Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard (original) (raw)
Related papers
Shorter flowering seasons and declining abundance of flower visitors in a warmer Arctic
Nature Climate Change, 2013
Advancing phenology in response to global warming has been reported across biomes 1,2 , raising concerns about the temporal uncoupling of trophic interactions 3,4 . Concurrently, widely reported flower visitor declines have been linked to resource limitations 5 . Phenological responses in the Arctic have been shown to outpace responses from lower latitudes and recent studies suggest that differences between such responses for plants and their flower visitors could be particularly pronounced in the Arctic 1,6 . The evidence for phenological uncoupling is scant because relevant data sets are lacking 7 or not available at a relevant spatial scale 8 . Here, we present evidence of a climate-associated shortening of the flowering season and a concomitant decline in flower visitor abundance based on a long-term, spatially replicated (1996-2009) data set from high-Arctic Greenland. A unique feature of the data set is the spatial and temporal overlap of independent observations of plant and insect phenology. The shortening of the flowering season arose through spatial variation in phenological responses to warming. The shorter flowering seasons may have played a role in the observed decline in flower visitor abundance. Our results demonstrate that the dramatic climatic changes currently taking place in the Arctic are strongly affecting individual species and ecological communities, with implications for trophic interactions.
Over the coming decades, the Arctic is expected to experience warming temperatures and variable changes in the timing of snowmelt. Both temperature and the timing of snowmelt are important drivers of phenology and reproduction on the tundra. However, few studies have considered their combined effects, making it difficult to predict the direction and magnitude of Arctic plant responses to changing climates. In this 1-year study, we examine how temperature and delayed snowmelt jointly impact the phenology and reproductive effort/success of four common heath tundra species: Empetrum nigrum L., Rhododendron lapponicum (L.) Wahlenb., Dryas integri-folia Vahl, and Arctostaphylos rubra Fernald. We erected snow fences during the winter to increase snowpack on six plots (paired with six control plots), resulting in a consistent 10-day delay in the timing of snowmelt. During the subsequent growing season, we tracked how temperature and the delayed snowmelt on the treatment plots affected the day of onset of species' phenophases, as well as their ability to flower and set fruit. Both temperature and snow addition were significant drivers of phenological onset in these species, though species showed different sensitivities to these factors, possibly as a result of differences in life history strategies. In addition, two of the four species responded positively to snow addition in terms of reproductive effort. Our results emphasize the importance of considering the simultaneous effects of the multiple drivers of Arctic plant phenology.
Global change biology, 2015
Recent changes in climate have led to significant shifts in phenology, with many studies demonstrating advanced phenology in response to warming temperatures. The rate of temperature change is especially high in the Arctic, but this is also where we have relatively little data on phenological changes and the processes driving these changes. In order to understand how Arctic plant species are likely to respond to future changes in climate, we monitored flowering phenology in response to both experimental and ambient warming for four widespread species in two habitat types over 21 years. We additionally used long-term environmental records to disentangle the effects of temperature increase and changes in snowmelt date on phenological patterns. While flowering occurred earlier in response to experimental warming, plants in unmanipulated plots showed no change or a delay in flowering over the 21-year period, despite more than 1 °C of ambient warming during that time. This counterintuiti...
Plant Ecology, 2012
Surface temperatures have risen globally during the last 30 years, especially in alpine areas. It is recognized that these increases are influencing phenology, physiology and distribution of plants. However, few studies have addressed the effects of climate warming at the species range boundary, where plants are expected to be more stressed. We analysed 11-year data sets of inflorescence production of four alpine plants (Carex foetida, Leucanthemopsis alpina, Senecio incanus, Silene suecica) at the southern boundary of their distribution range in the N-Apennines (N-Italy), in relation to air temperature and snow cover persistence. Inflorescence production of all species fluctuated greatly and was significantly affected by the variation of the mean temperature of June/July. We found significant relationships also between species data series and the snow cover persistence. Moreover, species responded differently to such parameters. One species showed a significant decrease of the reproductive effort, whereas the other three showed a stable trend of inflorescence production. We have shown that some alpine species are favoured by increased temperature and reduced snow cover even at the boundary of their range, where they are thought to be particularly sensitive to warming. However, the aptitude to cope with climate change might be limited by competition against thermophilous species migrating from lower altitude and in some cases by the low altitude of mountain peaks that prevent species upward migration. The individualistic response of species to climate change found here, support the statement that the composition of plant communities might rapidly change in the future.
Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community
Physiologia Plantarum, 2010
Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate springlike development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more frequent in some regions of the Arctic and that may ultimately drive plant community shifts.
Global Change Biology, 2008
Climate change scenarios predict an increased frequency of extreme climatic events. In Arctic regions, one of the most profound of these are extreme and sudden winter warming events in which temperatures increase rapidly to above freezing, often causing snow melt across whole landscapes and exposure of ecosystems to warm temperatures. Following warming, vegetation and soils no longer insulated below snow are then exposed to rapidly returning extreme cold. Using a new experimental facility established in sub-Arctic dwarf shrub heathland in northern Sweden, we simulated an extreme winter warming event in the field and report findings on growth, phenology and reproduction during the subsequent growing season. A 1-week long extreme winter warming event was simulated in early March using infrared heating lamps run with or without soil warming cables. Both single short events delayed bud development of Vaccinium myrtillus by up to 3 weeks in the following spring (June) and reduced flower production by more than 80%: this also led to a near-complete elimination of berry production in mid-summer. Empetrum hermaphroditum also showed delayed bud development. In contrast, Vaccinium vitis-idaea showed no delay in bud development, but instead appeared to produce a greater number of actively growing vegetative buds within plots warmed by heating lamps only. Again, there was evidence of reduced flowering and berry production in this species. While bud break was delayed, growing season measurements of growth and photosynthesis did not reveal a differential response in the warmed plants for any of the species. These results demonstrate that a single, short, extreme winter warming event can have considerable impact on bud production, phenology and reproductive effort of dominant plant species within sub-Arctic dwarf shrub heathland. Furthermore, large interspecific differences in sensitivity are seen. These findings are of considerable concern, because they suggest that repeated events may potentially impact on the biodiversity and productivity of these systems should these extreme events increase in frequency as a result of global change. Although climate change may lengthen the growing season by earlier spring snow melt, there is a profound danger for these high-latitude ecosystems if extreme, short-lived warming in winter exposes plants to initial warm temperatures, but then extreme cold for the rest of the winter. Work is ongoing to determine the longer term and wider impacts of these events.
The importance of secondary growth to plant responses to snow in the arctic
Functional Ecology, 2019
In arctic environments, drifting snow around large shrub patches during winter may enhance growth by insulating the soil and facilitating overwinter nutrient turnover, leading to increased summer plant growth and potentially widespread increases in shrub cover. To determine whether snow enhances growth of arctic plants, we examined the effect of 6 years of added snow on plant biomass allocation and growth of nine common vascular plant species collected in 2010 and 2011 on either side of snowfences established in 2005 across a gradient of shrub biomass and productivity near Toolik Lake, Alaska. The deciduous shrub Salix pulchra responded most positively to added snow showing an 88% increase in total ramet biomass, because increased secondary growth allowed plants to support more branches and leaves. Some graminoid species also showed growth increases, especially where they were more abundant and larger than nearby shrub species. Species sharing the same growth strategy (deciduous shr...