Subtropical ecosystems are receiving unprecedented changes in temperature as consequence of anthropogenic activities, which potentially affects soil respiration (Rs) and carbon (C) sequestration. Due to the large amounts of C store and cycle in subtropical forests, investigations about how Rs and C sequestration respond to warming will be critical for our understanding of future global-scale climate and biogeochemical cycling.
Prof. ZHOU Guoyi and his students of SCBG transferred soil samples and plant seedlings collected from a mixed forest to the growth chambers in two sites (300 m and 30 m a.s.l.), which induced an artificial warming of ca. 1 ℃ between the two corresponding forest mesocosms. The study tested whether the modification of abiotic factors induced by the downward translocation could alter Rs and soil C sequestration. And it also investigated the effects on the biotic factors by including root biomass and soil microbial biomass.
The results showed that Rs was greater in the warm site than in the control site, which were related to the higher aboveground biomass, litterfall and root biomass. Rs showed a significantly positive exponential relationship with soil temperature. The downward translocation tended to decrease soil C sequestration, which was attributed to the decreased C use efficiency of soil microorganisms and increased root growth under downward translocation.（The study entitled “Potential effects of warming on soil respiration and carbon sequestration in a subtropical forest” has been published in Plant and Soil）.
Fig. 1 Dynamics of soil temperature (a), volumetric water content (b) at 10 cm depth in the control and warm sites from July 2012 to December 2014. Data are means ± SE
Fig. 2 Relationships between soil respiration rate and soil temperature (a and b) and volumetric water content (c and d) (below 0.20 m3 m？3) at 10 cm depth in the warm and control sites
Fig. 3 Litterfall production in the warm and control sites in 2014. Data are mean ± SE