Browsing by Subject "Community structure"
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Item COMMUNITY STRUCTURE AND REGENERATION OF Abies spectabilis D. Don IN SHAILUNG, CENTRAL NEPAL(Amrit Campus, 2023-08-14) JOSHI, ADITYACommunity structure and regeneration of Abies spectabilis (D.Don) was studied in Abies spectabilis forest located in Shailung, Dolakha. Vegetation sampling was done by circular plot (20m diameter) method and the sample plots were located by systematic random sampling method. Two sites, northern and aspect, were selected for the study. Four horizontal transects running parallel to each other of about 200m altitudinal difference were designed for each aspect. Altogether 48 plots, six in each transect were established and the aerial distance between the plot was 50m. Number of woody plant species, number of individuals of each tree species, diameter at breast height (DBH) of each individual tree, number of seedlings and saplings of tree species were recorded in each plot. Various community attributes and population characteristics were analyzed. From each horizontal transect, soil was collected by pairing of plots in each transect from a depth of 30cm and pooled together. Three soil samples of 200 g from each transect were collected and their physicochemical characteristics were analyzed. On the basis of IVI Tsuga dumosa was dominant on lower elevation range on both aspects, while Abies spectabilis, was dominant at elevation range 2650m-2850m and 2850m-3050m, whereas, R. arboreum was dominant at elevation range above 3050m in northern aspect. Similarly, A. spectabilis and T. dumosa showed nearly equal dominance at elevation range 2650m-2850m, while A. spectabilis was dominant at elevation range 2850m-3050m and above 3050m in southern aspect. Altogether 40 plant species (13 tree species and 27 plant species in shrub layer) were found in the study area. The tree density of both sites increased with increase in elevation up to 2850m 3050m and decreased. Similarly, the basal area of tree gradually decreased after elevation range 2650m-2850m in both aspects. Comparatively tree density was higher in northern aspect and basal area was higher in southern aspect. Soil was slightly acidic in nature. The distinct variation in soil parameters were not observed in two sites as well as along altitude. Density-diameter curve of all tree species showed sustainable regeneration. But, density-diameter curve of A. spectabilis in both aspects slightly deviated from reverse J shaped structure and hence did not show sustainable regeneration. Seedling density was higher than sapling density. The distribution of seedlings and saplings were not uniform.Item Community Structure and Regeneration of Sub-alpine Abies spectabilis (D.Don) Mirb. Forest in Sagarmatha National Park, Eastern Nepal(Department of Botany, 2012) Nagarkoti, Amrit BahadurCommunity structure and regeneration pattern of Himalayan Fir, Abies spectabilis (D.Don) Mirb was studied along the elevation gradient 27500 to 3550 m. asl in mixed Abies spectabilis forest located between Guranse danda and Khumjung area of Sagarmatha National Park, Eastern Nepal (Central Himalaya). Vegetation in the study area was sampled through systematic random sampling method. A total of 45 plots of 0.1 ha (33 m x 33 m) were sampled between 2750 m to 3550 m each at 100 m elevation interval. Nine vertical transects were defined within the study area and quadrats were located along each transects. Five sampling plots were laid in each elevation one or the both side of the well-established footpath. The location for the first plot in each elevation was chosen on the side of the path where there was at least one mature Abies spectabilis tree was. The distance between two transects were between 30-200m.Other plots in the same elevation were laid at a distance of 30-200 m difference. The distance between the plots was determined on the basis of the accessibility and presence of Abies spectabilis trees. If Abies trees were not observed along the sampling transect,a sidewise search was conducted on either side of the path at the same elevation. Canopy cover, rock cover, logging, lopping, litter and grazing/trampling damage in each quadrat were determined by visual estimation method. Soil samples were collected from each quadrat from its four corners and their physiochemical characteristics were analyzed. Number of woody plant species, number of individuals of each tree species, diameter at breast height (DBH) of each individual tree, number of seedlings and saplings of tree species were recorded in each quadrat. Various community attributes (e.g. importance percentage, species diversity and beta diversity) and population characteristics (e.g. density- diameter bar diagram) were analyzed. Ordination methods were used to analyze species composition and to relate this to environmental variables. Generalized linear models were used to relate community attributes with environmental variables. Soil was slightly acidic with soil pH value 5.16. Soil carbon and soil nitrogen were 3.05% and 0.27% respectively. Thirty four species were recorded from the study forest. Rhododendron arboreum was the dominant tree species with the highest importance percentage (61.91%) and Abies spectabilis was the co-dominant species (22.72%). The value of beta-diversity for tree was 1.26. Simpson’s Index (0.44) which was less than Shannon Wiener’s Index (1.21). Species diversity of the forest was relatively high. Total tree density was highest at 3450m and lowest at 3550m. Total tree density found changed with increasing elevation but it decreased from 3550 m towards treeline. Density-diameter curve for all trees measured was nearly reverse J- shaped that indicate a continuous regeneration trend. But the slightly deviation in the curve for Abies spectabilis alone from the typical reverse J-shaped, indicate a discontinuous regeneration pattern. The seedling and sapling distribution were not found uniform however 40% of the studied sub-plots were with seedlings while 66.67% without sapling and 40% of plot had no Abies spectabilis trees. Seedling mortality was found relatively medium and development of seedlings into saplings was also low. The lower number