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Exploring the effects of pasture trees on plant community patterns
Author(s) -
Jakobsson Simon,
Plue Jan,
Cousins Sara A. O.,
Lindborg Regina
Publication year - 2019
Publication title -
journal of vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 115
eISSN - 1654-1103
pISSN - 1100-9233
DOI - 10.1111/jvs.12771
Subject(s) - understory , canopy , germination , shading , biology , grassland , plant community , tree canopy , plant ecology , plant cover , agronomy , ecology , botany , species richness , art , visual arts
Questions We aim to answer three questions: (a) what are the effects of canopy shading of different tree species on seed germination of eight understorey grassland species? (b) how is plant species’ occurrence in understorey communities affected by differences in canopy cover and does that depend on tree species composition? and (c) are there mechanistic links between the effects of trees on species’ germination and their occurrence in the understorey plant community? Location Semi‐natural wooded pastures in the biosphere reserve Östra Vätterbranterna, southern Sweden. Methods In this study, we examined the germination of eight grassland plant species in a seed sowing experiment under natural conditions in the field. Seeds were sown beneath and outside the canopy of two tree species within 48 plots split up by four wooded pasture sites. We combined observed germination responses with a plant community survey to assess the effects of canopy cover in relation to tree species composition on plant community responses. We analysed these data in relation to species’ seed mass and vegetative shade tolerance. Results Shade‐tolerant species germinated better beneath compared to outside tree canopies, without any clear advantage of large‐seeded over small‐seeded species. As expected, species’ shade tolerance was also positively related to canopy cover within the understorey plant community. Importantly, we found strong tree species‐specific effects of canopy shading on the species’ germination response, but not on their presence within the plant community. However, optimal canopy cover conditions for germination and for the mature plants differed across grassland species and depended on tree species. Conclusions Our results show that different tree species play key ecosystem engineering roles in shaping wooded grassland plant community composition at the germination stage. Management practices favouring specific tree species may therefore be highly relevant for targeted biodiversity conservation of wooded semi‐natural grasslands.