Effect of Gap Size on the Dynamic of Micro Environments during the Daytime at Castanopsis kawakamii Natural Reserve Forest, Sanming City, China

Abstract

The temporal dynamics of micro-environments within gap size affect the species regeneration. This study aimed to determine the effects of gap size on the variation of micro-environments during the daytime. Nine sampling gaps at Castanopsis kawakamii Natural Reserve Forest, Sanming City, China were divided into three sizes (small, medium and large). The micro-environments viz. soil temperature at 0, 5 and 10 cm depth, air temperature, light intensity, and air relative humidity were recorded for the entire gap area in every 2 h interval from 8 am to 6 pm. The results showed time-dependent variations for these variables. In each gap size, the maximum light intensity was recorded from 10 am to 2 pm at the center of the gap, which was higher at the north and west directions than south and east directions, except for the north direction in large gap size. Light intensity has a significant positive correlation with soil temperature compared with that under canopy. Soil temperature responds differently according to the size of the gap that increased with time from morning to afternoon in large gap size with the highest during 12 to 2 pm which is different from small and medium gap sizes. Air temperature has a significant negative correlation with air relative humidity, both in gap sizes and under canopy. It could be concluded that gap size has a significant impact on the micro-environments and the variables in five directions were varied depending on the light intensity.