Environmental constraints on the growth, photosynthesis and reproductive development of Dryas octopetala at a high Arctic polar semi-desert, Svalbard

Abstract

Opportunities exist in high Arctic polar semidesert communities for colonisation of unvegetated ground by long-lived clonal plants such as Dryas octopetala. This can be achieved by lateral spread of vegetative ramets, or by sexual reproduction and seedling recruitment. The objectives of this study were (1) to determine whether these two means of proliferation show differential sensitivity to contrasting components of the abiotic environment (temperature, soil nutrient and water availability) and (2) to evaluate the potential for D. octopetala to respond to climate change by an increase in cover and biomass in polar semi-desert communities. Factorial environmental manipulations of growing season temperature, soil nutrient and water status were conducted over 3 years at a polar semi-desert community in Svalbard, Norway (78°56.12'N, 11°50.4'E) and both clonal and sexual reproductive performance, together with instantaneous net photosynthesis (P), were recorded during the third season (1993). D. octopetala capitalised rapidly on an amelioration in the availability of inorganic nutrients (N, P and K) by an expansion in leaf area and biomass supported by increased P per unit leaf weight, and by apparent luxury uptake of nutrients (particularly P). Several facets of sexual reproductive development and seed viability were markedly improved by elevated temperatures or soil nutrient availability. Thus although D. octopetala is a long-lived clonal plant, with many traits characteristic of stress resistance syndrome, it showed considerable phenotypic plasticity in response to environmental manipulations. The results support the hypothesis that clonal growth confers survival potential during unfavourable years, together with the ability to capitalise on nutrient flushes and recycle nutrients internally. Continued investment in sexual reproduction ensures that seed setting is successful during favourable years, even if these occur infrequently. Cimate warming in the high Arctic could thus result in changes in the cover, biomass and the relative significance of clonal versus sexual proliferation of D. octopetala (and thus the genetic diversity of the population) but the long-term responses will probably be constrained by lack of available nutrients.

Soil geochemistry confines microbial abundances across an arctic landscape; implications for net carbon exchange with the atmosphere

“…Therefore, N and P levels in Kongsfjorden soils appear low relative to typical microbial nutritional needs. These results are consistent with previous studies on Ny-Alesund soils, which indicated P was more likely limiting than N or K for plant growth (Wookey et al 1995). Measured surface CH 4(g) release rates varied by five orders of magnitude across the sites, ranging from 0.02 to 157.0 lmoles CH 4(g) m -2 h -1 (Fig.…”

Evidence of Nonlinearity in the Response of Net Ecosystem CO2Exchange to Increasing Levels of Winter Snow Depth in the High Arctic of Northwest Greenland

“…In the Arctic, snow depth and rate of snowmelt dictate the duration of time available for resource assimilation by plants (Billings and Bliss, 1959;Galen and Stanton, 1993;Wookey et al, 1994Wookey et al, , 1995Walker et al, 1999), and a short growing season severely constrains vegetative growth (Thó rhallsdó ttir, 1998), in turn influencing reproductive performance of plants. Galen and Stanton (1993) showed a direct link between growing season length and plant performance in alpine buttercups (Ranunculus adoneus) similar to our data for C. tetragona.…”

Experimental approaches to predicting the future of tundra plant communities

“…Saxifraga oppositifolia and Cassiope tetragona), and there were indications of stronger responses to experimental warming during 'colder' growing seasons (both of which are consistent with Figure 3). Increases in reproductive growth (seed set, seed weight, and germinability) also appear to be general responses to warming in the short-term: Wookey et al (1995), for example, reported a 141% increase in seed germinability of Dryas octopetala at a high arctic polar semidesert, Svalbard, in association with warming over three growing seasons.…”