Combining long-term field data and remote sensing to test how tree diversity influences aboveground biomass recovery in logged tropical forests

结合长期实地数据和遥感来测试树木多样性如何影响被砍伐的热带森林的地上生物量恢复

• 批准号: NE/X000281/1
• 负责人: Andrew Hector
• 金额: $ 82.88万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX000281%2F1
• 关键词: Combining; long; term; field; data

The over-arching goal of this project is to test the unanswered question of whether the functioning of tropical forest ecosystems-such as how much biomass they produce-depends on how diverse they are and therefore whether replanting degraded forests with diverse mixtures of species can accelerate their recovery and help fund replanting costs through carbon credits.Tropical forests are being lost all over the world and of the remaining area more is degraded secondary forest than undisturbed old growth. This degradation occurs largely through selective logging which has negative effects of the functioning of the forest (e.g. how productive it is and how much carbon it stores) as well as on its biodiversity. This is important because work outside of the tropics in ecosystems like temperate grasslands has demonstrated a positive relationship between biodiversity and a range of ecosystem functions, including primary productivity. However, the challenges of scientific research in the tropics mean we have much less evidence of whether there is a positive relationship between levels of tree diversity and aboveground biomass production in tropical forest ecosystems. Indeed, some ecological theory suggests that species in these ecosystems are so similar ecologically that many species could be lost with little or no impact on how these ecosystems function. Twenty years ago, we started a collaboration with local foresters, conservationists and scientists in Sabah (Malaysian Borneo) to set up a long-term experiment to test whether there is a relationship between biodiversity and ecosystem functioning in these tropical forest ecosystems. The project, the Sabah Biodiversity Experiment, is one of the world's largest ecological experiments, making it of particular relevance to real-world efforts to restore and sustainably manage tropical forests. The experiment has adopted the existing forest restoration activity of 'enrichment planting' to plant more than 100,000 seedlings of native tree species across an area of 500 hectares of logged forest, allowing the recovery rates of naturally regenerating control plots to be robustly compared with those planted with different diversities (1, 4 or 16 species) and mixtures of tree species. We will assess restoration progress relative to nearby old growth forest, especially the neighbouring undisturbed area where we have repeatedly mapped and measured every tree within a 50-hectare area (the Danum Valley ForestGeo Plot) as part of a global network to monitor forest health.The large size of our research plots means they are difficult to repeatedly monitor in fine detail using traditional field methods. We will therefore combine targeted field sampling with cutting-edge remote sensing technologies to explore how tree enrichment planting has shaped the recovery of canopy structure, aboveground carbon stocks and plant diversity across hundreds of hectares of degraded forest. Our project will take advantage of existing data acquired for our study sites using two complementary technologies: LiDAR and satellite remote sensing. Airborne LiDAR uses a laser mounted on an airplane or helicopter to precisely measure the height of the vegetation and reconstruct the 3D structure of the forest canopy and underlying terrain in exquisite detail, allowing forest carbon stocks to be accurately mapped across entire landscapes. To get a more detailed and longer-term picture, the project will also use freely available satellite timeseries data (Sentinel 1-2, Landsat 8 and PlanetScope imagery) to map annual changes in forest aboveground carbon stocks (using Google Earth Engine).In the final phase we will work with local partners including the Sabah Forestry Department on a cost-benefit analysis of forest restoration and communicate these results so that they can inform their local and regional management policies for the conservation and restoration of forests and the carbon that they store.

该项目的总体目标是测试一个尚未解答的问题，即热带森林生态系统的功能（例如它们产生多少生物量）是否取决于它们的多样性，因此用不同的物种混合物重新种植退化的森林是否可以加速其恢复并通过碳信用额帮助资助重新种植成本。世界各地的热带森林正在消失，剩余面积中更多的是退化的次生林 比未受干扰的旧生长。这种退化主要是通过选择性伐木发生的，这对森林的功能（例如，森林的生产力和储存的碳量）以及生物多样性产生负面影响。这一点很重要，因为在热带地区以外的温带草原等生态系统中开展的工作已经证明了生物多样性与一系列生态系统功能（包括初级生产力）之间存在积极关系。然而，热带科学研究面临的挑战意味着我们关于热带森林生态系统中树木多样性水平与地上生物量生产之间是否存在正相关关系的证据要少得多。事实上，一些生态理论表明，这些生态系统中的物种在生态上非常相似，以至于许多物种可能会消失，而对这些生态系统的功能影响很小或没有影响。二十年前，我们开始与沙巴州（马来西亚婆罗洲）当地的林务工作者、自然资源保护主义者和科学家合作，开展一项长期实验，以测试这些热带森林生态系统的生物多样性和生态系统功能之间是否存在关系。该项目名为“沙巴生物多样性实验”，是世界上最大的生态实验之一，使其与现实世界恢复和可持续管理热带森林的努力特别相关。该实验采用了现有的“富集种植”森林恢复活动，在500公顷的采伐森林中种植了超过10万株本地树种幼苗，使自然更新对照地块的恢复率与种植不同多样性（1、4或16种）和混合树种的恢复率相比具有稳健的效果。我们将评估相对于附近原始森林的恢复进度，特别是邻近的未受干扰的区域，我们在该区域反复绘制和测量了 50 公顷区域内的每棵树（丹浓谷森林地理图），作为监测森林健康的全球网络的一部分。我们的研究图块面积较大，这意味着使用传统的实地方法很难重复详细地监测它们。因此，我们将有针对性的实地采样与尖端遥感技术相结合，探索树木富集种植如何影响数百公顷退化森林的树冠结构、地上碳储量和植物多样性的恢复。我们的项目将利用两种互补技术：激光雷达和卫星遥感，利用我们研究地点获取的现有数据。机载激光雷达使用安装在飞机或直升机上的激光器来精确测量植被的高度，并以精致的细节重建森林冠层和底层地形的 3D 结构，从而能够准确绘制整个景观的森林碳储量。为了获得更详细和更长期的情况，该项目还将使用免费提供的卫星时间序列数据（Sentinel 1-2、Landsat 8 和 PlanetScope 图像）来绘制森林地上碳储量的年度变化图（使用 Google Earth Engine）。在最后阶段，我们将与包括沙巴林业部在内的当地合作伙伴合作，对森林恢复进行成本效益分析，并传达这些结果，以便他们能够为当地和区域的森林恢复管理政策提供信息。 保护和恢复森林及其储存的碳。