Title: Rangeland health methodology: A study of Laekur, Gunnarsholt, southern Iceland

Type:
Final project
Year of publication:
2011
Document URL: Link
Supervisors: Johann Thorsson
Keywords:
rangeland, rangeland health, ecological site, landscape attributes, cryoturbation, Iceland

Abstract

Rangelands are non-arable areas used primarily, but not exclusively, for grazing livestock such as sheep, goats and cattle. Rangelands cover about one-half of the Earth’s land surface. Rangeland health is the degree to which the integrity of the soil, vegetation, water and air, as well as the ecological processes of the rangeland ecosystem, are balanced and sustained. Rangeland health assessment is carried out by measuring attributes and indicators present in the current state relative to an expected norm referred to as the reference state. In this study eight indicators, namely, grass cover, moss cover, surface strength, sward thickness, pedestal heights, bare soil, rock and shrub cover were used to assess a site at Laekur, 3 km south of Gunnarsholt, in Iceland. The indicators were used to evaluate the three processes since they are difficult to measure: Nutrient cycle, Water cycle and Energy cycle. Cryoturbation was added due to its importance in Iceland. At the study site a stratified random sampling scheme was adapted to collect data from three parallel 30m transects, oriented NE-SW. Six 50x50 cm plots were placed perpendicularly at 5 m, 15 m, and 25m. Each site had a total of 18 plots at each site. The reference area has high grass cover 72.6%, moss cover 26.8%, a surface strength of 81.8kNm-2, no bare soil areas, no shrubs, a surface strength of 16.7cm, no pedestals and no rock. In comparison, the lower land with poor condition had less grass cover 9.3%, moss cover 23.6%, change in grass cover into dominant shrubs of 33.7%, a high percentage of emerging bare soil 31.9%, reduction in surface strength of 58.1kNm-2, high sward thickness 6.6cm, high pedestal heights of 9.9cm and high rock percentages of 1.2%. I concluded that the land was in relatively good condition. Bare soil spots are found in both the upper land and the low land, but they are not connected. Signs of disturbances are present in the low land, putting it at risk compared to the reference area and the upper land.

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