Fluctuations and trends in spatio-temporal patterns of plant species and diversity in a sandy pasture

Aims The relative importance of species within an ecosystem shows spatio-temporal variability related to both the terrain features and numerous rapidly changing factors. Accordingly, functional and species patterns may show some level of persistence, or, due to various disturbances, fluctuations. Communities with high species richness were found to maintain a higher degree of stability than species-poor or perturbed vegetations; however, diversity and its stability may be spatio-temporally variable. Based on these considerations, our aim was to assess the responses of a sandy pasture, both species-wise and at the community level, to the relatively invariant habitat, and to the more rapidly changing environmental conditions.Location Hungary.Methods We surveyed the vegetation in an area of about 1 ha by means of high-resolution spatio-temporal sampling: we recorded the surface aerial cover (%) of the plant species during 15 campaigns covering spring, summer and autumn aspects for seven years (2013-2019) in 80 x 60 m grids. The biological activity of the ecosystem (above-ground biomass, soil respiration) was also followed up together with the environmental limiting factors.Results During the study period, which was characterized by significant warming, the grassland showed a balanced physiological performance with year-to-year variability. Fluctuating differentiation of the plant species with different environmental optima along with the terrain attributes was assumed to be responsible for this balanced physiological performance. Although community-level diversity remained stable, some species favoring cooler, wetter positions disappeared.Conclusions Terrain features of the study area within 1.5 m or less elevation differences created considerably heterogeneous conditions for a high number (114) of plant species with different ecological needs to co-occur. The stability of the diversity was found to show terrain relatedness, that is spatial as well as temporal patterns compared to the null model of spatio-temporal independence, and the ecosystem functions followed these patterns.