松嫩草甸寸草苔群落土壤微生物量磷的初步研究

Research on soil microbial biomass phosphorus in a Carex duriuscula community of Songnen meadow

松嫩草甸寸草苔群落是羊草群落轻微碱化演替的次生群落。对该群落土壤微生物量磷季节变化、垂直分布以及与土壤因子的关系进行初步研究。结果表明．0～10和20～30cm土层微生物量磷的季节变化趋势呈明显的单峰曲线，峰值出现在8月；10～20cm土层微生物量磷的季节变化不明显；表层（0～10cm）土壤微生物量磷含量高于10～20和20～30cm土层的含量。通径分析结果表明．速效氮、全磷、缓效钾以及土壤pH值和土壤温度对土壤微生物量磷的直接影响较大，而土壤速效磷主要是通过其他土壤因子间接影响土壤微生物量磷；紧实的土壤条件对土壤微生物代谢活动具有明显的限制作用．而土壤盐化状况对微生物代谢的限制作用不大。逐步回归分析结果表明．上层（O～20cm）土壤全磷含量是促进土壤微生物量磷累积的重要因素．而下层（20～30cm）土壤微生物对磷素的累积主要受到土壤可利用磷素的间接影响。

The C. duriuscula community in Songnen meadow developed as a secondary community of the Leymus chinensis community when the soil began to degrade and alkalize. Rudimentary research on the seasonal dynamics and vertical distribution of soil microbial biomass phosphorus （MBP） and on the relationship between MBP and soil factors showed that, the seasonal trends of MBP in the 0-10 and 20-30 cm soil layers can be distinctly described as a unimodal curve, with their peak values in August. The seasonal trend of MBP in the 10-20 cm soil layer was not distinct, while in the 0-10 cm soil layer it was higher than those in the 10-20 and 20- 30 cm soil layers. We studied the relationship between MBP and soil factors with path analysis, and concluded that soil available nitrogen （avail-N）, total phosphorus （total-P）, slowly available potassium （slowly avail-K）, pH and soil temperature had a considerable direct effect on MBP, while soil available phosphorus （avail-P） influenced MBP through other soil factors. Soil compaction had a distinctly negative influence on the microbial processes because there was less air in the soil, while soil salinity had little adverse effect on microbial processes. To make clearer the relationships between MBP and soil factors, we applied stepwise regression analysis, and found that the content of soil total phosphorus in the 0-20 cm soil layer was the major factor affecting accumulation of MBP, while the phosphorus that accumulated in soil microbes depended on the indirect effect of available phosphorus in the 20-30 cm soil layer.