The MANR and BURN treatment resulted in soils with 27%and 9%reduction in total phospholipid fatty acids(PLFAs)and 18%and 10%reduction in bacterial PLFAs,respectively,compared with the UNCUT treatment.However,no significant differences existed between slash removal treatments with respect to soil chemical properties,SOC chemical compositions,soil respiration and microbial communities;although PLFA patterns were notably different for the burned plots.Most factors affecting C dynamics and microbial communities were not sensitive to the differences imparted to the ecosystem due to manual slash removal or burning.Our results suggested that low-intensity burning after clear-cutting might have no significant effect on soil C pool and its dynamics compared with manual slash removal in subtropical plantations.
