Chin J Plant Ecol ›› 2022, Vol. 46 ›› Issue (4): 473-483.DOI: 10.17521/cjpe.2021.0346

• Research Articles • Previous Articles     Next Articles

Difference of microbial nutrient limiting characteristics in rhizosphere and bulk soil of coniferous forests under nitrogen deposition in southwest mountain, China

ZHANG Ying1,2, ZHANG Chang-Hong1,2, WANG Qi-Tong1,*(), ZHU Xiao-Min1, YIN Hua-Jun1   

  1. 1Chengdu Institute of Biology, Chinese Academy of Sciences, Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization of Chinese Academy of Sciences, and Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu 610041, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2021-09-29 Accepted:2021-11-20 Online:2022-04-20 Published:2022-01-07
  • Contact: WANG Qi-Tong
  • Supported by:
    National Natural Science Foundation of China(31872700);National Natural Science Foundation of China(32171757);National Natural Science Foundation of China(31901131);Chinese Academy of Sciences (CAS) Interdisciplinary Innovation Team(xbzg-zdsys-202112)


Aims Long-term nitrogen (N) deposition induces soil nutrient imbalance and profoundly affects nutrient cycling processes, ecological functions and the sustainable development of forest ecosystems. Although previous studies have found that N deposition increased phosphorus (P) limitation of forest trees in southwest mountainous areas, China, whether soil microorganisms showed synergistic response with plants remains unclear.

Methods In this study, we measured soil available nutrients, soil microbial biomass carbon (C), N, P and extracellular enzyme activities in a typical subalpine coniferous plantation (Pinus armandii) with chronic N addition treatments in southwest China. Furthermore, three models of ecoenzymatic stoichiometry, i.e., enzymatic ratio model, vector analysis model and threshold element ratio model were used to evaluate changes of microbial nutrient limitation under N addition.

Important findings The results showed that: 1) N addition significantly increased the P-acquiring enzyme activities by 52.5% and 53.2% in rhizosphere soil and bulk soil respectively, leading to a decrease of enzymatic N:P ratio by 7.8% and 4.8% compared to the control in rhizosphere soil and bulk soil respectively. 2) Vector model analysis found that vector angles of two soil compartments under N addition exceeded 45°, and the vector angles of rhizosphere soil and bulk soil were 52.2° and 49.0°, respectively. 3) The C:P threshold ratios (TERC:P) of microbes in two soil compartments were significantly reduced by N addition. Consequently, the ratio of TERC:P to available C:P (AvC:P) was much less than 1, and the response of rhizosphere microbes was more significant. Collectively, all three models of ecoenzymatic stoichiometry indicated that N deposition aggravated P-limitation of microbial metabolism, and the extent of P limitation was more intense in the rhizosphere soil, which was closely related to nutrient contents and stoichiometric ratios of soil and microbes. The findings of this study provide an important scientific basis for adaptive management of forest ecosystems under global climate change.

Key words: microbial nutrient limitation, soil enzyme stoichiometry, nitrogen deposition, rhizosphere/bulk soil, coniferous forest