Document Type : Research Paper
Authors
1 M.Sc. Student, Rangeland Management Department, Tarbiat Modares University
2 Associate Professor, Rangeland Management Department, Tarbiat Modares University
3 Full Professor, Arid and Mountainous Reclamation Department, Tehran University.
Abstract
This study aimed to investigate the effect of habitat kind on soil seed bank characteristics viz. density diversity, richness and similarity between seed bank and above ground vegetation. Two different habitats (grassland and forest) were selected in Vaz, Mazandaran province. The grassland habitat located in the upper end of the forest habitat, adjacent to each other. Then in each habitat, 7 transect perpendicular to slope gradient with 25 meter distance between transect were established; 10 1*1 m plots were selected along each transect. In each plot, 10 soil subsamples were collected and divided into two depths: 0-5 and 5-10 cm. soil sampling was done in winter, 2010. Soil samples were then transferred to and spread in the greenhouse. Germinated plant species were identified, counted and then removed. On the other hand, the above-ground cover of plant species in each plot was recorded in the next growing season. Finally, the number of seeds germinated in the greenhouse was recalculated per meter square and then the similarity between seed bank and aboveground vegetation was calculated in each plot using Sorenson similarity index. Non-paired and paired t-test was applied to compare soil seed bank characteristics between the two habitats and between the two depths, respectively. The results showed that all seed characteristics (with the exception of similarity between aboveground vegetation and soil seed bank in depth 5-10 cm) were significantly higher in grassland than forest. The lower seed characteristics in forest habitat could be related to lower seed input to soil, higher litter percentage and moisture in the above ground of forest habitat. These factors particularly soil moisture and litter could encourage the decomposition of seeds before penetrating soil. In total, the seed of only two shrublands species were germinated in the greenhouse.
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