Herbage production per plant functional type in relation to land use changes in Mediterranean rangelands

During the last few decades, lowland and semi-mountainous rangelands in the Mediterranean region have faced significant socioeconomic changes. The extensification and abandonment of traditional management practices, such as livestock raising and fuelwood collection, have led to major changes in structure and function of rangeland ecosystems through the extensive woody plant invasion and the evolution of natural vegetation towards next successional stages. In this study, plant functional types (PFT’s) were used in order to assess above ground herbage production dynamics in different stages of secondary succession along an extensification gradient. The study was carried out in Lagadas County, Thessaloniki, northern Greece at an altitude of 500 m a.s.l. During spring 2003, above ground herbage production was measured across four vegetation types representing sequential successional stages (abandoned fields, grasslands, open and dense shrublands, respectively). Live biomass was harvested at its peak stage in a total of 16 replicate plots of 3030 m., whereas in the Laboratory plant species were sorted and classified into plant functional groups based on their life cycle, life form and photosynthetic pathway. Each group’s herbage production was correlated with each vegetation type in order to identify patterns related to land use change and production dynamics. It was found that above ground herbage production significantly decreased towards later successional stages, while grasses and legumes were the most sensitive groups to land use change. Annual C3 grasses and annual forbs were making the majority of the total herbage production at the early stages, whereas perennial C4 grasses took over at the late ones. It was concluded that plant functional types can be a useful tool for the assessment of above ground herbage production dynamics in Mediterranean rangelands across different successional stages after the abandonment of prior use.