Despite containing extraordinary levels of biodiversity, lowland (<200m asl) tropical forests are extremely threatened globally. Southeast Asia is an area of high species richness and endemicity under considerable anthropogenic threat with, unfortunately, scant focus on its lowland forests. Here we (1) estimated its extent of lowland forest loss between 1998 and 2018, including inside protected areas, and (2) determined the vulnerability of this remaining forest. Maximum Likelihood Classification techniques were used to classify Landsat images to estimate lowland forest cover in 1998 and 2018. Bayesian Belief Networks incorporated 20 variables for evaluating vulnerability of the 2018 remaining forest. Analyses were conducted at two spatial scales: landscape patch (analogous to ecoregion) and country level. Over this 20-year period, >120,000sq.km. of forest (50% of forest present in 1998) was lost. Of the 14 lowland forest landscape patches, six lost >50% of their area. At the country scale, Cambodia suffered the greatest deforestation (>47,500sq.km). In 2018, only 18% of the lowlands were forested, and only 20% of these forests had some formal protection. Approximately 50% of the lowland forest inside protected areas (c. 11,000sq.km.) was also lost during the study period. Most lowland forest remaining is highly vulnerable, with eight landscape patches having more than 50% categorized as such. Our results add to a growing body of evidence that the presence of protected areas alone will not prevent further deforestation. We suggest that more collaborative conservation management strategies with local communities and conservation concessions specifically for lowland forests are urgently needed to prevent further destruction of these valuable habitats. Article impact statement: From 1998 to 2018, mainland Southeast Asia lost 50% of its lowland forest, including a 50% loss inside protected areas. This article is protected by copyright. All rights reserved.

中文翻译：

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东南亚大陆低地森林的损失和脆弱性

尽管包含极高水平的生物多样性，低地（<200m asl）热带森林在全球范围内受到极大威胁。东南亚是一个物种丰富度和地方性高的地区，受到相当大的人为威胁，不幸的是，人们很少关注其低地森林。在这里，我们 (1) 估计了 1998 年至 2018 年间低地森林丧失的程度，包括保护区内部，以及 (2) 确定了这片剩余森林的脆弱性。最大似然分类技术用于对 Landsat 图像进行分类，以估计 1998 年和 2018 年的低地森林覆盖率。贝叶斯信念网络纳入了 20 个变量来评估 2018 年剩余森林的脆弱性。分析在两个空间尺度上进行：景观斑块（类似于生态区）和国家水平。在这 20 年期间，>120，000 平方公里。的森林（1998 年现有森林的 50%）消失了。在 14 个低地森林景观斑块中，有 6 个失去了 50% 以上的面积。在国家范围内，柬埔寨遭受了最大的森林砍伐（> 47,500 平方公里）。2018 年，只有 18% 的低地被森林覆盖，而这些森林中只有 20% 得到了一些正式保护。在研究期间，保护区内大约 50% 的低地森林（约 11,000 平方公里）也消失了。大多数剩余的低地森林非常脆弱，其中八个景观斑块的分类比例超过 50%。我们的结果增加了越来越多的证据，表明仅存在保护区并不能阻止进一步的森林砍伐。我们建议，迫切需要与当地社区和专门针对低地森林的保护特许权的更多合作保护管理战略，以防止这些宝贵的栖息地进一步遭到破坏。文章影响说明：从1998年到2018年，东南亚大陆失去了50%的低地森林，其中保护区内损失了50%。本文受版权保护。版权所有。