Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical...Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical, chemical and biological properties. However, limited information is available on the fractal characteristics of deep soil layers under different land use patterns. In this study, the fractal dimensions of particle size distribution(PSD) and micro-aggregates in the 0–500 cm soil profile and soil anti-erodibility in the 0–10 cm soil profile for 10 typical land use patterns were investigated in the Zhifanggou Watershed on the Loess Plateau, China. The 10 typical land use patterns were: slope cropland, two terraced croplands, check-dam cropland, woodland, two shrublands, orchard, artificial and natural grasslands. The results showed that the fractal dimensions of PSD and micro-aggregates were all significantly influenced by soil depths, land use patterns and their interaction. The plantations of shrubland, woodland and natural grassland increased the amount of larger micro-aggregates, and decreased the fractal dimensions of micro-aggregates in the 0–40 cm soil profile. And they also improved the aggregate state and aggregate degree and decreased dispersion rate in the 0–10 cm soil profile. The results indicated that fractal theory can be used to characterize soil structure under different land use patterns and fractal dimensions of micro-aggregates were more effective in this regard. The natural grassland may be the best choice for improving soil structure in the study area.展开更多
There is debating over the question of whether the large-scale‘Grain for Green’program on the Loess Plateau of China threatens regional food security.Self-sufficiency index and cropland pressure index were used to a...There is debating over the question of whether the large-scale‘Grain for Green’program on the Loess Plateau of China threatens regional food security.Self-sufficiency index and cropland pressure index were used to assess food security on the Loess Plateau after the implementation of revegetation program.The results showed that the‘Grain for Green’program initially had a considerable impact on regional food security,where grain yield fell from 1999 to 2001,resulting in a lower grain self-sufficiency and increased farmland stress.Subsequently,grain yield in this region increased due to the elevated agricultural material input and increased construction of terraces and check dams.The grain self-sufficiency index would have increased to 96.55%if there were improvements to the agricultural conditions,such as fertilization and irrigation,which would have resulted in an increase in the crop yield per unit of 20%.However,the grain self-sufficiency increased to 105.25%via the construction of terraces and check dams.Thus,the government should further expand the‘Grain for Green’program in coordination with improvements to the agricultural production conditions and the construction of terraces and check dams on the Loess Plateau.展开更多
Soil organic carbon(SOC)plays an essential role in the carbon cycle and global warming mitigation,and it varies spatially in relation to other soil and environmental properties.But the national distributions and the i...Soil organic carbon(SOC)plays an essential role in the carbon cycle and global warming mitigation,and it varies spatially in relation to other soil and environmental properties.But the national distributions and the impact mechanisms of SOC remain debated in China.Therefore,how soil texture and climate factors affect the SOC content and the regional differences in SOC content were explored by analyzing 7857 surface soil samples with different land-use.The results showed that the SOC content in China,with a mean value of 11.20 g·kg^(-1),increased gradually from north to south.The SOC content of arable land in each geographical area was lower than in grassland and forest-land.Although temperature also played a specific role in the SOC content,precipitation was the most critical climate factor.The SOC content was positively correlated with the silt and clay content.The lower the temperature,the greater the effect of environmental factors on SOC.In contrast,the higher the temperature,the more significant impact of soil texture on SOC.The regional difference in SOC highlights the importance of soil responses to climate change.Tempera-ture and soil texture should be explicitly considered when predicting potential future carbon cycle and sequestration.展开更多
基金supported by the Strategic Technology Project of Chinese Academy of Sciences (XDA05060300)the Science and Technology R&D Program of Shaanxi Province (2011KJXX63)
文摘Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical, chemical and biological properties. However, limited information is available on the fractal characteristics of deep soil layers under different land use patterns. In this study, the fractal dimensions of particle size distribution(PSD) and micro-aggregates in the 0–500 cm soil profile and soil anti-erodibility in the 0–10 cm soil profile for 10 typical land use patterns were investigated in the Zhifanggou Watershed on the Loess Plateau, China. The 10 typical land use patterns were: slope cropland, two terraced croplands, check-dam cropland, woodland, two shrublands, orchard, artificial and natural grasslands. The results showed that the fractal dimensions of PSD and micro-aggregates were all significantly influenced by soil depths, land use patterns and their interaction. The plantations of shrubland, woodland and natural grassland increased the amount of larger micro-aggregates, and decreased the fractal dimensions of micro-aggregates in the 0–40 cm soil profile. And they also improved the aggregate state and aggregate degree and decreased dispersion rate in the 0–10 cm soil profile. The results indicated that fractal theory can be used to characterize soil structure under different land use patterns and fractal dimensions of micro-aggregates were more effective in this regard. The natural grassland may be the best choice for improving soil structure in the study area.
基金This work was supported by the National Key Research and Development Program of China[2017YFC0504704]National Natural Science Foundation of China[41601092,41731289]+2 种基金National Geological Prospecting special[DD20190504]Shaanxi Province Innovation Talent Promotion Project Technology Innovation Team[Grant 2018TD-037]Shaanxi Provincial Technology Innovation Guidance Project[Grant 2017CGZH-HJ-06].
文摘There is debating over the question of whether the large-scale‘Grain for Green’program on the Loess Plateau of China threatens regional food security.Self-sufficiency index and cropland pressure index were used to assess food security on the Loess Plateau after the implementation of revegetation program.The results showed that the‘Grain for Green’program initially had a considerable impact on regional food security,where grain yield fell from 1999 to 2001,resulting in a lower grain self-sufficiency and increased farmland stress.Subsequently,grain yield in this region increased due to the elevated agricultural material input and increased construction of terraces and check dams.The grain self-sufficiency index would have increased to 96.55%if there were improvements to the agricultural conditions,such as fertilization and irrigation,which would have resulted in an increase in the crop yield per unit of 20%.However,the grain self-sufficiency increased to 105.25%via the construction of terraces and check dams.Thus,the government should further expand the‘Grain for Green’program in coordination with improvements to the agricultural production conditions and the construction of terraces and check dams on the Loess Plateau.
基金supported by the National Natural Science Foundation of China(Grant No.42107368)Independent R&D project plan of State Forestry and Grassland Administration(No.LC-6-06)+1 种基金the Shaanxi Province Innovation Talent Promotion Plan Project Technology Innovation Team(No.2018TD-037)the National Natural Science Foundation of China(Grant No.51779204)。
文摘Soil organic carbon(SOC)plays an essential role in the carbon cycle and global warming mitigation,and it varies spatially in relation to other soil and environmental properties.But the national distributions and the impact mechanisms of SOC remain debated in China.Therefore,how soil texture and climate factors affect the SOC content and the regional differences in SOC content were explored by analyzing 7857 surface soil samples with different land-use.The results showed that the SOC content in China,with a mean value of 11.20 g·kg^(-1),increased gradually from north to south.The SOC content of arable land in each geographical area was lower than in grassland and forest-land.Although temperature also played a specific role in the SOC content,precipitation was the most critical climate factor.The SOC content was positively correlated with the silt and clay content.The lower the temperature,the greater the effect of environmental factors on SOC.In contrast,the higher the temperature,the more significant impact of soil texture on SOC.The regional difference in SOC highlights the importance of soil responses to climate change.Tempera-ture and soil texture should be explicitly considered when predicting potential future carbon cycle and sequestration.