Effects of Gaps on Soil Nutrients and Soil Microbial Carbon in a Pinus massoniana Forest, Southwestern China.

To study the influences of gap size on the variation in soil nutrients, soil microbial carbon (micro-C), soil samples from Pinus massoniana forests were collected in and around different forest gaps with size ranging from 40.38 to 1321.40 m2 in Guizhou Province. The soil nutrients (include SOC, TP, TK, TKN, valid-P, valid-K and hydro-N) and micro-C in soil samples were analyzed, and the artificial neural networks was employed to explore the importance of different soil nutrients and gap size concerning micro-C. The results indicate that the micro-Cgap ranged from 38.00 to 660.32 mg kg-1 with a mean value of 221.24 mg kg-1, and the micro-Cforest ranged from 110.70 to 685.62 mg kg-1 with a mean value of 356.16 mg kg-1. The micro-Cgap/micro-Cforest values increased with the increase of gap size in the range from 40 to 600 m2, and this trend inversed when gap size was greater than 600 m2. Micro-C was mainly associated with valid-P for both gaps and surrounding forests, large gap may lead to the loss of soil N. The results suggested that: (a) SOC, TK, TKN, hydro-N and valid-P are important factors to microbial in forest soils; (b) TP, valid- K, TKN, TK, valid-P and SOC are important factors to microbial in gap soils. In summary, gaps can increase the heterogeneity of soil nutrients and soil microbial, valid-P is a key factor affecting microbial abundance for Pinus massoniana forest. These promote the preservation of biodiversity and pedodiversity. [ABSTRACT FROM AUTHOR]