The signal of climate change in tree-line vegetation has been observed in the mountainous part of the Manaslu region in the country with the timberline moving upward in a decade, says a new report of National Academy of Science and Technology (NAST).
The timberline can be considered a visible ecological boundary and shows a strong link between the various climatic parameters. The tree-line vegetation in high altitude is highly sensitive to climate change and can be used as a suitable indicator to detect changes of past and recent climate variability. The findings of the preliminary study carried out on two dominant tree species in the upper range in the mountain part of Manaslu Conservation Area showed that the tree species namely Abies spectabilis (East Himalayan Fir) and Betula utilis (Bhojpatra) were shifting upward at a faster rate than the maximum natural rate in the last 10 years.
The study on 'Treeline Dynamic with Climate Change: A study in Manaslu Region, Nepal Himalaya' carried out by researchers at NAST from May 22 to June 11, 2010 showed that Abies Spectabilis is shifting at a rate between 1.5 metres and 3.4 metres a year.
Earlier, the Abies treeline was found to be at 3,907 metres above seal level while now the upward shift of these tree species has been found at 3,984 metres. Meanwhile, the findings of the study on similar Abies spectabilis tree species carried out in Sankhuwasabha district in 2009 showed that treeline vegetation is shifting at a faster rate—at 23 metres in ten years in the southern aspect while it was 17 meter in the same period in the northern aspect. Dinesh Raj Bhuju, chief of Science Faculty at NAST, said the impact of climate change is more pronounced and sensitive in the high altitude regions especially in the mountainous environment. "Due to climate change, shifting of treeline is becoming a global phenomenon and Nepal can't be an exception. The upward migration of Abies spectabilis might be due to climatic warming observed in the past decades," he said. The final findings on whether the changes observed in tree-line vegetation in the upper forest due to climate change or precipitation variability or both will be soon published in a month period, Bhuju said.
Meanwhile, the study shows that the regeneration of Abies spectabilis is found higher and better while regeneration of Betula utilis is very low, which means the dominance and adaptability of Abies species is favourable compared with Betula species. Studies have shown that the alpine species which are adapted to survive in cold conditions are underscored by the change in global temperature. The species from the lower elevation are extending their territory to higher altitudes; in fact it brings competition to high altitude species.
The preliminary results of the study also shows the invasion of Abies treeline in the area which was earlier habituated by Betula utilis. The Betula treeline is slowing, being invaded by Abies treeline, which means increasing temperature is less favorable to Betula tree species than to Abies, according to Narayan Prasad Gaire, researcher at NAST. The final findings will be shared after the dendrochronological analysis of tree species studied in Manaslu area that will be completed next month, he added.