Abstract
A strong increase in the mean annual air temperature during the past 50 years by up to 0.54 °C was recorded in the Altai region (45°–52° N; 84°–99° E) compared to the global value of 0.07 °C over the period 1901–2008. The impact of the climatic changes on the hydrology are complex in these mountainous forest ecosystems and not fully understood. We aim to reveal differences in the intrinsic water-use efficiencies (iWUE) strategy by larch (Larix sibirica Ledeb.) derived from stable carbon isotopes at contrasting sites, ranging from the steppe (Ersin, Chadan) to high-elevation (Mongun, Koksu) sites of the Altai over the past century. The iWUE trends increased rapidly for all study sites except Chadan, where a decreasing trend after 2010 has been observed. This decline can be related to increased amount of precipitation compared to increased drought at the other sites. In general, the iWUE is increased up to 14% (1985–2019 compared to 1919–1984), which is lower compared to other studies across the globe likely due to harsh climatic conditions. Vapor pressure deficit and maximal air temperature are impacting Siberian larch significantly and affecting their iWUE differently at the high-elevated and steppe sites of the Altai over the past century.
Highlights
The Altai-Sayan mountain range (ASMR) is a unique mountain region with widely contrasting eco-physiological conditions, representing vegetation from the steppe ecotone to the high elevation sites
Based on the air temperature data recorded from the 17 local weather stations for the period from 1966 to 2015, it was shown that the mean annual air temperature increased by up to 0.54 ◦ C [1] in the ASMR (45◦ –52◦ N to 84◦ –99◦ E), which is considerably more than the global value of 0.07 ◦ C or Northern-Hemisphere value of 0.10 ◦ C over the period 1901–2008 [2]
In order to better understand impact of climatic changes at the Altai-Sayan mountain range on Siberian larch trees, we aim to examine water-use efficiency strategies at different locations under centennial air temperature and vapor pressure deficit changes
Summary
The Altai-Sayan mountain range (ASMR) is a unique mountain region with widely contrasting eco-physiological conditions, representing vegetation from the steppe ecotone to the high elevation sites. Annual temperature and precipitation amount vary significantly from low (45◦ N, 84◦ E) to high (52◦ N, 99◦ E) latitudes and represent average surface air temperature ranging from −6 ◦ C to +7 ◦ C and an annual amount of precipitation ranging from 143 to 820 mm/year, respectively. Instrumental data observations from the local weather stations situated in the ASMR at the high altitudes (1500–2300 m a.s.l.) are usually limited to the past 30–40 years. Based on the air temperature data recorded from the 17 local weather stations for the period from 1966 to 2015, it was shown that the mean annual air temperature increased by up to 0.54 ◦ C [1] in the ASMR (45◦ –52◦ N to 84◦ –99◦ E), which is considerably more than the global value of 0.07 ◦ C or Northern-Hemisphere value of 0.10 ◦ C over the period 1901–2008 [2]
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