摘要:为预测降水变化对人工林生态系统土壤氮矿化过程的影响，以南亚热带马尾松（Pinus massoniana Lamb.）人工林为研究对象，采用PVC顶盖埋管法，研究穿透雨减少50%和不减雨（对照）下土壤氮矿化特征。铵态氮是南亚热带马尾松人工林无机氮存在的主要形态，土壤氮矿化以氨化作用为主。穿透雨减少显著降低了土壤净硝化速率、土壤含水量、pH、可溶性有机碳含量、过氧化物酶及丛枝菌根真菌饱和脂肪酸，而显著增加了土壤净氨化速率、硝态氮、N-乙酰-葡萄糖苷酶和蛋白酶，但是影响程度因季节和土层而异。土壤净氨化速率与N-乙酰-葡萄糖苷酶呈极显著负相关，土壤含水量是对土壤净硝化速率影响力最大的变量，β-葡萄糖苷酶、真菌饱和脂肪酸及细菌真菌饱和脂肪酸比的影响次之。表明短期降水减少显著改变了马尾松人工林的土壤理化性质、净氨化和硝化速率，这可能会进一步影响其树木生长和养分吸收。



Abstract:To better predict responses of soil nitrogen mineralization to the changes of precipitation variations in plantation ecosystem, a throughfall reduction experiment including 50% of throughfall and natural rainfall (control) treatments was conducted in Pinus massoniana plantation in southern subtropical China. Soil nitrogen mineralization rates were measured by closed-top tube incubation method. The soil nitrogen mineralization of Pinus massoniana plantation was dominated by ammonification. The throughfall reduction treatment significantly decreased soil net nitrification rate, soil water content, pH, soluble organic carbon, peroxidase and AMF PLFAs. Conversely, the throughfall reduction treatment significantly increased soil net ammonification rate, NO₃^--N N-acetyl-glucosidase and leucine-amino-peptidase, which varied with different seasons and the soil layers. Soil net ammonification rate was significantly negatively correlated with N-acetylglucosaminidase. The variable that had the greatest influence on the soil net nitrification rate was the soil water content, followed by β-glucosidase, fungal PLFAs and Bacteria/Fungi ratio. The results indicated that the short-term experimental throughfall reduction significantly altered soil physichemical properties, soil net ammonification rate and soil net nitrification rate, which could further affect the tree growth and nutrient uptake of Pinus massoniana plantation.





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