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三分之一以上的生产力。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地植物群和动物群。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（即碳固存和生物多样性保护）的能力因人类引起的森林干扰（如农业、伐木、火灾和破碎化）和极端气候事件造成的多重压力而大大降低。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对森林造成的变化。然而今天，点火源在大多数人类改造的地区很常见，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管理技术来准备他们的土地用于种植。有选择的伐木和破碎化使情况更加复杂，增加了剩余森林的易燃性。重要的是，在严重干旱事件期间，火灾更有可能逃离目标区域并进入周围的森林。这正是当前2015 - 16年厄尔尼诺南方涛动（ENSO）期间发生的情况-被认为是有史以来最强的三次事件之一。漫长的旱季使亚马逊和东南亚热带雨林的数千起火灾失去控制。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年份）增加了48%。因此，广泛的野火影响了我们在帕拉州Santarém地区附近的20个永久性地块中的一半，幸运的是，其他10个地块没有被烧毁。2010年，可持续亚马逊网络（SAN）沿着森林改造的梯度沿着建立了这些地块，自2014年以来，英国和巴西科学家（ECOFOR）的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独特的和详细的火灾前的碳动力学和植物功能特性（从ECOFOR），以及三个不同的类群（鸟类，甲虫和植物）和二次种子传播过程（从SAN）的分布信息。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，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评估。这种使用详细的火灾前数据检查火灾影响的能力使我们能够在人类改变的森林干扰梯度中开发三个主要研究途径：（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特征可以预测物种死亡率、生存和补充;（2）调查火灾对森林动物的影响（即鸟类和蜣螂）和相关的种子传播过程;以及（3）对当前极端ENSO事件的规模和影响的详细了解，探索遥感信息与地面措施之间的关系。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区域的碳排放和生物多样性损失估计。AFIRE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、更炎热和更长旱季的威胁。我们的研究结果将有助于制定缓解战略，以管理未来ENSO介导的干旱和严重野火对热带森林的影响。我们还希望AFIRE图能够成为对热带野火影响的长期研究的基础

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