Collaborative Research: Ecoclimate Teleconnections between Amazonia and Temperate North America: Cross-Region Feedbacks among Tree Mortality, Land Use Change, and the Atmosphere

最近在全球范围内发生的许多大规模树木死亡事件引发了人们的担忧，即气温变暖，或者与干旱和树皮甲虫等天敌结合在一起，可能会前所未有地减少或退化森林。亚马逊盆地的森林面积也因森林砍伐而大幅减少。由于树木在调节地面附近的气候方面扮演着如此重要的角色，树木因大量死亡或森林砍伐而丧失也意味着这种小气候的变化。随着足够多的树木死亡和足够大的森林面积减少，树木丧失对小气候的影响可能会加在一起，并开始在更大范围内影响气候(或宏观气候)。将气候和森林覆盖联系起来的计算机模型最近的结果表明，北美森林面积的大幅增加实际上导致了当地气候变暖，还造成了三个全球范围的气候影响：它增加了南北半球之间的能量交换，它改变了热带降雨带(称为热带辐合带)，以及它增加了南美洲亚马逊盆地的干旱。这引发了人们的担忧，即森林面积的减少可能是由森林枯死或砍伐造成的，也可能对全球和当地产生重要影响。特别是，这可能会通过所谓的气候遥相关将北美和南美的森林的命运联系起来。为了解决这一问题，该项目将使用一个预测森林如何对气候作出反应的模型，以评估因北美和南美洲的森林死亡和砍伐而导致的森林面积大规模减少的影响。为此，将在这两个地区的一系列野外地点进行有关森林面积减少如何影响地面附近小气候的测量。该项目将提供重要信息，说明一个半球森林面积的减少如何不仅影响当地的气候条件，也影响另一个半球的气候条件。为了寻找和探索未来可能发生的反应的潜在范围的界限，评估将评估所有森林被砍伐的极端条件，然后评估森林面积最近实际减少的后果。该项目还将提供关于模型中哪些因素最重要的关键信息，这些因素需要准确衡量，以改进预测。由于科学家不确定是什么条件导致树木大量死亡，该项目还将提供有关树木死亡原因和可能导致的气候变化的重要信息。总体而言，该项目将提供有助于制定政策的科学成果。它还将在美国和巴西科学家之间建立强有力的合作。最后，该项目将培训博士后学者，并通过使用图森的生物圈2号设施向公众和教师通报情况，每年有10万多名公众访问该设施。

Many recent cases of large scale tree death over the earth have raised concerns that warming temperatures may alone, or when combined with droughts and natural enemies like bark beetles, be reducing or degrading forests as never before. The area of forests is also being greatly reduced in the Amazon basin by deforestation. Because trees play such an important role in regulating the climate near the ground, losing trees to massive die offs or deforestation also means changes in that microclimate. With enough tree die off and large enough reductions in the area forested, the effects of tree loss on microclimates may add together and begin to affect the climate at much larger scales (or macro-climate). Recent results from computer models that link climate and forest cover have shown that a large increase in the area of forests in North America actually led to locally warmer conditions and also caused three global scale climate effects: it increased the amount of energy exchanged between the northern and southern hemispheres, it shifted the band of tropical rainfall (known as the Inter-tropical Convergence Zone), and it increased drought in the Amazon basin of South America. This raises the concern that decreases in the area forested, which could be caused by either die off or deforestation, could also have important effects both globally as well as locally. In particular, this could link the fates of forests in North America and South America through a so-called climate teleconnection. To address this, this project will use a model that predicts how forests respond to climate to evaluate the effects of large scale decreases in forest area from die off and deforestation in North and South America. To do this, measurements related to how decreases in forested area affects the microclimate near the ground will be made at a series of field sites in both regions. This project will provide important information about how decreases in forest area in one hemisphere could affect climate conditions not only locally but also in the other hemisphere. To find and explore the boundaries of the potential range of responses that could occur in the future, the assessment will evaluate extreme conditions where all forests are removed and then the consequences of actual recent decreases in forested area. The project will also provide key information on which factors in the models are the most important to accurately measure in order to improve predictions. Because scientists are uncertain about what conditions massive trigger tree die offs, the project will also provide important information about the reasons for tree death and the expected in climate that might result. Overall, the project will provide science results that can aide in developing policy. It will also build a strong collaboration between U.S. and Brazilian scientists. Finally, the project will train postdoctoral scholars and inform the public and teachers through use of the Biosphere 2 facility in Tucson, where more than 100,000 members of the public visit each year.