Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (1): 53-62.DOI: 10.3773/j.issn.1005-264x.2009.01.006

• Research Articles • Previous Articles     Next Articles

SOIL SYSTEM RESPIRATION AND ITS CONTROLLING FACTORS IN CUNNINGHAMIA LANCEOLATA AND PINUS MASSONIANA COMMUNITIES OF SUBTROPICAL CHINA

WANG Guang-Jun, TIAN Da-Lun(), YANG Wen-De, ZHU Fan, LI Shu-Zhan   

  1. College of Life Science and Technology, Central-South University of Forestry & Technology, Changsha 410004, China
  • Received:2008-02-28 Accepted:2008-06-05 Online:2008-02-28 Published:2009-01-30

Abstract:

Aims Cunninghamia lanceolata and Pinus massoniana forest ecosystems in subtropical China are important in national carbon budgets because of their large area and amount of carbon storage. Soil respiration is the second largest flux in the global carbon cycle, but the effect of these forest ecosystems on soil respiration is inadequately understood. Our objectives were to compare soil respiration rate, soil temperature, soil moisture and Q10 value of the two communities and to evaluate relationships between soil respiration rates and environment factors.
Methods We examined seasonal variations of soil respiration using an infrared gas exchange analyzer (Li-Cor 6400-09) from January to December 2007 in Tianjiling National Forestry Park, Changsha. Soil temperature and moisture were measured at the same time at 5 cm depth. At the middle of January, April, July and October, we examined whole samples of root biomasses at 60 cm depth. We evaluated Q10 values of soil respiration and correlations between soil respiration and environment factors.
Important findings The two communities had significantly different patterns in seasonal soil respiration processes. The two forests exhibited irregularly fluctuating curves during the study period with mean rates of soil respiration of 186.9 and 242.4 mg CO2·m-2·h-1 in C. lanceolata and P. massoniana stands, respectively. Significant relationships were found between soil respiration rate and soil temperature in both communities and are best described by exponential equations. However, no significant relationships were found between soil respiration and soil moisture. Soil temperature and moisture could explain changes in soil respiration of 91.7% and 78.0% in the C. lanceolata community and 5.4% and 8.4%, in the P. massoniana community. The relationship between soil respiration rate (y) and soil temperature (t) is described by the regression equation: y=34.09e 0.081 5t (R2=0.917, p<0.001), y=48.68e 0.075 4t (R2=0.780 3, p<0.001). R 2=0.917, p<0.001. The Q10 values in C. lanceolata and P. massoniana forests were 2.26 and 2.13, respectively, and tended to decrease when soil temperature increased from lower to higher scales. Seasonal patterns of soil respiration in these two forests were not only determined by soil temperature and soil moisture, but also by fine root mass and litter production.

Key words: subtropical forest, soil respiration, soil temperature, soil moisture, Q10 value, Cunninghamia lanceolata, Pinus massoniana