División de la Conservación de la Biodiversidad, Departamento de Ecología y Sistemática Terrestre, El Colegio de la Frontera Sur, San Cristóbal de Las Casas, Chiapas, México.
PLoS One. 2012;7(8):e42309. doi: 10.1371/journal.pone.0042309. Epub 2012 Aug 8.
Case studies of land use change have suggested that deforestation across Southern Mexico is accelerating. However, forest transition theory predicts that trajectories of change can be modified by economic factors, leading to spatial and temporal heterogeneity in rates of change that may take the form of the Environmental Kuznets Curve (EKC). This study aimed to assess the evidence regarding potential forest transition in Southern Mexico by classifying regional forest cover change using Landsat imagery from 1990 through to 2006. Patterns of forest cover change were found to be complex and non-linear. When rates of forest loss were averaged over 342 municipalities using mixed-effects modelling the results showed a significant (p<0.001) overall reduction of the mean rate of forest loss from 0.85% per year in the 1990-2000 period to 0.67% in the 2000-2006 period. The overall regional annual rate of deforestation has fallen from 0.33% to 0.28% from the 1990s to 2000s. A high proportion of the spatial variability in forest cover change cannot be explained statistically. However analysis using spline based general additive models detected underlying relationships between forest cover and income or population density of a form consistent with the EKC. The incipient forest transition has not, as yet, resulted in widespread reforestation. Forest recovery remains below 0.20% per year. Reforestation is mostly the result of passive processes associated with reductions in the intensity of land use. Deforestation continues to occur at high rates in some focal areas. A transition could be accelerated if there were a broader recognition among policy makers that the regional rate of forest loss has now begun to fall. The changing trajectory provides an opportunity to actively restore forest cover through stimulating afforestation and stimulating more sustainable land use practices. The results have clear implications for policy aimed at carbon sequestration through reducing deforestation and enhancing forest growth.
案例研究表明,墨西哥南部的森林砍伐正在加速。然而,森林转型理论预测,经济因素可以改变变化轨迹,导致变化率的空间和时间异质性,其形式可能是环境库兹涅茨曲线 (EKC)。本研究旨在通过使用 1990 年至 2006 年的 Landsat 图像对区域森林覆盖变化进行分类,来评估墨西哥南部潜在森林转型的证据。研究发现,森林覆盖变化的模式复杂且非线性。当使用混合效应模型对 342 个市镇的森林损失率进行平均处理时,结果显示森林损失率的平均值从 1990-2000 年的 0.85%显著(p<0.001)降低到 2000-2006 年的 0.67%。整个地区的年森林砍伐率从 1990 年代的 0.33%下降到 2000 年代的 0.28%。森林覆盖变化的空间变异性很大一部分无法用统计方法解释。然而,使用基于样条的广义加性模型的分析检测到森林覆盖与收入或人口密度之间的潜在关系,其形式与 EKC 一致。初步的森林转型尚未导致广泛的重新造林。森林恢复仍低于每年 0.20%。重新造林主要是与土地利用强度降低相关的被动过程的结果。在一些焦点地区,森林砍伐仍以较高的速度发生。如果决策者更广泛地认识到区域森林损失率现在已经开始下降,那么转型可能会加速。变化的轨迹为通过减少森林砍伐和加强可持续土地利用实践来积极恢复森林覆盖提供了机会。这些结果对旨在通过减少森林砍伐和增强森林生长来实现碳封存的政策具有明确的意义。