Leaf photosynthetic characteristics and net primary production of the polar willow (Salix polaris) in a high arctic polar semi-desert, Ny-Ålesund, Svalbard

Photosynthetic characteristics and their leaf-age dependence were examined to estimate ecophysiological ef- fects on net primary production (NPP) of a polar willow (Salix polaris), a dominant dwarf shrub species in a polar semi-desert area of Ny-Alesund, Svalbard. Leaves of S. polaris emerged just after snowmelt in early July in 2000; flowers were initiated within 1 week, and fruits in late July. Light-saturated rate of photosynthesis and stomatal con- ductance to water vapor increased rapidly to their maximum values within 1 week after leaf emergence and then de- creased gradually. Depending on the leaf age, photosynthetic rates saturated at photosynthetically active photon flux density (PPFD) of 200-400 µmol·m -2 ·s -1 , which is the light level usually available in the natural habitat. Optimum leaf temperature of photosynthesis ranged from 10 to 18°C, while air temperature in the habitat ranged from 8 to 20°C. These light and temperature responses of photosynthesis of S. polaris would be suitable for efficient carbon gain in the natural habitat characterized by highly variable light and temperature conditions. Using the photosynthetic and respira- tory characteristics, biomass distribution, and meteorological data, NPP of S. polaris in the current year was estimated to be 26.1 g C·m -2 . A model simulation of rising temperature conditions predicted a reduction of NPP because of a large increase in respiration. It was suggested that temperature condition and leaf phenological aspects strongly influ- ence the carbon fixation by plants in the high arctic area studied.

[1]  Gas exchange and water relations of two Rocky Mountain shrub species exposed to a climate change manipulation , 2000, Plant Ecology.

[2]  T. Callaghan,et al.  Environmental constraints on the growth, photosynthesis and reproductive development of Dryas octopetala at a high Arctic polar semi-desert, Svalbard , 1995, Oecologia.

[3]  T. Dawson,et al.  Patterns of water use and the tissue water relations in the dioecious shrub, Salix arctica: the physiological basis for habitat partitioning between the sexes , 1989, Oecologia.

[4]  T. Dawson,et al.  Intraspecific variation in the water relations of Salix arctica, an arctic-alpine dwarf willow , 1989, Oecologia.

[5]  F. Chapin.  Direct and indirect effects of temperature on arctic plants , 1983, Polar Biology.

[6]  G. Farquhar,et al.  Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves , 1981, Planta.

[7]  H. Muraoka,et al.  Net Photosynthesis, Respiration, and Production of the Moss Sanionia uncinata on a Glacier Foreland in the High Arctic, Ny-Ålesund, Svalbard , 2002 .

[8]  U. Molau,et al.  Leaf-trait Variation of Tundra Plants along a Climatic Gradient: An Integration of Responses in Evergreen and Deciduous Species , 2001 .

[9]  C. Lloyd.  The measurement and modelling of the carbon dioxide exchange at a high Arctic site in Svalbard , 2001 .

[10]  John E. Walsh,et al.  Polar regions (Arctic and Antarctic) , 2001 .

[11]  P. Grogan,et al.  Initial effects of experimental warming on above- and belowground components of net ecosystem CO2 exchange in arctic tundra , 2000, Oecologia.

[12]  Jed O. Kaplan,et al.  Trace gas exchange in a high‐Arctic valley: 1. Variationsin CO2 and CH4 Flux between tundra vegetation types , 2000 .

[13]  W. Oechel,et al.  Spatial and temporal variations in hectare‐scale net CO2 flux, respiration and gross primary production of Arctic tundra ecosystems , 2000 .

[14]  E. Rastetter,et al.  PLANT CARBON–NUTRIENT INTERACTIONS CONTROL CO2 EXCHANGE IN ALASKAN WET SEDGE TUNDRA ECOSYSTEMS , 2000 .

[15]  G. Henry,et al.  Sex- and Habitat-Specific Responses of a High Arctic Willow, Salix arctica, to Experimental Climate Change , 1999 .

[16]  A. Michelsen,et al.  RESPONSES IN MICROBES AND PLANTS TO CHANGED TEMPERATURE, NUTRIENT, AND LIGHT REGIMES IN THE ARCTIC , 1999 .

