Responses of alpine shrubs to simulated environmental change during three years in the mid-latitude mountain, northern Japan

Effects of artificial warming on phenology, individual leaf traits, vegetat ive growth, and reproduction of five alpine species (two deciduous and thre e evergreen shrubs) were investigated during three years in the mid-latitud e alpine, northern Japan. Eleven open-top chambers (OTCs) were set up on a fellfield (1680 m a.s.l.) in the Taisetsu Mountains by which air temperatur e at plant height was increased by ca 2 degreesC. Vaccinium uliginosum (dec iduous shrub) showed earlier leaf emergence in every season and earlier flo wering only in the first season in the OTCs. By contrast, acceleration of l eaf emergence in the OTCs was not clear for other species, i.e. Arctous alp inus (deciduous shrub), Ledum palustre, V. vitis-idaea, and Empetrum nigrum (evergreen shrub). Both deciduous species showed longer leaf life-span in the OTCs every season. All evergreen species had higher leaf survival rates in the OTCs, indicating extension of leaf life-span. Leaf nitrogen concent ration and leaf mass per unit leaf area (mg cm(-2)) generally tended to dec rease in the OTCs. Relationships between the individual leaf traits and cum ulative air temperature during the leaf developing period were not clear. T otal leaf production during the three seasons increased in the OTCs in A. a lpinus, L. palustre, V. vitis-idaea, and E. nigrum. All evergreen shrubs sh owed larger shoot growth in the OTCs but both deciduous shrubs did not show significant changes. In contrast to the vegetative growth, deciduous shrub s produced more flowers in the OTCs. Fruit production was not influenced by the OTCs for all species. The extension of photosynthetic period in the OT Cs may contribute to the larger vegetative growth or flower production.