Soil respiration (R_S) is a critical process in the global carbon (C) cycle and the primary path whereby plant–fixed C returns to the atmosphere via soil microbes, plant roots and soil fauna. 

The land use change from tropical forests to rubber plantations has had a great influence on ecosystem‐level C exchange and soil C dynamics. However, the effects of stand age on the variation in R_S in tropical forests are still largely unknown. 

Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) conducted a study to assess the variation of soil respiration and its components in rubber plantations of different stand age.  

The result has been published in European Journal of Soil Science. 

The researchers selected four rubber plantations, one 12-year-old (young-aged), one 24-year-old (mature-aged), one 32-year-old (mature-aged), and one 49-year-old (oldgrowth-aged) plantation. They used a trenching method to partition R_S into autotrophic respiration (R_A) and heterotrophic respiration (R_H) in rubber plantations of four different stand ages 

They found that soil respiration components and their temperature sensitivities varied among rubber plantations of different stand age. Soil respiration had a clear seasonal variation with higher values in the rainy, warm season than those in the dry, cold season. 

They further found that R_S tended to increase with the increasing stand age. While the biotic and abiotic factors that affect R_S varied among rubber plantations of different stand age, R_S was greatest in the old-growth rubber plantation.  

The contribution of autotrophic respiration (R_A) to R_S was higher in the mature stands. The old-growth plantation had relatively higher Q₁₀ values than the young and mature plantations. 

"Our results highlight the importance of environmental factors in determining the variation in R_S in rubber plantations with different stand age. With considering the stand age effect, the accuracy of soil respiration estimation will be improved under future climate scenarios", said Prof. ZHANG Yiping, correspondence author of the study.