The pattern of forest dieback in Horton Plains National park was investigated during a one year research project conducted in 2006.  During the project three hectares of the forest was sampled in three sites showing different degree of dieback (namely Anderson I, Anderson II and Thotupolakanda).  Totupolakanda site is represented a severe dieback site while Anderson I site has undergone moderate dieback.  Anderson II is a comparatively healthy site.  During this study the nature and possible causes of forest dieback in the selected sites in the park area were investigated.  A total number of 6191 trees belonging to 39 species in 26 genera and 17 families were recorded.   Of the total number of trees recorded, 1343 were canopy dominant trees while 4643 were found in the sub-canopy.  In addition 105 trees were recorded in the understory while 100 live fallen trees were also recorded.  The most dominant families were Lauraceae, Myrtaceae and Symplocaceae.  Cinnamomum ovalifolium was the most abundant species in Anderson I site and Symplocues cordifoliya were the most abundant species in Anderson site II.  Cinnamomum ovalifolium and Syzygium rotundifolium were the dominant species in Totupolakanda site. Highest percentage of canopy and understory trees was recorded in Anderson I site and the highest percentage of sub canopy trees was recorded in Anderson II site.  Percentage of unhealthy trees in Anderson II site is larger than the other two sites and it was about 39.78%. Further, the highest percentage of healthy tree was also recorded in Anderson II site.  The study finds that the bark damage by sambar (Cervus unicolor) may entice stem defect of a tree which will eventually lead to a death of a tree.  However, the causes of foliage discoloration, defoliation or crown dieback could not be evaluated.


KEY WORDS: Forest dieback, Montane grasslands, Montane forest, Sambar

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