Climate Change Increases Drought Stress of Juniper Trees in the Mountains of Central Asia

Abstract

Assessments of climate change impacts on forests and their vitality are essential for semi-arid environments such as Central Asia, where the mountain regions belong to the globally important biodiversity hotspots. Alterations in species distribution or drought-induced tree mortality might not only result in a loss of biodiversity but also in a loss of other ecosystem services. Here, we evaluate spatial trends and patterns of the growth-climate relationship in a tree-ring network comprising 33 juniper sites from the northern Pamir-Alay and Tien Shan mountain ranges in eastern Uzbekistan and across Kyrgyzstan for the common period 1935–2011. Junipers growing at lower elevations are sensitive to summer drought, which has increased in intensity during the studied period. At higher elevations, juniper growth, previously favored by warm summer temperatures, has in the recent few decades become negatively affected by increasing summer aridity. Moreover, response shifts are observed during all seasons. Rising temperatures and alterations in precipitation patterns during the past eight decades can account for the observed increase in drought stress of junipers at all altitudes. The implications of our findings are vital for the application of adequate long-term measures of ecosystem conservation, but also for paleo-climatic approaches and coupled climate-vegetation model simulations for Central Asia.

Juniper Tree-Ring Data from the Kuramin Range (Northern Tajikistan) Reveals Changing Summer Drought Signals in Western Central Asia

“…The correlations between the regional chronology and the climate factors reveal that the radial growth of the Zeravshan juniper in the low elevation area of Kuramin Range was mainly limited by the water availability. This linkage resembles other findings in the dryland of the inner Asia and suggests the influence of moisture conditions on the juniper growth there [35,37,[46][47][48]. As shown in some studies [22,49], the combination of low precipitation and high temperatures in the previous growing season results in less accumulation of photosynthetic matter for the next year.…”

Warming‐induced upward migration of the alpine treeline in the Changbai Mountains, northeast China

“…The relationship between summer mean temperature (SMT) and STD had the strongest correlations; that is, SMT largely corresponded to the annual growth of B. ermanii . This finding consists with the prevailing view that high altitude and latitude treelines are controlled by summer temperatures (Gehrig‐Fasel, Guisan, & Zimmermann, ; Kirdyanov et al., ; Linderholm et al., ; MacDonald, Kremenetski, & Beilman, ; Seim et al., ). We therefore used the STD chronology series to reconstruct the SMT of our transects for the last 160 years (Appendix S4).…”

Wild Apple Growth and Climate Change in Southeast Kazakhstan

“…The tree-ring based reconstructions indicate increased drought stress on conifer tree growth in the mountains of Central Asia. Rapid increase in the rate of warming occurred in the last two decades, which caused the increase of summer aridity [14,17]. Juniper and spruce growing at the lower elevations are most sensitive to the drought stress, while conifers from the upper elevation showed significantly increased response to the temperature trend [15][16][17].…”

“…Past tree-ring studies from the Tian Shan Mountains demonstrated strong relationships between climate and spruce and juniper growth, which facilitated reconstructions of summer temperature and moisture variability [14][15][16][17][18]. The tree-ring based reconstructions indicate increased drought stress on conifer tree growth in the mountains of Central Asia.…”