Optimising the recovery of degraded tropical rainforest logging

热带雨林是一个特别而重要的栖息地：它们是地球上生物多样性最丰富的地方之一，是全球碳循环的重要组成部分，将二氧化碳锁在树木中。热带雨林中珍贵的硬木也是许多国家的主要收入来源，但这些树生长缓慢，而且越来越稀有。其结果是，许多国家现在有大片退化的伐木森林，木材生产的净收入正在下降，因为有价值的树木变得更难找到，开采成本也更高。在许多国家，这些退化的森林只是被砍伐，用于其他活动，如生产棕榈油、放牧或为快速生长的树种开辟林地。对于这些退化的森林，有一个更积极的替代未来可以得到保障：允许它们再生，以恢复高价值硬木储备，并促进碳捕获。这是一项长期投资-硬木需要数十年的时间才能生长到可以砍伐的大小-因此，为了在短期内提供必要的喘息空间，种植在退化森林中的快速生长物种可以在森林恢复的同时持续收获价值较低的木材。这种被称为马赛克种植的方法可能会为当地经济和全球保护提供一个双赢的局面：森林在恢复的同时产生收入。然而，这也可能是双输的：收获和种植对森林的破坏太严重，商业木材生长太慢，无法提供良好的回报。那么，答案在哪里呢？这个项目将解决这个紧迫的问题。获得直接的答案是一项挑战。热带雨林的生长速度太慢，无法进行实验和观察会发生什么，我们也不能等待一代人来研究如何最好地管理今天的森林。我们的解决方案是使用虚拟实验。与真实世界相比，模拟雨林生长要容易得多，速度快许多倍，风险也低得多。在这个项目中，我们将开发一个基于个体的热带雨林树木群落模拟，并将其应用于现实世界中优化退化伐木区恢复的问题。该模型将模拟树木功能群的诞生、生长和死亡，基于在单个树木规模上运行的关键光合作用和呼吸过程，并跟踪水和碳的循环。它将建立在一些现有模拟的基础上，但提供了更大的灵活性来审查管理情景，包括森林起始条件的变化和具体管理选择，如种植密度、种植结构、藤本植物采伐和采伐频率，所有这些都是在更广泛的全球气候变化的背景下进行的。我们将使用马来西亚沙巴州SAFE项目研究站点提供的大量经验现场数据来校准和验证该模型。

Tropical rainforests are an extraordinary and important habitat: they are some of the most biodiverse places on Earth and are a vital part of the global carbon cycle, locking away carbon dioxide in trees. The valuable hardwoods in tropical rainforests are also a key source of income for many countries, but these trees are slow growing and increasingly rare. As a result, many countries now have huge areas of degraded, logged forest and the net income from timber production is declining as valuable trees become harder to find and more expensive to extract. In many countries, these degraded forests are simply cleared and used for other activities, such as palm oil production, grazing or woodlots for fast-growing tree species. There is a more positive alternative future that could be secured for these degraded forests: allowing them to regenerate to restore stocks of high value hardwoods and promote carbon capture. That is a long-term investment - hardwoods take many decades to grow to a size where they can be logged - so to give the necessary breathing space in the short term, fast-growing species planted within degraded forest could provide an ongoing harvest of less valuable timber while the forest recovers. This approach - called mosaic planting - might provide a win-win situation for local economies and global conservation: forests recover while generating income. However, it could also be lose-lose: harvesting and planting damage the forest too badly and the commercial timber grows too slowly to provide a good return. So, where does the answer lie? This project will address this urgent question. Getting direct answers is a challenge. Rainforests grow too slowly to conduct experiments and see what happens, and we can't wait a generation to work out how best to manage forests today. Our solution is to use virtual experiments instead. Simulating rainforest growth is a lot easier, many times faster and very much less risky than experimenting with the real world. In this project, we will develop an individual-based simulation of tropical rainforest tree communities, and apply it to the real-world problem of optimising the restoration of degraded logging estates. The model will simulate the birth, growth and mortality of tree functional groups, based on the key photosynthesis and respiration processes that operate at the scale of individual trees and tracking the cycling of water and carbon. It will build on a number of existing simulations, but provide greater flexibility to examine management scenarios, including variation in forest starting conditions and specific management options such as planting density, planting composition, liana cutting and logging frequency, all within the context of wider global climate change. We will calibrate and validate the model using extensive empirical field data available from the SAFE Project study site in Sabah, Malaysia.