Plant functional trait responses to grassland succession over 25 years

Many grasslands and arable fields have been abandoned in Europe in the last decades. So far, however, ecologists have not been able to establish one general, unifying theory for successionally induced chances in species composition following abandonment. In fact, the course of succession seems to be unique for each site and year. Here we focused on the analysis of plant functional traits in order to detect general trends in trait responses to succession which would prove independent of site characteristics. We studied permanent plot series of 14 grassland sites in SW Germany that had been abandoned for 25 yr. Species composition as well as the course of succession varied significantly among the grasslands. Response to succession was analysed for the following traits: 'plant height', 'canopy structure', 'specific leaf area' (SLA), 'storage organs, 'vegetative spread', 'plant persistence', 'seed bank longevity. 'start of flowering', 'duration of flowering' and 'seed mass'. We compared a univariate with a multi-variate approach. In the univariate approach, attributes of each trait were analysed separately employing GLM whereas in the multivariate approach all traits were handled together in NMS. Both analyses indicated similar trait responses to succession. There was a significant increase in the proportion of species characterized by the following attributes: plant height > 0.6 in leaves distributed regularly along the stern, vegetative spread > 100 mm. start of flowering later than May, duration of flowering 1-2 months and seeds of either low or high mass.