Impact of resin tapping on the radial growth and climate sensitivity of naturally- regenerated Pinus roxburghii (Chir pine) in Western Nepal

Abstract

The study investigated the effect of resin tapping on radial growth and climate sensitivity of naturally regenerated Pinus roxburghii (chirpine) in Western Nepal. We collected core samples (dbh>30cm) from the community forest in the Salyan district: 26 from tapped and 33 from untapped trees situated in similar climatic, topographic, and ecological conditions. A tree-ring width chronology spanning 52 years was developed for both tapped and untapped trees. Statistical analyses, such as Pearson correlation and t-test, were used. Results indicate the untapped trees exhibited significantly higher basal area increment (BAI: p < 0.05) than those of tapped trees, indicating that resin tapping negatively impacts tree growth. Furthermore, both tapped and untapped trees exhibited a positive correlation between radial growth and temperatures in May, June, July and August suggesting critical role of temperature in influencing the growth of Pinus roxburghii trees whether they have been tapped for resin or not. The rainfall in January, February, March, April, August, October, and December positively influenced the radial growth of both tapped and untapped trees, with only the rainfall in January having a significant effect on growth. Radial growth is impacted by the resin tapping while decreasing its recovery strength after stress as well. This study highlights the need for alternative resin-tapping practices that minimize negative impacts on tree growth. It also emphasizes the importance of considering rainfall and temperature patterns when planning tapping activities to ensure sustained resin production and promote tree health.