The Himalayan shrub rhododendron (Rhododendron campanulatum) is a dominant shrub species at upper treeline and above in alpine and sub-nival vegetation zone in the Himalayan region, yet the dendroclimatic potential of the species has not been explored.
In a study published in Dendrochronologia, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) revealed that the radial growth of R. campanulatum is positively related to temperatures throughout the year, but strongly sensitive to winter (December-February) minimum temperature at the upper treeline in the central Himalaya.
The researchers established a ring-width chronology (227 years) of a Himalayan shrub rhododendron for first time at the upper Krummholz treeline in the Mt. Gaurishankar massif, central Himalaya, Nepal, which documents the high longevity of this species.
Growth-climate relations revealed that radial growth of R. campanulatum in alpine vegetation beyond upper treeline is strongly sensitive to low winter temperature. Cool-warm episodes in the central Himalaya coincide with other regional temperature records from the Himalaya and vicinities
The researchers also established a robust reconstruction on minimum winter temperature for the past 169 years in the central Himalayan region. Winter temperature in the central Himalaya is teleconnected with the December-February India-Burma trough. The shift in winter temperature during recent decades coincides with continental-scale warming.
The results imply that growth of R. campanulatum may benefit from future winter warming, and thus potential upslope expansion of alpine vegetation under sufficient soil moisture conditions.
“Our results demonstrated that Rhododendron shrub-ring chronology can be used as a high-resolution proxy for studying long-term environmental changes in the Himalayan alpine vegetation,” said Dr. FAN Zexin, principal investigator of the study.
FAN Zexin Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China