Zhao, K., Wang, Zh., Jia, Zh.* and Ma, L.*2017. Effects of Spatial-Temporal Variation and Biological Factors on Stem Respiration of Larix principis-rupprechtii Mayr. Baltic Forestry 23(3): 564-575.

   This study was conducted to expose the rule of stem respiration change in temporal variations, spatial variations, biological factors and analyze the reasons of the stem respiration change for investigated stem respiration rate (Rs) in Prince Rupprecht's Larch (Larix principis-rupprechtii Mayr) plantation using the soil carbon flux system (Li-8100) during the growing season (May to September) and the non-growing season (October) in Saihanba National Forest Park. The results are listed below. (1) The daily dynamics and seasonal dynamics of Rs obeyed single-peak curves. (2) Except for September, Rs significantly differed among stem heights. (3) The annual Rs changed with the increased thinning intensity (TI) as follows: TI 20% (1.68 μmol m-2 s-1) < TI 15% (1.83) < control (1.89) < TI 30% (1.92) < TI 35% (2.82). (4) The annual CO2 emission per unit area changed with crown height (CH) as follows: CH 2:3 (8.32 t ha-1) (control, non-pruned) > CH 1:3 (7.60) (intense pruning) > CH 1:2 (7.21) (slight pruning). (5) The Rs of trees with large and middle diameter grades (diameter at breast height DBH 170-210 vs. 120-160 mm) were not significantly different, but were both higher than trees with small diameter grade (DBH 70-110 mm). This study clarifies the response of stem respiration rate to various influencing factors and helps to accurately estimate the carbon emissions from stem respiration.

   Keywords: biological factors, carbon emission, Larix principis-rupprechtii, spatial-temporal variations, stem respiration