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Climate change is expected to be heterogeneous across the world, with high impacts on the Himalayan ecosystems. There is a need to precisely document cambial phenology and wood formation in these regions to better understand climate-growth relationships and how trees face a warming climate. This study describes the dynamics of cambial phenology in pindrow fir (Abies pindrow) along its altitudinal gradient in the Himalaya. The stages of xylem phenology, and the duration and rate of wood formation were assessed from anatomical observations during the growing season from samples collected weekly from three sites at various altitudes (2392–2965 m a.s.l.) over two years. There were significant differences in the duration and rate of cell formation along the altitudinal gradient, which decreased at increasing altitudes. The growing season duration decreased by 5.2 and 3.7 days every 100 m of increase in altitude in 2014 and 2015, respectively, while the rate of cell formation decreased from 0.38 and 0.44 cells /day to 0.29 and 0.34 cells/day in 2014 and 2015, respectively. Cell production decreased from 63.3 and 67.0 cells to 38.3 and 45.2 cells with a decrease of 4.3 and 3.8 cells per 100 m increase in altitude in 2014 and 2015, respectively. The higher precipitation in 2015 increased the growth rate and resulted in a higher xylem production. Our findings give new insights into the dynamics of cambial phenology and help in better understanding of the potential impacts of climate change on tree growth and forest productivity of Himalayan forests.

The Himalaya is one of the major mountain ecosystems that is most likely to be impacted by climate change. The main drawback in understanding climate change in the remote Himalayan ecosystems is the lack of long-term instrumental climate records. Reconstructing past climates from tree-rings offers a useful proxy for adding data to the instrumental climate records. In this study, climatically sensitive tree-rings of Himalayan fir (Abies pindrow) were used for reconstruction of mean June–July temperatures of Kashmir valley. Total ring-width chronology was built from 60 tree-ring cores growing near the higher altitudinal limits of the species. The radial growth showed a strong positive response to growing season temperature. The strong response of site chronology to mean June–July temperatures was used for reconstruction purposes. Mean June–July temperatures of Kashmir valley were reconstructed since 1773 from residual site chronology. Though the reconstruction did not show any strong long-term trend, on a centennial-scale, 20th-century summers were the warmest with a mean annual summer temperature of 22.99 °C. Seven of the warmest years and five of the warmest decades were seen in the 20th century. The reconstruction for 1773–2012 showed 23 extreme hot summers above the hot threshold of a 23.47 °C mean temperature and 19 extreme cold years below the cold threshold of a 22.46 °C mean summer temperature. The cold years in the reconstruction did not coincide with known volcanic eruptions. This reconstruction will help in providing a better understanding of regional climate change.

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