Assessment of Plant Competition and Tree Typical Crown Area in Thinned and Un-Thinned Stands of Community Managed Pine Plantation

The forest conditions of Nepal can be enhanced by the application of proper management techniques and sivicultural treatments like thinning. Nepal has been implementing thinning practices in some of the forests and their effect has been visibly observed on the plant completion and tree typical crown area. Thus, this research work was objectively carried out to assess and compare the plant competition and tree typical crown area in thinned and un-thinned stands of planted Pine forest. Three community forest namely Srcihhap Deurali, Bajhbisauna and Sansari Danda were selected as the study site. Total 30 circular sample plots having an area of 100m2 were established in each of the community forest such that 15 plots each were allocated to thinned and un-thinned stands. The diameter, crown width and the distance between subject tree and its competitors were measured and competition indices and tree typical crown area were estimated.

The result in Sansari Danda Community Forest showed that the intensity of plant competition was slightly higher on un-thinned stands than in thinned. With the application of Independent Samples-t test it was found that the results were not significantly different at 5 % level of significance between thinned and un-thinned stands. Similar results were observed in other community forests as well. . It was found that the typical tree crown area was about 31.52 (±0.88) m2 in the thinned stand which was comparatively higher than in un-thinned stand having value 20.88 (±3.71) m2 in Sansari Danda Community Forest. The results were significantly different between thinned and un-thinned stands with the application of Mann-Whitney U test (P=0.031) at 5% level of significance. This research illustrates the effect of thinning on pine plantation and its importance on present Nepalese context. Therefore, it will be helpful tool for scientific community and decision makers who are involved in silviculture science. 

Keywords: Thinning, plant competition, tree typical crown area.