Shifted Ecological Baselines in the Brazilian Savannah

热带稀树草原是热带地区的“灰姑娘”生态系统;被忽视和过度开发。尽管亚马逊雨林几乎覆盖了南美洲的一半，但与更好地宣传和研究的亚马逊雨林相比，只有一小部分受到保护。为了减少亚马逊地区的森林砍伐，热带草原被大量开发为牧场和农田，但人们对集约化农业对这一丰富多样的环境的影响知之甚少。为促进养牛用草的生长而对景观进行的密集燃烧和为农业而进行的清理与植物物种的损失和碳释放到大气中有关，然而，最近限制火灾的努力也使森林开始侵入萨凡纳，进一步危及萨凡纳物种。火一直是萨凡纳生态中不可或缺的一个自然方面，但放火和灭火似乎都是有害的。那么，南美大草原的自然燃烧模式是什么呢？自然火灾是否平衡了防止森林入侵的同时也保护了这个全球重要生物群落的自然结构？在这里，我们要问，随着时间的推移，巴西大草原的火灾模式是如何变化的？这些变化是如何影响这些稀树草原上的植物组成的？而且，我们能否通过在增加树木覆盖率和保护独特的萨凡纳环境之间建立最有益的“权衡”来帮助萨凡纳保护？为了回答这些问题，我们将研究来自巴西大草原的现代植物物种，这些物种经历了很少，适度和密集的人类活动。随后，通过分析湖泊沉积物中保存的木炭碎片和植物花粉以及不同植物在土壤中留下的化学信号，将重现过去1000年的火灾活动和萨凡纳植物物种的变化。这种分析的结合将在巴西和英国科学家的合作下完成，并将使我们能够了解农业，火灾模式和植被之间的关系如何随着时间的推移改变了巴西稀树草原的构成。这种理解将被用来创建一个火灾管理计划，这将有助于保护和恢复巴西萨凡纳。

Savannahs are the "Cinderella" ecosystems of the tropics; overlooked and over-exploited. Despite covering almost half of South America, only a tiny fraction are protected, in comparison to the better-publicised and researched Amazon rainforest. Savannahs are heavily exploited as cattle pastures and agricultural fields in order to reduce deforestation in the Amazon, but the impacts of intensive farming on this rich and diverse environment are poorly understood. Intensive burning of the landscape to promote the growth of grasses for cattle and clearance for agriculture has been linked to the loss of plant species and the release of carbon into the atmosphere, however, recent efforts to limit fires have also seen forests begin to encroach into the savannah, further endangering savannah species. Fire has always been an integral natural aspect of savannah ecology, but both setting and extinguishing fires appears to be harmful. So what is the natural burning pattern of South American savannahs? Do natural fires balance the prevention of forest invasion but also preserve the natural structure of this globally important biome?Here we ask, how have fire patterns changed through time in Brazilian savannahs? How have these changes affected the composition of plants in these savannahs? And, can we aid savannah conservation by establishing the most beneficial 'trade-off' between increasing tree cover and preserving the unique savannah environment? In order to answer these questions, we will examine the modern plant species from Brazilian savannahs that have experienced little, moderate and intensive human activity. Following which, the last 1000 years of fire activity and changes to savannah plant species will be recreated through the analysis of charcoal fragments and plant pollen preserved in lake sediment and the chemical signal left in soils by different plants. This combination of analyses will be done in partnership between Brazilian and UK scientists and will allow us to understand how the relationships between changes in farming, fire patterns and vegetation through time have changed the make-up of Brazilian savannahs. This understanding will then be used to create a fire management plan that will aid in the conservation and restoration of the Brazilian savannah.