School of Agriculture and Food Science, University of Queensland, Brisbane, Queensland, 4072, Australia.
Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90736, Umeå, Sweden.
Microb Ecol. 2020 Feb;79(2):432-442. doi: 10.1007/s00248-019-01414-7. Epub 2019 Aug 1.
Widespread and continuing losses of tropical old-growth forests imperil global biodiversity and alter global carbon (C) cycling. Soil organic carbon (SOC) typically declines with land use change from old-growth forest, but the underlying mechanisms are poorly understood. Ecological restoration plantations offer an established means of restoring aboveground biomass, structure and diversity of forests, but their capacity to recover the soil microbial community and SOC is unknown due to limited empirical data and consensus on the mechanisms of SOC formation. Here, we examine soil microbial community response and SOC in tropical rainforest restoration plantings, comparing them with the original old-growth forest and the previous land use (pasture). Two decades post-reforestation, we found a statistically significant but small increase in SOC in the fast-turnover particulate C fraction. Although the δC signature of the more stable humic organic C (HOC) fraction indicated a significant compositional turnover in reforested soils, from C pasture-derived C to C forest-derived C, this did not translate to HOC gains compared with the pasture baseline. Matched old-growth rainforest soils had significantly higher concentrations of HOC than pasture and reforested soils, and soil microbial enzyme efficiency and the ratio of gram-positive to gram-negative bacteria followed the same pattern. Restoration plantings had unique soil microbial composition and function, distinct from baseline pasture but not converging on target old growth rainforest within the examined timeframe. Our results suggest that tropical reforestation efforts could benefit from management interventions beyond re-establishing tree cover to realize the ambition of early recovery of soil microbial communities and stable SOC.
广泛而持续的热带原始森林丧失危及全球生物多样性，并改变全球碳（C）循环。土壤有机碳（SOC）通常随着从原始森林到土地利用的变化而下降，但潜在机制尚不清楚。生态恢复种植园提供了恢复森林地上生物量、结构和多样性的既定手段，但由于有限的经验数据和对 SOC 形成机制的共识，它们恢复土壤微生物群落和 SOC 的能力尚不清楚。在这里，我们研究了热带雨林恢复种植园中土壤微生物群落的响应和 SOC，将其与原始原始森林和先前的土地利用（牧场）进行了比较。在重新造林后的二十年，我们发现 SOC 在快速转化的颗粒 C 部分有一个统计上显著但很小的增加。尽管更稳定的腐殖质有机 C（HOC）部分的 δC 特征表明在重新造林的土壤中发生了显著的组成转化，从 C 牧场衍生的 C 到 C 森林衍生的 C，但与牧场基线相比，这并没有转化为 HOC 的增加。匹配的原始雨林土壤的 HOC 浓度明显高于牧场和重新造林的土壤，土壤微生物酶效率和革兰氏阳性菌与革兰氏阴性菌的比例也遵循相同的模式。恢复种植园具有独特的土壤微生物组成和功能，与基线牧场不同，但在考察的时间范围内并未与目标原始雨林趋同。我们的结果表明，热带重新造林工作可以受益于管理干预措施，而不仅仅是重新建立树木覆盖，以实现土壤微生物群落和稳定 SOC 早期恢复的目标。
