Wallwork Abby, Banin Lindsay F, Dent Daisy H, Skiba Ute, Sayer Emma
Lancaster Environment Centre Lancaster University Lancaster UK.
UK Centre for Ecology & Hydrology Penicuik UK.
Funct Ecol. 2022 Dec;36(12):3175-3187. doi: 10.1111/1365-2435.14221. Epub 2022 Nov 10.
Regenerating tropical forests are increasingly important for their role in the global carbon cycle. Carbon stocks in above-ground biomass can recover to old-growth forest levels within 60-100 years. However, more than half of all carbon in tropical forests is stored below-ground, and our understanding of carbon storage in soils during tropical forest recovery is limited.Importantly, soil carbon accumulation does not necessarily reflect patterns in above-ground biomass carbon accrual during secondary forest succession, and factors related to past land use, species composition and soil characteristics may influence soil carbon storage during forest regrowth.Using tree census data and a measure of tree community shade tolerance (species-specific light response values), we assessed the relationship between soil organic carbon stocks and tree functional groups during secondary succession along a chronosequence of 40- to 120-year-old naturally regenerating secondary forest and old-growth tropical forest stands in Panama.While previous studies found no evidence for increasing soil C storage with secondary forest age, we found a strong relationship between tree functional composition and soil carbon stocks at 0-10 cm depth, whereby carbon stocks increased with the relative influence of light-demanding tree species. Light demanding trees had higher leaf nitrogen but lower leaf density than shade-tolerant trees, suggesting that rapid decomposition of nutrient-rich plant material in forests with a higher proportion of light-demanding species results in greater accumulation of carbon in the surface layer of soils. . We propose that soil carbon storage in secondary tropical forests is more strongly linked to tree functional composition than forest age, and that the persistence of long-lived pioneer trees could enhance soil carbon storage as forests age. Considering shifts in tree functional groups could improve estimates of carbon sequestration potential for climate change mitigation by tropical forest regrowth. Read the free Plain Language Summary for this article on the Journal blog.
正在恢复的热带森林因其在全球碳循环中的作用而变得越来越重要。地上生物量中的碳储量可在60至100年内恢复到原始森林水平。然而，热带森林中超过一半的碳储存在地下，而我们对热带森林恢复过程中土壤碳储存的了解有限。重要的是，土壤碳积累不一定反映次生林演替过程中地上生物量碳积累的模式，与过去土地利用、物种组成和土壤特性相关的因素可能会影响森林再生过程中的土壤碳储存。利用树木普查数据和树木群落耐荫性指标（特定物种的光响应值），我们沿着巴拿马40至120年自然再生次生林和原始热带森林林分的时间序列，评估了次生演替过程中土壤有机碳储量与树木功能组之间的关系。虽然先前的研究没有发现土壤碳储量随次生林年龄增加的证据，但我们发现0至10厘米深度处树木功能组成与土壤碳储量之间存在很强的关系，即碳储量随着喜光树种的相对影响而增加。与耐荫树种相比，喜光树木的叶片氮含量较高，但叶片密度较低，这表明在喜光树种比例较高的森林中，营养丰富的植物材料快速分解导致土壤表层碳积累更多。我们认为，热带次生林中的土壤碳储存与树木功能组成的联系比与森林年龄的联系更紧密，并且随着森林老化，长寿先锋树的持续存在可能会增强土壤碳储存。考虑树木功能组的变化可以改进对热带森林再生缓解气候变化碳固存潜力的估计。在期刊博客上阅读本文的免费通俗易懂摘要。
