Impact of management intensity on the plant diversity and soil carbon of grasslands in different agro-climatic regions of Sweden

Abstract: Biodiversity loss is a global issue and within the EU and Sweden, funding is available for practices that can enhance biodiversity. Semi-natural grasslands, either cut or grazed, have proven to host a wide range of biodiversity that can serve important eco-system functions. While dependent on human management through cutting or animal husbandry, it is reported that intensive management can be detrimental to biodiversity. Over- or under grazing, fertilizing, and soil disturbance (ploughing) can damage key species in grasslands. Land management also affects soil carbon. Globally, soil carbon stocks are being depleted due to unsustainable land conversion and land management. For example, 90% of semi-natural grasslands in Sweden have been converted to arable land or production forest within the last century. Generally, grasslands, natural and semi-natural, are reported to sequester and stock significant amounts of atmospheric carbon, making them a valuable resource in mitigating carbon dioxide levels in the atmosphere. Fertilizing grasslands can boost the carbon sequestration, but at the same time can be negative for biodiversity. The aim of this thesis was to better understand how varying management intensity affects plant diversity and soil carbon under different climate conditions. This research is based on data gathered on different locations in the south and north of Sweden, which may show differences in the results, since the role of climatic differences in these properties is well known. The results showed that extensively managed fields did host a wider plant diversity in the fields in the south of Sweden compared to more intensively managed fields, but not significantly so in the north. The fields in the north did however host more species on average than the fields in the south. No significant difference between neither management intensity nor climatic differences was seen with soil carbon, perhaps because of the fields closeness to steady-state. It is discussed whether there may be a trade-off between managing grasslands for carbon sequestration and biodiversity, and that it may be more reasonable to manage the remaining semi�natural grasslands in Sweden and Europe for optimal biodiversity, rather than carbon sequestration. Carbon sequestration may be better targeted at converting carbon depleted arable lands to grasslands which likely already holds nutrients in the soil.