Wu Xue, Liang Yueming, Zhao Wenwu, Pan Fujing
Guangxi Key Laboratory of Theory and Technology for Environmental Pollution Control, Guilin University of Technology, Guilin, 541004, China.
Karst Dynamics Laboratory, Ministry of Natural Resources, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, 541004, China.
BMC Plant Biol. 2025 Jan 2;25(1):8. doi: 10.1186/s12870-024-06016-1.
Nutrient limitation is a universal phenomenon in terrestrial ecosystems. Root and mycorrhizal are critical to plant nutrient absorption in nutrient-limited ecosystems. However, how they are modified by N and P limitations with advancing vegetation successions in karst forests remains poorly understood. The present study compared the diversity indices, composition, and co-occurrence network of arbuscular mycorrhizal fungi (AMF) between grassland, shrubland, shrub-tree forest, and tree forest in subtropical karst forests, as well as soil nutrients and fine root functional traits (e.g., specific root length (SRL), specific root area (SRA), diameter, biomass, and N and P contents).
The fine roots diameter, biomass, and N and P contents increased with advancing succession, whereas SRL and SRA decreased. Network complexity and Richness and Chao1 indices of AMF increased from grassland to shrub-tree forest but decreased in tree forest. The fine roots N and P contents were positively related to their diameter and biomass, soil nutrients, and AMF composition but were negatively correlated with SRL and SRA. Moreover, these two parameters increased with the increase of soil nutrients. The variations in fine roots N and P contents were mainly explained by soil nutrients and fine root functional traits in grassland and by the interactions of soil nutrients, fine root functional traits, and AMF in the other three stages. Additionally, the interactive explanation with AMF increased from shrubland to shrub-tree forest but decreased in tree forest.
Our results indicated that mycorrhizal strategy might be the main nutrient acquisition strategy under N and P co-limitation. In contrast, the root strategy is the main one when an individual is subject to limitations in N or P in karst ecosystems. Root and mycorrhizal nutrient acquisition strategies are generally mutualistic, mycorrhizal strategy enhances plant nutrient acquisition under N and P co-limitation.
养分限制是陆地生态系统中的普遍现象。在养分受限的生态系统中，根系和菌根对植物养分吸收至关重要。然而，随着喀斯特森林植被演替的推进，它们如何受到氮和磷限制的影响仍知之甚少。本研究比较了亚热带喀斯特森林中草地、灌丛、灌乔林和乔木林的丛枝菌根真菌（AMF）的多样性指数、组成和共生网络，以及土壤养分和细根功能性状（如比根长（SRL）、比根面积（SRA）、直径、生物量以及氮和磷含量）。
细根直径、生物量以及氮和磷含量随演替推进而增加，而SRL和SRA则下降。AMF的网络复杂性以及丰富度和Chao1指数从草地到灌乔林增加，但在乔木林中下降。细根氮和磷含量与它们的直径、生物量、土壤养分和AMF组成呈正相关，但与SRL和SRA呈负相关。此外，这两个参数随土壤养分的增加而增加。细根氮和磷含量的变化在草地中主要由土壤养分和细根功能性状解释，而在其他三个阶段则由土壤养分、细根功能性状和AMF的相互作用解释。此外，与AMF的交互解释从灌丛到灌乔林增加，但在乔木林中下降。
我们的结果表明，菌根策略可能是氮和磷共同限制下的主要养分获取策略。相比之下，在喀斯特生态系统中，当个体受到氮或磷限制时，根系策略是主要策略。根系和菌根养分获取策略通常是互利的，菌根策略在氮和磷共同限制下增强了植物养分获取。
