This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolatin...This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolating functions,and non-linear regression methods.The source regions of the Yangtze and Yellow Rivers were selected as the research areas.Results illustrate that:(1) There is significant non-linear relationship between NPP and GT in various typical years;(2) The maximum value of NPP is 6.17,5.87,7.73,and 5.41 DM·t·hm-2 ·a-1 respectively,and the corresponding GT is 7.1,10.0,21.2,and 8.9 o C respectively in 1980,1990,2000 and 2007;(3) In 1980,the sensitivity of NPP to GT is higher than in 1990,2000 and 2007.This tendency shows that the NPP presents change from fluctuation to an adaptation process over time;(4) During 1980～2007,the accumulated NPP was reduced to 8.05,and the corresponding carrying capacity of theoretical livestock reduced by 11%;(5) The shape of the demonstration region of ecological compensation system,livelihood support system,and science appraisal system in the source regions of Yangtze and Yellow Rivers are an important research for increasing the adaptation capacity and balancing protection and development.展开更多
Active layer thickness（ALT） is critical to the understanding of the surface energy balance, hydrological cycles, plant growth, and cold region engineering projects in permafrost regions. The temperature at the botto...Active layer thickness（ALT） is critical to the understanding of the surface energy balance, hydrological cycles, plant growth, and cold region engineering projects in permafrost regions. The temperature at the bottom of the active layer, a boundary layer between the equilibrium thermal state（in permafrost below） and transient thermal state（in the atmosphere and surface canopies above）, is an important parameter to reflect the existence and thermal stability of permafrost. In this study, the Geophysical Institute Permafrost Model（GIPL） was used to model the spatial distribution of and changes in ALT and soil temperature in the Source Area of the Yellow River（SAYR）, where continuous, discontinuous, and sporadic permafrost coexists with seasonally frozen ground. Monthly air temperatures downscaled from the CRU TS3.0 datasets, monthly snow depth derived from the passive microwave remote-sensing data SMMR and SSM/I, and vegetation patterns and soil properties at scale of 1：1000000 were used as input data after modified with GIS techniques. The model validation was carried out carefully with in-situ ALT in the SAYR interpolated from the field-measured soil temperature data. The results of the model indicate that the average ALT in the SAYR has significantly increased from 1.8 m in 1980 to 2.4 m in 2006 at an average rate of 2.2 cm yr–1. The mean annual temperature at the bottom of the active layer, or temperature at the top of permafrost（TTOP） rose substantially from –1.1°C in 1980 to –0.6°C in 2006 at an average rate of 0.018°C yr–1. The increasing rate of the ALT and TTOP has accelerated since 2000. Regional warming and degradation of permafrost has also occurred, and the changes in the areal extent of regions with a sub-zero TTOP shrank from 2.4×104 to 2.2×104 km2 at an average rate of 74 km2 yr–1. Changes of ALT and temperature have adversely affected the environmental stability in the SAYR.展开更多
Six typical red clay profiles were sampled from Tangxi （TX）, Langyaz （LYZ）, South Shangshanwen （SSW）, Xianqiao （XQ）, Qijian （Q J） and Huhaitang （HHT） of Jinhua-Quzhou Basin, Zhejiang Province of China to e...Six typical red clay profiles were sampled from Tangxi （TX）, Langyaz （LYZ）, South Shangshanwen （SSW）, Xianqiao （XQ）, Qijian （Q J） and Huhaitang （HHT） of Jinhua-Quzhou Basin, Zhejiang Province of China to evaluate the characteristics of grain size composition, distribution and parameters of red clays and to reveal the origin of red clays and interpret possible implications for paleoclimate in subtropical China. The results showed that red clays in TX, LYZ and SSW were fine and uniform, with no 〉 2 mm gravels and little 〉 63μm fraction. They had a high content of 10-50 μm fraction, so-called ＂basic dust fraction＂, and showed unimodal distributions, which were very comparable to those of the Xiashu Loess in southeastern China and the loess in North China. All these features reflected marked aeolian characteristics of the red clays in these areas. Red clays in XQ and QJ were much coarser than those in TjjX, LYZ and SSW, with high contents of 〉 63μm fraction and even containing 〉 2 mm gravels in some layers. The grain size distribution patterns showed significantly progressive trends from the lower profile to the upmost layer and could not be compared with those of the loess in North China or the Xiashu Loess, implying they might be derived from underlying parent rocks and had some inherited properties from bedrock. Red clays in HHT had high contents of 〉 63μm fraetion and contain many 〉 2 mm gravels in each layer. The grain size frequency curves showed multiple-peaks and some abrupt variations were also observed on the profile, revealing its alluvial or diluvial origin in HHT. The multiple origins of red clays reflected the diversity and complexity of the Quaternary environment in South China. It can be concluded that grain size is an effective proxy indicator for the origin of most deposits.展开更多
