MSc

A study was conducted to find impact of eco restoration on soil seed bank in Eastern Attappady and relate it to the structural attributes of vegetation in the area. Fifteen sites were randomly selected, which includes three biomass conservation areas (BCA), seven plantation and five non ecorestored sites (NER). From each site, 10 quadrates of size 20 X 20 m2 were selected and vegetation attributes of trees and regeneration enumerated. Soil seed bank sampling was done at an interval of four months in a year. Five soil samples of 30 X 30 cm2 surface area to a depth of 5 cm were collected. To assess the seed density and species composition in the seed banks, seedling emergence technique was used. Sorensen similarity index were calculated to find similarities in species composition between soil seed banks, aboveground vegetation and regeneration.
Rainfall regimes of the region were observed as one of the main driving forces for the vegetation structure. Cluster analysis of above ground vegetation revealed that Palliyara and Sambarcode BCA’s and Agali plantation, which fall in the wetter region of the study area were clustered together. Pattimalam, Kottathara and Vellamari plantations which were in drier tract, were proximal to NER clusters. Floristic diversity studies revealed that species richness was higher in biomass area compared to plantation area. Species richness between plantations varied significantly. Simpson index obtained varied from 0.73 to 0.86 in plantations. Floristic diversity of the area was maximum in BCA's of wetter areas, followed by BCA of drier tracts, plantations and non-ecorestored areas.
Regeneration study revealed that average regeneration in plantation was 2.42 individuals/m2, while in biomass areas it was 2.11 individuals/m2. In non-eco-restored (NER) areas, the regeneration was found to be low (0.47 individuals/m2). Cluster analysis revealed that Agali, Palliyara and Sambarcode plantations along with Sambarcode BCA had higher overall regeneration. Plantations like Pattimalam, Vellamari and Melechavadiyoor had low regeneration. The reason for lower regeneration can be attributed to edaphic and biotic constraints probably due to their location closer to human settlements.
Soil seed bank study revealed that mean seed density in the study area was 153.3 seeds/m2. Leucaena leucocephala, Albizia odoratissima, Senna siamea, Santalum album, Samanea saman and Erythroxylum monogynum were the tree species represented in the soil seed bank. Seed bank was predominated by herbs and shrubs. Seed bank density was observed to be lower in the NER regions, where the degradation is maximum and highest in the BCA regions where the degradation is less. Study revealed that mean seed density of plantations area was 176.8 seeds/m2. Seed density for BCA was estimated to be 247.4
seeds/m2 while that for NER was 35.6 seeds/m2. In soil seed bank, Leucaena leucocephala was dominating and with potential to destroy species diversity of the area. Study revealed that seed bank differs with season. In the present study, most of the seeds germinated in pre monsoon followed by monsoon periods. Soil seed bank diversity (Shannon Weiner index) of study area was found to be ranging from 0 to 0.98.
Sorensen similarity index between aboveground vegetation and soil seed bank were low ranging from 0 to 0.14 for study area. Seedling bank resulting from seed rain seems to be a major role player in vegetation establishment than seed bank. The study concluded that evidences of a viable seed bank were not visible as a result of ecorestoration efforts.