Longer-term responses of Amazonian vegetation to fire

亚马逊植被对火灾的长期反应

• 批准号: NE/G000816/1
• 负责人: Jos Barlow
• 金额: $ 9.63万
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2008
• 资助国家: 英国
• 起止时间: 2008 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG000816%2F1
• 关键词: Longer; term; responses; Amazonian; vegetation

Tropical forests hold more species of plant and animal than any other kind of terrestrial environment. They also store vast amounts of greenhouse gases in their trees and soils. The Brazilian Amazon accounts for 40% of all these remaining forests, and is therefore of enormous global importance for protecting Earth's species and climate. Humid tropical forests do not normally burn, yet their future is becoming increasingly uncertain due to the threat of man-made fires. Human activities such as logging and forest fragmentation open up the forest habitat and make it more flammable, while agriculture in areas adjacent to remaining forest has greatly increased the number of fire incidents. Furthermore, there is now convincing evidence that regional climatic changes predicted for the next century could make the Amazon both dryer and hotter, increasing the frequency and intensity of extreme drought events and raising the flammability of enormous areas of forest. Severe Amazonian droughts occurred in 1997 and 2005, and led to widespread forest fires devastating thousands of square kilometers of forest. When a forest burns for the first time flame heights rarely exceed 30-40 cm, and the fire moves through the leaf litter. Although these fires appear relatively innocuous, they are actually highly destructive as most rainforest trees have a low tolerance of heat, and their slow rate of spread means that flames stay in contact with trees for long periods of time. As a result, even low-intensity fires kill between 8 and 40 % of trees larger than 10cm in diameter. They are also the first step in positive feedback cycle, where increased tree mortality produces a more open forest and increases the fuel available on the forest floor, making the forest more flammable, and increasing the severity of any subsequent fire. Forests that have burned more than once have lost around 80% of their trees >10cm in diameter. We are only beginning to understand the implications of wildfires for tropical forest vegetation, and many important questions remain. For example, we cannot yet explain why rates of tree mortality vary from 8 to 40% depending on the region of forest, and we have almost no information on the longer-term effects of fire on tropical forest trees. We need more information on how long forests take to recover (if indeed they can fully recover), what happens to the makeup of tree species following recurrent fires, and how these responses may vary across the Amazon basin. This proposal will address these areas of uncertainty by examining what happens to forests 11-12 years after they last burned, in eight different regions of the Brazilian Amazon. These include four regions in core, mature Amazonian forests which have experienced a minimal influence from fires over the last millennia, and four regions of transitional forests which are close to the forest-savannah boundaries and much smaller in stature (holding only about half of the total wood volume). All these areas contain extensive areas of forest that have burned once, forest that have burned more than once in the past two decades, and unburned forest that has no recent history of fire. I have avoided selecting forests that have been extensively logged. By sampling tress and saplings in the three burn treatments (burned once, burned twice, unburned) in each of these areas, I will be able to test predictions about tree mortality and regeneration after fire in 'transitional' and 'core' Amazonian forests. This information will improve our understanding of the response of tropical forests to fires over a large area and over long time periods. Furthermore, it will provide information essential for assessing the resilience of the Amazon to human pressure, and the potential consequences of land-use and climate change.

热带森林比任何其他陆地环境都拥有更多的动植物物种。他们还在树木和土壤中储存了大量的温室气体。巴西亚马逊占所有这些剩余森林的40%，因此在保护地球物种和气候方面具有巨大的全球重要性。潮湿的热带森林通常不会燃烧，但由于人为火灾的威胁，它们的未来变得越来越不确定。伐木和森林破碎化等人类活动打开了森林生境，使其更加易燃，而与剩余森林相邻地区的农业大大增加了火灾事件的数量。此外，现在有令人信服的证据表明，预测下世纪的区域气候变化可能使亚马逊变得更加干燥和炎热，增加极端干旱事件的频率和强度，并增加大片森林的易燃性。1997年和2005年，亚马逊河流域发生了严重的干旱，并导致了大范围的森林火灾，摧毁了数千平方公里的森林。当森林第一次燃烧时，火焰的高度很少超过30-40厘米，火焰穿过落叶层。虽然这些火灾看起来相对无害，但它们实际上具有高度破坏性，因为大多数热带雨林树木的耐热性很低，而且它们的缓慢传播速度意味着火焰与树木接触很长一段时间。因此，即使是低强度的火灾也会杀死8%至40%直径超过10厘米的树木。它们也是正反馈循环的第一步，树木死亡率的增加会产生更开阔的森林，并增加森林地面上可用的燃料，使森林更易燃，并增加任何后续火灾的严重性。多次燃烧的森林已经失去了大约80%直径> 10厘米的树木。我们才刚刚开始了解野火对热带森林植被的影响，许多重要的问题仍然存在。例如，我们还不能解释为什么树木的死亡率根据森林的区域而从8%到40%不等，我们几乎没有关于火灾对热带森林树木的长期影响的信息。我们需要更多的信息来了解森林需要多长时间才能恢复（如果它们确实可以完全恢复的话），经常性火灾后树种的组成会发生什么变化，以及这些反应在亚马逊流域可能会有什么不同。该提案将通过研究巴西亚马逊河流域八个不同地区的森林在最后一次燃烧后11-12年的情况来解决这些不确定性领域。这些地区包括四个核心地区，成熟的亚马逊森林，在过去的几千年里受到火灾的影响最小，还有四个过渡森林地区，靠近森林-稀树草原边界，身材小得多（仅占木材总量的一半左右）。所有这些地区都有大面积的森林被烧毁过一次，在过去20年里被烧毁过一次以上，以及最近没有火灾历史的未烧毁森林。我避免选择那些被大量砍伐的森林。通过在这些地区的三个燃烧处理（燃烧一次，燃烧两次，未燃烧）中对树木和树苗进行采样，我将能够测试“过渡”和“核心”亚马逊森林火灾后树木死亡率和再生的预测。这些信息将提高我们对热带森林对大面积和长时间火灾的反应的理解。此外，它还将为评估亚马逊对人类压力的恢复能力以及土地使用和气候变化的潜在后果提供必要的信息。

项目成果

The critical importance of considering fire in REDD+ programs

• DOI: 10.1016/j.biocon.2012.03.034
• 发表时间: 2012-10-01
• 期刊: BIOLOGICAL CONSERVATION
• 影响因子: 5.9
• 作者: Barlow, Jos;Parry, Luke;Cochrane, Mark A.
• 通讯作者: Cochrane, Mark A.

Metacommunity patterns of Amazonian Odonata: the role of environmental gradients and major rivers

• DOI: 10.7717/peerj.6472
• 发表时间: 2019-05-06
• 期刊: PEERJ
• 影响因子: 2.7
• 作者: Alves-Martins, Fernanda;Brasil, Leandro Schlemmer;Hortal, Joaquin
• 通讯作者: Hortal, Joaquin

Drivers of regional and local diversity of Amazonian stream Odonata

• DOI: 10.1111/icad.12327
• 发表时间: 2019-05-01
• 期刊: INSECT CONSERVATION AND DIVERSITY
• 影响因子: 3.5
• 作者: Alves-Martins, Fernanda;Calatayud, Joaquin;Hortal, Joaquin
• 通讯作者: Hortal, Joaquin