Our objectives are to examine the effects of hummock-depression spatial heterogeneity on plant communities and soil properties,and to understand the process of maintaining and adjusting microtopography-mediated hydrol...Our objectives are to examine the effects of hummock-depression spatial heterogeneity on plant communities and soil properties,and to understand the process of maintaining and adjusting microtopography-mediated hydrological inputs and their spatial fluctuations that produce obvious microhabitats.We set up 36 plots(1 m×1 m)and sampled 45 plant and 225 soil samples in flooded(FH)and non-flooded hummocks(NFH)and depressions of the marshy,and the surrounding non-wetland meadows as well as in the Yellow River Source Zone,west China.We evaluated whether the alpine marshy wetland has a fertile island effect by the comparison method.Our results show that hummock presence can increase the spatial heterogeneity of the microhabitat and promote the plant diversity and soil fertility of the Kobresia tibetica community.Plant height,coverage,above-ground biomass,species richness and diversity were significantly higher in the FH and NFH microhabitat than in the areas between hummocks and surrounding non-wetland meadows.Compared with broad alpine meadows,the hummock-depression complex provided a microhabitat favorable to the growth of Cyperaceae.In the 0-50 cm soil layer,the closer the soil layer was to the ground surface,the higher its soil organic carbon and total nitrogen contents.Thus,in deeper layers,the gap between soil nutrients in wetland hummock-depression microhabitat and in the surrounding alpine meadows becomes smaller.Hence,the wetland hummock-depression microhabitat formed a fertile island pattern.Therefore,these results contribute toward improving our understanding of ecosystem restoration in alpine marshy meadows.展开更多
Water is a crucial factor influencing eco-environment conservation in the Loess Area in China. Soilmoisture is also an indispensable factor to plant growth because of limited water supply. In this paper,previous studi...Water is a crucial factor influencing eco-environment conservation in the Loess Area in China. Soilmoisture is also an indispensable factor to plant growth because of limited water supply. In this paper,previous studies of soil moisture are summarized from methods and contents. Meanwhile, some problems inthe relevant researches are pointed out and discussed. Some solutions are brought forward.展开更多
基金supported by the National Basic Research Program of China (973 Program,Grant No. 2007CB411507 and Grant No.2010CB951704)
文摘This paper studies the relationship between net primary productivity (NPP) and annual average air temperature (GT) at 0cm above ground in permafrost regions by using revised Chikugo NPP model,cubic spline interpolating functions,and non-linear regression methods.The source regions of the Yangtze and Yellow Rivers were selected as the research areas.Results illustrate that:(1) There is significant non-linear relationship between NPP and GT in various typical years;(2) The maximum value of NPP is 6.17,5.87,7.73,and 5.41 DM·t·hm-2 ·a-1 respectively,and the corresponding GT is 7.1,10.0,21.2,and 8.9 o C respectively in 1980,1990,2000 and 2007;(3) In 1980,the sensitivity of NPP to GT is higher than in 1990,2000 and 2007.This tendency shows that the NPP presents change from fluctuation to an adaptation process over time;(4) During 1980～2007,the accumulated NPP was reduced to 8.05,and the corresponding carrying capacity of theoretical livestock reduced by 11%;(5) The shape of the demonstration region of ecological compensation system,livelihood support system,and science appraisal system in the source regions of Yangtze and Yellow Rivers are an important research for increasing the adaptation capacity and balancing protection and development.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41301068, 41121061)the State Key Laboratory of Frozen Soils Engineering (Grant No. Y252J41001,)the Foundation for Excellent Youth Scholars of CAREERI, CAS (Grant No. 51Y351051)
文摘Active layer thickness（ALT） is critical to the understanding of the surface energy balance, hydrological cycles, plant growth, and cold region engineering projects in permafrost regions. The temperature at the bottom of the active layer, a boundary layer between the equilibrium thermal state（in permafrost below） and transient thermal state（in the atmosphere and surface canopies above）, is an important parameter to reflect the existence and thermal stability of permafrost. In this study, the Geophysical Institute Permafrost Model（GIPL） was used to model the spatial distribution of and changes in ALT and soil temperature in the Source Area of the Yellow River（SAYR）, where continuous, discontinuous, and sporadic permafrost coexists with seasonally frozen ground. Monthly air temperatures downscaled from the CRU TS3.0 datasets, monthly snow depth derived from the passive microwave remote-sensing data SMMR and SSM/I, and vegetation patterns and soil properties at scale of 1：1000000 were used as input data after modified with GIS techniques. The model validation was carried out carefully with in-situ ALT in the SAYR interpolated from the field-measured soil temperature data. The results of the model indicate that the average ALT in the SAYR has significantly increased from 1.8 m in 1980 to 2.4 m in 2006 at an average rate of 2.2 cm yr–1. The mean annual temperature at the bottom of the active layer, or temperature at the top of permafrost（TTOP） rose substantially from –1.1°C in 1980 to –0.6°C in 2006 at an average rate of 0.018°C yr–1. The increasing rate of the ALT and TTOP has accelerated since 2000. Regional warming and degradation of permafrost has also occurred, and the changes in the areal extent of regions with a sub-zero TTOP shrank from 2.4×104 to 2.2×104 km2 at an average rate of 74 km2 yr–1. Changes of ALT and temperature have adversely affected the environmental stability in the SAYR.
