As a pivotal component of terrestrial biomes, forest ecosystems play a vital role in climate regulation, the hydrologic cycle and carbon sequestration. The boreal forest of the Holarctic is one of the earth’s largest biomes and is also one of the ecosystems that is most sensitive to climate change. This region is also the source of rivers in many nearby countries, which plays an important role in the ecosystem dynamics and climate stability of Central and North Asia. However, the study of the Altai Mountains is mainly limited to the local scope, lack of large-scale studies across the latitudinal gradient.

Under the guidance of Prof. HUANG Jianguo, KANG Jian from South China Botanical Garden of Chinese Academy of Sciences, established a wide network composed of 34 tree-ring chronologies (including two species: Larix sibirica Ledeb. and Pinus sibirica Du Tour.) distributing along a broad latitudinal gradient ranging from 45^。to 55^。N and covering the boreal forest of the Altai-Sayan Mountains of Central Asia. The researchers analyzed the spatial pattern of radial growth of trees, the main limiting climate factors and the relationship between radial growth and large-scale climate circulation.

They found that the chronologies with an obvious clustering pattern were divided into northeastern (NR) and southwestern region (SR). Tree radial growth in both regions was positively associated with summer temperature (June and July). Tree radial growth in the NR region was positively associated with early spring precipitation and spring Palmer Drought Severity Index (PDSI) whereas, in the SR region, it was characterized by negative correlations with early summer precipitation and summer PDSI. The warm pool El Ni^~no-Southern Oscillation (WP ENSO) and North Atlantic Oscillation (NAO) regulated tree radial growth through their influence on regional precipitation and temperature.

These results suggest that tree radial growth in the region may decline with future projected climate change. This study provides a more comprehensive understanding to tree growth-climate associations across Central Asia. “Our study is helpful to further understand the climatic factors affecting the tree radial growth in boreal species and provides a basis for forest management and ecological restoration in Central Asia,” said Prof. HUANG.

The study was published in Agricultural and Forest Meteorology, entitled “Radial growth responses of two dominant conifers to climate in the Altai Mountains, Central Asia”. For further reading, please refer to: https://doi.org/10.1016/j.agrformet.2020.108297.