Plant Species Diversity and Tree Carbon Stock in A Shorea Robusta Gaertn. Community Forest, Nawalparasi, Nepal

Abstract

Carbon trading and biodiversity conservation are hot issues at present global climate change. Carbon stock in tropical ecosystem is greater per hectare than elsewhere. Shorea robusta Gaertn. is one of the major forest components species in the tropical ecosystem of Nepal. Documentation of associated species in the tropical Shorea robusta community forest, their species richness and the carbon stock patterns are major objectives of this study. Thus, this present study has been initiated in the lowland (200 m asl), Bishnu Nagar Community Forest, Nawalparasi, Nepal. This forest has an area of 196.72 ha studied systematically after sampling it into 30 quadrates of 20 × 20 m 2 each encompassing all management blocks demarcated by Community Forest Users Groups (CFUGs). Species encountered inside each quadrat have been recorded and individual trees were tagged permanently for a year. Carbon stock for each tree calculated after using allometric equation. In addition, soil nitrogen, phosphorus, potash and pH were also measured. Detrended correspondence analysis (DCA), non metric multidimensional scaling (NMDS), correlations and regression methods were applied through R statistical packages. This study documented a total of 68 vascular plant species under 41 families and 61 genera. Fabaceae was the most dominant family (9 species) followed by Araceae (3 species). The first axis of DCA explained 7% of the total variance in the data set. Most species showed the significant linear relation to the major gradient (DCA I st axis length = 1.4 unit). Abundance of Indigofera decora was highly correlated towards plots with the highest value of NMDS 5

1, may represent the grazing indicator. Likewise, Albizia julibrissin and Typha angustifolia significant on the NMDS 2 may represent the moisture loving species. Soil nitrogen, phosphorus, organic matter and species richness were significantly correlated to the NMDS 1 but species richness is more significant to the NMDS 2 . The average carbon stock value found to be 115 tons per hectare and tree stem volume was measured as 225.2 m 3 per hectare. Key words: Composition, detrended correspondence analysis (DCA), disturbance, Non-metric Multi Dimensional Scaling axis1 (NMDS 1 ) , Non-metric Multi Dimensional Scaling axis 2 (NMDS 2 ), Silviculture.