Response of Pinus wallichiana to Climate Change: A Case Study from Manaslu Conservation Area, Western Nepal
This study mainly focuses on dendro-ecological response of Pinus wallichiana to climate change. The study was carried out in two community managed forests, namely Thangming and Chhak of Prok VDC in Manaslu Conservation Area (MCA) in western Nepal. Vegetation sampling was done by quadrate method, and the sample quadrates were located by stratified random sampling technique. Four vertical transects were laid along the elevation gradient running parallel to each other with 200 m difference starting from 2,100 m asl to 2,700 m asl. Altogether 28 quadrates (size: 20 m × 20 m) were laid on both north and south-facing slopes (18 in north and 10 in south). Diameter at Breast Height (DBH), basal diameter and height of each individual tree of P. wallichiana were recorded. A total of 105 tree cores were collected by using Swedish increment borer. A detailed ecological survey was carried out in each plot with GPS recording. The forests of both aspects were dominated by P. wallichiana. Northern aspect was associated with Cedrus deodara, Rhododendron arboreum, Castanopsis indica, etc. The north facing slope had denser forests (1437.5 no. /ha) than the south-facing slope (643.75 no. /ha). Tree density of P. wallichiana decreased with increase in altitude in southern aspect; however, no such consistent trend was seen in the northern aspect. There was significant difference in P. wallichiana density between two aspects (t-statistic 0.37, p< 0.05). The average seedling and sapling density of P. wallichiana on the north and south slopes was 173.75 no./ha; 293.75 no./ha and 218.75 no./ha; 256.25 no./ha respectively. From the tree ring analysis a 91 years old tree was recorded from northern aspect of the forest. The average annual radial growth was 1.30 mm/yr and 0.90 mm/yr for northern and southern aspect respectively. The ring pattern showed the fluctuation in the ring width with the temporal change in environmental condition. The growth of P. wallichiana was favored by pre-monsoon temperature and monsoon rainfall. This shows that fluctuation in any climatic condition in these months will change the growth pattern of the P. wallichiana.