基金Supported by the National Natural Science Foundation of China(Nos.41071002 and 41071142)the Zhejiang Provincial Natural Science Foundation of China(Nos.LQ13D010002 and X506313)the Knowledge Innovation Program of the Chinese Academy of Sciences(Nos.KZCX2-YW-409 and KZCX2-EW-405-1)
文摘Six typical red clay profiles were sampled from Tangxi （TX）, Langyaz （LYZ）, South Shangshanwen （SSW）, Xianqiao （XQ）, Qijian （Q J） and Huhaitang （HHT） of Jinhua-Quzhou Basin, Zhejiang Province of China to evaluate the characteristics of grain size composition, distribution and parameters of red clays and to reveal the origin of red clays and interpret possible implications for paleoclimate in subtropical China. The results showed that red clays in TX, LYZ and SSW were fine and uniform, with no 〉 2 mm gravels and little 〉 63μm fraction. They had a high content of 10-50 μm fraction, so-called ＂basic dust fraction＂, and showed unimodal distributions, which were very comparable to those of the Xiashu Loess in southeastern China and the loess in North China. All these features reflected marked aeolian characteristics of the red clays in these areas. Red clays in XQ and QJ were much coarser than those in TjjX, LYZ and SSW, with high contents of 〉 63μm fraction and even containing 〉 2 mm gravels in some layers. The grain size distribution patterns showed significantly progressive trends from the lower profile to the upmost layer and could not be compared with those of the loess in North China or the Xiashu Loess, implying they might be derived from underlying parent rocks and had some inherited properties from bedrock. Red clays in HHT had high contents of 〉 63μm fraetion and contain many 〉 2 mm gravels in each layer. The grain size frequency curves showed multiple-peaks and some abrupt variations were also observed on the profile, revealing its alluvial or diluvial origin in HHT. The multiple origins of red clays reflected the diversity and complexity of the Quaternary environment in South China. It can be concluded that grain size is an effective proxy indicator for the origin of most deposits.
基金Thank the members of the research team for their kind support in the experiment,and thank the Science and Technology Department of Qinghai Provincial for the funding of the application basic project(2019-ZJ-7035)Discipline Innovation and Introducing Talents Program of Higher Education Institutions(the 111 Project,D18013)Changjiang Scholars and Innovation Team Development plan(IRT_17R62).
文摘Our objectives are to examine the effects of hummock-depression spatial heterogeneity on plant communities and soil properties,and to understand the process of maintaining and adjusting microtopography-mediated hydrological inputs and their spatial fluctuations that produce obvious microhabitats.We set up 36 plots(1 m×1 m)and sampled 45 plant and 225 soil samples in flooded(FH)and non-flooded hummocks(NFH)and depressions of the marshy,and the surrounding non-wetland meadows as well as in the Yellow River Source Zone,west China.We evaluated whether the alpine marshy wetland has a fertile island effect by the comparison method.Our results show that hummock presence can increase the spatial heterogeneity of the microhabitat and promote the plant diversity and soil fertility of the Kobresia tibetica community.Plant height,coverage,above-ground biomass,species richness and diversity were significantly higher in the FH and NFH microhabitat than in the areas between hummocks and surrounding non-wetland meadows.Compared with broad alpine meadows,the hummock-depression complex provided a microhabitat favorable to the growth of Cyperaceae.In the 0-50 cm soil layer,the closer the soil layer was to the ground surface,the higher its soil organic carbon and total nitrogen contents.Thus,in deeper layers,the gap between soil nutrients in wetland hummock-depression microhabitat and in the surrounding alpine meadows becomes smaller.Hence,the wetland hummock-depression microhabitat formed a fertile island pattern.Therefore,these results contribute toward improving our understanding of ecosystem restoration in alpine marshy meadows.
基金Graduate Fund of Beijing Forestry University (183).
文摘Water is a crucial factor influencing eco-environment conservation in the Loess Area in China. Soilmoisture is also an indispensable factor to plant growth because of limited water supply. In this paper,previous studies of soil moisture are summarized from methods and contents. Meanwhile, some problems inthe relevant researches are pointed out and discussed. Some solutions are brought forward.
