Agricultural intensification and changes in cultivated areas, 1970-2005
Agricultural intensification and changes in cultivated areas, 1970-2005
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DOI：
10.1073/pnas.0812540106
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发表时间：
2009-12-08
影响因子：
11.1
通讯作者：
Grau, Ricardo
中科院分区：
文献类型：
--
作者：
Rudel, Thomas K.;Schneider, Laura;Grau, Ricardo
农业集约化是否会减少耕地面积，并且通过将生产集中在其他土地上从而节省一些土地呢？这种土地节省出于很多原因都很重要，其中包括被腾出的土地在固碳和提供其他环境服务方面能力的增强。由于难以测量被节省土地的范围，所以无法充分探究从农业集约化到耕地面积减少再到被节省土地增加这一假设的因果链。我们分析了产量提高同时耕地面积减少从而实现土地节省的历史情况。我们使用联合国粮食及农业组织关于1970年至2005年（尤其强调1990年至2005年期间）10种主要农作物类型耕地趋势的国家级数据。在此期间，耕地的增长比人口增长缓慢，但无论是在全球还是在国家层面，产量提高与耕地减少同时发生的情况都很少见。在此期间，除了有粮食进口和保护预留计划的国家外，在国家层面上，农业集约化通常并没有伴随着耕地面积的减少或停滞。如果没有明确的政策干预，不能对耕地弃耕以及随之而来的环境服务进行未来预测。
Does the intensification of agriculture reduce cultivated areas and, in so doing, spare some lands by concentrating production on other lands? Such sparing is important for many reasons, among them the enhanced abilities of released lands to sequester carbon and provide other environmental services. Difficulties measuring the extent of spared land make it impossible to investigate fully the hypothesized causal chain from agricultural intensification to declines in cultivated areas and then to increases in spared land. We analyze the historical circumstances in which rising yields have been accompanied by declines in cultivated areas, thereby leading to land-sparing. We use national-level United Nations Food and Agricultural Organization data on trends in cropland from 1970-2005, with particular emphasis on the 1990-2005 period, for 10 major crop types. Cropland has increased more slowly than population during this period, but paired increases in yields and declines in cropland occurred infrequently, both globally and nationally. Agricultural intensification was not generally accompanied by decline or stasis in cropland area at a national scale during this time period, except in countries with grain imports and conservation set-aside programs. Future projections of cropland abandonment and ensuing environmental services cannot be assumed without explicit policy intervention.