水位梯度对小叶章湿地土壤微生物活性的影响

Influence of Water Level Gradient on Marsh Soil Microbial Activity of Calamagrostis angustifolia

通过3a野外控制试验，研究了不同水位梯度（-10～30cm）条件下，小叶章湿地植物地上生物量和0～15cm以及15～50cm土壤总有机碳（TOC）、微生物量碳（MBC）、基础呼吸（BR）、微生物商（Cmic／Corg）、代谢商（qCO2）的变化规律．结果表明，不同水位条件下植物地上生物量差异显著（P〈0．05），积水水位10cm的植物地上生物量最高，且积水水位0～20cm保持较高的生产力；积水水位变化对土壤TOC、MBC、BR、Cmic／Corg、qCO2影响显著（P〈0．05）．土壤TOC和BR对积水水位变化的响应趋势一致，0～1.5cm土壤TOC和BR在零积水水位最高；15～50cm土壤TOC和BR随着积水水位的升高而降低，与土壤MBC和Cmic／Corg的变化趋势相同，其中MBC变化最为明显；而qCO2随着积水水位的增加而增大．随着积水水位的增加，土壤微生物群落发生改变和土壤微生物活性降低，其中积水水位30cm的土壤微生物活性最低，对有机碳的累积与分解过程产生影响．

Plant aboveground biomass, total organic carbon （ TOC ） , microbial biomass carbon （ MBC ） , basal respiration （BR） , microbial quotient（ Cmic/Corg） and metabolic quotient（ qCO2 ） in 0-15 em and 15-50 cm marsh soil of Calamagrostis angustifolia under different water levels were investigated with controlled experiment. The result showed that water level exerted significant effect on plant biomass, which was the highest under 10 cm waterlogged level and of higher productivity under 0-20 cm waterlogged level. TOC, MBC, BR, Cmic/Corg and qCO2 differed significantly under different water levels. BR and TOC responded to different waterlogged levels in the same way. BR and TOC of 0-15 cm marsh soil were the highest under 0 cm waterlogged level, however, BR and TOC of 15-50 cm marsh soil decreased respectively with increasing water, which was corresponding with soil MBC and Cmic/Corg, and qCO2 increased with increasing water. As a result, microbial community is altered and microbial activity is decreasing by increasing waterlogged level,and microbial activity is the lowest under 30 cm waterlogged level, which affects organic carbon accumulation and decomposition.