Rhizospheric and heterotrophic respiration of a warm-temperate oak chronosequence in China

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• 作者：Junwei Luan^a ; ^b ; ¹ ; ^{luan_jw@yahoo.com.cn} ; Shirong Liu^a ; ^b ; ^{liusr@caf.ac.cn} ; Jingxin Wang^c ; ^{jxwang@wvu.edu} ; Xueling Zhu^d ; ^{zhubt110@hotmail.com} ; Zuomin Shi^a ; ^b ; ^{shizm@caf.ac.cn}
• 关键词：Soil respiration ; Heterotrophic respiration ; Root respiration ; Forest age ; Fine root biomass ; Soil organic carbon ; Light fraction organic carbon ; Q₁₀
• 刊名：Soil Biology & Biochemistry
• 出版年：2011
• 出版时间：March 2011
• 年：2011
• 卷：43
• 期：3
• 页码：503-512
• 全文大小：951 K

文摘

Plot trenching and root decomposition experiments were conducted in a warm-temperate oak chronosequence (40-year-old, 48-year-old, 80-year-old, and 143-year-old) in China. We partitioned total soil surface CO₂ efflux (R_S) into heterotrophic (R_H) and rhizospheric (R_R) components across the growing season of 2009. We found that the temporal variation of R_R and R_H can be well explained by soil temperature (T₅) at 5 cm depth using exponential equations for all forests. However, R_R of 40-year-old and 48-year-old forests peaked in September, while their T₅ peaks occurred in August. R_R of 80-year-old and 143-year-old forests showed a similar pattern to T₅. The contribution of R_R to R_S (RC) of 40-year-old and 48-year-old forests presented a second peak in September. Seasonal variation of R_R may be accounted for by the different successional stages. Cumulative R_H and R_R during the growing season varied with forest age. The estimated R_H values for 40-year-old, 48-year-old, 80-year-old and 143-year-old forests averaged 431.72, 452.02, 484.62 and 678.93 g C m⁻², respectively, while the corresponding values of R_R averaged 191.94, 206.51, 321.13 and 153.03 g C m⁻². The estimated RC increased from 30.78 % in the 40-year-old forest to 39.85 % in the 80-year-old forest and then declined to 18.39 % in the 143-year-old forest. We found soil organic carbon (SOC), especially the light fraction organic carbon (LFOC), stock at 0–10 cm soil depth correlated well with R_H. There was no significant relationship between R_R and fine root biomass regardless of stand age. Measured apparent temperature sensitivity (Q₁₀) of R_H (3.93 ± 0.27) was significantly higher than that of R_R (2.78 ± 0.73). Capillary porosity decreased as stand age increased and it was negatively correlated to cumulative R_S. Our results emphasize the importance of partitioning soil respiration in evaluating the stand age effect on soil respiration and its significance to future model construction.