Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Sci Total Environ. 2024 Oct 15;947:174672. doi: 10.1016/j.scitotenv.2024.174672. Epub 2024 Jul 14.
Tropical forests are sensitive to nitrogen (N) and phosphorus (P) availability, and under nutrient application the variation of soil organic carbon (SOC) preserving mechanism remains to be explored. To reveal the forest-specific SOC preservation via biochemical selection in response to nutrient application, we investigated a monoculture (Acacia plantation) and a multispecies forest both with chronic fertilization in subtropical regions, and measured specific fingerprints of plant- and microbial-derived C compounds. In addition, to quantify the effect of P application on SOC content among tropical forests, we conducted a meta-analysis by compiling 125 paired measurements in field experiments from 62 studies. In our field experiment, microbial community composition and activity mediated forest-specific responses of SOC compounds to P addition. The shift of community composition from fungi towards Gram-positive bacteria in the Acacia plantation by P addition led to the consumption of microbial residual C (MRC) as C source; in comparison, P addition increased plant species with less complex lignin substrates and induced microbial acquisition for N sources, thus stimulated the decomposition of both plant- and microbial-derived C. Same with our field experiment, bulk SOC content had neutral response to P addition among tropical forests in the meta-analysis, although divergences could happen among experimental durations and secondary tree species. Close associations among SOC compounds with biotic origins and mineral associated organic C (MAOC) in the multispecies forest suggested contributions of both plant- and microbial-derive C to SOC stability. Regarding that fungal MRC closely associated with MAOC and consisted of soil N pool which tightly coupled to SOC pool, the reduce of fungal MRC by chronic P addition was detrimental to SOC accumulation and stability in tropical forests.
热带森林对氮（N）和磷（P）的有效性敏感，在施加养分的情况下，土壤有机碳（SOC）的保存机制变化仍有待探索。为了揭示通过营养应用对生物化学选择的森林特有 SOC 保存机制，我们研究了亚热带地区的单一栽培（相思林）和多物种森林，这两个地区都进行了长期施肥，并测量了植物和微生物衍生的 C 化合物的特定指纹。此外，为了量化 P 应用对热带森林 SOC 含量的影响，我们通过编译来自 62 项研究的 125 项现场实验中的配对测量数据进行了荟萃分析。在我们的现场实验中，微生物群落组成和活性介导了 SOC 化合物对 P 添加的森林特异性响应。在 P 添加下，从真菌向革兰氏阳性细菌的群落组成转变导致微生物残留 C（MRC）作为 C 源被消耗；相比之下，P 添加增加了具有较少复杂木质素底物的植物物种，并诱导微生物获取 N 源，从而刺激了植物和微生物衍生 C 的分解。与我们的现场实验一样，尽管在实验持续时间和次生树种之间存在差异，但在荟萃分析中，热带森林的 bulk SOC 含量对 P 添加呈中性反应。在多物种森林中，与生物起源有关的 SOC 化合物与与矿物有关的有机 C（MAOC）之间存在密切关联，这表明植物和微生物衍生的 C 都对 SOC 稳定性有贡献。由于与 MAOC 密切相关的真菌 MRC 由土壤 N 库组成，而土壤 N 库与 SOC 库紧密耦合，长期 P 添加减少真菌 MRC 不利于热带森林 SOC 的积累和稳定。
