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Seed limitation, not soil legacy effects, prevents native understorey from establishing in oak woodlands in Scotland after removal of Rhododendron ponticum
Author(s) -
Maclean Janet E.,
Mitchell Ruth J.,
Burslem David F. R. P.,
Genney David,
Hall Jeanette,
Pakeman Robin J.
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.12664
Subject(s) - bryophyte , understory , native plant , vegetation (pathology) , vascular plant , introduced species , woodland , plant community , environmental science , revegetation , botany , biology , agronomy , ecology , canopy , medicine , pathology , species richness , ecological succession
Following removal of the invasive species Rhododendron ponticum , the native understorey plant community typically fails to reestablish itself. Potential explanations for this failure include (1) lack of an appropriate native seed source; (2) inability of seed to penetrate a dense bryophyte layer; and (3) persistence of chemical “legacy effects” in the soil. We established an experiment to test these competing hypotheses in an Atlantic oak woodland where R. ponticum had been removed. The following experimental treatments were applied singly and in combination: (1) addition of a native seed mix to test for seed limitation; (2) removal of the established ground vegetation at the start of the experiment (which principally consisted of bryophytes) to test for the impact of a barrier layer; (3) addition of activated carbon to test for chemical legacy effects in the soil; and (4) fertilization as an additional measure to promote the establishment of native vascular plants. Application of the native seed mix was revealed to be an effective way to increase the cover of native vascular plants and was particularly effective when applied after the removal of the bryophyte layer. The application of activated carbon and/or fertilizer, however, had no effect on the cover of native vegetation. We conclude that reports of R. ponticum exerting chemical legacy effects long after its removal may have been overstated and that seed limitation and inability to successfully establish in a dense bryophyte layer provided the strongest barriers to natural recolonization by the native plant community following R. ponticum removal.