Browsing by Subject "Disturbances"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Plant community structure and regeneration of Quercus Semecarpifolio Sm.Forests in disturbed and undisturbed areas(Department of Botany, 2010) Thakuri, Pratistha SinghRegeneration behavior of tree species is characterized by their population structure which depends upon the presence of adequate number of seedlings and saplings. Quercus semecarpifolia is a main forest forming evergreen tree species from upper temperate to lower sub alpine regions of the Himalaya. Vegetation structure and regeneration of Quercus semecarpifolia were studied in two forests of midhills of Central Nepal with different disturbance levels; one was distrubed forest at Simbhanjyang, Makawanpur, and another was undisturbed forest in Shivapuri National Park, Kathmandu. A systematic random sampling method, using square quadrats, was used for vegetation and soil sampling. Soil was collected from each quadrat and their physicochemical characteristics (soil pH, organic carbon and total nitrogen) were analysed. In each quadrat, presence/absence of herbs and shrubs; and the total number of individuals of tree species, sapling and seedling were recorded. Community attributes such as importance value index, species richness and species diversity were determined for both forests and compared. Density-diameter relations for trees, and the spatial pattern of distribution of seedlings and saplings were analyzed to understand regeneration pattern. Altogether 86 and 57 species of flowering plants were found in disturbed and undisturbed forests, respectively. Tree species diversity was higher in undisturbed forest while herb and shrub diversity was higher in disturbed forest. There was significant (p<0.05) difference in soil pH, soil nitrogen, soil organic carbon, litter coverage, total tree density, density of Quercus semecarpifolia tree, sapling and seedling of Quercus semecarpifolia, density of seedlings of all tree species, and total species richness between two forests. Sapling density of Quercus semecarpifolia declined with increasing tree basal area in both forests and seedling density was also decreased with increasing basal area in undisturbed forest whereas no relation was found in disturbed forest. Significant increase in regeneration of Quercus semecarpifolia along with other tree species in disturbed forest might be due to disturbances in the canopy of trees.Item Variation in Plant Functional Traits along altitudinal gradient and land-use types in Sagarmatha National Park and Buffer zone(Department of Botany, 2013) Shah, SrijanaPlant traits are the charactersistics of a plant species which act as useful predictors of the response to the environmental stimuli. They represent specific functional adaptations to various environmental stresses. This study deals with the variation in plant functional traits along elevation gradient and landuse types in Sagarmatha National Park and Buffer Zone, Solukhumbu district, Nepal. Two field investigations at different seasons (April and September) were made for collecting samples. A relatively large samples was used (involving 60 genera, belonging to 31 families). The land-use types selected included disturbed (cultivated land, exploited forest, and meadow) and less disturbed (natural forest) categories. Altogether, 11 different traits of plants, which included life form, growth form, plant height, clonality, spinescence, leaf dry matter content, stem specific density, bark thickness, twig dry matter content, twig drying time, and specific root length were examined. The selected dominant species have been divided into three different categories of growth form (herb, shrub and tree). It was found that plants adapt in various ways to deal with the changing environmental conditions for which they shows different traits. The application of plant functional traits is very useful to understand vegetation-environment relationships. Statistical analyses showed significant differences between traits along both the elevation gradient and land-use types. In the disturbed land-use categories, we found high variation in a particular trait. Correlation analyses revealed that most of the traits were interrelated. Herbs and shrubs were found to be dominant in the higher elevation and in disturbed landuse categories. Species recorded at high altitude were mostly short basal herbs, while spinesescense and tall trees were observed at the lower altitude. Species recorded in meadows and exploited forests showed high variation in traits due to disturbance mainly grazing, fire, trampling, litter collection, etc. Altitudinal variation, climatic condition and disturbance most strongly influence trait expressions of the study site. Plants show these traits for their defense against the adverse conditions. Keywords: functional traits, altitudinal gradient, land-use types, disturbances.