Environment or management? Relative importance for floristic composition of sub-Mediterranean hay meadows in Central Italy

Questions What are the separate and combined effects of natural and management factors on floristic assemblage in sub-Mediterranean hay meadows? How are hay meadow dynamics affected by the environment excluding management? Location Central Apennines, Italy. Methods Vegetation was studied in 66 hay meadows by random plots, recording four groups of explanatory variables: management, soil, topography, and space. Using partial ordinations, the explanatory variables of the variation in floristic composition and plant traits were divided into sets. Then, to emphasize the relationship between purely environmental variables and vegetation, we considered only the partial ordination executed with soil and topographic variables using management and spatial data as covariables. Results The soil variables had the highest marginal explanatory power. Organic matter was the main driver of floristic composition, indicating a gradient associated also with soil moisture. The pure effect of spatial variables was very important, reflecting historical processes. On the contrary, management and topography variables sets were relatively weak predictors. Partial ordination showed that two topographic variables, slope and height above the plain, had an important weight in the hay meadow floristic assemblage, influencing soil fertility. Conclusions This analysis (a) confirms the determining function of soil fertility and moisture in driving plant species composition and traits; (b) focuses on the marginal power of current management when past traditional agro-pastoral activity undergoes changes in mode and intensity; (c) highlights the role of spatial variables and site history; and (d) improves knowledge about topographical factors as drivers of species composition. The maintenance of hay meadow mosaics requires preservation of grasslands in complete topographical catenae and prevention of the abandonment of parcels on steep slopes. Considering the spatial variability of the studied communities, it is necessary to include a high number of geographically and ecologically different areas in a conservation network.