Soil Respiration Of Pinus Tabulaeformis Forest During The Growing Season At Huoditang Forest Region In The Qinling Mountains

In order to research the major factors affecting soil respiration in Pinus tabulaeformis forest ecosystem in the Qinling Mountains and to obtain a relational model between soil respiration and key factors, by using LI-6400, a portable photosynthesis measuring system, soil respiration rate of P. tabulaeformis forest during the growing season at Huoditang was measured. Leaf area index was measured by LAI-2000 canopy analyzer. At the same time, variation of soil temperature, soil water content, radicula biomass and litter were also determined. The results showed that:(1) Soil respiration showed a unimodal curve between 8:00 to 18:00, and usually reached its maximum between 13:00^-15:00, the daily change remained the same between soil temperature and soil respiration.(2) Throughout the growing season, soil respiration rate had obvious seasonal variation and showed a unimodal curve. Soil respiration reached the maximum in late August, the value was 3.69μmol·m-2·s^-1, and the minimum in late November 0.52μmol·m-2·s^-1. The average value during the growing season was 1.82μmol·m-2·s^-1. Soil respiration rate containing litter was 2.72μmol·m-2·s^-1 each month, while the control was 1.97μmol·m-2·s^-1. The contribution of litter to soil respiration rate was 38.11%.(3)Leaf area index reached the maximum 4.32 in August, and decreased to the minimum 3.72 in November. The average during the growing season was 3.93. Radicula biomass in June reached the lowest at 255.77 g/m², while the highest was 324.57 g/m² in September. The average during the growing season is 296.26 g/m²(4) Main factor affecting the soil respiration was soil temperature at 5cm depth. Q10 of the soil respiration during the growing season was 3.63. The relevance between soil respiration and soil water content was not notable. Leaf area index, radicula biomass, littter had significant influence on the soil respiration rate. In addition, models between various kinds of influence factors and the soil respiration were set up. This has significant meaning for estimating the carbon cycle of Pinus Tabulaeformis forest ecosystem in the Qinling Mountains.