BIODIVERSITY AND LAND-USE IMPACTS ON TROPICAL ECOSYSTEM FUNCTION (BALI)

热带地区的人为干扰和土地利用变化正在导致生物多样性的不可挽回的变化和生态系统生物地球化学的重大变化。然而，对于人类驱动的生物多样性变化如何反馈到改变生物地球化学过程，我们仍然知之甚少。这一知识差距极大地限制了我们模拟和预测热带生态系统对当前和未来环境变化的反应的能力。我们在理解生物多样性的变化如何改变热带生态系统过程方面面临一些重大挑战，即：(1)热带高度分类多样性如何与生态系统功能相联系，(2)在干扰对功能多样性和生物地球化学产生影响之后，营养水平和分类组之间的相互作用如何发生变化，以及(3)如何利用地块一级的测量来衡量整个景观。我们已经成立了一个联盟来应对这些关键挑战，以启动一项大规模、重复和完全综合的研究，该研究汇集了一个拥有技能和专业知识的多学科团队，研究必要的分类学和营养类群、不同的生物地球化学过程以及它们之间的复杂相互作用。为了了解和量化土地利用变化对重点生物多样性类群活动的影响以及这对生物地球化学的影响，我们将：(I)分析关于重点生物多样性类群分布的现有数据；(Ii)在改变森林生态系统稳定性(SAFE)项目点(处理包括森林退化、碎片化、油棕榈转化)和关键辅助地点(Maliau盆地--贫瘠土壤上的老树种、Lambir丘陵--肥沃土壤上的老树种、沙巴生物多样性实验--恢复林、INFAPRO-面貌恢复林)抽样进行景观尺度的处理；(Iii)开展操纵生物多样性关键组成部分和地下碳通量途径的新实验。这些操作将集中在树木和藤本植物、菌根真菌、白蚁和蚂蚁上，因为这些生物可能是人类改造的热带森林中生物地球化学循环的改变因素。我们将使用尖端技术的组合来测试这些目标生物群体如何相互作用，以影响生物地球化学循环。此外，我们还将整理和分析其他分类群的存档数据，包括受保护关注的脊椎动物。关键的统一概念是认识到所谓的“功能特征”在将分类多样性与生态系统功能联系起来的过程中发挥着关键作用。我们将专注于确定与植物相关的关键功能特征，以及它们如何在SAFE的干扰梯度上变化。特别是，我们提出了叶片功能性状(如物理和化学顽固性、含氮量等)。在决定关键的生态系统过程中发挥关键作用，并对大气成分产生重大影响。最重要的是，尖端的航空遥感技术表明，在景观尺度上绘制叶片功能特征、化学和生理图谱是可能的，因此我们将使用这些新的航空遥感方法来量化森林退化、树冠结构、生物地球化学循环和树木分布的景观尺度模式。然后，基于过程的数学模型将与功能多样性和生物地球化学循环的遥感图像和地面测量相联系，以将我们的发现提升到干扰梯度之上。

Anthropogenic disturbance and land-use change in the tropics is leading to irrevocable changes in biodiversity and substantial shifts in ecosystem biogeochemistry. Yet, we still have a poor understanding of how human-driven changes in biodiversity feed back to alter biogeochemical processes. This knowledge gap substantially restricts our ability to model and predict the response of tropical ecosystems to current and future environmental change. There are a number of critical challenges to our understanding of how changes in biodiversity may alter ecosystem processes in the tropics; namely: (i) how the high taxonomic diversity of the tropics is linked to ecosystem functioning, (ii) how changes in the interactions among trophic levels and taxonomic groups following disturbance impacts upon functional diversity and biogeochemistry, and (iii) how plot-level measurements can be used to scale to whole landscapes. We have formed a consortium to address these critical challenges to launch a large-scale, replicated, and fully integrated study that brings together a multi-disciplinary team with the skills and expertise to study the necessary taxonomic and trophic groups, different biogeochemical processes, and the complex interactions amongst them.To understand and quantify the effects of land-use change on the activity of focal biodiversity groups and how this impacts biogeochemistry, we will: (i) analyse pre-existing data on distributions of focal biodiversity groups; (ii) sample the landscape-scale treatments at the Stability of Altered Forest Ecosystems (SAFE) Project site (treatments include forest degradation, fragmentation, oil palm conversion) and key auxiliary sites (Maliau Basin - old growth on infertile soils, Lambir Hills - old growth on fertile soils, Sabah Biodiversity Experiment - rehabilitated forest, INFAPRO-FACE - rehabilitated forest); and (iii) implement new experiments that manipulate key components of biodiversity and pathways of belowground carbon flux. The manipulations will focus on trees and lianas, mycorrhizal fungi, termites and ants, because these organisms are the likely agents of change for biogeochemical cycling in human-modified tropical forests. We will use a combination of cutting-edge techniques to test how these target groups of organisms interact each other to affect biogeochemical cycling. We will additionally collate and analyse archived data on other taxa, including vertebrates of conservation concern. The key unifying concept is the recognition that so-called 'functional traits' play a key role in linking taxonomic diversity to ecosystem function. We will focus on identifying key functional traits associated with plants, and how they vary in abundance along the disturbance gradient at SAFE. In particular, we propose that leaf functional traits (e.g. physical and chemical recalcitrance, nitrogen content, etc.) play a pivotal role in determining key ecosystem processes and also strongly influence atmospheric composition. Critically, cutting-edge airborne remote sensing techniques suggest it is possible to map leaf functional traits, chemistry and physiology at landscape-scales, and so we will use these novel airborne methods to quantify landscape-scale patterns of forest degradation, canopy structure, biogeochemical cycling and tree distributions. Process-based mathematical models will then be linked to the remote sensing imagery and ground-based measurements of functional diversity and biogeochemical cycling to upscale our findings over disturbance gradients.