Dr Alison Donnelly's trip to the Arctic

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  Caribou near one of the phenology enclosures

• Dr Alison Donnelly, a research lecturer in the Centre for the Environment and the Department of Botany, has recently returned from two months of fieldwork in the Arctic where she had the opportunity to work with the research team of Professor Eric Post (Pennsylvania State University, USA) who has been investigating ecosystem dynamics near the Greenlandic town of Kangerlussuaq for nearly two decades. The main focus of this long-term project is to explore the reason(s) for an increased mortality rate among the caribou (Figure 1) population at the fringes of the Greenlandic ice-sheet (Figure 2). Prof. Post hypothesized that climate warming causes a mismatch in the timing between caribou calving and plant emergence. Spring warming results in plants, upon which the caribou calves depend as a primary source of food, emerging earlier in the season than usual. Thus, when the caribou arrive at their calving ground the vegetation has already reached an advanced stage of growth and contains higher levels of tannins (chemical defences) than newly emergent plants, thus rendering them indigestible to the young calves. In some years, more than 50% of the calves died
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  The Greenlandic ice-sheet

• Alison’s interest in this research was inspired by a recent review she co-authored in which mismatches in the timing of interdependent species attributed to climate warming in natural, agricultural and aquatic ecosystems were examined. Phenology is the study of the timing of life-stage events in plants and animals and is effective as a means of examining synchrony/asynchrony between species within an ecosystem. Synchrony in the timing of phenophases, such as between plant emergence and caribou calving, is critical to the survival of some species.
  

• The focus of Alison’s research in Greenland was on plant phenology where she worked with Jeff Kerby (a researcher in the Post Laboratory) to observe and record a range of phenophases within a range of plants. On a daily basis Alison recorded the phenology of all plants within 30 plots located at different altitudes. Half of the plots were fitted with warming cones (Figure 3), which slightly raised the ambient temperature. The phenophases recorded included leaf emergence, leaf-bud open (Figure 4), flower set, flower-bud open and full bloom (Figure 5). The plants were divided into shrubs/trees, herbaceous plants, sedges and grasses and included birch, rhododendron, mountain avens (Figure 6), weak arctic sedge and meadow grass.

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Jeff Kerby (Penn State University) and Alison discussing plant phenology in one of the warming cones

 

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  Leaf bud open Betula nana

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  Rhododendron lapponicum in full bloom

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  Dryas integrifolia (entire-leaf mountain avens) full bloom

• This short research mission formed part of the annual monitoring campaign, which has been ongoing since the 1990s, and observations will continue until the end of this summer season. However, differences in phenology between warmed and ambient plots were apparent even over such a short time period. The plants undergoing the warming treatment showed an advance in development compared to the ambient plots, with for example, leaves opening earlier in the warming cones. Similarly, there was also a clear difference in phenology between the higher and lower altitude plots whereby plant emergence was delayed at higher elevation.
  Alison will give a talk on the research findings as part of the School’s seminar series in October next and all are very welcome to attend.