To feed the increasing world population, more food needs to be produced from agricultural land systems. Solutions to produce more food with fewer resources while minimizing adverse environmental and ecological consequ...To feed the increasing world population, more food needs to be produced from agricultural land systems. Solutions to produce more food with fewer resources while minimizing adverse environmental and ecological consequences require sustainable agricultural land use practices as supplementary to advanced biotechnology and agronomy. This review paper, from a land system perspective, systematically proposed and analyzed three interactive strategies that could possibly raise future food production under global change. By reviewing the current literatures, we suggest that cropland expansion is less possible amid iferce land competition, and it is likely to do less in increasing food production. Moreover, properly allocating crops in space and time is a practical way to ensure food production. Climate change, dietary shifts, and other socio-economic drivers, which would shape the demand and supply side of food systems, should be taken into consideration during the decision-making on rational land management in respect of sustainable crop choice and allocation. And ifnally, crop-speciifc agricultural intensiifcation would play a bigger role in raising future food production either by increasing the yield per unit area of individual crops or by increasing the number of crops sown on a particular area of land. Yet, only when it is done sustainably is this a much more effective strategy to maximize food production by closing yield and harvest gaps.展开更多
在青藏高原高寒草甸区设置模拟增温和氮添加处理,研究长期增温与外源氮输入对高寒草甸群落生产及其分配的影响.结果表明:开顶箱增温装置造成小环境暖干化,即显著提高地表空气温度1.6℃,提高表层土壤温度1.4℃,降低土壤含水量4.7%.2012、...在青藏高原高寒草甸区设置模拟增温和氮添加处理,研究长期增温与外源氮输入对高寒草甸群落生产及其分配的影响.结果表明:开顶箱增温装置造成小环境暖干化,即显著提高地表空气温度1.6℃,提高表层土壤温度1.4℃,降低土壤含水量4.7%.2012、2013和2014年不施氮处理下增温分别降低地上生物量61.5%、108.8%和77.1%,在高氮(40和80kg N·hm^(-2)·a^(-1))处理下增温对群落地上生物量无显著影响,这说明增温的影响依赖于氮添加水平,且施氮补偿了增温导致的土壤氮损失.增温导致根冠比增加,2012、2013和2014年不施氮处理下增温分别增加根冠比98.6%、60.7%和97.8%.在不增温处理下,植物群落地上、地下生物量的变化率均表现出低氮(10、20 kg N·hm^(-2)·a^(-1))促进、高氮抑制的趋势,达到饱和阈值时的氮添加剂量分别为56.0和55.5 kg N·hm^(-2)·a^(-1);而在增温处理下,地上、地下生物量随施氮量增加呈线性增加趋势.这说明增温改变了高寒草甸生物量分配对外源氮输入的响应模式,增温导致的土壤无机氮含量变化是生物量分配模式改变的主要原因.由氮添加试验估算的高寒草甸氮饱和阈值表明,高寒草甸对氮输入的敏感性高于其他类型草地.展开更多
Aims Understanding carbon(C)and nitrogen(N)dynamics and their dependence on the stand density of an even-aged,mature forest provides knowledge that is important for forest management.This study investigated the differ...Aims Understanding carbon(C)and nitrogen(N)dynamics and their dependence on the stand density of an even-aged,mature forest provides knowledge that is important for forest management.This study investigated the differences in ecosystem total C and N storage and flux between a low-density stand(LD)and a high-density stand(HD)and examined the effects of stand density on aboveground net primary productivity(ANPP),total belowground C allocation(TBCA)and net ecosystem production(NEP)in a naturally regenerated,65-to 75-year-old Pinus densiflora S.et Z.forest.Methods LD(450 trees ha^(−1))and HD(842 trees ha^(−1))were established in an even-aged,mature P.densiflora forest in September 2006.The forest had been naturally regenerated following harvesting,and the stand density was naturally maintained without any artificial management such as thinning.The diameter at breast height(DBH≥5.0cm)of all live stems within the stands was measured yearly from 2007 to 2011.To compare C and N storage and fluxes in LD and HD,C and N pools in aboveground and belowground biomass,the forest floor,coarse woody debris(CWD)and soil;soil CO_(2) efflux(R_(S));autotrophic respiration(R_(A));litter production;and soil N availability were measured.Further,ANPP,TBCA and NEP were estimated from plot-based measurement data.Important Findings Ecosystem C(Mg C ha^(−1))and N(Mg N ha^(−1))storage was,respectively,173.0±7.3(mean±SE)and 4.69±0.30 for LD and 162±11.8 and 4.08±0.18 for HD.There were no significant differences in C and N storage in the ecosystem components,except for soils,between the two stands.In contrast,there were significant differences in aboveground ANPP and TBCA between the two stands(P<0.05).Litterfall,biomass increment and R_(S) were major C flux components with values of,respectively,3.89,3.74 and 9.07 Mg C ha^(−1) year^(−1) in LD and 3.15,2.94 and 7.06 Mg C ha^(−1) year^(−1) in HD.Biometric-based NEP(Mg C ha^(−1) year^(−1))was 4.18 in LD and 5.50 in HD.Although the even-aged,mature P.densiflora forest ha展开更多
基金supported and financed by the National Basic Research Program of China(973 Program,2010CB951504)the National Natural Science Foundation of China(41271112)the National Non-Profit Institute Research Grant of Chinese Academy of Agricultural Sciences,China(IARRP-2014-2)
文摘To feed the increasing world population, more food needs to be produced from agricultural land systems. Solutions to produce more food with fewer resources while minimizing adverse environmental and ecological consequences require sustainable agricultural land use practices as supplementary to advanced biotechnology and agronomy. This review paper, from a land system perspective, systematically proposed and analyzed three interactive strategies that could possibly raise future food production under global change. By reviewing the current literatures, we suggest that cropland expansion is less possible amid iferce land competition, and it is likely to do less in increasing food production. Moreover, properly allocating crops in space and time is a practical way to ensure food production. Climate change, dietary shifts, and other socio-economic drivers, which would shape the demand and supply side of food systems, should be taken into consideration during the decision-making on rational land management in respect of sustainable crop choice and allocation. And ifnally, crop-speciifc agricultural intensiifcation would play a bigger role in raising future food production either by increasing the yield per unit area of individual crops or by increasing the number of crops sown on a particular area of land. Yet, only when it is done sustainably is this a much more effective strategy to maximize food production by closing yield and harvest gaps.
