Assessing the ecological impacts of extensive sheep grazing in Iceland

Abstract

The sustainability of sheep grazing in Iceland has been repeatedly questioned as in some areas high stocking rates have been associated with extensive soil erosion and ecosystem degradation. We synthesized all available information on the effects of sheep grazing on vegetation, soil properties and other organisms in the rangelands of Iceland, with special focus on the grey literature. We compiled 347 documents, but only 44 contained extractable data, reporting on 16 studies. The scarcity of studies prevented us from drawing general conclusions for most ecological variables across environmental conditions, but some consistent trends were found. The extent of bare ground was significantly higher in grazed areas and grazing affected plant community structure. The potential for increased soil erosion in grazed areas remains a problem in Icelandic rangelands. A better understanding of the ecological impacts of sheep grazing is required to inform sustainable grazing practices adapted to the local conditions of this region.Keywords: extensive grazing, rangeland, soil erosion, sustainable management, tundra YFIRLIT Áhrif sauðfjárbeitar á íslensk vistkerfiSjálfbaerni sauðfjárbeitar á Íslandi hefur oft verið dregin í efa enda tengja margir beit við mikla jarðvegseyðingu og hnignun vistkerfa. Hér tökum við saman þaer rannsóknir sem birtar hafa verið um áhrif sauðfjárbeitar á vistkerfi íslenskra úthaga. Alls fundust 16 rannsóknir, birtar í 44 skjölum, flest á skýrsluformi. Fyrir flestar vistfraeðibreytur voru rannsóknirnar of fáar til að draga maetti almennar ályktanir útfrá þeim. Safngreining (e. meta analysis) sýndi þó að beit hefur áhrif á uppbyggingu plöntusamfélaga og eykur rof í gróðurþekjunni. Úthaginn verður þar af leiðandi viðkvaemari fyrir jarðvegsrofi. Ljóst er að afla þarf betri þekkingar á áhrifum beitar á vistkerfi íslenskra úthaga svo tryggja megi sjálfbaera sauðfjárbeit sem haefa aðstaeðum á hverju svaeði fyrir sig.

The sheep in wolf's clothing? Recognizing threats for land degradation in Iceland using state‐and‐transition models

“…A livestock quota was introduced in 1985 but by the time the stocking rates were reduced, the ecosystems in many grazing commons had already shifted to a severely degraded state ( S5 ). The numbers of sheep are nowadays half of those in the early 1980s but are still high relative to historical abundances (Marteinsdóttir et al, ). In parallel, improved access to winter fodder led to the gradual abandonment of winter grazing, reducing grazing pressure around farms.…”

“…Narrative descriptions in STMs are generally supported by different sources of data, from informal historical observations and expert knowledge to controlled experiments (Bestelmeyer et al, ). To build the general STM framework for Iceland, we used a recent compilation on the ecological impacts of sheep grazing in Iceland (Marteinsdóttir et al, ), paleoecological evidence, historical records, and expert knowledge (for more details and specific sources see Tables S1 and S2).…”

“…Once the system has shifted into an alternative state, releasing grazing pressure alone may not be sufficient to revert back to the previous state and intensive management actions, such as seeding or shrub control, may be required (Bestelmeyer et al, ). Such examples are relatively common in Iceland (Marteinsdóttir, Barrio, & Jónsdóttir, ). For example, in some rangelands in the highlands, no apparent plant community responses were detected after 4 years of grazing protection (Jónsdóttir, Magnússon, Gudmundsson, Elmarsdóttir, & Hjartarson, ).…”

Assessing spatial patterns of soil erosion in a high‐latitude rangeland

“…From the mid-1990s numbers have been relatively stable (Marteinsdóttir, Barrio, & Jónsdóttir, 2017). At the farm Svalbard (Figure 1a) sheep numbers have been more-or-less constant for the period 1980-present.…”

“…From the mid-1990s numbers have been relatively stable (Marteinsdóttir, Barrio, & Jónsdóttir, 2017). At the farm Svalbard ( Figure 1a The vegetation on the study sites was dominated by low-growing shrubs, notably bog bilberry (Vaccinium uliginosum), crowberry (Empetrum nigrum) and dwarf willow (Salix herbacea).…”