Abstract:

Aims: The Yarlung Zangbo Grand Canyon National Nature Reserve, characterized by unique topographic and climatic conditions, harbors the world’s most complete montane vertical vegetation spectrum and supports highly diverse, distinctive, and well-developed vegetation. Previous studies in the Reserve have mainly focused on forest and primary vegetation at low and middle elevations, whereas high elevation shrublands, herbaceous vegetation, and secondary vegetation have received much less attention. As a consequence, existing vegetation surveys and classification systems have not fully reflected the vegetation diversity of the region. This study aims to compile a more complete vegetation classification system for the Reserve and to clarify its newly recorded alliances. 

Methods: Based on surveys of 493 plots, 590 quadrats, and 16,648 survey points conducted within the Reserve, together with previous literature, and following the principles of A revised scheme of vegetation classification system of China, we compiled a vegetation classification system for the Reserve. 

Results: The vegetation of the Reserve was classified into 5 Vegetation Formation Groups, 20 Vegetation Formations, 34 Vegetation Subformations, and 162 Alliances. Compared with previous studies, 75 Alliance types were newly recorded (27 for forest types, 25 for shrubland types, 20 for herbaceous vegetation types, and 3 for swamp and aquatic vegetation types). Representative newly recorded types include Castanopsis indica Forest, Juniperus squamata Forest, Quercus semecarpifolia Forest, Ficus glaberrima Forest, Aster motuoensis Shrubland, evergreen broadleaf forest dominated by Lithocarpus species, high-elevation cold-temperate evergreen broadleaf shrubland dominated by Rhododendron species and forb alpine meadow grassland, secondary vegetation types such as Exbucklandia populnea Forest and Beilschmiedia robusta Forest. 

Conclusions: This study further develops the vegetation classification system of the Reserve, resulting in a more complete classification scheme, including more fully documented forest vegetation as well as previously underrepresented shrublands and herbaceous vegetation at high elevations, and secondary vegetation. Together with the newly recorded alliance types, this provides a more complete account of the abundant of vegetation diversity as well as the baseline data on vegetation types in the Reserve, offering a scientific basis for future vegetation research, biodiversity conservation and ecological protection in the region.

Key words: Yarlung Zangbo Grand Canyon, vegetation types, vegetation classification system, alliance, national nature reserve