Divergent responses to climatic conditions in radial growth of Abies fargesii along elevation at the eastern edge of the Tibetan Plateau

Key message

A gradual change exists in the altitudinal response of earlywood growth of Abies fargesii to hydrothermal conditions, with temperature being the main climatic factor controlling its latewood growth.

Abstract

The Tibetan Plateau, as the “Third Pole”, has witnessed profound and intricate effects of climate change in recent decades. This may result in different responses of tree radial growth to climatic factors in this region, varying with elevation and growth stages. To accurately reveal these different responses we established totalwood, earlywood and latewood width chronologies of Abies fargesii at four elevations. Our results showed that: (1) As the elevation increases, the response of radial growth of Abies fargesii to climatic factors shifted from restriction primarily by water deficiency caused by rapid warming, to weak restriction by winter precipitation with favorable hydrothermal conditions, and then to double restriction owing to insufficient heat and excessive moisture. This pattern was inconsistent with the relationship between the radial growth and climatic factors for latewood observed at the low and middle–low elevations. (2) There existed a temporal variability in the relationship between tree radial growth and restrictive climate factors. This unstable relationship was mainly observed in the middle–low elevation within suitable ecological conditions and during the later stages of tree radial growth with lower growth rates. This is related to the fact that more suitable ecological conditions and lower growth rates make tree growth more susceptible to climatic fluctuations. Considering these findings, if the climate would experience further cooling and humidity increasing in the study region, the growth of Abies fargesii might be more adversely affected at high elevation. For economic and ecological considerations, the afforestation of Abies fargesii should be prioritized in the middle–low elevation zones where favorable for the population distribution.