دانلود رایگان مقاله اثرات تضادی آبیاری و کوددهی بر تنوع گیاهی در مراتع یونجه

Abstract

Extensive grassland management practices are crucial drivers to maintain biodiversity. However, it is challenging to combine biodiversity conservation with high agricultural yields. Traditional lowland meadow irrigation used to be a common management practice to improve hay production. However, it has been widely abandoned throughout Europe due to land use intensification. In an observational field study we examined the long-term impact of traditional irrigation, fertilization and biomass production on plant diversity of hay meadows. Traditional meadow irrigation enhanced plant alpha diversity (Simpson diversity and Evenness) and beta diversity (heterogeneity of multivariate dispersions). However, we found annual differences in the strength and significance of these effects, possibly due to different weather conditions. In contrast, plant species richness was unaffected by irrigation but consistently negatively influenced by the amount of applied N fertilizer. Moreover, we found significant relations between plant alpha diversity and biomass which were either unimodal (plant species richness and Simpson diversity) or negative (Evenness). Our results confirm the generally negative effects of fertilization on plant species richness. The moderately higher plant alpha and beta diversity in irrigated meadows may be a result of the heterogeneous within and between site environmental conditions induced by the annually repeated irrigation events. We conclude that traditional meadow irrigation is compatible with the conservation of plant diversity. Even stronger conservation benefits could be expected from diversified irrigation schemes that include longer-term inundation to favor even more hygrophilic plant communities.

Conclusions

Our study confirms the reduction of plant species richness through grassland fertilization. In contrast, traditional meadow irrigation had moderate positive effects on plant alpha (Simpson and Evenness) and beta diversity. However, the effect sizes differed between study years and the positive effects were not consistently significant. This underlines the importance of long-term studies. We conclude that traditional meadow irrigation is compatible with biodiversity conservation in European grasslands. It requires low financial input and might thus be an interesting option for biological conservation, even if benefits to arthropods were less clear than to plants (Schirmel, Alt, Rudolph, & Entling 2014). Moreover, irrigation may be beneficial for famers by improving both biomass production (Cook, Cutting, Buhler, & Cummings 2004; Stearne & Cook 2014) and forage quality (Leibundgut & Kohn 2014a). The current irrigation schemes in our study area are adapted to the maintenance of mesophilic Arrhenaterion grasslands and are applied relatively uniformly across the study region. We expect that a diversification of irrigation schemes, with longer-term inundation on selected sites within the landscape would yield much higher conservation benefits by favoring more hygrophilic plant communities.