Influence of Short and Long Period Abandonment from Agriculture on Vegetation and Soil Seed Bank Composition Compared to Undisturbed Forest in Zagros Region

Land degradation and environmental heterogeneities are factors that affect forest ecosystems worldwide and their characteristics. Despite the significant role of soil seed bank to the rehabilitation of degraded plant communities, the floristic studies in many terrestrial ecosystems have focused only on aboveground vegetation. This study carried out to investigate the effect of land-use change from forest to agriculture and long-term and short-term abundance of this disturbance on aboveground vegetation and soil seed bank in Cheghasabz forest park in Ilam County. A total of 66 sample plots (1 m × 1 m) were established using a random systematic method to measure the aboveground vegetation. For soil seed bank, around each of the sample plots, a sample 20 cm × 20 cm area to a depth of 10 cm randomly collected. The seedling emergence method (in greenhouse) and the Braun-Blanquet cover-abundance scale was used to study of soil seed bank and vegetation, repectively. The results showed that in all three studied areas, the number of species in the soil seed bank decreased compared to aboveground vegetation. The dominant life form in the three studied areas were therophytes for both the soil seed bank and aboveground vegetation. The phytocorya distribution of plant species in all land uses also showed that the elements of Irano-Turanian and Iran-Touran-Mediterranean are dominant for both soil seed bank and aboveground vegetation. The density of soil seed bank decreased significantly in agricultural land use. Along DCA axes, based on soil seed bank and aboveground vegetation two distinct vegetation composition separated. The first group includes plots of the soil seed bank and aboveground vegetation in long-term abandoned lands and forest stands, and the second group consisted of seed bank and vegetation of short-term abandoned lands. Long-term abandonment from agriculture as a management measure and relying on the seed bank can be efficient in restoration of vegetation and returning to pre-disturbance conditions.