Growth and Climate Sensitivity of Pinus Roxburghii (Chir pine) from Melamchi Region of Nepal Himalaya: Research through Education

Abstract

Climate change is affecting multiple sectors in Nepal including its diverse forests. Tree-rings data have many applications including the growth of species, and climate change impacts on tree species, among others. The Melamchi region has witnessed rapid climate change and extreme events and associated environmental hazards in recent years. In this context, a dendrochronological educational research field work was carried out in the Melamchi region of Nepal with the objective to assess the growth and regeneration of trees in different forests including the climatic response of chir pine (Pinus roxburghii Sarg.). Tree-core samples were collected and analyzed by following the standard dendrochronological method. The average diameter at breast height (DBH) of pine was 29.62 cm while the average annual radial growth was 2.71 mm per year and the average basal area increment was 1153.92 mm² per year. We observed many false ring bands in tree rings likely due to intra-annual climatic variability and or due to anthropogenic disturbances in the studied forest stands. An 83 years long tree ring width site chronology of chir pine spanning from 1941 to 2023 AD was developed which shows long-term growth variability. The study found a significant positive relationship (based on correlation coefficient) between the pine chronology and precipitation in current year February, negative relationship with May month precipitation and February month temperature (average and maximum). The study also highlights that growth climate response of the chirpine is stable to changing over time i.e. the response to the February and May month precipitation and February month temperature is persistent over time while response with May month temperature is positively intensified but response to June and previous year October precipitation is weakening during recent years. The study also indicated that pine trees are sensitive and responsive not only to the climate change but also to the prevailing disturbances events, and growth of which can be affected by both of the phenomena. Educational research field studies are effective means in transferring theoretical knowledge to practical research aspects.