Fig. 2

Response of Soil Microbial Carbon Use Efficiency (CUE) to Different Factors. Microorganisms absorb carbon from the soil, with part of it used for growth(G) and the other part for respiration(R). The inner circle represents the proportion of carbon used for growth in the total carbon absorbed by microorganisms, which is called microbial carbon use efficiency (CUE). Six key factors are covered, starting from the top and proceeding clockwise: plant community composition and diversity; soil pH; substrate quality, nutrient availability and stoichiometric ratios (C: E represents the ratio of carbon (C) content to essential element (E) content in the substrate); soil texture (sand, loam, clay) and aggregates; water and thermal condition limitations (climate warming, drought, and humidity); external nutrient inputs (K, N, Ca, P)