Seasonal Changes in Soil Respiration with An Elevation Gradient in Abies nephrolepis (Trautv.) Maxim. Forests in North China

Abstract

Soil respiration (Rs) plays an important role in regulating carbon cycle of terrestrial ecosystems and presents temporal and spatial heterogeneity. Abies nephrolepis is a tree species that prefers the cold and wet environment and is mainly distributed in Northeast Asia and East Asia. The Rs variations of Abies nephrolepis forests communities are generally environmental-sensitive and can effectively reflect the adaptive responses of forest ecosystems to climate change. In this study, the growing-seasonal variations of Rs, soil temperature, soil water content and soil properties of Abies nephrolepis forests were analyzed along an altitude gradient (2000, 2100, 2200 and 2300 m) over two years on Wutai Mountain in North China. As the main results showed, soil respiration keeps the same change trend as soil temperature and reached peaks in July at 2000 m in 2019 and 2020. During 26 th July to 25 th October in 2019 and 27 th May to 23 rd October in 2020, on the whole, the soil temperature independently explained 76.2% of Rs variations while the soil water content independently explained 26.8%. Soil temperature and soil water content jointly explained 81.8% of Rs variations. Soil properties explained 61.8% and 69.6% of Rs variation in 2019 and 2020, respectively. Soil organic carbon content and soil enzyme activity had the significant (P < 0.01) negative and positive relationships, respectively, with Rs variation. With altitudes evaluated from 2000 to 2300 m, soil respiration temperature sensitivity (Q 10 ) and the soil organic carbon content increased by 12.4% and 10.4%, respectively, while invertase activity, cellulase activity and urease activity dropped by 41. 2%, 29.45% and 38.19%, respectively. The results demonstrate that (1) soil temperature is the major factor affecting Rs variations in Abies nephrolepis forests; (2) weakened microbial carbon metabolism in high-altitude areas results in the accumulation of soil organic carbon; (3) with a higher Q 10 , forest ecosystems in high-altitude areas might be more easily affected by climate change; (4) climate warming might accelerate the consumption of soil organic carbon sink in forest ecosystems, especially in high-altitude areas.

Warming Stimulated Soil Respiration in a Subalpine Meadow in North China

“…Li et al [46] reported a significant linear regression relationship existed between soil temperature and soil respiration under both warming and control conditions, and their correlation was weaker under warming condition than control condition. Tian et al [47] showed that 76.9% and 25.8% of variation in soil respiration were controlled by soil temperature and soil water content alone in the Abies nephrolepis forest in Mount Wutai. In our study, soil temperature explained more variations of soil respiration under control condition than those under warming condition which indicted warming decreased the reliance of soil respiration on soil temperature.…”