College of Commerce, Nihon University, 5-2-1 Kinuta, Setagaya-ku, Tokyo, 157-8570, Japan.
Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo, 192-0397, Japan.
Sci Rep. 2023 Jul 27;13(1):12163. doi: 10.1038/s41598-023-38934-9.
Disturbances caused by invasive ungulates alter soil environments markedly and can prevent ecosystem recovery even after eradication of the ungulates. On oceanic islands, overgrazing and trampling by feral goats has caused vegetation degradation and soil erosion, which can alter soil chemistry. To understand the effects of the changes on plant performance, we conducted a laboratory experiment to assess herbaceous species growth under various soil conditions with phosphorous, nutrients, and acidity. Subsoil was collected from Nakodo-jima in the northwest Pacific. Six herbaceous species dominating the island were grown in soils with three levels of added CaCO and PO and two levels of added KNO. After 4 weeks of growth, the total dry plant weight was significantly lower with no added PO, regardless of the addition of KNO. Three species weighed more under PO and KNO addition in high-pH soil, whereas the remaining three weighed less. Our results indicated that herbaceous species growth is limited primarily by phosphorous availability; the limitation is dependent on soil pH, and the trend of dependency differs among species. This implies that ecosystems with extreme disturbances cannot recover without improving the soil chemistry.
入侵有蹄类动物造成的干扰会显著改变土壤环境，即使在有蹄类动物被根除后，也可能阻止生态系统的恢复。在海洋岛屿上，野山羊的过度放牧和踩踏导致植被退化和土壤侵蚀，从而改变土壤化学性质。为了了解这些变化对植物性能的影响，我们进行了一项实验室实验，评估了在不同土壤条件下，磷、养分和酸度对草本物种生长的影响。我们从西北太平洋的中岛采集了底土。在添加了 CaCO 和 PO 的土壤中种植了在岛上占主导地位的六种草本物种，并添加了两种 KNO 水平。经过 4 周的生长，无论是否添加 KNO，不加 PO 的总干植物重量明显较低。在高 pH 值土壤中，三种物种在添加 PO 和 KNO 时的重量增加，而其余三种物种的重量则减少。我们的结果表明，草本物种的生长主要受到磷供应的限制；这种限制取决于土壤 pH 值，而且不同物种的依赖性趋势不同。这意味着在没有改善土壤化学性质的情况下，受到极端干扰的生态系统无法恢复。
