How a winter wildfire affect plant community in subalpine grassland of western Sichuan, China?

Abstract

Aims It had been reported that there are relationships among soil physiochemical properties, soil microbial characteristics, and plant community structures. However, there is still a dispute about the best path of shaping plant community structure by fire. To assist with sustainably managing grassland ecosystem, a hypothesis was put forward on shaping of the plant community structure by winter wildfire in a subalpine grassland of western Sichuan, in which the effects of fire on soil environment (soil physiochemical properties and soil microbial characteristics) could explain the changes of post-fire plant community structure and diversity. Methods To test the abovementioned hypothesis, variables of soil physiochemical properties, soil microbial properties, and plant community structure in naturally burned and unburned areas at different locations were studied. For determination of the direct and indirect effects of fire on plant community structure and diversity, we simulated five paths that fire shapes the plant community structure and diversity by using structural equation modelling according to the result of non-metric multidimensional scaling analysis. Important findings The winter fire had little direct effects on plant community. The best-fit value was given by the path model in which winter fire changed soil microbial properties, which in turn affected plant community structure directly or indirectly by modifying soil physiochemical properties. The results suggested that the effects of the low-intensity fire on soil physiochemical properties and plant community structure may be achieved through mortality and reproduction of soil microbes. However, as the soil is a whole environment, it needs to be studied further to explore the roles of microbial activities in regulating soil biochemical cycle after fire, especially the nitrogen cycle.