Regional Model of Carbon, Nitrogen and Water Flows Through Terrestrial Ecosystems of the Amazon Basin

亚马逊流域陆地生态系统碳、氮和水流区域模型

• 批准号: 9524050
• 负责人: Daniel Nepstad
• 金额: $ 40万
• 依托单位: Woodwell Climate Research Center, Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-10-01 至 1999-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9524050&HistoricalAwards=false
• 关键词: Regional; Model; Carbon; Nitrogen; Water

9524050 Nepstad Modeling the effects of seasonal and interannual drought on the flow of water, carbon and nitrogen through Amazonian forests. Do trees of the Amazon forest experience significant drought stress? It seems that the answer to such a basic question should already be known, but, as is the case for many subjects in tropical ecology, our ignorance is vast. Drought stress in Amazonian forests is important because it determines how much water passes through the trees and enters the atmosphere. Knowing how much water the trees use will help us determine how cutting the forests and creating cattle pastures will affect flows of water in rivers and transfer of water vapor to the atmosphere. Water use is also important because it affects how well the trees grow and how much heat-trapping carbon dioxide the trees remove from the atmosphere. Amazonian droughts could become more frequent in the future if deforestation leads to a reduction in rainfall, as some climate models predict. If trees utilize water stored only in the top one or two meters of soil, as most ecologists and hydrologists currently assume, it is easy to calculate that water stress must develop during the 3-5 month dry periods that characterize most of Amazonia. However, most of Amazonia is covered by very deep soils that can store large quantities of water to several meters depth, and so the soils may protect the forest against dry seasons and against unusually dry years. If this is a general phenomenon, then Amazonian forests may experience significant drought stress only if a long-term decrease in rainfall occurs as the result of a general change in climate. In the proposed research, the hypothesis that Amazonian forests experience drought only during years of very low rainfall will be tested through field measurements of forests at three places where drought is more or less severe. The relationship between drought and the activity of microbes in the soil will also be examined at these sites. In order to integr ate the effects of drought on plants, microbes, and flows of water, and to make predictions about other locations in Amazonia and the tropics generally, these field measurements will be used to adapt a computer model to Amazon ecosystems. Through comparison of field measurements with model predictions, the effect of rooting depth, soil properties, and plant type on estimates of tropical forest water use and forest growth will be determined, laying the basis for an improved generation of climate and ecosystem models for the tropics. ??

9524050 Nepstad季节性和年际干旱对亚马逊森林水、碳和氮流动影响的模拟。亚马逊森林的树木是否经历了严重的干旱压力？似乎这样一个基本问题的答案应该是已知的，但是，就像热带生态学的许多学科一样，我们的无知是巨大的。亚马逊森林的干旱压力很重要，因为它决定了有多少水通过树木进入大气。了解树木消耗了多少水将有助于我们确定砍伐森林和建立牧场将如何影响河流中的水流和水蒸气向大气的转移。水的使用也很重要，因为它会影响树木的生长情况，以及树木从大气中吸收多少吸热二氧化碳。正如一些气候模型预测的那样，如果森林砍伐导致降雨量减少，未来亚马逊地区的干旱可能会变得更加频繁。如果像大多数生态学家和水文学家目前假设的那样，树木只利用储存在土壤顶部一到两米的水，那么很容易计算出，在亚马逊大部分地区特征的3-5个月的干旱期，水压力一定会产生。然而，亚马逊的大部分地区都被非常深的土壤覆盖，这些土壤可以储存数米深的大量水分，因此土壤可以保护森林免受干旱季节和异常干旱年份的影响。如果这是一种普遍现象，那么亚马逊森林只有在气候普遍变化导致降雨长期减少的情况下才可能经历严重的干旱压力。在拟议的研究中，亚马逊森林只在降雨量非常少的年份经历干旱的假设将通过对干旱或多或少严重的三个地方的森林进行实地测量来验证。在这些地点还将研究干旱与土壤中微生物活动之间的关系。为了综合干旱对植物、微生物和水流的影响，并对亚马逊河流域和热带地区的其他地区进行预测，这些实地测量结果将用于使计算机模型适应亚马逊河流域的生态系统。通过田间测量与模型预测的比较，将确定生根深度、土壤性质和植物类型对热带森林水分利用和森林生长的估计的影响，为改进热带气候和生态系统模型的生成奠定基础。? ?