Effect of grazing on the vegetation of shore meadows along the Bothnian Sea, Finland

Published source details Jutila H. (1999) Effect of grazing on the vegetation of shore meadows along the Bothnian Sea, Finland. Plant Ecology, 140, 77-88.
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Summary

Close to the town of Pori in southwest Finland, there started a Life-Nature project on seashore meadows planned to be included in the European Nature 2000 network. The grazed meadows are nationally valuable traditional agricultural habitats of high importance for avifauna, as well as other fauna and flora. The main aim is to manage the meadows sympathetically for avifauna and other wildlife. Several studies have shown that grazing cattle influences positively many bird species. The objective of this study was to evaluate the effects of cattle grazing on shoreline meadow vegetation.

Study area: The study was conducted along transects in four grazed and five ungrazed shore meadows on the southwest coast of Finland, near the town of Pori (61˚30'-61˚33'N, 21˚28'-21˚41' E) in Turku-Pori region.

Grazing: Three transects had been grazed from the beginning of the (20th) century. In one transect grazing (at Eteläranta) ceased at the beginning of the 1970's and started again from 1990. The 'ungrazed' transects have been ungrazed for several decades. Two of the meadows (delta meadows) were located in the mouth of the Kokemäenjoki River, the rest were along the sea shore. Areas grazed and cattle stocking rates were:

Kuuminainen - 35 ha 1/ha
Pihlavaluoto - 80 ha 0.3/ha
Eteläranta - 12 ha 1.7/ha
Fleiviiki - 40 ha 1/ha (delta meadow)

Ungrazed meadows were located at: Hevoskari; Riitsarka; Paarnoori; Eteläranta; and Teemuluoto (delta meadow).

Vegetation monitoring: Transects were established in the meadows. The start of each transect was established where the emergent vegetation began, i.e. approximately at the mean summer sea level, and ran perpendicularly from the shoreline up a gentle topographical gradient towards abutting woodland. Quadrats (1 mÂ², n = 411) were randomised for each of the vegetation zones and percentage cover of each vascular plant species was estimated in each during 1993 and 1994.

Vegetation cover: Overall summed cover of all vascular plant species was less in grazed compared to ungrazed areas. All elevation classes, except 50–70 cm (a.m.s.l.), showed this pattern. The covers of annuals, perennials and dicots were decreased, and the cover of monocots was increased, by grazing.

Vegetation abundance: Abundances of pteridophytes (vascular plants that do not bear seeds: e.g. ferns, horsetails, club mosses) did not significantly differ between grazed and ungrazed meadows. The abundances of annuals+biennials, perennials, dicots and pteridophytes were decreased while the cover of monocots increased under grazing. This trend was similar in all elevation classes. In the seashore meadows grazing decreased the cover of chamaephytes (low-growing perennials whose overwintering buds are borne at or just above the surface of the ground) and therophytes (a plant which survives unfavourable seasons as seeds; annual species are therophytes) and in the delta meadow cover of geophytes (perennials with underground bulbs, tubers, or corms) and hemicryptophytes (a plant whose growth-points (buds) survive seasons with adverse conditions (e.g. winter) resting on the soil surface) increased but these results were influenced by differences in elevation.

Vegetation height and biomass: Vegetation height and dry biomass were less in the grazed than in the ungrazed plots. Creeping bent Agrostis stolonifera, common sedge Carex nigra, red fescue Festuca rubra, saltmarsh rush Juncus gerardii, autumn hawkbit Leontodon autumnalis, spreading meadow-grass Poa subcaerulea (Syn: P.humilis) and silverweed Potentilla anserina were more abundant in grazed meadows, abundances of meadowsweet Filipendula ulmaria, marsh bedstraw Galium palustre, marsh pea Lathyrus palustris and common reed Phragmites australis were greater in ungrazed meadows.

Cattle grazing had varied effects on different vegetation zones and on different species. Overall, it appears that stress-tolerant perennial monocots and halophytes are favoured by grazing in the shoreline communities. Over the timescale of this study, the results did not concur with similar studies that grazing seems to benefit rarer species, annuals and dicots.

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