Soil erosion alters soil chemical properties and limits grassland plant establishment on an oceanic island even after goat eradication

Soil erosion after vegetation degradation induced by disturbance by feral goats, an invasive mammal, can lead to loss or accumulation of soil at a local scale and can alter soil chemical properties. This alteration of soil properties can in turn affect the establishment of plant species. We evaluated relationships among the extent of soil erosion, soil chemical properties, and the distribution of plant species in grassland ecosystems after goat eradication on Nakodo-jima Island in the northwestern Pacific. In 105 1 × 1–m quadrats, changes were measured in the position of topsoil over 2 years. Surface soils were sampled for analysis of chemical properties, and plant species in the quadrat were recorded. Changes in the position of topsoil were related to the area of bare ground. Soil loss occurred at sites where areas of bare ground were extremely large. Significantly higher values of soil exchange acidity and smaller amounts of available phosphorus, total carbon, and total nitrogen were detected in soils at sites with large soil losses. Most of the 11 dominant plant species were absent from sites with large losses of soil. The presence of eight species was significantly negatively related to soil exchange acidity, and three species were significantly positively related to available phosphorus. Our results indicated that exposure of subsoils at the soil surface after vegetation degradation can increase soil loss, which can alter soil chemical properties, and this alteration can continue to limit the establishment of plant species, even long after goat eradication.