The National Field Station of Freshwater Ecosystem of Liangzi Lake, College of Life Sciences, Wuhan University, Wuhan, 430072, China.
Ecol Appl. 2023 Jun;33(4):e2843. doi: 10.1002/eap.2843. Epub 2023 Mar 26.
The invasion of exotic plants in the river-lake ecotone has seriously affected the nutrient cycling processes in wetland soil. The South American species Alternanthera philoxeroides (Mart.) Griseb. is rapidly invading the river-lake ecotone in subtropical China, and has become the dominant species in the river-lake ecotone. However, there have been few studies on the effects of A. philoxeroides invasion on soil phosphorus (P) cycling and bioavailability in this ecotone. Here, we measured the bioavailable P fractions, physicochemical properties and nutrient content in the surface soils of the native plant (Zizania latifolia (Griseb.) Turcz and Nelumbo nucifera Gaertn.) communities and the adjacent invasive A. philoxeroides communities in three river-lake ecotones with different nutrient substrates in the subtropical Dongting Lake basin over a 3-year period to reveal the effects of A. philoxeroides invasion on the morphology and concentrations of soil bioavailable P. The principal coordinate analysis results showed that the A. philoxeroides invasion significantly altered the bioavailable P concentrations in the soil of native plant communities in the different river-lake ecotones, and this effect was not disturbed by the heterogeneity of the soil matrix. However, the effects of invasion into different native plant communities on the fractions of soil bioavailable P were different. Compared with native Z. latifolia and N. nucifera communities, A. philoxeroides invasion increased the concentration of inorganic P by 39.5% and 3.7%, respectively, and the concentration of organic P decreased by 32.7% and 31.9%, respectively. In addition, the invasion promoted P cycling and accumulation in the river-lake ecotone, which resulted in average decreases in the soil N:P and C:P ratios of 7.9% and 12.5%, respectively. These results highlight the impact of exotic plant invasions on nutrient cycling in wetland ecosystems in the river-lake ecotone, and this process may be detrimental to the late recovery of native plants.
外来植物入侵河湖交错带严重影响湿地土壤养分循环过程。南美洲物种空心莲子草（Mart.）Griseb.正在迅速入侵中国亚热带的河湖交错带，并已成为该交错带的优势物种。然而，对于空心莲子草入侵对该交错带土壤磷（P）循环和生物有效性的影响，研究甚少。在这里，我们在亚热带洞庭湖流域的三个具有不同养分基质的河湖交错带中，测量了原生植物（菰（Griseb.）Turcz 和莲（Gaertn.））群落和相邻入侵空心莲子草群落的表层土壤中生物有效磷（P）的各个组分、理化性质和养分含量，以揭示空心莲子草入侵对土壤生物有效 P 形态和浓度的影响。主坐标分析结果表明，空心莲子草入侵显著改变了不同河湖交错带原生植物群落土壤中生物有效 P 的浓度，而这种影响不受土壤基质异质性的干扰。然而，入侵对不同原生植物群落的土壤生物有效 P 各组分的影响是不同的。与原生菰和莲群落相比，空心莲子草入侵分别使无机 P 浓度增加了 39.5%和 3.7%，有机 P 浓度分别降低了 32.7%和 31.9%。此外，入侵促进了河湖交错带的 P 循环和积累，导致土壤 N：P 和 C：P 比值平均分别降低了 7.9%和 12.5%。这些结果突出了外来植物入侵对河湖交错带湿地生态系统养分循环的影响，这一过程可能不利于原生植物的后期恢复。
