Chin J Plant Ecol ›› 2021, Vol. 45 ›› Issue (3): 224-241.DOI: 10.17521/cjpe.2020.0302

• Research Articles • Previous Articles     Next Articles

Vegetation geography of evergreen broad-leaved forests in Yunnan, southwestern China

ZHU Hua()   

  1. Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
  • Received:2020-09-04 Accepted:2020-12-29 Online:2021-03-20 Published:2021-05-17
  • Contact: ZHU Hua
  • Supported by:
    Natural Science Foundation of China(41071040);Natural Science Foundation of China(31970223);major project of Yunnan Science and Technology Department-Yunnan University joint fund(2018FY001-(002))


Aims Yunnan in southwestern China supports an extremely rich biodiversity and various vegetation types dominated by evergreen broad-leaved forest. Of these, three major types—monsoon evergreen broad-leaved forest (MEB), semi-wet evergreen broad-leaved forest (SWEB) and middle-montane wet evergreen broad-leaved forest (MMEB)—have not had a detailed scientific comparison. This article compares their floristic composition, species diversity, physiognomy, biogeography, and possible historical evolution, and gives suggestions for their conservation priorities.
Methods Six 1 hm2 sampling plots, representing the three evergreen broad-leaved forests in Yunnan, were set up based on the present distribution of primary forest. All trees in each plot were identified and their diameter at breast height (DBH)(minimum 5 cm) and height measured. In four plots, all plants, including understory shrubs, herbs, lianas, and epiphytes, were surveyed for life forms and biogeographical element analyses at plot level. Importance value indices (IVI) of tree species were calculated for each plot. At the vegetation level, all seed plants for the three major vegetation types were inventoried to compare their floristic composition and biogeography.
Important findings At plot level, the three forest types differ considerably in species composition, diversity, physiognomy, and biogeography, although they are commonly dominated by species of the families Fagaceae, Lauraceae and Theaceae. The MEB in southern Yunnan is extremely rich in species and is characterized by a tropical physiognomy. It is dominated by tropical Asian species, which is similar to the tropical lower montane evergreen forest in southeast Asia. The SWEB on plateaus and the MMEB in central and northern Yunnan are characterized by a subtropical physiognomy and are dominated by Sino-Himalayan and Chinese endemic species, which are unique in southwestern China. At the vegetation sub-type level, the three forest types commonly have species-rich families, which tend to have cosmopolitan distributions, but the families with fewer species exhibit other distribution types. The SWEB and the MMEB showed similar biogeographical patterns in the proportions of tropical (44.91% and 44.04%, respectively) and temperate (46.29% and 48.19%) elements, with northern temperate distributions comprising the highest percentage (18.36% in the SWEB and 19.95% in the MMEB) of total genera. In MEB, tropical elements comprised 78.05% of the total genera, with elements with tropical Asian distributions contributing the highest percentage (29.02%). Similarity between SWEB and MMEB was high at species level, but lower similarities were shown between MEB and both of the SWEB and MMEB with 17.1% and 15.4% respectively at species levels. These results indicate divergence of the three forest floras, possibly from events in the geological history of Yunnan. The SWEB and the MMEB should be given high conservation values due to their uniqueness and abundant Chinese endemic species. Especially, the SWEB should be given the highest protection.

Key words: evergreen broad-leaved forest, species composition, physiognomy, biogeography, Yunnan