TREE DIVERSITY, CARBON STOCK AND REGENERATION PATTERN IN SHOREA ROBUSTA GAERTN. FORESTS ALONG THE ALTITUDINAL GRADIENT IN EASTERN NEPAL
Date
2023-08-14
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Publisher
Amrit Campus
Abstract
The forest with good regeneration can store a sufficient amount of carbon. The Shorea robusta
Gaertn. (Sal) forests of Nepal are facing the problem of poor regeneration. The present study
aimed to find out the tree diversity, carbon stock and regeneration status of Shorea robusta
forests along an altitudinal gradient in eastern Nepal. The study was conducted in three
community forests of Sunsari and Dhankuta District. The forests were Ramdhuni Kalijhora
community forest (82-170 m a.s.l.), Patrangbari community forest (440-695 m a.s.l.) and
Khanidada Malbase community forest (650-990 m a.s.l.) which were regarded as lower, middle
and upper altitudinal range forest respectively in the present study. The stratified random
sampling method was used for the sampling. Altogether, 90 circular plots (30 in each forest)
were laid for trees and saplings each and 180 plots were (60 in each forest) laid for seedlings.
Physico-chemical parameters (Nitrogen, potassium, phosphorus, organic matter, moisture, pH
and bulk density) were analyzed from all 90 plots. The present investigation has recorded 43 tree
species under 25 families and 35 genera. The Dominance-Diversity curve (DD curve) showed
the highest IVI of Shorea robusta in all three altitudinal ranges. The value of Shannon Diversity
index was higher in high altitudinal range (1.078) followed by low (0.966) and middle altitudinal
range (0.833). Species richness increased with increasing altitudes (from 82 m to 990 m a.s.l).
The tree carbon stock ranged from 134 – 372 t ha–1
.Similarly soil carbon stock was higher in
high altitudinal range (60.03 t ha–1
) and lower in middle altitudinal range (27.69 t ha–1
). The
seedling of Shorea robusta was higher in low altitudinal range and lower in high altitudinal
range. Contrast results were obtained for sapling i.e. lower in low and middle altitudinal ranges
and higher in high altitudinal range. The regeneration of Shorea robusta was affected by various
edaphic factors and anthropogenic activities. The regeneration status of seedlings and trees in the
forests was healthy but poor in terms of saplings. Organic matter, nitrogen and sand percentage
were positively correlated to altitudinal range. However, potassium, pH, silt and clay content
showed a negative correlation with altitudinal ranges. Bulk density and moisture content were
negatively correlated. Therefore, the establishment of seedlings to saplings in the study areas was
very crucial for the sustainability of forests.
Description
Keywords
Tree diversity,, distribution, sapling, seedling, soil parameters