Collaborative Research: The Sustainability of Riparian Forests in Expanding Amazonian Agricultural Landscapes

合作研究：河岸森林在扩大亚马逊农业景观中的可持续性

• 批准号: 1660034
• 负责人: Christopher Neill
• 金额: $ 65.47万
• 依托单位: Woodwell Climate Research Center, Inc.
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1660034&HistoricalAwards=false
• 关键词: Collaborative; Research; Sustainability; Riparian; Forests

The conversion of large areas of Amazon forest vegetation for intensive crop production is one of the major forces shaping the Earth. Riparian forest buffers along streams can reduce the potential negative effects of forest clearing on stream water quality and stream habitat by intercepting nutrients, providing shade to reduce temperature and protecting stream channels. This project investigates how deforestation, cropland expansion and intensification, and increased fertilizer use influence the structure and sustainability of riparian forests, and ultimately affect their capacity to keep nutrient runoff from reaching streams. Research will take place in the Amazon state of Mato Grosso, Brazil's global hotspot of deforestation where soybean cultivation has expanded rapidly in the last two decades. Producers in the region are now shifting from single-cropped soybeans to double-cropped soybeans and corn, which greatly increases fertilizer inputs. This project addresses the globally important issue of how to protect and sustain water quality and aquatic resources in tropical regions, where high deforestation and rapid cropland expansion are increasingly common. By improving understanding of the trajectories and causes of riparian forest change and predicting the movement of nitrogen through riparian zones, these results will provide a basis for managing the negative impacts of tropical agricultural intensification. The project team will convey findings to policymakers and farmers in Brazil and the US by conducting two workshops on the scientific basis for riparian forest management and conservation. This project will investigate whether riparian forest fragments in cropland maintain their vegetation structure over time and how that structure is influenced by alterations to watershed hydrology and microclimate that are typical of cropland areas. Investigators will determine whether riparian forests bordering streams in croplands intercept and remove nitrogen from watersheds and whether this nitrogen removal function is sufficient to prevent excess nitrogen from reaching streams in cropland watersheds with high fertilizer inputs. The project will quantify how changes to riparian forest structure in croplands alter stream temperature, metabolism, nutrient uptake and downstream nutrient export. This will be accomplished by comparing riparian forests in replicated watersheds within intact tropical forest, soybean-only cropland and soybean-corn cropland. The project focuses on the following three hypotheses: (1) Riparian forests in cropland watersheds have higher tree mortality, lower tree growth and a more open canopy than either upland forests or riparian forests in forested watersheds. (2) Cropland watersheds have lower evapotranspiration, greater runoff and nutrient export, higher water tables, and wetter stream side slopes than forest watersheds but denitrification in riparian zones is insufficient to prevent excess nitrogen from reaching streams in double-cropped watersheds. (3) More open canopies in cropland riparian forest will increase stream temperature and metabolism. This project will create a new conceptual framework for understanding how deforestation, cropland expansion, and agricultural intensification influence tropical riparian forests and streams.

亚马逊森林植被的大量农作物的转化是塑造地球的主要力量之一。沿溪流的河岸森林缓冲区可以通过拦截养分来减少森林清理对溪流水质和溪流栖息地的潜在负面影响，从而提供阴影以降低温度并保护溪流通道。该项目调查了森林砍伐，农田的扩张和增强以及增加肥料的使用如何影响河岸森林的结构和可持续性，并最终影响其防止营养径流到达溪流的能力。研究将在巴西全球森林砍伐热点马托·格罗索（Mato Grosso）进行研究，在过去的二十年中，大豆种植迅速扩大。现在，该地区的生产商正在从单作大豆转移到双重大豆和玉米，这大大增加了肥料的投入。该项目解决了如何保护和维持在热带地区的水质和水生资源的全球重要问题，在这些项目中，越来越多的森林砍伐和快速农田扩张变得越来越普遍。通过提高对河岸森林变化的轨迹和原因的理解，并预测氮通过河岸地区的运动，这些结果将为管理热带农业强化的负面影响提供基础。该项目团队将通过在河岸森林管理和保护的科学基础上进行两个讲习班，向巴西和美国的决策者和农民传达发现。该项目将调查农田中的河岸森林碎片是否会随着时间的流逝维护其植被结构，以及该结构如何受到农田地区典型的流域水文学和微气候的改变。研究人员将确定与农田中与溪流接壤的河岸森林是否截获并从流域清除氮，以及这种去除氮的去除功能是否足以防止过量的氮在高肥投入的农田流域中到达农田流域。该项目将量化农田中河岸森林结构的变化如何改变河流温度，代谢，养分吸收和下游营养出口。这将通过比较完整的热带森林，仅大豆的农田和大豆 - 米肉地的复制流域中的河岸森林来实现。该项目的重点是以下三个假设：（1）与高地森林或森林流域的河岸森林或河岸森林相比，农田流域的河岸森林具有更高的树木死亡率，较低的树木生长和更开放的树冠。 （2）与森林流域相比，农田流域的蒸散量更低，径流和营养较高的出口，更高的水桌和更湿的溪流侧面坡度，但河岸地区的硝化含量不足以防止多余的氮气进入双拼合流域的流中。 （3）农田河岸森林中更多开放的檐篷将增加河流温度和新陈代谢。该项目将创建一个新的概念框架，以了解森林砍伐，农田的扩张和农业强化如何影响热带河岸森林和溪流。