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Natural enemies, climate, and the maintenance of tropical tree diversity

天敌、气候和热带树木多样性的维持

基本信息

批准号：
NE/J007463/1
负责人：
Robert Freckleton
金额：
$ 11.01万
依托单位：
University of Sheffield
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FJ007463%2F1
关键词：
Natural enemies climate maintenance tropical

项目摘要

At least 50% of earth's plant and animal species is found in tropical rainforests, but this rich biodiversity is under threat from deforestation and climate change. Ecologists are interested in understanding why these habitats are so diverse, and how their diversity will change in the future. One leading explanation for high plant biodiversity in tropical forests is the Janzen-Connell Effect. This theory suggests that pests such as plant-feeding insects and fungal diseases can help maintain tropical biodiversity if (1) they specialise on particular plant species, and (2) they cause 'density-dependent' mortality (i.e., they kill more seeds and seedlings where these are locally abundant). This pest pressure acts as a negative feedback mechanism, putting locally rare plant species at an advantage and preventing any one species from reaching high abundance. Recent research shows that this form of density-dependence from both insects and fungi plays a key role in the maintenance of plant diversity in the tropics. We now want to discover how this process changes under different climatic regimes. Wetter tropical forests have more plant species than drier forest, and we will test the theory that more intense density-dependent pest pressure in these places is a factor behind these differences. We will also investigate whether future changes to the climate (higher or lower rainfall) are likely to alter the strength of the Janzen-Connell Effect, and consequently plant diversity. Our work will take place in Panama, where we will take advantage of a steep gradient in rainfall and soil humidity from the dry (Pacific) coast to the humid (Atlantic) coast to test our hypotheses. We will carry our experiments in the field and in controlled nursery conditions that manipulate the density of seeds and seedlings and the presence of fungal pathogens and plant-feeding insects, and we will analyse long-term data and build mathematical models to explore whether and to what extent climate change will alter tropical plant diversity.

地球上至少有50%的动植物物种生活在热带雨林中，但这种丰富的生物多样性正受到森林砍伐和气候变化的威胁。生态学家有兴趣了解为什么这些栖息地如此多样化，以及它们的多样性在未来将如何变化。对热带森林植物生物多样性高的一个主要解释是Janzen-Connell效应。这一理论表明，害虫，如植物饲养昆虫和真菌疾病，可以帮助维持热带生物多样性，如果（1）他们专门针对特定的植物物种，（2）他们造成“密度依赖”的死亡率（即，它们杀死更多的种子和幼苗，而这些种子和幼苗在当地是丰富的）。这种虫害压力作为一种负反馈机制，使当地稀有植物物种处于优势地位，并阻止任何一种物种达到高丰度。最近的研究表明，昆虫和真菌的这种密度依赖形式在维持热带地区植物多样性方面发挥着关键作用。我们现在想知道这个过程在不同的气候条件下是如何变化的。潮湿的热带森林比干燥的森林有更多的植物物种，我们将测试这些地方更强烈的密度依赖性害虫压力是这些差异背后的一个因素的理论。我们还将调查未来气候变化（降雨量增加或减少）是否可能改变Janzen-Connell效应的强度，从而改变植物多样性。我们的工作将在巴拿马进行，我们将利用从干燥（太平洋）海岸到潮湿（大西洋）海岸的降雨和土壤湿度的陡峭梯度来测试我们的假设。我们将在田间和受控苗圃条件下进行实验，控制种子和幼苗的密度以及真菌病原体和食草昆虫的存在，我们将分析长期数据并建立数学模型，以探讨气候变化是否会改变热带植物多样性以及在多大程度上改变热带植物多样性。