Ts variation is likely to explain the diurnal variation of Rs rather than SWC. In the measurement campaign of June, we found the maximum Rs rate exceed twice the minimum rate (from 3.43 to 9.91 μmol m-2s-1). Also, Rs occasionally showed distinctive diurnal variations. The Rs-SWC relationship shows that soil respiration increased with increases in SWC of below 45%, while the Rs declined with increases in SWC of over 45%. The relationship between Rs and Ts can be described with the exponential Q10 function, in which a comparatively higher Q10 value of 6.45 was estimated than that of previous averages (= 2 to 3). Seasonal variations of the Rs were considerably corresponded to both Ts and SWC with different patterns. Over 10-month observation, results showed the highest Rs and the most significant spatial variations in Rs in the summer seasons with maximum Rs averaged over 20 locations of 4 - 8.36 μmol m-2s-1. Once a month, we observed the Rs averaged over the 20 locations and the diurnal variation at 2 locations with soil temperature (Ts) and soil volumetric water contents (SWC) measurements. Rs rates were measured from April 2012 to February 2013 by using a closed dynamic chamber system.
The 20 measuring locations were set in a 200m2 plot, in which we inserted a 5-cm collar for Rs measurement. We selected a 200m2 plot in a conservatively managed moso bamboo stand in Natinal Taiwan University Forest, central Taiwan. We aimed to evaluate the seasonal and diurnal variations of Rs in a moso bamboo (Phyllostachys pubescens) forest in central Taiwan with their abiotic drivers. Understanding soil respiration (Rs) in moso bamboo stands is crucial for accessing potential impact of bamboo invasion on terrestrial carbon cycle in Asian regions.
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