Deforestation Threatens the Mekong, but New Trees Are Growing in Surprising Places
More than70 million peoplelive in Southeast Asia's Mekong region, where trees and forests have multiple benefits for people and biodiversity. Trees lock soils in place, preventing landslides and protecting crops, while forests help regulate rainfall and water cycles. Wood and other forest products provide millions of people with food, materials and economic opportunities in rural communities across Myanmar, Vietnam, Cambodia, Laos and Thailand. The entire planet relies on the Mekong's forests to store carbon and mitigate climate change.
但是这些森林受到威胁。在过去的几十年中，农业和大量伐木的扩大导致了广泛的森林丧失和退化。尽可能该地区森林地区的三分之一在1973年至2009年之间丧失。在2010年至2017年之间，湄公河的五个国家损失了30万公顷的森林，这是纽约市规模的四倍。
同时，森林砍伐只是故事的一半。在森林内外，在整个地区也出现了新树木 - 农田，灌木丛以及城镇和村庄。新的WRI分析，一部分纽约森林宣言五年评估报告led byClimate Focus, used satellite data to assess forest change in the Mekong, as well as — for the first time ever — change in tree density (the number of trees per hectare) outside the forest.
在湄公河上，森林外的树木正在增加
我们的分析发现，在湄公河地区，森林丧失仍在超过森林的增长。越南，老挝和柬埔寨遭受了最大的损失，而缅甸的净损失却很小。泰国是唯一获得净收益的国家。在我们的分析中，在常规周期中发生增益和损失的商业树木种植园没有被视为森林砍伐或恢复。
但是好消息是，在森林之外，例如在农业地区和定居点，除老挝以外的所有国家的树木密度净收益，缅甸的净收益最高。这些树木为宅基地提供食物和菲尔伍德，保护山坡免受侵蚀和过滤沉积物的影响，以改善水质。总共468万公顷的非森林土地在2010年至2018年之间的树木密度增加了，该地区比瑞士小。
Thailand: More Trees Inside和在森林外
泰国是关于森林和树木的亮点。尽管它已经失去了巨大的森林 -an estimated 43% of its forest area between 1973 and 2009- 该国正在扭转这一趋势。我们发现，在2010年至2017年之间，泰国是唯一在森林地区和森林外的树木净收益的湄公河国家。它的森林地区增长了1.7％，树木的存在增长了1.2％。在森林之外，2010年被认为是贫瘠的土地在2018年增加了4.5％。在农场和农田上，树木与树木混合或边界作物以稳定土壤并保护产量，树木密度增加了0.6％。
As part of a new national strategy, Thailand recently announced ambitions to increase its forest area by 23% before 2030, as part of its Nationally Determined Contribution under the Paris Agreement. The country has gained recognition for several innovative projects, from mangroverestorationto社区主导的森林植物。Our estimates indicate that Thailand has added nearly half a million hectares of forest area since 2010.
我们如何衡量恢复？
Measuring increased tree cover on an international scale is extremely challenging. While deforestation is highly visible from space — it happens quickly and leaves a stark footprint — measuring restoration is more difficult. Trees grow slowly and are often widely spaced apart, especially in rural landscapes. Measuring this growth requires higher-resolution satellite data and different methods of interpreting satellite imagery.
Forty-one countries have endorsed theNew York Declaration on Forestssince its inception in 2014, including Thailand and Vietnam. Its goals include halving deforestation by 2020 (and ending it by 2030) and restoring 150 million hectares of degraded land by 2020 (increasing to 350 million hectares by 2030). To assess progress toward these goals, our team investigated two questions: How much tree cover has been lost? And how much land is actually under restoration?
For this analysis, we combined novel satellite-based algorithms fromthe University of Maryland's GLAD Lab以及食品和农业组织的数据收集技术Collect Earth tool生产有史以来第一个评估，以测量所有类型的土地上的树木覆盖率变化。该方法捕获了多种类型的恢复活动：从森林内部的茂密的天然树覆盖到森林外的农场，灌木丛和定居点的稀疏树木覆盖物。尽管这项研究仅评估湄公河地区的国家，但该方法可以在全球应用。
Forest Landscape Restoration Pays Off for People
The新报告表明监视恢复对于取得实际进步至关重要。泰国和越南已成为该地区纽约森林宣言的两个签署者。他们还拥有一些最有前途的树木覆盖率。但是，监控不仅是控股国家对其承诺负责。跟踪土地在何处和如何再生，为政府，专家和现场利益相关者（如社区，非政府组织和企业）提供了有关其在恢复方面的投资的宝贵信息。
Measuring progress encourages communities to restore land because it provides evidence that restoration efforts work. By visualizing where trees are growing, we can go to those places and see if people there are benefitting from pay-offs in water quality, food productivity and livelihoods. Often, they are. In fact, new analysis by theFood and Land Use Coalition表明，仅森林恢复就提供了全球1750亿美元的经济机会，其中大部分将直接流向依赖土地和照顾土地的农村社区。
The future of the world's forests is in our hands, and it's time to act. Measuring tree restoration, both inside and outside forests, is a crucial first step toward achieving the goals that the New York Declaration on Forests set out five years ago. By doing so, we can ultimately beat deforestation and climate change.