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Small-scale structures and grazing intensity in semi-natural pastures

effects on plants and insects

Pihlgren, Aina (2007). Small-scale structures and grazing intensity in semi-natural pastures. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:13
ISBN 91-576-7312-1
[Doctoral thesis]

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Semi-natural grasslands characterized by nutrient poor soils are among the most species-rich habitats in Europe and they harbour many red-listed species. The area of semi-natural grasslands has decreased drastically due to intensified land use or abandonment of farms. Ceased grazing can lead to encroachment of shrubs and trees and reduced plant species richness. The aim of this thesis is to study the effects of spatial structures and grazing intensity on plant assemblages, plant reproduction and phytophagous insects. Pastures with scattered trees and shrubs grazed by cattle in south central Sweden were used as study sites. The studied spatial structures were two trees: Betula pendula, Pinus sylvestris, two shrubs: Juniperus communis, Rosa dumalis, and dung rejects, grazing rejects (ungrazed patches) and grazed patches. Trees and shrubs are long-lived structures and they significantly influenced plant assemblages. For example, R. dumalis shrubs had a positive effect on tall, grazing sensitive species and a negative effect on short, less competitive species. Structures that could function as grazing refuges, i.e. shrubs, dung and grazing rejects increased plant reproduction. Grazing intensity also had a strong effect on plant reproduction and intensive grazing decreased the quantity of flowers and fruits. The effect of spatial structures on four plant species of the Fabaceae family and their seed predators was also studied. The four species varied in abundance between the structures but in shrub rejects and dung rejects reproduction was higher than in grazed patches. The available oviposition places, i.e. pods, for seed predators were considerable higher in shrub and dung rejects than in grazed patches. But no clear patterns in predation rate between structures were found. For two species long pods were more predated than short pods indicating oviposition selection at pod level. In conclusion, regulation of grazing intensity and shrub cover are important tools when managing pastures for both plants and phytophagous insects.

Authors/Creators:Pihlgren, Aina
Title:Small-scale structures and grazing intensity in semi-natural pastures
Subtitle:effects on plants and insects
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:19
ALLI. Pihlgren, A. & Lennartsson, T. Floral resources in semi-natural grasslands - significance of grazing intensity and spatial variation. Manuscript. II. Pihlgren, A. & Lennartsson, T. Shrub effects on herbs and grasses in semi-natural grasslands - positive, negative or neutral relationships? Submitted. III. Pihlgren, A. Effects of spatial structures on reproduction and seed predation of four legumes (Fabaceae) in semi-natural pastures. Manuscript. IV. Lenoir, L. & Pihlgren, A. 2006. Effects of grazing and ant/beetle interaction on seed production in the legume Vicia sepium in a seminatural grassland. Ecological Entomology 31, 601-607.
Place of Publication:Uppsala
ISBN for printed version:91-576-7312-1
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:natural pastures, grazing intensity, reproduction, plant ecology, betula pendula, pinus sylvestris, juniperus communis, rosa, leguminosae, seeds, predation, apion, coleoptera, pest insects, sweden
Keywords:Apion, Bruchus, Betula pendula, functional traits, grazing refuge, Juniperus communis, Pinus sylvestris, reproduction, Rosa dumalis, seed predation
Permanent URL:
ID Code:1344
Department:(NL, NJ) > Dept. of Ecology
(S) > Dept. of Ecology
Deposited By: Aina Pihlgren
Deposited On:22 Feb 2007 00:00
Metadata Last Modified:02 Dec 2014 10:11

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