钠添加对亚热带森林凋落物分解及其微生物活性的影响

以南京紫金山针叶林优势种马尾松(Pinus massoniana Lamb.)和阔叶林优势种栓皮栎(Quercus variabilis Bl.)凋落物为材料,通过室外连续6个月不同钠水平处理(0、0.005%、0.050%和0.500%的NaCl水溶液),研究了钠元素对亚热带森林凋落物分解系数、土壤微生物活性和土壤胞外酶活性的影响。结果表明:0.005%NaCl水溶液能够正向调节土壤微生物的呼吸活性,加快土壤中凋落物的分解过程。而0.500%NaCl水溶液处理显著降低了2种林型中土壤微生物活性和凋落物的分解系数,减弱了凋落物分解系数与碳、氮、磷矿化相关的土壤微生物胞外酶活性之间的相关性。0.500%NaCl水溶液长期处理有可能减缓森林土壤有机质养分的释放,增加陆地森林生态系统碳的储存。

Effects of Sodium Addition on Litter Decomposition and Soil Microbial Activities in Subtropical Forests

A six-month field experiment was conducted to study the influence of Na addition (0.005％,0.05％ and 0.5％ water solution of NaCl) on the litter decomposition coefficient of Quercus variabilis Bl.and Pinus massoniana Lamb and the activities of soil microbes and soil enzyme in subtropical broad-leaf and needle forests.Na of 0.005％ had positive effects on soil substrate-induced respiration and could enhance the decomposition of litter in the soil.Na of 0.5％ inhibited the activities of soil microbes and litter decomposition coefficient,and the correlations between litter decomposition coefficient and enzyme activities involved in soil carbon,nitrogen and phosphorus mineralization were weakened in both of the forest types.The high concentration of Na may slow down the release of soil organic matter and nutrients in forest,resulting in the carbon storage in terrestrial forest ecosystems in the long term.