Human Impacts on Water Use by Deep-Rooted Amazonian Forests

人类正在改变亚马逊的高地景观， 几乎是连绵不断的高山森林到牧场的马赛克， 次生林、被砍伐的森林和原始森林遗迹。 大规模的生态变化伴随着这一激进的 地球生物圈的变化知之甚少，但 可能非常重要。 例如，最好的预测 这种转变的区域气候影响表明， 在未来的几年里，亚马逊河流域将变得更加干燥和温暖， 气候变化可能会在中南部的谷物带发生， 巴西 我们预测亚马逊河后果的能力很差 森林砍伐可以追溯到一个令人惊讶的缺乏比较 原始森林和人类生态系统的信息 特别是在主要的森林地带 从贝伦向南到戈亚尼亚，向西到 英亩。 例如，没有发表的研究比较 这120万平方公里的主要和次要生态系统的水文 地区 对蒸散量和水量的唯一估计 基于经验测量的亚马逊生态系统平衡 在中部和北方的原始森林中进行 亚马逊，远离农业前沿。 据推测，深层土壤和明显的季节性 支持“森林转换弧”的特点 利用水和矿物质养分的根深蒂固的原始森林 以现有文献没有预测的方式， 潮湿热带森林生态学 深层土壤功能 森林，包括碳储存、旱季吸水、湿 季节蓄水、细根生产和养分吸收 是潮湿热带森林研究最少的方面， 我们必须了解它，以预测生态变化， 伴随着森林的转变。 这项关于根深蒂固的亚马逊森林和 取代这些森林的生态系统将有助于 测试上面的假设。 初步研究结果 表明亚马逊河流域的新生态系统 根浅且功能不同。 本研究将 为建立一个与季节有关的模型提供基础 降雨对根和冠层动态的影响， 潮湿的热带森林。

Humans are transforming the upland landscapes of Amazonia from nearly continuous expanses of high forest to mosaics of pasture, secondary forests, logged forests and primary forest remnants. The large-scale ecological changes that accompany this radical alteration of Earth's biosphere are poorly understood, but probably very important. For example, the best predictions of regional climatic impacts of this transformation suggest that Amazonia will be drier and warmer in the years to come and that climatic shifts may follow in the grain belt of south-central Brazil. Our poor ability to predict the consequences of Amazonian deforestation can be traced to a surprising dearth of comparative information for primary forests and the anthropogenic ecosystems that are replacing them, particularly in the major zone of forest conversion extending from Belem south to Goiania and west to Acre. For example, there are no published studies comparing the hydrology of primary and secondary ecosystems of this 1.2 M km2 region. The only estimates of evapotranspiration and water balance for Amazonian ecosystems based on empirical measurements were conducted on primary forests in central and northern Amazonia, far from the advancing agricultural frontier. It is hypothesized that the deep soils and pronounced seasonal drought that characterize the "arc of forest conversion" support deep-rooted primary forests that use water and mineral nutrients in ways that are not predicted by the existing literature on moist tropical forest ecology. Deep-soil functions of these forests, including carbon storage, dry season water uptake, wet season water storage, fine root production, and nutrient uptake are the least studied aspects of moist tropical forest and yet must be understood to predict the ecological changes that will accompany forest conversion. This research on water use by deep-rooted, Amazon forests and the ecosystems that are replacing these forests will assist in testing the hypothesis above. Results from initial studies suggest that the new ecosystems of Amazonia are relatively shallow-rooted and functionally distinct. This study will provide the basis for development of a model relating seasonal patterns of rainfall to root and canopy dynamics in deep-rooted, moist tropical forests.