of sapling might be due to moderate disturbance (grazing and trampling) by livestock or environmental factors. Therefore, regeneration of Abies spectabilis was not sustainable. Keywords: Central Himalayan; Community structure; species richness elevation gradient ; regeneration ; Abies spectabilis; multivariate analyses; DCA; beta diversity; Simpson’s index; density-diameter curve; correlation coefficient matrix; GLM regression.Item Fish Diversity and Community Structure in Ghodaghodi Lake, Kailali(Department of Zoology, 2015) Joshi, DipendraGhodaghodi Lake is an ox-bow perennial Lake of Ghodaghodi Lake Complex, situated in Kailali district. The present study was conducted to understand the fish diversity, community structure and distribution pattern in Ghodaghodi Lake. A total of 13 fish species were recorded from the different section of Ghodaghodi Lake, belonging to five order, eight family and eleven genera. According to fish catch the dominant order and family of Ghodaghodi Lake were found to be Cypriniformes (40%) and Cyprinidae (40%) respectively. The dominant fish species of Ghodaghodi Lake was Labeo gonius followed by Mystus tengara, Nandus nandus, Channa striatus. The correlation between temperature and fish diversity was found to be positively correlated (0.1755, 0.5374, 0.9771 and 0.5652) in all four stations. Similarly, fish diversity and water depth are positively correlated in station I (0.2476), II (0.4376) and IV (0.7597) while station III shows negative correlation (-0.2011). All four stations showed positive correlation (0.8242, 0.8074, 0.9345 and 0.6508) between dissolved oxygen and fish diversity. Similarly, positive correlation was observed between pH value and fish diversity (0.7701, 0.8256, 0.5767 and 0.7337). The highest diversity index (2.46), species richness (6.14) and evenness (0.96) of fish were recorded from station III during the month January. Lowest diversity index (1.75) and evenness (0.90) was found in station II and during the month of October (2.25 and 0.88). Similarly, lowest species richness was found in station I (3.91) and during the month July (5.82). Fish diversity and number of fishes in Ghodaghodi Lake were found to be decreased. This could be due to pollution, illegal fishing and excessive proliferation of aquatic weeds.Item Taxonomic diversity and community structure of insect pollinators in Shivapuri-Nagarjun National Park, Central Nepal(Institute of Science and Technology, Zoology, 2022) Dyola, UrmilaInsect pollinators are important agents mediating useful services for human and the ecosystem. Large number of wild plants and agricultural crops depend on the pollinators for their pollination. Global trend has shown decline of several taxa of pollinators and indicating habitat loss as major driving factor. Several studies have been done on pollinators in agricultural and natural areas however there are very few works describing their distribution and diversity in protected area despite the fact that these areas are globally important for preserving disturbance-intolerant pollinators. Wild flowering plants of the park may play an important role for conservation of pollinators. This study explored the taxonomic diversity and the community structure of insect pollinators; bees, butterflies, and hoverflies of Shivapuri-Nagarjun National Park (SNNP). Furthermore, five least collected wild bees during two years of survey were used as model pollinators to check the distribution. The research also documented plant-pollinators interaction to find out the key pollinators, plants that serve as hubs of pollinators, and seasonal variations of pollinators.The survey was done in SNNP for two consecutive years (2018–2019) in four different habitats; Open trail, Forest trail, Managed habitat, and Grassland using both belt transect and colored pan traps methods in three different elevations that ranges from 1,400m–2,700m. The results showed 42 and 34 species of bees and hoverflies respectively. Out of them, 11 species: Amegilla candida, A. fallax, A.insularis, A. quadrifasciata, Elaphropoda impatiens, Ceratina perforatrix, Colletes similis, Megachile conjuncta, Nomia iridescens, Xylocopa collaris, and X. violacea are new country records of bee and Graptomyza nigripes, Lycastris albipes, and Volucella trifasciata are new country records of hoverflies. Likewise, community structure of pollinators presented a total of 167 different species; the butterflies being the most dominant group (48.50%) followed by bees (29.94%) and hoverflies (21.56%). Diversity indices in alpha level was analysed; the Open trail was comparatively more diverse (4.85), followed by the Managed habitat (4.30). Whittaker Beta diversity analyzed the high species turnover between Forest trail and Managed habitat. Environmental variables like humidity, atmospheric temperature, and flower resources in different elevation have a significant effect (p<0.05) on pollinating insects. The species distribution model showed Nomada mutabilis, Thyreus decorus, T. himalayensis, Megachile femorata, and X. violacea are spread out across a broad region vii in the park. The accuracy of model predictions for all five bees are statistically well specified (AUC is greater than 0.07). The plant-pollinator interactions were complex and asymmetrical showing Eristalis tenax, E. cerealis, and Pieris canidia as key pollinators. Ageratina adenophora, Bidens pilosa, and Trifolium repens were observed as the most visited plants by pollinators. Seasonal comparisons showed that there is high species turnover of bees and hoverflies between spring and autumn seasons ( p<0.05). Based on these results, it is clear that the park provides suitable habitats for many species of pollinators. Open trials with a rich herb and shrub coverage can provide foraging habitat to pollinators. High diversity and abundance of insects in Open trial can aid good pollination service in this habitat. Other habitats like managed area, grassland, and forest can be important determinants of wild bees resulting different pollinator community. Frequent visits of pollinators in exotic plants compared to native plants could alter the native plant- pollinator interaction in long term if former plants are not managed.