Effects of landscape fragmentation at a fine scale on Mediterranean mountain grassland plant diversity

Abstract European mountain grasslands are affected by abandonment and are being colonized by shrubs and forest. Grassland fragmentation is caused when the forest matrix grows, and surrounding grassland is split into fragments. Multiple studies have been done on grassland fragmentation but in anthropic matrices. Grassland isolation would not be a constraint for plant dispersion since the distance between grassland fragments is usually short. However, when they are abandoned, the surrounding forest can change the environmental characteristics and small fragments can disappear. We studied abandoned Mediterranean mountain grasslands in an oak forest matrix. We surveyed the grassland communities and their soil properties in multiple fragments of different sizes and isolation distances. We classified the grassland species into different groups by habitat preference and life form and calculated the landscape fragmentation variables. We analyzed the effect of fragmentation on the richness of the grassland groups and communities. Results showed that the fragmentation variables did not have any effect on the grasslands, except at the extreme ends of the gradient of the vegetation succession. The smallest grasslands favored perennial and wetter species over annual or drier species due to wetter soil conditions and less availability of light. Annual species are more abundant in southern aspect fragments with drier conditions across the fragments. The lack of connectivity among fragments is not a problem for grassland communities at a fine scale. Annual and drier grassland species remain even in the smallest fragments, but their conservation requires maintaining a minimum fragment size more than it does landscape connectivity.