[17]  J. Welker,et al.  CO2 FLUX IN ARCTIC AND ALPINE DRY TUNDRA : COMPARATIVE FIELD RESPONSES UNDER AMBIENT AND EXPERIMENTALLY WARMED CONDITIONS , 1999 .

[18]  F. Xiong,et al.  Photosynthetic temperature response of the Antarctic vascular plants Colobanthus quitensis and Deschampsia antarctica , 1999 .

[19]  Takehiro,et al.  Microbial biomass in relation to primary succession on arctic deglaciated moraines , 1999 .

[20]  A. Kume,et al.  Ecological Significance of Different Growth Forms of Purple Saxifrage, Saxifraga oppositifolia L, in the High Arctic, Ny-Alesund, Svalbard , 1999 .

[21]  F. Stuart Chapin,et al.  THE RESPONSE OF TUNDRA PLANT BIOMASS, ABOVEGROUND PRODUCTION, NITROGEN, AND CO2 FLUX TO EXPERIMENTAL WARMING , 1998 .

[22]  T. Callaghan,et al.  PLANT COMMUNITY RESPONSES TO SIMULATED ENVIRONMENTAL CHANGE AT A HIGH ARCTIC POLAR SEMI-DESERT , 1998 .

[23]  H. Koizumi,et al.  Respiration of the belowground parts of vascular plants: its contribution to total soil respiration on a successional glacier foreland in Ny‐Ålesund, Svalbard , 1998 .

[24]  I. Washitani,et al.  Combined effects of light and water availability on photosynthesis and growth of Arisaema heterophyllum in the forest understory and an open site , 1997, Oecologia.

[25]  F. Chapin,et al.  CLIMATIC EFFECTS ON TUNDRA CARBON STORAGE INFERRED FROM EXPERIMENTAL DATA AND A MODEL , 1997 .

[26]  G. F. Sassenrath-Cole,et al.  Photosynthesis in Fluctuating Light Environments , 1996 .

[27]  N. Baker.  Photosynthesis and the Environment , 1996, Advances in Photosynthesis and Respiration.

[28]  F. Stuart Chapin,et al.  Responses of Arctic Tundra to Experimental and Observed Changes in Climate , 1995 .

[29]  W. Oechel,et al.  The effects of climate charge on land-atmosphere feedbacks in arctic tundra regions. , 1994, Trends in ecology & evolution.

[30]  T. Callaghan,et al.  Differential growth, allocation and photosynthetic responses of Polygonum viviparum to simulated environmental change at a high arctic polar semi-desert , 1994 .

[31]  T. Callaghan,et al.  COMPARATIVE RESPONSES OF PHENOLOGY AND REPRODUCTIVE DEVELOPMENT TO SIMULATED ENVIRONMENTAL-CHANGE IN SUB-ARCTIC AND HIGH ARCTIC PLANTS , 1993 .

[32]  T. Dawson,et al.  Plants as mosaics: leaf-, ramet-, and gender-level variation in the physiology of the dwarf willow, Salix arctica , 1993 .

[33]  N. Grulke,et al.  Comparative Life History Characteristics of Two High Arctic Grasses, Northwest Territories , 1988 .

[34]  S. Wijk.  Influence of climate and age on annual shoot increment in Salix herbacea , 1986 .

[35]  S. Wijk.  Performance of Salix herbacea in an alpine snow-bed gradient , 1986 .

[36]  J. Svoboda,et al.  Polar deserts, their plant cover and plant production in the Canadian High Arctic , 1984 .

[37]  Plant communities and plant production in the western Queen Elizabeth Islands , 1984 .

[38]  P. Nobel.  Leaf anatomy and water use efficiency. , 1980 .

[39]  L. Tieszen,et al.  A MODEL OF STAND PHOTOSYNTHESIS FOR THE WET MEADOW TUNDRA AT BARROW, ALASKA' , 1976 .

[40]  J. H. M. Thornley,et al.  Mathematical models in plant physiology , 1976 .

[41]  W. Larcher.  Physiological Plant Ecology , 1977 .

[42]  L. Viereck,et al.  Alaska Trees and Shrubs , 1976 .

[43]  J. W. Wilson.  Annual Growth of Salix arctica in the High-Arctic , 1964 .