A key issue in understanding tropical forest disturbance is what drives farmers practicing customary shifting cultivation to clear crop fields in old-growth forest over secondary forest fallows. These farmers typically hold a stock of secondary forest fallows that can be used for cropping in rotation, built up over time in part through initial clearing of old-growth forest. In this paper we examine the most recent field cleared by 2046 indigenous and folk peasant households in 138 communities along three major rivers of the Peruvian Amazon to identify the factors that influence their choice of field location (upland or lowland forests) and type of forest cleared (old-growth or secondary). Data are drawn from a large-scale household and community surveys and remote sensing analysis of Landsat and ArcGIS Worldview imagery. We find that rates of old-growth forest clearing are low and that such land quickly returns to secondary forest cover: about 31% of households cleared forest on the upland (terra firme) but only 8% of households cleared upland old-growth forest. Regression modeling results identify the contextual, historical and household factors that influence the choice to clear upland forest (old-growth or secondary). Access to lowland for floodplain agriculture is associated with lower rates of old-growth forest clearing and higher educational attainment of household heads with increased clearing. Analysis of household land portfolios points to the importance of the size of land holdings, the degree of upland orientation, and the number and age of fallows held at the time of the forest clearing decision in clearing old-growth forest on the upland. Measures to reduce old-growth forest loss around Amazonian communities are discussed.

理解热带森林干扰的一个关键问题是什么促使农民实行习惯性轮垦，以在次生林休耕的老林中清理农田。这些农民通常持有可用于轮作的次生林休耕存量，部分是通过对原始森林的初步清理而积累起来的。在本文中，我们研究了秘鲁亚马逊三大河流沿岸 138 个社区的 2046 个土著和民间农户最近清除的田地，以确定影响他们选择田地位置（高地或低地森林）和清除森林类型的因素（老生长或次要）。数据来自对 Landsat 和 ArcGIS Worldview 影像的大规模家庭和社区调查以及遥感分析。terra Firme），但只有 8% 的家庭清除了高地原始森林。回归建模结果确定了影响清除高地森林（老林或次生林）选择的背景、历史和家庭因素。进入低地进行洪泛区农业与较低的原始森林砍伐率和随着砍伐增加的户主受教育程度提高有关。对家庭土地组合的分析表明，在森林清除决定时，土地持有规模、高地定向程度以及休耕的数量和年龄对清除高地上的老生林的重要性。讨论了减少亚马逊社区周围原始森林流失的措施。