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悬而未决的问题，即热带森林生态系统的功能--如它们产生多少生物量--是否取决于它们的多样性，从而重新种植具有不同物种混合的退化森林是否可以加速它们的恢复，并通过碳信用为重新种植费用提供资金。世界各地的热带森林都在丧失，剩下的地区更多的是退化的次生林，而不是未受干扰的老树。这种退化主要是通过选择性采伐发生的，这对森林的功能(例如，它的生产力有多高，它储存了多少碳)以及它的生物多样性产生了负面影响。这一点很重要，因为在热带以外的温带草原等生态系统中的工作表明，生物多样性与包括初级生产力在内的一系列生态系统功能之间存在正向关系。然而，热带科学研究的挑战意味着，我们对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向关系的证据要少得多。事实上，一些生态学理论表明，这些生态系统中的物种在生态上是如此相似，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。20年前，我们开始与沙巴州(马来西亚婆罗洲)的当地森林管理员、自然资源保护者和科学家合作，建立一个长期实验，以测试这些热带森林生态系统中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，因此与现实世界恢复和可持续管理热带森林的努力特别相关。该试验采用了现有的森林恢复活动，在500公顷的原木林地上种植了10多万株乡土树种的苗木，使自然更新对照样地的恢复率与种植不同多样性(1、4或16种)和树种混交的林地相比强劲。我们将评估与附近老树林相关的恢复进度，特别是邻近的未受干扰的地区，在那里，我们作为监测森林健康的全球网络的一部分，反复绘制和测量50公顷区域内的每一棵树(Danum山谷ForestGeo地块)。我们的研究地块规模很大，这意味着很难使用传统的现场方法重复进行详细监测。因此，我们将结合有针对性的实地采样和尖端遥感技术，探索树木增厚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。我们的项目将利用为我们的研究地点使用两项互补技术--激光雷达和卫星遥感--获得的现有数据。机载激光雷达使用安装在飞机或直升机上的激光来精确测量植被的高度，并以精致的细节重建森林树冠和底层地形的3D结构，从而能够准确绘制整个景观的森林碳储量图。为了获得更详细和更长期的图像，该项目还将使用免费获得的卫星时间序列数据(Sentinel 1-2、Landsat 8和PlanetScope Imagery)绘制森林地上碳储量的年度变化图(使用谷歌地球引擎)。在最后阶段，我们将与包括沙巴州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，并将这些结果传达出去，以便他们能够为当地和地区保护和恢复森林及其储存的碳的管理政策提供信息。