A previous dendroecological study on fir growth from the northern declivity of Mt. Everest found a temperature signal at higher elevation and a moisture signal at lower elevation belt. However, no study has yet investigated the response of a tree species along with its entire elevation distribution range in the southern declivity of the world's highest elevation gradient, the Mt. Everest region.
In a study published in Agricultural and Forest Meteorology, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and their collaborators investigated the growth and climate sensitivity of Abies spectabilis (Himalayan silver fir) along an elevation gradient in the Sagarmatha (Mt. Everest) National Park (SNP). They wanted to identify the key climatic factors limiting the growth of A. spectabilis along its elevational distribution range and assess the changes in long-term tree growth rates at various elevations.
The researchers developed six tree ring-width chronologies of A. spectabilis, , spanning 98 to 310 years, along an elevation gradient (3400-4100 meters above the sea level) in the Mt. Everest region, the central Himalaya.
They found that temperature during and preceding the growing season was the primary limiting factor for growth. Moisture availability during spring was the second relevant growth factor, especially in lower-elevation forest belts. Low spring moisture availability reduced Himalayan fir growth at low- to middle-elevations.
They further found positive growth trend at the treeline site over the recent decades, which was likely related to the effect of the warming climate. The negative growth trends at low- to mid-elevation belts might relate to recent intensified drought conditions during the spring season.
"Our findings emphasize the importance of understanding the vulnerability of forests at middle and low elevations to future climate change," said FAN Zexin of XTBG.
Contact
FAN Zexin Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
E-mail: fanzexin@xtbg.org.cn
First published: 22 June 2023
