Abstract
The subalpine coniferous forests on the eastern Qinghai-Tibet Plateau provide a natural laboratory for studying the effect of climate warming on terrestrial ecosystems. Research on differences between tree species in their responses to experimental warming can provide insights into their regeneration behavior and community composition under a future warmer climate. We used open-top chamber (OTC) to determine the short-term effect of two levels of air temperature (ambient and warmed) and light (full light and ca. 10% of full-light regimes) on the early growth and physiology of Betula albo-sinensis and Abies faxoniana seedlings. The OTC manipulation increased mean air temperature and soil surface temperature by 0.51 and 0.34°C, respectively, in a 60-year-old plantation and 0.69 and 0.41 °C in forest openings, respectively. Warming generally increased plant growth, biomass accumulation, and advanced physiological pro cesses for seedlings of both species. In response to warming, both tree species allocated relatively more biomass to foliage and had significantly decreased root/ shoot ratios (R/S), which might provide the two species with an adaptive advantage when other environmental factors were not limiting. Warming may enhance photosynthesis in the two seedlings by increasing efficiency of PSII in terms of increases in Fv/Fm, photosynthetic pigment concentrations, and apparent quantum yield (Φ)However, the effects of warming on seedling growth and physiological performance varied by light conditions and species. For B. albo-sinensis seedlings, the effects of warming were pronounced only under full-light condi tions, while the growth and physiological responses of A. faxoniana seedlings to warming were found only under low-light conditions. Competitive and adaptive relation ships between the two species may be altered as a result of response differences to warming manipulation. The short-term beneficial impact of warming on the early growth and development of the two species suggests that global warming may lead to changes in regeneration dynamics and species composition in subalpine coniferous forest ecosystems.
基金项目
国家自然科学基金(30800165)
国家自然科学基金(30530630)
Knowledge Innovation Program of the Chinese Academy of Sciences(KSCX2-YW-N-066-03-01)
Talent Plan of the Chinese Academy of Sciences, and the forefront project of Chengdu Institute of Biology(08B2031)
NETL
NSTL
万方数据