7440-44-0 Carbon Journal Article Soil 27YLU75U4W N762921K75 Nitrogen Phosphorus bacterial community carbon climate warming co-limitation ectomycorrhiza enzymes activity exploration types fine root biomass fine root morphology fine root production long-term soil warming long‐term soil warming microbial biomass carbon microbial carbon use efficiency microbial growth microbial necromass carbon nitrogen nutrient limitation nutrients phosphorus soil microbes soil phosphorus