Effects of long-term removal of sheep-grazing in a series of British upland plant communities: Insights from plant species composition and traits

Abstract

Environmental and management pressures are considered a threat for preserving plant communities worldwide. Identification of long-term impacts of changing management practices on plant community composition must, therefore, be a major priority to ensure improvement in conservation value. Land abandonment/wilding is one topical area where there is little available information on long-term impacts. To address this, here, we describe plant species compositional change over relatively long-time scales in a range of four British upland communities (high-level grasslands, intermediate grasslands, blanket bogs and high-level bogs) and its relationships with a series of life-history and plant trait variables. Our aims were to determine whether the business-as-usual sheep grazing practice was maintaining these communities, and if grazing was to be removed as part of abandonment/wilding strategies, would there be a conservation benefit. We used a series of long-term experimental grazing-exclosure studies at twelve sites (>40 years) on the Moor House National Nature Reserve in northern England. Each site consisted of paired plots; i.e. sheep-grazed versus ungrazed. Our results showed that there was relatively little change in dominant plant species with most change occurring within sub-dominant species. Similarly, different temporal responses in plant species richness were detected between the experiments (richness was reduced in three experiments, only one increased). In any case, the vegetation temporal trajectories were moving in similar direction in grazed and ungrazed plots at most sites. Interestingly, blanket bog experiments showed a clear compositional convergence for both grazed and ungrazed plots, although, the between-site differences related to a combination of elevation and past burning testament. Finally, the bryophytes (especially liverworts) and lichens were the groups that contributed most to the reductions in species richness. Moreover, implementation of a no-stock grazing strategy under a land abandonment/wilding approach will not bring about much plant change in the short-term in the plant communities studied here.