Converting mangroves to other land cover types can induce large emissions of carbon dioxide, depending on the type of land use and land cover (LULC) change. However, mangroves may also recover their ecosystem carbon stocks rapidly following restoration, potentially offsetting carbon stock losses. While studies have quantified these tradeoffs at global scales using coarse metrics, fewer studies have quantified them at national scales at higher resolution. Here, we used high-resolution data sets of LULC for mangroves in Thailand to quantify district-level gross and net changes in mangrove carbon stocks from ~1960 to 2014. We found emissions based on gross gain and loss statistics (7.18 ± 0.24 million Mg C) to be greater than those associated with emissions based on net area change statistics (1.65 ± 0.26 million Mg C) by a factor of four. The difference in estimates arises from slower rates of carbon stock recovery following reforestation relative to carbon stock loss following LULC change. Overall, we found the greatest gains in mangrove carbon stocks to be from mangrove expansion in areas of accreting sediments, which were strongly correlated with district-level extent of undisturbed mangroves. Our results show that net loss statistics may greatly underestimate emissions associated with LULC change in mangroves. Additionally, our findings suggest that gains in mangrove carbon stocks associated with natural establishment at the periphery of standing mangroves may offset substantial carbon stock losses at national scales.

中文翻译：

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净损失统计数据低估了红树林土地利用和土地覆盖变化的碳排放

将红树林转变为其他土地覆盖类型会导致大量二氧化碳排放，具体取决于土地利用类型和土地覆盖 (LULC) 变化。然而，红树林也可能在恢复后迅速恢复其生态系统碳储量，从而可能抵消碳储量损失。虽然研究已经使用粗略的指标在全球范围内量化了这些权衡，但很少有研究在国家范围内以更高分辨率对它们进行量化。在这里，我们使用泰国红树林的 LULC 高分辨率数据集来量化 1960 年至 2014 年期间红树林碳储量的地区级总变化和净变化。我们根据总收益和损失统计数据发现排放量（7.18 ± 24 万 Mg C) 比基于净面积变化统计的排放量（1.65 ± 26 万 Mg C）大四倍。估计的差异是由于重新造林后的碳库恢复速度相对于 LULC 变化后的碳库损失而言较慢。总体而言，我们发现红树林碳储量的最大收益来自于红树林在沉积物区域的扩张，这与地区级未受干扰的红树林范围密切相关。我们的结果表明，净损失统计数据可能大大低估了与红树林 LULC 变化相关的排放量。此外，我们的研究结果表明，与常设红树林外围自然建立相关的红树林碳储量的增加可能会抵消全国范围内的大量碳储量损失。我们发现红树林碳储量的最大收益来自于红树林在沉积物堆积区域的扩张，这与地区一级未受干扰的红树林范围密切相关。我们的结果表明，净损失统计数据可能大大低估了与红树林 LULC 变化相关的排放量。此外，我们的研究结果表明，与常设红树林外围自然建立相关的红树林碳储量的增加可能会抵消全国范围内的大量碳储量损失。我们发现红树林碳储量的最大收益来自于红树林在沉积物堆积区域的扩张，这与地区一级未受干扰的红树林范围密切相关。我们的结果表明，净损失统计数据可能大大低估了与红树林 LULC 变化相关的排放量。此外，我们的研究结果表明，与常设红树林外围自然建立相关的红树林碳储量的增加可能会抵消全国范围内的大量碳储量损失。