Seasonal and spatial variation in soil respiration in afforested sugarcane fields on Entisols, Taiwan

Abstract

Afforestation increases the carbon stock in forest ecosystems. However, the spatial distribution of soil respiration (Rs) and its sensitivity to global climate change in tropical afforestation areas are still uncertain. The objectives of this study were (1) to quantify the seasonal and spatial variations and (2) to investigate the factors that control the seasonal and spatial variations in Rs in afforested sugarcane fields on Entisols, Taiwan. The estimated total annual Rs ranged from 8.99 to 11.67 Mg C ha−1 year−1, with a mean of 10.66 Mg C ha−1 year−1 in the Pingdong site. Rs and the abiotic factors such as soil temperature and soil moisture measurements displayed high seasonal and spatial variations. Seasonally, the Rs was significantly related to the soil temperature and soil moisture. The soil temperature was confirmed to be the primary driver of temporal variability in the study, with soil moisture playing a secondary role, especially in the wet season. Spatially, the decreased coefficient of variation (CV) values of soil moisture in the spatial variation were likely the result of the homogenous soil texture, which was the result of well-cultivated soil and good drainage systems. Moreover, tree characteristics such as tree volume and litterfall were also biotic factors influencing the Rs. Finally, our study highlighted the potential importance of understanding the response of Rs to the environmental and physiological processes co-control, especially in a younger age of afforested sugarcane fields on Entisols.