Forest Structure and Regeneration Pattern of Betula Utilis D. Don in Manaslu Conservation Area, Nepal

Abstract

Forest structure and regeneration of Betula utilis (D. Don) was studied in birch forest located in Samagaun valley (3500 -4000 m) of Manaslu Conservation Area. Vegetation sampling was done by quadrat method. Altogether 40 quadrats were sampled to determine the Importance Value Index (IVI) of tree species, and distribution pattern of seedlings and saplings. Regeneration was assessed by density -diameter curve. Four tree species were recorded from the forest. Betula utilis was the dominant tree species with the highest Importance Value Index (173.22) in mixed Betula forest and 262.96 in pure Betula forest and Abies spectabilis was the co -dominant species (65.95) in mixed Betula forest while Rhododendron campanulatum was the co-dominant species (37.03) in pure Betula forest. Density of Betula utilis increased with increase in elevation where as density of other tree species decreased with increase in elevation. Mixed Betula forest at lower elevation was young. The density diameter curve of the tree population of Betula utilis, both on mixed and pure forests, deviated slightly from the typical reverse J shaped structure and hence did not show the sustainable regeneration. The sapling density was higher than seedling density. The distribution of seedlings and saplings were not uniform among the sampling plots.

Population Structure of Rhododendron Campanulatum D. Don and Associated Tree Species along the Elevational Gradient of Manaslu Conservation Area, Nepal

“…The total sapling density of all tree species was higher than seedling density which is not a normal demographic development. Similar trend was also observed by Gaire et al 2010 at Langtang andSujakhu (2013) at Samagoan. There is a positive relationship between total basal area and seedling and sapling ( Fig.…”

“…Liang et al (2014) reported that the growth of Betula at the upper timberlines is limited by moisture. Sujakhu (2013) also emphasized that the current environment conditions were not favourable for the establishment of B. utilis seedlings. Moisture and deep shade might be detrimental for seedling establishment.…”

Population structure and distribution of Abies spectabilis (D. Don) in Central Nepal Himalaya: A comparison with the total woody vegetation of the forests at the three different elevation ranges in Manang District

“…The tree, sapling and seedling density of A. spectabilis recorded in this study is comparable with the density in the other parts of the Nepal Himalaya. A. spectabilis sapling density was 648 stems/ha in Manaslu Conservation Area (Sujakhu et al, 2013) and the sapling density declined with increase in elevation. In the same area, A. spectabilis tree density is 412 stem/ha and basal area is 11.64 m 2 /ha.…”

“…In the same area, A. spectabilis tree density is 412 stem/ha and basal area is 11.64 m 2 /ha. The total tree density was more in the mixed forest (2,054 stems/ha) than in the pure forest (1,707 stems/ha) (Sujakhu et al, 2013). Kunwar and Sharma (2004) found out A. spectabilis density ranged from 250 to 510 trees/ha in Amaldapani and Juphal community forests of Dolpa District.…”

“…Abies spectabilis (D. Don) is a high altitude Himalayan fir found in central to western Nepal, up to Afghanistan in the west, between 2400-4400 m elevations at temperate and alpine zones (Stainton, 1972;Jackson, 1994;Yadav et al, 2004;Ghimire et al, 2008). It extends up to the treeline, and Betula utilis forest succeeds at higher altitudes (Ghimire et al, 2008;Sujakhu et al, 2013). Among the several Himalayan conifers, A. spectabilis is proved for its dendroclimatic potential along the entire Himalayan range (Suzuki, 1990;Bhattacharyya et al, 1992;Yadav and Singh, 2002;Yadav et al, 2004;Sano et al, 2005;Gaire et al, 2011Gaire et al, , 2014.…”