Plant clipping may cause overestimation of soil respiration in a Tibetan alpine meadow, southwest China

The chamber-based method is currently the most popular approach used for measuring soil respiration of various ecosystems. When this method is applied, aboveground plant tissues within the chamber need to be clipped some time (usually 24 h) before measuring soil respiration. However, plant clipping may change soil temperature and hence soil respiration because soil respiration is highly temperature-dependent, particularly in cold regions. To determine to what extent soil respiration may be changed by the clipping, we measured soil temperature and respiration of an alpine meadow of southwest China using a chamber-based method over an annual cycle. Based on the measurements, an exponential equation was built to describe the relationship between soil respiration and temperature. Concurrently we measured the soil temperature in clipped and unclipped plots on sunny days of the study months in another independent experiment; subsequently soil respiration was estimated for these plots using the exponential equation. Though daily mean soil temperature was insignificantly different between the clipped and unclipped plots, the clipping increased soil temperature at 5 cm depth by up to 4.3A degrees C at daytime but decreased by up to 1.4A degrees C at nighttime during the growing season. The changes were 2.2 and 1.5A degrees C at daytime and nighttime, respectively, in the non-growing season. It was calculated that the clipping manipulation caused an overestimation of soil respiration by 28.6 and 21.2% for the growing and non-growing seasons, respectively; nevertheless, this calculated overestimation should differ from the actual one because the data were collected on sunny days only.