From Sheep to Insects, Herbivores’ Impact on Tundra Soil and Plants

The tundra is a fairly simple ecosystem, in terms of the number of species that dwell there. The forces acting on it, though, and the challenges it faces with climate change are not. This complexity is revealed by the interactions among an array of herbivores, the plants they eat and the land that sustains them all.
Dr. Isabel Barrio is headed for Iceland, where the tundra rangelands are important grazing locations for the country’s many sheep, but also its wild herbivores. These plant-eaters affect the dynamics of the ecosystem with their diet and by trampling vegetation. Their activity also amplifies a major threat for this region and others like it: soil erosion. The soil is volcanic and thin here, presenting an extreme of a problem common to different environments worldwide.
What’s more, climate change is expected to compound the issue. Dr. Barrio intends to pin down how herbivore grazing combines to affect soil degradation, how well plants can recover and how humans can respond.

At high latitudes like Iceland’s, the climate is warming at unprecedented rates, making the tundra especially vulnerable. Extreme weather, like torrential rains, linked to climate change risks intensifying soil erosion. The tundra is already slow to recover from disturbances and the main colonizers of barren soils – mosses and lichens – will not respond well to rising temperatures. Dr. Barrio will take a novel approach to examining herbivores’ role in all this. While most studies have looked at vertebrates, for their larger size and greater impact, she will consider the combined effect of the whole range of herbivores in this ecosystem, including sheep, geese and even insects. The influence of these small but numerous invertebrates is likely to change, as they are sensitive to and dependent on the external temperature. If any of these factors throws the ecosystem too far off balance, complete degradation of the rangelands could result.

Dr. Barrio’s experiments will explore a spectrum of environmental conditions. She will fence off plots allowing her to compare areas with and without the influence of sheep. She’ll check spots with higher or lower risk of soil erosion, depending on the amount of vegetation and the age of the soil, younger volcanic soil being more prone to erosion. In the short term, she’ll assess the impact on plant growth and flowering; in the longer term, the variety of plants growing in the tundra could be altered.

The potential for damaging this ecosystem irrevocably is a risk for biodiversity, clearly, and with implications for the culturally important activity of sheep farming in Iceland. With the knowledge gained from her studies, Dr. Barrio could advise the industry on when to release their flocks in the highlands, in order to minimize the environmental risks, or on the numbers of sheep the tundra can support. Her results here could inform land restoration practices and will also be relevant to similar ecosystems (like mountain tops) and to locations facing similar problems (like the impact of livestock on soil erosion in New Zealand and Australia).
Dr. Barrio explains that Iceland has been struggling with the degradation of its soils since the early 1900s. Now, with climate change only threatening to worsen the problem, here and everywhere it is time to act.

Scientific title : The Influence Of Herbivore Communities In Tundra Ecosystems Following Anthropogenic Changes In Soil And Climate

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From Sheep to Insects, Herbivores’ Impact on Tundra Soil and Plants

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