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Shrub effects on herbs and grasses in semi‐natural grasslands: positive, negative or neutral relationships?
Author(s) -
Pihlgren A.,
Lennartsson T.
Publication year - 2008
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.2007.00610.x
Subject(s) - shrub , litter , seedling , grassland , grazing , biology , vegetation (pathology) , agronomy , abundance (ecology) , woody plant , shoot , ecology , medicine , pathology
The present study investigated how the abundance and sexual reproduction of herbs and grasses relates to the presence of shrubs of Rosa dumalis in three semi‐natural pastures in Sweden. Shrubs may affect grassland plants negatively by competition, positively by serving as grazing refuge, or neutrally. At different distances from shrubs of R. dumalis , data were collected on plant abundance, frequency of reproductive shoots, vegetation height and litter depth. In one grassland, data were collected on seedling density and frequency of reproductive shoots in the presence and absence of grazing. The shrubs functioned as grazing refuges with taller vegetation, deeper litter and higher probability of reproduction by plants. The overall number of plant species remained the same at all distances from shrubs. Most species showed a neutral relationship with shrubs. Proportionately, 0·08–0·26 of the species showed a negative pattern to shrubs and 0·14–0·30 a positive pattern. Seedling density was negatively correlated with litter depth and peaked at 60–90 cm from shrubs. Establishment of seedlings of small‐seeded species was negatively related to shrubs probably because of thicker litter layer close to shrubs. The observed patterns were compared with different functional traits, such as Ellenberg values, plant height, growth form and Raunkiaer life form. Plant height from data in the literature was the trait that best explained the relationship of plant species to shrubs because tall species were more common in proximity to shrubs. It was concluded that shrubs increase the heterogeneity in grasslands and that intensive shrub‐clearing may negatively affect biodiversity.