五种荒漠灌木群落土壤有机碳垂直分布及其与根系分布的关系

Vertical distribution of soil organic carbon and its relation to root distribution in five desert shrub communities

研究土壤有机碳与根系分布之间关系对评估碳储量和固碳潜力具有重要意义,而我国荒漠区灌木群落土壤有机碳与植物根系之间的关系尚不清楚。本研究选取深根性表层型灌木（表层根系生物量最大）梭梭（Haloxylon ammodendro）和中间锦鸡儿（Caragana intermedia）、深根性非表层型（表层根系生物量不是最大）灌木白刺（Nitratia tangutorum）、浅根性表层型灌木红砂（Reaumuria songarica）及浅根性非表层型灌木霸王（Sarcozygium xanthoxylon）为优势种的5种荒漠灌木群落为研究对象,测定100 cm深度内不同层次根系生物量及土壤有机碳含量,探讨灌木群落土壤有机碳的垂直分布格局及其与根系之间的关系。结果显示：（1）0~100 cm土壤有机碳密度与群落0~20 cm根系生物量碳密度显著正相关,与其他层次或累积深度不显著相关;（2）梭梭群落0~100 cm土壤有机碳密度显著低于与其他4个群落（P〈0.01）,其他4个群落无显著差异（P〉0.05）;（3）优势种为表层型的梭梭、中间锦鸡儿和红砂群落土壤有机碳密度与群落及优势种根系变化趋势一致,优势种为浅根性非表层型的霸王群落仅表层40 cm土壤有机碳与优势种灌木根系分布规律一致,优势种为深根性非表层型的白刺群落土壤有机碳与优势种根系分布规律一致。本研究表明,荒漠灌木群落0~100 cm土壤有机碳储量与群落0~20 cm根系生物量显著相关,群落优势种根系分布类型是影响土壤有机碳垂直分布格局的重要因素。

Exploring the relationship between soil organic carbon （SOC） and root distribution is essential for evaluating carbon stock and sequestration potential in terrestrial ecosystems. However, the relationship between SOC and root in shrub communities in desert grassland of China is not clear yet. In this study, we selected five shrub communities Haloxylon ammodendro and Caragana intermedia with deep root but root biomass concentrated in the shallow soil layer, Nitratia tangutorum with deep root and root biomass not concentrated in the shallow soil layer, Reaurnuria songarica with shallow root and root bimass concentrated in the shallow soil layer, Sarcozygium xanthoxylon with shallow root but root bimass not concentrated in the shallow soil layer, to ex- plore the relationship between SOC and root biomass in shrub communities. Root biomass density （RBD） and soil organic carbon density （SOCD） in different soil layers of a 0-100 cm soil profile were investigated. Our results showed that （ 1 ） the SOCD in the 0-100 cm soil profile was positively correlated with the RBD in 0-20 cm layer, while it had no significant correlationship with RBD in other layers; （2） the SOCD in 100 cm soil profile of H. ammodendron community was significantly lower than those of the other communities （P〈0.01） , however, there were no significant differences among the other four communities （P〉0.05） ; （3） the vertical distributon of SOCD in H. ammodendro, C. intermedia and R. songarica communities were similar with the root distribution of communities and their dominant species, but in N. tangutorum community, it was similar with the root distribution of dominant species. In S. xanthoxylon community, it was only similar with the root distribution of community in 0-40 cm soil. This study indicated that the SOC in 0-100 cm soil profile of shrub communities was significantly associated with root biomass in 0-20 cm soil, and the vertical distributions of dominant shrub root system was a key factor af- fecting the vertical distribution of SOC.