Compositae family comprises the largest number of species of invasive alien plants (IAPs) in China. Two IAPs can co-invade the same habitat. Drought can alter the litter decomposition of IAPs and soil enzyme activities. This study aims to estimate the independent and combined effects of two composite IAPs (Bidens pilosa and Solidago canadensis) on litter decomposition and soil enzyme activities under drought. A polyethylene litterbags experiment (5 g litters of B. pilosa, 5 g litters of S. canadensis or 5 g litters of B. pilosa and S. canadensis in an equal proportion per polyethylene litterbag) was performed. The polyethylene litterbags were treated with a gradient of drought, i.e. control, light level of drought and heavy level of drought. The decomposition coefficient of the two composite IAPs and soil enzyme activities was determined. The co-invasion of the two composite IAPs posed a synergistic effect on urease activity. The mixed litters of two composite IAPs and the litters of B. pilosa had higher decomposition rates than S. canadensis. Urease activity was increased in light droughts, but it was decreased in heavy drought. Heavy drought reduced the decomposition rate of the mixed litters of two composite IAPs and the litters of B. pilosa. Drought did not affect the decomposition rate of S. canadensis litters. Thus, heavy drought can decrease the nutrient cycling rate under the co-invasion of the two composite IAPs and the independent invasion of B. pilosa rather than the independent invasion of S. canadensis.
摘要：
重度干旱降低两种菊科入侵植物凋落物共同降解的速率
当前，中国已分布的入侵植物隶属于菊科的种类数量最多。更关键的是，两种入侵植物可以在同一生境中形成共同入侵。此外，干旱可以影响入侵植物的凋落物降解和土壤酶活性。基于此，本研究旨在解析干旱背景下两种菊科入侵植物鬼针草(Bidens pilosa)和加拿大一枝黄花(Solidago canadensis)对凋落物降解和土壤酶活性的单一影响和复合影响。本研究主要通过聚乙烯凋落袋实验完成，其中每一个凋落袋装入5 g入侵植物鬼针草的凋落物，或装入5 g入侵植物加拿大一枝黄花的凋落物，或装入5 g两种菊科入侵植物鬼针草和加拿大一枝黄花等比例混匀的凋落物。干旱处理水平设置为：对照、轻度干旱和重度干旱。实验结束后测定两种菊科入侵植物凋落物单一降解速率和共同降解速率以及土壤酶活性。两种菊科入侵植物凋落物共同降解对土壤脲酶活性的影响为叠加效应。两种菊科入侵植物凋落物共同降解速率以及入侵植物鬼针草凋落物单一降解速率显著高于入侵植物加拿大一枝黄花凋落物单一降解速率。轻度干旱显著增加土壤脲酶活性，但重度干旱显著降低土壤脲酶活性。重度干旱显著降低两种菊科入侵植物凋落物共同降解速率以及入侵植物鬼针草凋落物单一降解速率，但干旱处理未显著影响入侵植物加拿大一枝黄花凋落物单一降解速率。因此，重度干旱可能通过减缓营养循环速率显著影响两种菊科入侵植物共同入侵进程以及入侵植物鬼针草单一入侵进程，但并未显著影响入侵植物加拿大一枝黄花单一入侵进程。
关键词:
鬼针草(Bidens pilosa),
共同入侵,
凋落物降解速率,
土壤酶活性,
土壤理化性质,
加拿大一枝黄花(Solidago canadensis)
