Montane ecosystems occur throughout the world, and harbor many endemic species. They also provide key ecological services, including the catchment of water resources and the storage of organic carbon. These ecosystems are vulnerable to global climate change and increasing human pressures, including forestry and their conversion to arable land. In the extensive and biodiverse Mexican montane regions, ongoing deforestation and conversion to arable lands has led to diminished ecosystem health and services. Here, we undertook a comprehensive evaluation of carbon stocks within Mexican montane habitats in the Flora and Fauna Conservation Area of Nevado de Toluca. This aimed to integrate these habitats into Mexican and global census of forest carbon, the first step needed to convert on carbon credit markets to incentivize conservation of this region by local communities. Our study evaluated both, living biomass and belowground soil organic carbon in sites within forests, alpine grasslands and converted arable land. We addressed the following questions: (1) What are the organic carbon stocks, including the soil component, of our studied montane habitats? (2) What are the avoided CO2 emissions from maintaining natural forests and preventing conversion to arable land? And (3) Within our study area, are organic carbon stocks in the soil correlated to carbon stocks in aboveground living biomass? We found whole ecosystem organic carbon stocks ranged from 68 Mg OC ha–1 in unburnt alpine grasslands to 668 Mg OC ha–1 in Abies religiosa forests. By avoiding conversion of the A. religiosa forests to arable lands, we show that emissions of 1,122 to 1,671 Mg CO2 ha–1 are avoided. Notably, the belowground soil organic carbon stock comprised ≥ 40% of the total ecosystem organic carbon stock. We recommend soil organic carbon stocks should be included within Mexican and global forestry carbon stock inventories, and should be considered within voluntary carbon-credit markets used to incentivize the conservation of Mexican montane habitats.

中文翻译：

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墨西哥山地栖息地的有机碳储量：植被类型和土地利用的变化

山地生态系统遍布世界各地，并拥有许多特有物种。它们还提供关键的生态服务，包括水资源的集水和有机碳的储存。这些生态系统容易受到全球气候变化和不断增加的人类压力的影响，包括林业及其向耕地的转变。在广阔且生物多样性丰富的墨西哥山地地区，持续的森林砍伐和耕地转化导致生态系统健康和服务减少。在这里，我们对内华达州托卢卡动植物保护区内墨西哥山地栖息地的碳储量进行了综合评估。这旨在将这些栖息地整合到墨西哥和全球森林碳普查中，第一步需要转换碳信用市场，以激励当地社区保护该地区。我们的研究评估了森林、高山草原和转化耕地中的活生物量和地下土壤有机碳。我们解决了以下问题：（1）我们研究的山地栖息地的有机碳储量是什么，包括土壤成分？(2) 维护天然林和防止转耕地避免的 CO2 排放量是多少？(3) 在我们的研究区域内，土壤中的有机碳储量与地上生物量的碳储量是否相关？我们发现整个生态系统的有机碳储量范围从未烧毁的高山草原中的 68 Mg OC ha-1 到冷杉林中的 668 Mg OC ha-1。通过避免转换 A. 从 religiosa 森林到耕地，我们表明可以避免 1,122 到 1,671 Mg CO2 ha-1 的排放。值得注意的是，地下土壤有机碳储量占生态系统总有机碳储量的 ≥ 40%。我们建议土壤有机碳储量应包括在墨西哥和全球林业碳储量清单中，并应考虑在用于激励墨西哥山地栖息地保护的自愿碳信用市场中。