The northeastern China, the United States, and the western Europe are important agricultural regions both on the global and regional scales. The westem Europe has a longer history of agricultural land development than...The northeastern China, the United States, and the western Europe are important agricultural regions both on the global and regional scales. The westem Europe has a longer history of agricultural land development than the eastem United States. These two regions have changed from the deforestation and reclamation phase in the past to the current land abandonment and reforestation phase. Compared with the two regions, large-scale land exploitation has only been practiced in the northeastern China during the last century. After a short high-intensity deforestation and reclamation period, agricultural and forest lands are basically in a dynamic steady state. By comparing domestic and international agro-forestry development and considering the ecological environment and socio-economic bene- fits that can be derived from agro-forestry, this paper suggests that large area of reforestation would be inevitable in future though per- sistent and large agricultural demand in coming decades even more. And local reforestation at slope farmland with ecological vulner- ability should be imperative at present to avoid severer damage. At the same time, from the perspective of Land Change Science, the results demonstrate that the research on land use change in the agro-forestry ecotone is typical and critical, particularly those dealing with the analysis of spatial and temporal characteristics and the simulation of climate, hydrology, and other environmental effects.展开更多
With rapid urbanization and economic growth, Chinese traditional rice-legume production is increasingly replaced by vegetable and horticultural flower production, which could affect soil properties. This study was con...With rapid urbanization and economic growth, Chinese traditional rice-legume production is increasingly replaced by vegetable and horticultural flower production, which could affect soil properties. This study was conducted near Kunming City, Yunnan Province, Southwest China to investigate how soil phosphorus （P） sorption and desorption processes respond to land use changes and to relate P sorption and desorption parameters to soil properties. Soil samples （0-20, 20-40, 40-60, 60-80 and 80-100 cm） were collected from five sites representing four land use types： rice-legume production in a two-crop, one-year rotation （Rice）, vegetable production in open fields （Vegetable）, recent （〈 3 years） conversion from open fields to plastic-film greenhouse vegetable and flower production at two sites （VFCS1 and VFCS2）, and longer-term （〉 10 years） plastic-film greenhouse vegetable and flower production （VFCL）. The changes in land use affected soil pH, electrical conductivity, available N and P and organic carbon content in topsoil and subsoil. In turn, these changes of soil properties influenced soil P sorption capacity. The P sorption maximum （Smax） was affected by land use types, soil sampling depth and their interactions （P 〈 0.0001）. For surface soil, Smax was in the order of Rice （1 380 mg kg-1） 〉 VFCL （1 154 mg kg-1） 〉 VFCS2 （897 mg kg-1） 〉 VFCS1 （845 mg kg-1） 〉 Vegetable （747 mg kg-1）. The lowest Sm^x generally occurred at the surface （except for Rice at 80-100 cm） and increased with depth. The amount of P desorbed during the 8 successive extractions was in the range 23%-44% of sorbed P, and was not affected by land use types or sampling depths. The decreases in Smax suggested that soil P sorption capacity decreased when rice-legume production converted to more intensive vegetation and flower production and caution should be exercised when applying P fertilizer to minimize potential leaching and runoff P loss to the environment.展开更多
基金Under the auspices of Strategic Pilot Science and Technology Projects of Chinese Academy of Sciences (No.XDA05090310)
文摘The northeastern China, the United States, and the western Europe are important agricultural regions both on the global and regional scales. The westem Europe has a longer history of agricultural land development than the eastem United States. These two regions have changed from the deforestation and reclamation phase in the past to the current land abandonment and reforestation phase. Compared with the two regions, large-scale land exploitation has only been practiced in the northeastern China during the last century. After a short high-intensity deforestation and reclamation period, agricultural and forest lands are basically in a dynamic steady state. By comparing domestic and international agro-forestry development and considering the ecological environment and socio-economic bene- fits that can be derived from agro-forestry, this paper suggests that large area of reforestation would be inevitable in future though per- sistent and large agricultural demand in coming decades even more. And local reforestation at slope farmland with ecological vulner- ability should be imperative at present to avoid severer damage. At the same time, from the perspective of Land Change Science, the results demonstrate that the research on land use change in the agro-forestry ecotone is typical and critical, particularly those dealing with the analysis of spatial and temporal characteristics and the simulation of climate, hydrology, and other environmental effects.
基金Supported by the Yunnan Provincial Department of Science and Technology,China(No.2006YX35)the National Natural Science Foundation of China(No.31260504)
文摘With rapid urbanization and economic growth, Chinese traditional rice-legume production is increasingly replaced by vegetable and horticultural flower production, which could affect soil properties. This study was conducted near Kunming City, Yunnan Province, Southwest China to investigate how soil phosphorus （P） sorption and desorption processes respond to land use changes and to relate P sorption and desorption parameters to soil properties. Soil samples （0-20, 20-40, 40-60, 60-80 and 80-100 cm） were collected from five sites representing four land use types： rice-legume production in a two-crop, one-year rotation （Rice）, vegetable production in open fields （Vegetable）, recent （〈 3 years） conversion from open fields to plastic-film greenhouse vegetable and flower production at two sites （VFCS1 and VFCS2）, and longer-term （〉 10 years） plastic-film greenhouse vegetable and flower production （VFCL）. The changes in land use affected soil pH, electrical conductivity, available N and P and organic carbon content in topsoil and subsoil. In turn, these changes of soil properties influenced soil P sorption capacity. The P sorption maximum （Smax） was affected by land use types, soil sampling depth and their interactions （P 〈 0.0001）. For surface soil, Smax was in the order of Rice （1 380 mg kg-1） 〉 VFCL （1 154 mg kg-1） 〉 VFCS2 （897 mg kg-1） 〉 VFCS1 （845 mg kg-1） 〉 Vegetable （747 mg kg-1）. The lowest Sm^x generally occurred at the surface （except for Rice at 80-100 cm） and increased with depth. The amount of P desorbed during the 8 successive extractions was in the range 23%-44% of sorbed P, and was not affected by land use types or sampling depths. The decreases in Smax suggested that soil P sorption capacity decreased when rice-legume production converted to more intensive vegetation and flower production and caution should be exercised when applying P fertilizer to minimize potential leaching and runoff P loss to the environment.
