华南地区5种人工幼林的土壤呼吸及其季节性变化

为了解华南人工林的碳固存机制,对广东鹤山的尾叶桉(Eucalyptus urophylla)纯林、30种树种混交林、10种树种混交林、红椎(Castanopsis hystrix)纯林、厚荚相思(Acacia crassicarpa)纯林5种人工林(林龄2–5 a)的土壤总呼吸(Rs)和自养呼吸(Ra)的季节变化进行了研究。结果表明,从2007年到2012年,5种人工林的Rs为81.3~103.9 mg C m–2h–1,Ra为11.2~22.3 mg C m–2h–1,自养呼吸贡献率(RC)为12.4%~26.9%,且5种人工林间的Rs、Ra及RC差异不显著。5种人工林湿季的Rs均显著大于干季的,平均高出311.4%;Ra、RC的季节性差异不显著。湿季土壤温度与Rs具有显著相关性,土壤温度解释了90.2%的变异,而两者关系在干季不显著。人工林间的微环境和土壤条件差异不明显,可能是由于造林时间短,土壤还处于干扰的恢复过程中,导致人工林间土壤呼吸差异不显著。

Soil Respiration and Its Seasonal Variation among Five Young Plantations in South China

In order to understand the mechanisms of soil carbon sequestration of plantations in South China, the total soil respiration (R_s) and autotrophic respiration (R_a) and their seasonal dynamics of five plantations in Heshan, Guangdong at 2-5-year-old were studied from 2007 to 2012. The plantations include Eucalyptus urophylla plantation, 30 species mixed plantation, 10 species mixed plantation Castanopsis hystrix plantation, and Acacia crassicarpa plantation. The results showed that average R_s, R_a and contribution rate of R_a to R_s (RC) of these plantations ranged within 81.3-103.9 mg C m^-2h^-1, 11.2-22.3 mg C m^-2h^-1, and 12.4%-26.9%, respectively. The average R_s in wet season of these plantations were 311.4% higher than that in dry season; while R_a and RC had not significant difference between wet and dry seasons. The soil temperature in wet season had significant relation with R_s among five plantations, which explained the variation of R_s for 90.2%, but they had no relation in dry season. The difference of microenvironment and soil condition among these young plantations was no obvious, in which soil was still restoring from disturbance, so that soil respiration had no significant difference among five plantations.