The stmctufe types of the waterfront settlements in the north of Jiangxi Province were analyzed. According to the relationship between location and water, die waterfront setdements in northern Jiangxi were classifi...The stmctufe types of the waterfront settlements in the north of Jiangxi Province were analyzed. According to the relationship between location and water, die waterfront setdements in northern Jiangxi were classified into tiiree categofies. The structuial commonalities of the three kinds of waterfront settlements were cleady interpreted. On this basis and combined with the field research data and relevant data, the characteristics of the waterfront setdements in northern Jiangxi were summarized: treating water as the main skeleton, choosing location by the distance £com watet, magnetic effect and organic textute. The characteiistic space of watetfront settLemeiits found in the investigation process was classified and elaborated, which has certain reference significance for tiie space study of waterfront settlements.展开更多
Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and...Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and altitudinal patterns of foliar and root δ13C and determined which environmental factors influenced foliar δ13 C most.Foliar δ13 C of alpine steppe was significantly higher than that of alpine meadow and temperate steppe.For alpine meadow,root δ13C was significantly higher than of foliar δ13C.Foliar δ13C increased with altitude at an average rate of 0.60‰ km 1 for the whole grassland ecosystem.This rate was lower than that at species level.However,there were no significant relationships between root δ13C and altitude.Atmospheric pressure was a more important factor than temperature and precipitation in its influence on the altitudinal pattern of foliar δ13C at the community level.展开更多
Aims Litter is frequently buried in the soil in alpine grasslands due to grassland degradation,serious rodent infestation and frequent strong winds.However,the effects of various litter positions on litter decompositi...Aims Litter is frequently buried in the soil in alpine grasslands due to grassland degradation,serious rodent infestation and frequent strong winds.However,the effects of various litter positions on litter decomposition rates and nutrient dynamics under nitrogen(N)enrichment in such areas remain unknown.Methods A field experiment was performed in the alpine grasslands of northwest China to investigate the influence of litter position(surface,buried in the soil and standing)and N enrichment on litter decomposition,using data from two dominant grass species(Festuca ovina and Leymus tianschanicus)in control and N-enriched plots.Important Findings Litter decomposition rates were much faster in buried litter and slower in standing litter than in surface litter.N enrichment significantly affected litter quality and then influenced decomposition.But no significant differences in litter mass remaining were observed between control and N-enriched soil burial.These results indicated that N enrichment significantly affected litter decomposition by changes in litter quality.In addition,all litter exhibited net carbon(C)and phosphorus(P)release regardless of treatments.Litter exhibited net N accumulation for litter from the control plots but showed N release for litter from N enrichment plots.These suggested that litter decomposition can be limited by N and N enrichment influenced N cycling of litter.Current study presented direct evidence that soil buried litter exhibited faster mass loss and C release,and that soil burial can be a candidate explanation why litter decomposes faster than expected in dryland.展开更多
文摘The stmctufe types of the waterfront settlements in the north of Jiangxi Province were analyzed. According to the relationship between location and water, die waterfront setdements in northern Jiangxi were classified into tiiree categofies. The structuial commonalities of the three kinds of waterfront settlements were cleady interpreted. On this basis and combined with the field research data and relevant data, the characteristics of the waterfront setdements in northern Jiangxi were summarized: treating water as the main skeleton, choosing location by the distance £com watet, magnetic effect and organic textute. The characteiistic space of watetfront settLemeiits found in the investigation process was classified and elaborated, which has certain reference significance for tiie space study of waterfront settlements.
基金supported by National Key Basic Research Program of China (Grant No.2010CB950902)National Natural Science Foundation of China(Grant No.31070427)National High-tech R&D Program of China(Grant No.2009BAC61B01)
文摘Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and altitudinal patterns of foliar and root δ13C and determined which environmental factors influenced foliar δ13 C most.Foliar δ13 C of alpine steppe was significantly higher than that of alpine meadow and temperate steppe.For alpine meadow,root δ13C was significantly higher than of foliar δ13C.Foliar δ13C increased with altitude at an average rate of 0.60‰ km 1 for the whole grassland ecosystem.This rate was lower than that at species level.However,there were no significant relationships between root δ13C and altitude.Atmospheric pressure was a more important factor than temperature and precipitation in its influence on the altitudinal pattern of foliar δ13C at the community level.
基金This work was supported financially by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20050103)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2019D01C066)+1 种基金Tianshan Cedar Project of Xinjiang Uygur Autonomous Region(2020XS26)the National Natural Science Foundation of China(41425007,41673079)。
文摘Aims Litter is frequently buried in the soil in alpine grasslands due to grassland degradation,serious rodent infestation and frequent strong winds.However,the effects of various litter positions on litter decomposition rates and nutrient dynamics under nitrogen(N)enrichment in such areas remain unknown.Methods A field experiment was performed in the alpine grasslands of northwest China to investigate the influence of litter position(surface,buried in the soil and standing)and N enrichment on litter decomposition,using data from two dominant grass species(Festuca ovina and Leymus tianschanicus)in control and N-enriched plots.Important Findings Litter decomposition rates were much faster in buried litter and slower in standing litter than in surface litter.N enrichment significantly affected litter quality and then influenced decomposition.But no significant differences in litter mass remaining were observed between control and N-enriched soil burial.These results indicated that N enrichment significantly affected litter decomposition by changes in litter quality.In addition,all litter exhibited net carbon(C)and phosphorus(P)release regardless of treatments.Litter exhibited net N accumulation for litter from the control plots but showed N release for litter from N enrichment plots.These suggested that litter decomposition can be limited by N and N enrichment influenced N cycling of litter.Current study presented direct evidence that soil buried litter exhibited faster mass loss and C release,and that soil burial can be a candidate explanation why litter decomposes faster than expected in dryland.