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首页> 外文期刊>Regional Environmental Change >Regional patterns and controls of biomass in semiarid woodlands: lessons from the Northern Argentina Dry Chaco
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Regional patterns and controls of biomass in semiarid woodlands: lessons from the Northern Argentina Dry Chaco

机译：半干旱林地生物量的区域格局和控制：阿根廷北部干旱地区的经验教训

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摘要

Land use change, particularly in forested ecosystems, has a direct impact on the global carbon cycle. Consequently, the regional assessment of biomass and the understanding of its current spatial controls are research priorities for regional ecology and land use. Field data and satellite imagery were combined here to map woodlands and estimate their above-ground biomass (AGB) in the Dry Chaco ecoregion of northern Argentina. Allometric equations were used to derive AGB from diameter at breast height data collected at 50 samples during 2007. In order to generate the AGB regional map, this information was later associated with MODIS-Terra spectral data (NDVI) using the Random Forest (RF) method. Finally, AGB spatial patterns were associated with potential biophysical and human controlling factors through correlation and regression analyses. Results indicate that the use of RF and NDVI of the dry season derived from MODIS-Terra was suitable to map regional AGB, what makes this methodology applicable to other dry woodlands. The RF model used to map AGB showed a mean deviation of 2.9 % and a precision of 15 % for one prediction. At this regional scale of analysis, biophysical rather than human factors controlled AGB spatial patterns, in part because the region includes a wide range of environmental situations. Wanner conditions showed a higher biomass, suggesting an energetic limitation for AGB accumulation. However, human controls (distance to towns, cultivation, and roads) also conditioned AGB patterns, suggesting lower AGB values near cultivated areas. The relation between AGB and water availability was surprisingly weak, but partially obscured by the land use history and degradation due to extensive cattle ranching. We propose that a combination of environmental factor and land use affects the AGB regional patterns and promotes unexpected relationships with environmental factors. This work represents the first spatially explicit AGB (patterns and controls) analysis for an extensive subtropical dry woodland area (113,000 km~2) and shows how biophysical and human factors co-control regional patterns.
机译：土地利用的变化，特别是森林生态系统中的土地变化，对全球碳循环具有直接影响。因此，对生物量进行区域评估和对其当前空间控制的理解是区域生态和土地利用的研究重点。这里将现场数据和卫星图像结合在一起，以绘制森林图，并估计阿根廷北部Dry Chaco生态区的地上生物量（AGB）。异速方程用于从2007年期间收集的50个样本的胸高直径数据得出AGB。为了生成AGB区域图，此信息随后使用随机森林（RF）与MODIS-Terra光谱数据（NDVI）相关联方法。最后，通过相关性和回归分析，AGB空间格局与潜在的生物物理和人类控制因素相关。结果表明，使用源自MODIS-Terra的干旱季节的RF和NDVI可以绘制区域AGB的地图，这使该方法学适用于其他干旱林地。用于绘制AGB的RF模型显示平均偏差为2.9％，一次预测的精度为15％。在该区域分析范围内，生物物理因素而非人为因素控制了AGB空间格局，部分原因是该区域包括各种环境情况。 Wanner条件显示出较高的生物量，表明AGB积累存在能量限制。但是，人为控制（到城镇，耕种和道路的距离）也限制了AGB模式，表明耕地附近的AGB值较低。 AGB和水的可利用性之间的关系令人惊讶地薄弱，但由于大量的牧场放牧而被土地利用的历史和退化所部分掩盖。我们建议，环境因素和土地使用的结合会影响AGB区域格局，并促进与环境因素的意料之外的关系。这项工作代表了对广阔的亚热带干旱林地面积（113,000 km〜2）的首次空间显式AGB（模式和控制）分析，并显示了生物物理和人为因素如何共同控制区域模式。

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