Drought signal in the tree-rings of three conifer species from Northern Pakistan

Abstract Anthropogenic and climatic stressors have affected the forests of Pakistan in recent decades. Several studies have been conducted to understand forest growth and its relation to the changing climate in this region, but more work needs to be done to understand this complex environment. In this study, we have collected tree core samples of three conifer species (Pinus wallichiana, Picea smithiana, and Abies pindrow) from three different sites in northern Pakistan to understand their radial growth patterns with the goal of finding a relationship between ring-width and climatic parameters (temperature, precipitation, and drought). A 610-year (AD 1406 to 2015), a 538-year (AD 1478-2015), and a 306-year (AD 1710-2015) long tree-ring width chronology of Pinus wallichiana, Picea smithiana, and Abies pindrow were developed, respectively, using living trees. The ring-width chronologies of these three species showed a strong positive link with self-calibrated Palmer Drought Severity Index (scPDSI) rather than precipitation or temperature alone, indicating soil moisture is the primary limiting climatic factor for the growth of these species in the sample sites. The chronologies of Pinus wallichiana and Picea smithiana exhibited growth suppressions during AD 1570-1610 and the second half of 17th century while their growth was heightened from AD 1540-1560. From 1900 to 1920 is the lowest growth in the Abies pindrow and also low growth in Picea smithiana suggesting dry conditions. All three chronologies have exhibited the most extreme increase in growth in recent decades for the period of good sample depth, suggesting that this region is experiencing climate change with a strong trend towards wetter conditions.