POPULATION STRUCTURE OF RHODODENDRON ARBOREUM SMITH, AND ASSOCIATED TREE SPECIES ALONG THE ALTITUDINAL GRADIENT IN A MIXED FOREST OF RAINASKOT, LAMJUNG, NEPAL
Date
2023-08-14
Authors
Journal Title
Journal ISSN
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Publisher
Amrit Campus
Abstract
Population structure is the number of individuals present in each of the definite girth
classes of tree species. The main objectives of this study was to determine the
population structure and regeneration of Rhododendron arboreum and its associated
tree species along the three altitudinal range in a mixed forest of Rainaskot Lamjung.
The study area was divided into three altitudinal range: lower (1200-1400masl),
middle (1400-1600masl) and upper (1600 -1653masl). Altogether 75 circular
quadrants, 25 from each altitudinal range were laid by using random systematic
sampling method. Circular plot of 10m radius were laid for the study. Height and
Diameter at breast height of the trees (>10cm dbh), associated trees (>10cm dbh),
were recorded within main plot. Number of saplings and seedlings were recorded
within main plot. Finally five soil samples were prepared from 25 soil samples
collected from the center of the main plot within each altitudinal range. Total fifteen
soil samples were taken for analysis such as Soil pH, organic matter, soil texture and
3 macro nutrients (NPK). A total of 13 tree species belonging to 11 different families
were reported. The species richness in the forest increases with increasing altitude.
The most frequent and dense tree species in the forest was R. arboreum with IVI
value 77.7 and was present in 93.33% of the total sampling plots. The density of R
arboreum was 257.52 individualha-1 with basal area 16.40 m2
ha-1
. In altitude wise
comparison of density of R. arboreum with total tree density, upper altitudinal range
had (393.28 individualha-1
), middle altitudinal range (248.19 individualha-1
), and the
lower altitudinal range had (127.28 individualha-1
). IVI of R. arboreum was quite
lower (68.19%) in the lower altitudinal range with compared to middle (70.02%) and
upper altitudinal range (105.52%). The R. arboreum shows reverse J-shaped
population structure and fair regeneration status in overall forest having higher
number of seedlings compared to saplings. However, the numbers of saplings were
less than the adults except in lower altitudinal range. The height class distribution of
R. arboreum shows a reverse J-shaped distribution with little deviation in the upper
altitudinal range. The soil pH of forest was found to be acidic. The seedlings, saplings
and adults density were positively correlated with the nutrients such as nitrogen,
phosphorus and organic matter except pH, potassium, canopy cover and litter depth.
The anthropogenic disturbance, ecological diversity, and soil characteristics are
responsible for the variation in population and regeneration attribute of the forest.
Description
Keywords
Species diversity, Species diversity, Canopy, Soil parameters