A single application of fertilizer can affect semi-natural grassland vegetation over half a century

Abstract

Restoration of species-rich semi-natural grassland requires not only a seed source but also appropriate soil properties. In Europe, approximately 10 years are required for the properties of fertilized soils to reach suitable conditions and be considered successfully restored. However, restoration may require additional time in Japan because heavier precipitation causes leaching of basic cations from soils, resulting in soil acidification; volcanic ejecta also forms active Al and Fe hydroxides with high phosphate sorption. Within this context, we aimed to answer the following questions: i) whether and how the impacts of fertilization remain in the soil properties after half a century in Japan; and ii) how fertilization affects the restoration of semi-natural grasslands in Japan. We investigated the vegetation and soil properties of a Zoysia japonica pasture improved half a century ago with a single application of fertilizer and an adjacent semi-natural grassland (native pasture) in Japan, and found the following: (1) the two pastures had similar dominance of Z. japonica, but differed in the species composition; (2) the improved pasture exhibited lower species richness than the native pasture; (3) soil nutrients, including N, P, K, Mg, and Ca, were higher in the improved pasture than in the native pasture; and (4) many chemical properties of the soils were associated with species composition; namely, the vegetation on nutrient-rich soil had more alien species and fewer native species. We conclude that a single dose of fertilization can affect soil properties in semi-natural grasslands over half a century in Japan, leading to species loss and changing the species composition. We suggest that fertilized soils under grazing in Japan may require more than half a century to restore the nutrients to suitable levels for the establishment of a species-diverse grassland.

Contribution of genetic analyses to semi‐natural grassland biodiversity conservation in Japan

“…Vegetation height increases owing to soil eutrophication caused by chemical fertilizer use and management abandonment have reduced species diversity by reducing the available light for dwarf species in the understory (Hautier et al, 2009; Melts et al, 2018; Sala et al, 2000). Furthermore, soil eutrophication, resulting from the application of at least one fertilizer, facilitates the dominance of alien herbaceous plant species and reduces the diversity of native herbaceous plant species (Tsutsumi et al, 2022). These quantitative and qualitative degradations of semi‐natural grassland environments have increased the risk of shrinkage and/or extinction of local populations of semi‐natural grassland species.…”