草丘微地貌对苔草泥炭沼泽枯落物分解的影响

The influence of hummock microtopography on plant litter decomposition in Carex peat mire

苔草沼泽在北半球高纬度地区广泛分布,草丘微地貌是苔草泥炭沼泽普遍存在的外貌特征,草丘和丘间环境差异可能会引起枯落物分解的异质性。为此,选择长白山区敦化东明林场典型臌囊苔草(Carex schmidtii)沼泽为研究对象,采用分解袋法对臌囊苔草枯落物在草丘及丘间位置的分解差异及其影响因素进行研究。结果表明:草丘和丘间枯落物干重损失具有相似的变化趋势,但丘间枯落物总干重损失(40.20%±4.22%)和分解速率(0.0021±0.0001)d^(-1)均高于草丘枯落物总干重损失(21.70%±2.25%)和分解速率(0.0012±0.0001)d^(-1),且丘间枯落物分解速率具有较大的波动性;草丘和丘间粗孔分解袋枯落物干重损失分别比对应位置的细孔分解袋枯落物干重损失高(1.81%±0.32%)和(2.91%±0.30%),在草丘和丘间枯落物分解速率上,微生物贡献分别是土壤动物贡献的6.37倍和5.65倍,而丘间土壤动物和微生物对枯落物分解速率的贡献分别是草丘的1.79倍和1.59倍。相关分析显示,草丘丘间枯落物干重损失与相应位置积温呈显著正相关(P<0.05),而枯落物干重损失与草丘水位呈显著负相关(P<0.05),与丘间水位呈显著正相关(P<0.05)。本研究表明,在草丘微地貌格局下,不同的水热组合影响土壤动物和土壤微生物分布及群落组成,从而对枯落物分解产生影响,而其丘间不稳定的水分环境则是影响苔草泥炭沼泽枯落物分解的关键环境因子。

Carex peat mire is widespread in high latitude regions of northern hemisphere. Hummock microtopography is a pervasive feature ofCarex peat mire and the difference of microenvironment inside and outside tussocks created byCarex may lead to spatial heterogeneity in litter decomposition. A litter decomposition experiment through litterbag method was conducted to study the spatial heterogeneity of litter decomposition inside and outside tussocks in aCarex schmidtii peat mire in Changbai Mountain, Northeast China. Results showed that patterns of litter dry weight loss inside and outside tussocks were consistent throughout the study. The total litter dry weight loss and decomposition rate inside tussocks were lower than that outside tussocks （21.70%±2.25% vs. 40.20%±4.22%; 0.0012±0.0001 d-1 vs. 0.0021±0.0001 d-1）. Litter dry weight loss from the litterbags with large mesh inside and outside tussocks was 1.81%±0.32% and 2.91%±0.30% higher than that from the small mesh litterbags, respectively. The contribution of soil microorganisms to the litter decomposition rates inside and outside tussocks were 6.37 times and5.65 times that of soil fauna, respectively. However, the contributions of soil fauna and soil microorganisms to the litter decomposition rates outside the tussocks were 1.79 times and 1.59 times that inside the tussocks, respectively. Correlation analysis demonstrated that the dry weight loss of litter was significantly positively related with the accumulated temperature （P〈0.05）. The litter dry weight loss was negatively related with the water level inside tussocks （P〈0.05）, but positively related with the water level outside tussocks （P〈0.05）. The results suggested that soil temperature and soil water content were different between positions inside and outside tussocks, which affected the distribution and structure of fauna and microorganisms, and further affected litter decomposition rate. The water regime outside tussocks was a key environmental factor affecting litter decomposition inCarex peat mire.