ELEVATIONAL DISTRIBUTION OF TREE DIVERSITY IN LOWER HIMALAYA: A CASE STUDY OF PHULCHOKI HILL, NEPAL
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Changes in tree species composition with elevation have been studied at three distinct altitudinal ranges on the basis of dominance, in sub-tropical and temperate forests on south slopes of Phulchoki hill, central part of lower Himalaya, Nepal. The greatest number of tree species was found in the low altitude (1600 m), followed by intermediate altitude (1950 m). The highest altitude (2650 m) contained only one distinct tree species (Oak). Site I has higher species diversity (Shannon Index: 2.1863, Evenness Index: 0.852) and density (5575 individual per hectare) dominated by Castonopsis indica, Quercus glauca, Myrica esculenta and myrsine capitellate. Site II has average species diversity (Shannon Index: 1.759, Evenness Index: 0.9) and an average density (2150 individual per hectare) dominated by Rhododendron arboretum, Castanopsis tribuloides and Quercus incana. At site III the forest is entirely dominated by Quercus semicarpifolia, a high altitude Oak. A linear trend of decreasing tree species diversity and density along with elevations was seen which might be because of intense afforestation by communities at lower elevation as site I and II under community managed forest and lower altitudinal ecozone with clear zonation of elevational vegetation types.International Journal of Environment Volume-4, Issue-3, June-August 2015Page: 130-139Keywords:
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Dominance (genetics)
Afforestation
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Tree (set theory)
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The present study was carried out to analyze the species diversity and quantitative analysis of mangrove forest in three riverine ecosystems at River Kisap, River Ayer Hangat and River Kilim at Kilim Geoforest Park. One hundred plots, each of size 20 m × 20 m, were established at a distance of 250 m apart along the three rivers. Every existing species that occurred within the plot and trees of diameter at breast height of 1 cm and above were enumerated and identified. The data were analyzed for species richness, diversity and evenness. The species richness were computed based on the Jacknife method, species diversity index were calculated using Simpson’s Index, Shannon-Wiener Index and Brillouin’s Index. The evenness indexes were measured by Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index of evenness. A total of 11488 individual trees representing 58 species, 39 genus, and 23 families were recorded. The most abundant species was Rhizophora apiculata (3449) and Ceriops tagal (2060). The diversity results show that Shannon-Wiener, Simpson’s index of diversity and Brillouin index was high (2.0 to 3.0), (0.7 to 0.8), to (2.0 to 3.0) respectively and the evenness index however was low (0.1 to 0.2).
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During the spring of 2004,studies were conducted to investigate the community and species diversity of spring birds community in Hohhot which includes seven different urbanization level habitats. In total,32 species,which belong to 19 orders,9 families,were recorded. Based on the principles of community ecology,we evaluate and discuss structural characteristics by means of the Shannon-wiener index(H′),species evenness(J),richness index in spring bird community . The results indicated that: the diversity index and species evenness in park and nursery are the highest in seven typical habitats,on the contrary,the diversity index and species evenness in shopping center and traffic occupancy are lower than others.
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Five common indices were compared to see which of them would be most suitable in the study of long time changes in a phytoplankton community. Margalefs index d showed the same course during the year as did the number of species. This is also valid for Brillouin's, Shannon's, Simpson's and McIntosh's indices when based on number of individuals. Brillouin's and Shannon's indices based on cell number were found to differ from the diversity values obtained by Simpson's and McIntosh's indices depending on their different sensitivity to the two components of diversity, species richness and species evenness. Diversity indices including species richness and evenness (e.g. all except Margalef's) are recommended, but their different sensitivity to their species richness and evenness component should not be overlooked. A description of the phytoplankton composition should always be given together with diversity indices. This is very important since any index used gives no information on the species and their ecology.
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Plant species diversity of a logged-over coastal forest within the Pasir Tengkorak Forest Reserve, Langkawi Island,Malaysia was assessed by establishing a 1-ha plot. All plants above 1.0 cm dbh (diameter of a tree at breast height), or4.5 feet above ground level, the accepted point of diameter measurement for most trees were enumerated. Speciesdiversity was defined as a combination of species richness and evenness. The jackknife estimate and species-area curvewere applied to estimate the species richness. It was estimated using Simpson’s index of diversity, Shannon-Weinerfunction and Brillouin index. Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’sindex of evenness were also used to estimate species evenness. A total of 3414 individual trees representing 120 species,81 genera and 31 families were recorded. Species with highest relative abundance were Swintonia sp1 (0.12), Garciniaeugnifolia (0.09) and Syzygium sp1 (0.05). The jackknife estimate of species richness was 132.9 and the regress ionequation to estimate species richness was Ln Sˆ = 2.53 + 0.24 ln (A) with r2 = 96.0 %. Species diversity was high withSimpson’s index of diversity with a value of 0.96, while Shannon-Weiner index was 5.42 and Brillouin’s Index was5.14. However, Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index ofevenness were 0.264, 0.378, and 0.419, respectively. Results indicated that species richness and species diversity werehigh, but evenness was low in this logged-over coastal forest.
