Cultivating the dry forests of South America: Diversity of land users and imprints on ecosystem functioning
Cultivating the dry forests of South America: Diversity of land users and imprints on ecosystem functioning
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DOI：
10.1016/j.jaridenv.2014.05.027
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发表时间：
2015-12-01
影响因子：
2.7
通讯作者：
Jobbagy, Esteban G.
中科院分区：
文献类型：
--
作者：
Baldi, German;Houspanossian, Javier;Jobbagy, Esteban G.
在南美洲干查科和奇基塔尼亚的干旱森林，过去10年里，种植面积从10%上升到19%，而且几乎没有生物物理、经济或政治方面的限制，似乎阻止了进一步的扩张。虽然通常与同质的农业综合企业系统有关，但农业及其在该领土上的扩张涉及各种各样的土地使用者。在这里，我们(i)根据现有的科学文献和技术报告确定并绘制了最明显的土地使用者群体，（ii）描述了他们相关的景观格局和（iii）基于218个样本点应用的不同遥感工具的植被功能。我们确认了14个本地或外国土地使用者群体，由个人或法人组织组成，致力于牧场或作物生产，或两者兼而有之。这些群体在围场规模上表现出很大的差异，这表明围场大小相差60倍。12年的MODIS-NDVI数据显示，初级生产力的大小差异不大且不显著（差异为1.2倍），但其季节性和长期变异性差异很大，包括植被变绿和褐化率的变化（差异高达4倍）、生长期长度（193 ~ 278天y(-1)）、每年种植季节数（1 ~ 1.75）和年际变异系数（高达0.13）。资本化集团下农业的特点是非常大的围场，不太稳定的生产力模式，更多的季节差异。相反，所有小农在季节和年际上都表现出更稳定的生产力。这些干旱地区的森林砍伐和耕种对景观结构和初级生产动态并没有单一的影响，而是根据其发生的人类和生产环境而变化。(C) 2014 Elsevier Ltd.版权所有。
In the South American dry forest of the Dry Chaco and Chiquitania, the area under cultivation rose from 10% to 19% over the last 10 years, and little biophysical, economical, or political constrains seem to prevent further expansion. Although typically associated to a homogeneous agribusiness system, agriculture and its expansion in this territory involve a diverse array of land users. Here we (i) identified and mapped the most conspicuous groups of land users based on existing scientific literature and technical reports, and (ii) described their associated landscape pattern and (iii) vegetation functioning based on different remote sensing tools applied to a set of 218 sample points. We recognized 14 groups of land users of local or foreign origin, composed by individuals or corporative organizations, and dedicated either to pasture or crop production, or its combination. These groups displayed a wide variation in the scale of their operations as suggested by a 60-fold difference in paddock sizes. Twelve years of MODIS-NDVI data showed small and non-significant differences in the magnitude of primary productivity ( 1.2-fold difference) but strong contrasts in its seasonality and long-term variability, including shifts in the rates of vegetation greening and browning (up to 4-fold differences), growing period length (193 to 278 days y(-1)), number of cultivation seasons per year (1-1.75), and inter-annual coefficient of variation (up to 0.13). Agriculture under capitalized groups was characterized by very large paddocks, less stable productivity patterns, and more divergent seasonality. Instead, all smallholders showed more stable productivities both seasonally and inter-annually. Deforestation and cultivation in these dry regions does not have a single imprint on landscapes configuration and primary production dynamics, but one that shifts depending on the human and productive context under which they take place. (C) 2014 Elsevier Ltd. All rights reserved.