文摘在青藏高原高寒草甸区设置模拟增温和氮添加处理,研究长期增温与外源氮输入对高寒草甸群落生产及其分配的影响.结果表明:开顶箱增温装置造成小环境暖干化,即显著提高地表空气温度1.6℃,提高表层土壤温度1.4℃,降低土壤含水量4.7%.2012、2013和2014年不施氮处理下增温分别降低地上生物量61.5%、108.8%和77.1%,在高氮(40和80kg N·hm^(-2)·a^(-1))处理下增温对群落地上生物量无显著影响,这说明增温的影响依赖于氮添加水平,且施氮补偿了增温导致的土壤氮损失.增温导致根冠比增加,2012、2013和2014年不施氮处理下增温分别增加根冠比98.6%、60.7%和97.8%.在不增温处理下,植物群落地上、地下生物量的变化率均表现出低氮(10、20 kg N·hm^(-2)·a^(-1))促进、高氮抑制的趋势,达到饱和阈值时的氮添加剂量分别为56.0和55.5 kg N·hm^(-2)·a^(-1);而在增温处理下,地上、地下生物量随施氮量增加呈线性增加趋势.这说明增温改变了高寒草甸生物量分配对外源氮输入的响应模式,增温导致的土壤无机氮含量变化是生物量分配模式改变的主要原因.由氮添加试验估算的高寒草甸氮饱和阈值表明,高寒草甸对氮输入的敏感性高于其他类型草地.
基金National Research Foundation of Korea(2006-000108630,2009-0076529,A307-K004:JSPS-NRF-NSFC A3 Foresight Program)Korea University(2013).
文摘Aims Understanding carbon(C)and nitrogen(N)dynamics and their dependence on the stand density of an even-aged,mature forest provides knowledge that is important for forest management.This study investigated the differences in ecosystem total C and N storage and flux between a low-density stand(LD)and a high-density stand(HD)and examined the effects of stand density on aboveground net primary productivity(ANPP),total belowground C allocation(TBCA)and net ecosystem production(NEP)in a naturally regenerated,65-to 75-year-old Pinus densiflora S.et Z.forest.Methods LD(450 trees ha^(−1))and HD(842 trees ha^(−1))were established in an even-aged,mature P.densiflora forest in September 2006.The forest had been naturally regenerated following harvesting,and the stand density was naturally maintained without any artificial management such as thinning.The diameter at breast height(DBH≥5.0cm)of all live stems within the stands was measured yearly from 2007 to 2011.To compare C and N storage and fluxes in LD and HD,C and N pools in aboveground and belowground biomass,the forest floor,coarse woody debris(CWD)and soil;soil CO_(2) efflux(R_(S));autotrophic respiration(R_(A));litter production;and soil N availability were measured.Further,ANPP,TBCA and NEP were estimated from plot-based measurement data.Important Findings Ecosystem C(Mg C ha^(−1))and N(Mg N ha^(−1))storage was,respectively,173.0±7.3(mean±SE)and 4.69±0.30 for LD and 162±11.8 and 4.08±0.18 for HD.There were no significant differences in C and N storage in the ecosystem components,except for soils,between the two stands.In contrast,there were significant differences in aboveground ANPP and TBCA between the two stands(P<0.05).Litterfall,biomass increment and R_(S) were major C flux components with values of,respectively,3.89,3.74 and 9.07 Mg C ha^(−1) year^(−1) in LD and 3.15,2.94 and 7.06 Mg C ha^(−1) year^(−1) in HD.Biometric-based NEP(Mg C ha^(−1) year^(−1))was 4.18 in LD and 5.50 in HD.Although the even-aged,mature P.densiflora forest ha
