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# Secondary Succession and Summer Herbivory in a Subarctic Grassland: Community Structure and Diversity

Kristjan Zobel, Mari Moora, Valerie K. Brown, Pekka Niemelä and Martin Zobel
Ecography
Vol. 20, No. 6 (Dec., 1997), pp. 595-604
Published by: Wiley on behalf of Nordic Society Oikos
Stable URL: http://www.jstor.org/stable/3683248
Page Count: 10
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## Abstract

A field experiment was established in a subarctic grassland in the Finnish Lapland to study the role of summer herbivory in plant community succession. Perennial vegetation and moss cover were removed in an area of $324\ {\rm m}^{2}$. The site was divided into four blocks, of which two were fenced to prevent herbivory by large mammals (reindeer, hare). Early successional changes in the vegetation were assessed. Mean species richness per 3 × 3 m plot was consistently higher in the fenced area, indicating that herbivory can suppress small-scale diversity. Herbivory affected the height of several plant species. However, there was no correlation between frequency and height of individual species. There was a weak indication that taller species were more successful in early succession when grazed. Light competition is apparently not a key process determining successional change. Thus, in early stage of succession, summer herbivory has little effect on diversity by limiting light competition, and most species are equally successful in grazed and ungrazed plots. There was some indirect evidence about competitive interactions in the developing community. However, unlike temperate grasslands, large mammal herbivory and competition for light seem not to be important determinants of community change in this subarctic grassland (at least what concernes early successional stages). This may be explained by the harshness of local climate, and abundance of light due to the polar day.

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