An inventory of isolated tree stands surrounded by desert pastures in Southern Tibet (A.R. Xizang, China) revealed more than
50 sites with vigorous trees of
Juniperus convallium Rehder & E.H. Wilson and
Juniperus tibetica Kom and additional more than 10 records where juniper trees had been destroyed between 1959–1976. The tree stands are not
restricted to any specific habitat, and occur within an area stretching 650 km westwards from the current forest border of
Southern Tibet. The trees are religious landmarks of the Tibetan Buddhists. The highest trees were found at an elevation of
4,860 m. Vegetation records, rainfall correlations and temperature data collected by local climate stations and successful
reforestation trials since 1999 indicate that forest relicts fragmented through human interference could regenerate if current
cattle grazing and deforestation practices are halted. The drought line of
Juniperus forests in Southern Tibet is approximately 200–250 mm/a. A first pollen diagram from Lhasa shows forest decline associated
with the presence of humans since at least 4,600 yr BP. The currently degraded commons developed in the last 600 yr. To date,
no findings of remains of ancient forests in the Central Tibetan Highlands of the Changtang have been reported.
Keywords China - Environmental change - Forest history - Habitat fragmentation -
Juniperus
-
Kobresia
- Tibet