Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, 510650, China.
Department of Geography and Resource Management, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
J Environ Manage. 2021 Oct 1;295:113142. doi: 10.1016/j.jenvman.2021.113142. Epub 2021 Jun 26.
The impact of human activities on soil carbon (C) storage in tropical forests has aroused wide concern during the past decades, because these ecosystems play a key role in ameliorating global climate change. However, there remain uncertainties about how land-use history alters soil organic carbon (SOC) stability and storage in different forests. In this study, we measured the C content and mass distributions of soil aggregates, density fractions, mineral-bound C and microbial biomass C in the organic horizon, 0-10 cm and 10-20 cm soil layers in coniferous forest and evergreen broadleaf forest at Dinghushan Biosphere Reserve in tropical China. The broadleaf forest had larger SOC stocks than the coniferous forest, but the proportion of SOC stored in different density fractions at 0-10 cm soils was similar between forest types, while a greater proportion of SOC was stored in microaggregates in the coniferous forest. Most of the SOC was held as light fraction C in the organic horizon in the coniferous forest, whereas the concentrations of mineral-bound C were higher in the broadleaf forest. These findings indicate clear differences in the protection of SOC between broadleaf and coniferous forests growing on the same soil type. We propose that historic conversion of broadleaf forest to coniferous forest has reduced soil C sequestration capacity by altering the diversity and quality of plant inputs to the soil, which in turn affected macroaggregate formation, soil chemical properties and microbial biomass. Our results thus demonstrate that changes in forest tree species composition could have long-lasting effects on soil structure and carbon storage, providing crucial evidence for policy decisions on forest carbon sink management.
人类活动对热带森林土壤碳（C）储存的影响在过去几十年中引起了广泛关注，因为这些生态系统在改善全球气候变化方面发挥着关键作用。然而，关于土地利用历史如何改变不同森林中土壤有机碳（SOC）稳定性和储存仍然存在不确定性。在这项研究中，我们测量了中国热带鼎湖山生物圈保护区针叶林和常绿阔叶林有机层、0-10 cm 和 10-20 cm 土壤层中土壤团聚体、密度分数、矿物结合碳和微生物生物量 C 的 C 含量和质量分布。阔叶林的 SOC 储量大于针叶林，但两种林型 0-10 cm 土壤中不同密度分数储存的 SOC 比例相似，而针叶林中 SOC 更多地储存在微团聚体中。在针叶林的有机层中，大部分 SOC 以轻组分 C 的形式存在，而在阔叶林，矿物结合碳的浓度更高。这些发现表明，在同一土壤类型上生长的阔叶林和针叶林在保护 SOC 方面存在明显差异。我们提出，阔叶林向针叶林的历史转化通过改变植物输入土壤的多样性和质量，从而影响大团聚体的形成、土壤化学性质和微生物生物量，从而降低了土壤的碳固存能力。因此，我们的研究结果表明，森林树种组成的变化可能对土壤结构和碳储存产生持久影响，为森林碳汇管理的政策决策提供了重要证据。
