摘要
森林土壤呼吸(RS)一般分为自养呼吸(RA)和异养呼吸(RH)两个组分,各组分对环境变化具有不同的响应,对土壤和生态系统的碳平衡产生重要影响。对全球不同生物群区、林龄的森林RS及其组分RH的研究文献进行检索与分析,结果表明:林地RS沿北方森林-温带针叶林-温带落叶林-热带林次序逐步升高,非相邻区系之间差异显著(α<0.05)。土壤异养呼吸组分(RH)及其贡献率(RH/RS),仅北方森林与热带林之间有显著性差异,其余区系之间无显著性差异(α>0.05)。异养呼吸组分贡献率(RH/RS),随着RS的不断增加,呈现出RH/RS率降低的总体趋势。对于林地RS,幼龄林显著高于中龄林和成熟林。RH/RS率随树龄增加而略微升高,但龄组之间没有显著性差异(α>0.05)。各生物群区及林龄的RH与RS之间显著性相关分析,为全球森林碳收支的估测提供有效的方法和数据基础。
Soil surface CO2 flux （Rs ） is overwhelmingly the product of respiration by roots （autotrophic respiration, RA ） and soil organisms （heterotrophie respiration, RH）. Partitioning soil carbon dioxide efflux with highly variable results has received considerable attention, as differential responses of these components to environmental change have profound implications for soil and ecosystem C balance. The contribution of each group needs to be understood to evaluate implications of environmental change on soil carbon cycling and sequestration. We present results of a strict literature search of soil surface CO2 flux and partitioning studies and analyze global trends in soil carbon dioxide flux and partitioning between biomes, and age classes. There are statistically different and increasing trends in soil surface CO2 flux between biomes following the sequence of biome types as boreal 〈 temperate coniferous 〈 temperate deciduous and tropical, whereas, it is somewhat surprising that no difference was found between neighboring biomes. RH is each strongly （R2 = 0.62 ） correlated to annual Rs across a wide range of forest ecosystems, biome type, measurement method and stand ages. Published data from all biome types indicate relatively wide range for the 95% confidence intervals, spanning 60% of flux contributions throughout the range of Rs. The results for forest ecosystems in different biomes confirm the general decline of RH/Rs with increasing Rs. Of the groups and Ru included in this comparison, only boreal and tropical forest sites are significantly different from each other. Boreal sites showed significantly higher （ ol 〈 0. 05） RH/Rs ratios than tropical sites, while either temperate or tropical forests did not differ in ratios from any of the other forest types. Significant difference emerged from the comparison of Rs and RH/Rs for forest stands of different age （ α〈 0.05 ）. Increasing stand age corresponded to smaller confidence intervals and generally lower flux sums for Rs, while, there is no significant difference between the three age groups （α〉 0.05 ）. While chronosequence studies report mild increase in the RH/Rs ratio with age, for the mean of RH/Rs ratio and variance, of young class is larger than that of intermediate and mature groups, no significant difference could be detected for different age groups in the global data set （α 〉 0.05 ）. Site-specific measurements are always more desirable than the application of inferred broad relationships. Measuring Rs is straightforward and commonly done; however, belowground measurements are difficult and expensive. Thus the relationships and RH/Rs rate for each biome presented here provide a new approach and useful baselines that can help constrain estimates of terrestrial carbon budgets.
出处
《生态学报》
CAS
CSCD
北大核心
2008年第9期4078-4087,共10页
Acta Ecologica Sinica
基金
国家"十一五"国家科技支撑资助项目(2006BAD03A07)
国家林业局重点资助项目(2006-68)~~
