Climate change influences on species interrelationships and distributions in High-Arctic Greenland

Biotic communities in Northeast Greenland have an insular character as a consequence of the complex geomorphologic nature of the ice-free land and its interdigitation with glacial ice and the sea. Post Pleistocene movements of most plants and animals into the region have generally followed East and North Greenland coastal routes, and the majority of the plants have North American affinities. Climatic change, bringing about reduction in the extent of sea ice adjacent to the coast and changes in seasonality and associated precipitation and air movements, influences patterns of activity, growth, reproduction and dispersal of all life forms present. Climate associated changes in the biotic communities of the region are altering inter-species interactions, notably pollination, seed dispersal and plant-herbivore relations.

Sexual reproduction and dispersal of propagules, primarily seeds, are essential processes underlying maintenance of genetic biodiversity in plant communities in Northeast Greenland. Wind and water transport of seeds are primary methods by which plants disperse and become established in the High Arctic, but birds and mammals are also involved. In Northeast Greenland, dispersal of viable seeds may occur by passage through the guts of geese and muskoxen.

Research at Zackenberg on the role of insects in pollination of flowering plants has shown that Diptera species, primarily flies, dominate among the insect species visiting flowers each summer. Diptera, Lepidoptera (butterflies and moths), Hymenoptera (bumble bees and small wasps) and one Hemiptera (true bugs) species have constituted the primary pollinators at Zackenberg. Arctic willow Salix arctica, white arctic bell heather Cassiope tetragona and mountain avens Dryas octopetala, are the primary species represented in the pollen present on pollinating insects at Zackenberg. The effects of climate warming that may enhance environmental conditions for plant growth in Northeast Greenland and accelerate invasion of new species will also be tied to the relationship of specific plant species to their insect pollinators. Those plants that are self pollinated may have an initial advantage in an environment where insects and their plant relationships are being altered by the changing climate.

An increase in growth and dispersal of shrubs in the Arctic is occurring as a consequence of climate warming. Increases in shrubs with more upright growth form, especially willows, will generate microhabitats not previously present in the High Arctic. The new habitats will make possible the invasion of new insect, mammal and bird herbivores, as well as their parasites and predators.