Chin J Plant Ecol ›› 2008, Vol. 32 ›› Issue (5): 1061-1071.DOI: 10.3773/j.issn.1005-264x.2008.05.011

• Original article • Previous Articles     Next Articles

RESPONSES OF PHENOLOGY AND GROWTH OF BETULA UTILIS AND ABIES FAXONIANA IN SUBALPINE TIMBERLINE ECOTONE TO SIMULATED GLOBAL WARMING, WESTERN SICHUAN, CHINA

XU Zhen-Feng1, HU Ting-Xing1,*(), ZHANG Yuan-Bin2, XIAN Jun-Ren1, WANG Kai-Yun2,3   

  1. 1Faculty of Forestry, Sichuan Agricultural University, Ya’an, Sichuan 625014, China
    2Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
    3Shanghai Key Laboratory of Urbanization Processes and Ecological Restoration, East China Normal University, Shanghai 200062, China
  • Received:2007-11-22 Accepted:2008-04-22 Online:2008-11-22 Published:2008-09-30
  • Contact: HU Ting-Xing

Abstract:

Aims Betula utilis andAbies faxoniana are two typical, important plants in timberline ecotone in subalpine regions of western Sichuan, China. Their responses in phenology, growth and leaf and branch traits to simulated global warming can be studied using the open-top chamber (OTC) method. The main purposes of our experiment are to determine how two species change their phenology, whether shoot growth is enhanced and whether responsive patterns of deciduous and evergreen species are consistent. We reported the second year’s responses of plants to the OTC treatment.

Methods During the 2007 growing season, we observed phenological events (bud break, leaf expansion and defoliation) and measured branch and leaf growth rates, traits and distribution patterns. Microclimate data between OTCs and control plots (CK) were automatically recorded at 15-minute intervals. We analyzed phenological events, leaf area, branch length, etc. for OTCs and CKs by the Mann-Whitney U-test. Specific leaf area (SLA) was analyzed by the Wilcoxon’s signed ranks test.

Important findings Air temperature at vegetation height (1.2 m) increased by 2.9 oC during the growing season, and soil temperature at 5 cm depth did not differ between OTC and CK throughout the growing season. Abies faxonianashowed earlier bud break in the OTC, and B. utilishad extended foliage period and individual leaf longevity in the OTC. Elevated temperature resulted in higher leaf and branch growth rates and basal diameter relative growth rates for both species. There were significant differences in SLA and leaf size for B. utilisbetween the OTC and the CK. Different responses (positive, negative or no effects) were found in branch length, branch number and leaf distribution pattern for both species. Therefore, evergreen conifer and deciduous broad-leaved species differ in their responses to warming.

Key words: ecotone in timberline, Betula utilis, Abies faxoniana, phenology, growth, open-top chamber