Effects of seasonal variation on soil microbial community structure and enzyme activity in a Masson pine forest in Southwest China

Soil microbial communities and enzyme activities play key roles in soil ecosystems. Both are sensitive to changes in environmental factors, including seasonal temperature, precipitation variations and soil properties. To understand the interactive mechanisms of seasonal changes that affect soil microbial communities and enzyme activities in a subtropical masson pine (Pinus massoniana) forest, we investigated the soil microbial community structure and enzyme activities to identify the effect of seasonal changes on the soil microbial community for two years in Jinyun Mountain National Nature Reserve, Chongqing, China. The soil microbial community structure was investigated using phospholipid fatty acids (PLFAs). The results indicated that a total of 36 different PLFAs were identified, and 16:0 was found in the highest proportions in the four seasons, moreover, the total PLFAs abundance were highest in spring and lowest in winter. Bacteria and actinomycetes were the dominant types in the study area. Seasonal changes also had a significant (P < 0.05) influence on the soil enzyme activity. The maximum and minimum values of the invertase and catalase activities were observed in autumn and winter, respectively. However, the maximum and minimum values of the urease and phosphatase acid enzymatic activities were found in spring and winter, respectively. Canonical correspondence analysis (CCA) analysis revealed that the seasonal shifts in soil community composition and enzyme activities were relatively more sensitive to soil moisture and temperature, but the microbial community structure and enzyme activity were not correlated with soil pH in the study region. This study highlights how the seasonal variations affect the microbial community and function (enzyme activity) to better understand and predict microbial responses to future climate regimes in subtropical area.