Role of environmental factors on forest soil respiration characteristics in Jinyun Mountain of Chongqing, southwestern China

Taking Phyllostachys pubescens forest and broadleaved forest in Jinyun Mountain of Chongqing as object, the characteristics of daily, seasonal and annual variations of soil respiration and interactions between soil respiration and environmental factors were studied. Soil respiration rate in P. pubescens forest and broadleaved forest in Jinyun Mountain was measured by LI-8100. The results showed that: 1) daily variations in soil respiration rates of two stands slightly varied. The highest soil respiration rate of P. pubescens and broadleaved forest appeared in 16:00 to 18:00 and 10:00 to 20:00, respectively, while the minimum occurred at 06:00 and in 04:00 to 10:00, respectively. Monthly variations of soil respiration showed that growing season was significantly higher than non-growing season in the two stands. The seasonal variations of soil respiration were obvious in P. pubescens forest. The soil respiration rate was rising from the beginning of March, peaking at 5.00-6.18 g/(m2day) in July or August. And then it declined. However, the variations of soil respiration rate were relatively flat in broadleaved forest. In the two stands, all the variations of soil respiration rate were single-peak curve. Moreover, the annual variations of soil respiration in broadleaved forest were significantly greater than P. pubescens forest. 2) Single-factor analysis showed that soil respiration rate of P. pubescens forest was significantly positively correlated with soil temperature and atmospheric temperature. The soil respiration in broadleaved forest was significantly positively correlated with soil temperature and soil moisture content, while was significantly negatively correlated with atmospheric temperature. Soil respiration in broadleaved forest was greater consistent with meteorological factors than in P. pubescens forest. 3) Path analysis indicated that soil temperature and atmospheric temperature were two main factors affecting soil respiration in P. pubescens forest. In addition, soil temperature and soil moisture content were main factors affecting soil respiration in broadleaved forest.