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Effects of stocking rates for yak on community composition in K. parva alpine meadow had been studied for two years. The results showed: in warm-season pasture, with the increase of stocking rates, coverage, average height, aboveground and its percentage composition for functional groups of grasses and sedges decreased, and they were significantly and negatively correlated with stocking rates (P<0.05), and on the contrary, functional groups of palatable and toxic weeds increased, and they had a positively correlation with stocking rates (P<0.05). Besides, there was a significant and positive correlation between overage and aboveground biomass of different functional groups (P<0.05). As for control grassland, the community dominiated by a few plants, structure of that was simple and lack of species, which led to species richness, diversity and evenness index were minimum for grassland not grazed and ingested, and under light grazing, the influences of ingestion by yaks on plant community were very small, which caused species richness, diversity and evenness index were not high. However, moderate grazing increased utilizing efficiency of resources and complexity of plant community, and so species richness, diversity and evenness index were maximum, which supported hypothesis of intermediate disturbance, heavy grazing accompanying with frequent ingestion and serious influence on plant community, resulted in a low evenness, richness and diversity index. The order of species number (S), richness index (Ma), diversity index (Shannon-Wiener index H' and Simpson index D), evenness index (Pielow index J') under different stocking rates was: control
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The tropical montane rain foreston Wuzhi Mountain,Hainan has abundant species.In a 1hm 2 there are 54 families,100 genus,177 plant species and 1337 individuals.The result of a floristic geographical study shows the major types of genus are tropical components(89.0%).It fully reflects the tropical characteristics of the montane rain forest on Wuzhi Mountain,Hainan.The result of diversity indices shows that in plot 1,Margalef index is 17.822,Shannon Wiener index is 5.900,evenness is 0.859,Simpson index is 0.028,evenness is 3.866.In plot 2,Margalef index is 17.381,Shannon Wiener index is 5.621,evenness is 0.823,Simpson index is 0.050,evenness is 6.775.It reflects that the tropical montane rain forest has high species diversity and high evenness,and the diversity of a low elevation plot is higher than that of a high elevation one.Fourty four singleton and 25 doubleton,respectively accounting for 24.9% and 14.1% of the total species number,are identified in the plots.These species with a low density and small population are more declined to extinct than the dominant species under any disturbance.The loss of the singleton and doubleton species will lead to a low species diversity in the community.
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The natural field margin ecotone from the field border and into a cropped field hosts a diversity of plant species. In conventional cropped fields, biodiversity suffers from fertilizer and pesticide application. In our study at Danish conventional spring-barley fields, we laid out bufferzones with no pesticide application spraying after sowing, with the widths: 24, 12, 6 and 4 m (and control) to the field edge hedgerow. Through one season: plant species number, biodiversity and evenness for each bufferzone at the distances: 18, 9, 5, 2 and 0 m from the hedgerow were significantly affected by distance to the hedge and by width of bufferzone. The bufferzones affected: species number (total of 92 weed species), species diversity (1.27 to 0.44) and species evenness index (0.63 to 0.87), and revealed that the bufferzone of 24 m gave the largest improvementof the field margin for plants. Decreasing the bufferzone widths provided smaller biodiversity and larger evenness of plants at distances larger than the buffer width: the distance at which diversity (Shannons) was reduced by half the difference between hedge- and field diversity was 1.2, 3.1, 6.7, 10.8 and 10.9 m in bufferwidth treatments of 0, 4, 6, 12 and 24 m; likewise, the half-way distance for Smiths and Wilsons evenness index was 1.2, 1.7, 5.4, 14.0 and 30.2 m in the bufferwidth treatments of 0, 4, 6,12 and 24 m. Based on modelled diversity and evenness indexes a positive effect of buffer was evident from 6 m bufferzone. The average diversity over the distances from 0 to 18 m was 0.66, 0.75, 0.98, 1.14 and 1.11 in bufferwidth treatments of 0, 4, 6, 12 and 24 m and the average evenness over the distances from 0 to 18 m was 0.82, 0.80, 0.74, 0.66 and 0.63, in bufferwidth treatments of 0, 4, 6, 12 and 24 m. Furthermore, the accumulated number of species revealed that a bufferzone width of at least 6 m was needed to significantly increase the species richness at all distances between 2 and 18 m. At 18 m distance, the accumulated number of species was 37.1, 39.7, 41.2, 42.4 and 42.7 in bufferwidth treatments of 0, 4, 6, 12 and 24 m.
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Species diversity is a combination of species richness with species evenness. It helps us differentiate between communities or areas that have the same number of different species, but not in the same abundance. The spatial distribution pattern of plant species is an important topic in plant ecology, the assessment of which is an essential part of research into plant communities. This study aimed to investigate the differences between richness, diversity, and evenness indices obtained for random, uniform, and clumped distribution patterns. For this investigation, three plant distribution patterns were simulated and then random sampling was performed with 10 plots of the size 1 m2 for each pattern, each with five repeats for greater accuracy. Finally, the number of species, the Margalef index, and the Menhinick index for richness, the Simpson index and the Shannon-Wiener index for diversity, and the Simpson index, the Shannon-Wiener index, and the Pielou index for evenness were computed and compared. The results of the analysis of variance showed a significant difference between richness, diversity, and evenness indices in different distribution patterns. Accordingly, Shannon-Wiener diversity is the best index when the management objective is more concerned with rare species. Also, Simpson’s diversity, would be more appropriate where dominant species are more important.
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