AFIRE - Assessing ENSO-induced Fire Impacts in tropical Rainforest Ecosystems

热带森林储存了世界森林碳的一半以上，并产生了所有陆地系统生产力的三分之一以上。它们也是生物多样性的热点地区，拥有世界上很大一部分陆生动植物。然而，越来越多的证据表明，热带森林提供重要生态系统服务（即碳封存和生物多样性保护）的能力已因与人为引起的森林干扰（如农业、伐木、火灾和破碎化）和极端气候事件相关的多重压力而大幅降低。在这些干扰中，火灾是最大的威胁。雨林并没有与火共同进化，物种也没有适应火或它给森林带来的变化。然而今天，在大多数人为改造的地区，火源是常见的，因为许多生活在热带森林中的当地农民传统上使用火作为一种管理技术来准备他们的土地种植。选择性采伐和破碎化加剧了这种情况，这增加了剩余森林的可燃性。关键是，在严重干旱事件期间，火灾更有可能逃离目标区域，进入周围的森林。这正是2015-16年厄尔尼诺Niño南方涛动（ENSO）期间发生的事情——被认为是有记录以来最强的三个事件之一。漫长的旱季使得亚马逊和东南亚热带雨林的数千起火灾失去了控制。特别是在巴西亚马逊地区，2015年底发生了87,000多起火灾事件，比2014年（非enso年）增加了48%。结果，广泛的野火影响了我们在帕尔<e:1>州圣塔姆姆地区附近的20块永久土地中的一半，而幸运的是，其他10块土地没有被烧毁。可持续亚马逊网络（SAN）在2010年沿着森林改造的梯度建立了这些地块，自2014年以来，英国和巴西科学家（ECOFOR）的一个联合项目一直在该地区开展研究。因此，我们在这里提出的工作受益于关于碳动态和植物功能特征的独特和详细的火灾前信息（来自ECOFOR），以及三个不同分类群（鸟类，蜣螂和植物）的分布和次级种子传播过程（来自SAN）。独特的是，我们的永久地块网络是在2015年火灾之前沿着现有的森林改造梯度建立的，这使我们能够对不同森林干扰类别的火灾影响进行首次严格的评估。这种利用详细的火灾前数据来检查火灾影响的能力使我们能够在人为改变的森林扰动梯度中开发三种主要的研究途径：(1)非常严重的野火对植物群落和碳动态的影响，从而评估哪些植物功能性状可以预测物种的死亡、生存和补充；(2)调查火灾对森林动物（如鸟类和屎壳郎）的影响及其种子传播过程；(3)深入了解当前极端enso事件的规模和影响，探索遥感信息与地面测量之间的关系。遥感产品与火灾严重程度的实际测量之间更好的联系将使我们能够扩大整个地区的碳排放和生物多样性损失估计。fire的结果至关重要，因为随着气候变化，世界各地的热带森林可能会受到更干燥、更炎热和更长的旱季的威胁。我们的研究结果将有助于为缓解战略提供信息，以管理未来enso介导的干旱和严重野火对热带森林的影响。我们还期望AFIRE地块能够成为长期研究热带野火影响的基础

Tropical forests store more than a half of the world's forest carbon and produce over one third of the productivity of all terrestrial systems. They are also biodiversity hotspots, and host a large proportion of the world's terrestrial flora and fauna. However, growing evidence shows that the ability of tropical forests to perform important ecosystem services (i.e. carbon sequestration and biodiversity conservation) has been dramatically reduced by multiple pressures associated with human-induced forest disturbances (e.g. agriculture, logging, fire and fragmentation) and extreme climate events. Of these disturbances, fire represents of the greatest threats. Rainforests have not co-evolved with fire, and species have not adapted to withstand fire or the changes it imposes on the forests. Yet today, ignition sources are common in most human-modified regions, as many local farmers living within tropical forests traditionally use fire as a management technique to prepare their land for planting. This is compounded by selective logging and fragmentation, which increase the flammability of the remaining forests. Critically, fires are much more likely to escape their target area and enter the surrounding forests during severe drought events.This is exactly what happened during the current 2015-16 El Niño Southern Oscillation (ENSO) - considered one of the three strongest events ever recorded. The prolonged dry season allowed thousands of fires to get out of control in Amazonian and SE Asian tropical rainforests. Specifically in the Brazilian Amazon, the end of 2015 was marked by over 87,000 fire events, a 48% increase in relation to 2014 (a non-ENSO year). As a result, the widespread wildfires affected half of our 20 permanent plots near the Santarém region in the state of Pará, while fortunately preserving the other ten plots unburned. The Sustainable Amazon Network (SAN) has established these plots along a gradient of forest modification in 2010, and since 2014 a joint project between UK and Brazilian scientists (ECOFOR) has been carrying out research in this region. Consequently, the work we are proposing here benefits from unique and detailed pre-fire information on carbon dynamics and plant functional traits (from ECOFOR) as well as the distribution of three distinct taxa (birds, dung beetles and plants) and secondary seed dispersal processes (from SAN). Uniquely our network of permanent plots is established along an existing gradient of forest modification before the 2015 fires, allowing us to undertake the first rigorous evaluation of fire effects across different forest disturbance classes. This ability to examine fire impacts using detailed pre-fire data allows us to develop three major avenues of research across a human-modified gradient of forest disturbances: (1) the impacts of very severe wildfires on plant communities and carbon dynamics, assessing therefore which plant functional traits may predict species mortality, survival and recruitment; (2) an investigation into the fire impacts on forest fauna (i.e. birds and dung beetles) and associated seed dispersal processes; and (3) the development of a detailed understanding of scale and impacts of the current extreme ENSO-event, exploring the relationship between remote sensing information and ground-based measures. The better linkages between remote-sensing products and actual measures of fire severity will allow us to scale up the carbon emission and biodiversity loss estimates across the whole region. The results fo AFIRE are critically important, as tropical forests around the world may be threatened by drier, hotter and longer dry seasons with climate change. Our findings will help inform mitigation strategies to manage the impacts of future ENSO-mediated droughts and severe wildfires on tropical forests. We also expect AFIRE plots to form the basis of much longer-term research on the impacts of tropical wildfire