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Festuca campestris density and defoliation regulate abundance of the rhizomatous grass Poa pratensis in a fallow field
Author(s) -
Bork Edward W.,
Hewins Daniel B.,
Tannas Steven,
Willms Walter D.
Publication year - 2018
Publication title -
restoration ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 100
eISSN - 1526-100X
pISSN - 1061-2971
DOI - 10.1111/rec.12532
Subject(s) - poa pratensis , tiller (botany) , tussock , agronomy , biology , sowing , festuca arundinacea , phalaris arundinacea , grassland , graminoid , festuca , poaceae , forb , ecology , wetland
Invasion by the rhizomatous grass Kentucky bluegrass ( Poa pratensis ) is a global phenomenon, including into foothills rough fescue ( Festuca campestris ) grasslands of southwestern Alberta, Canada. In order to better understand the competitive relationships between these species, we conducted a fallow field study where rough fescue bunchgrass tussocks were transplanted at one of three planting densities (15, 30, or 45 cm spacing), and then subject to various treatments in a factorial design, including one‐time intensive summer defoliation and seeding of bluegrass into adjacent bare soil. Rough fescue plants exhibited marked intraspecific competition, as high planting densities increased tussock mortality, while decreasing plant tiller counts and relative inflorescence production, together with plant and tiller‐specific mass. However, high densities of the bunchgrass also reduced the cover and biomass of encroaching bluegrass, coincidental with reduced resource (soil moisture and light) availability in mid‐summer. Although summer defoliation increased rough fescue tiller counts, this disturbance reduced plant and tiller mass, and also increased Kentucky bluegrass. We conclude that while high densities of nondefoliated stands of rough fescue may increase resistance to bluegrass encroachment, a reduction in either fescue plant density or vigor via defoliation can increase the risk of bluegrass invasion within northern temperate grassland.