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Impacts of colonial waterbirds on vegetation and potential restoration of island habitats
Author(s) -
Ayers Christopher R.,
HansonDorr Katie C.,
O'Dell Sadie,
Lovell Charles D.,
Jones Michael L.,
Suckow Jason R.,
Dorr Brian S.
Publication year - 2015
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.12169
Subject(s) - vegetation (pathology) , habitat , ecology , sowing , biomass (ecology) , restoration ecology , introduced species , invasive species , biology , geography , agronomy , medicine , pathology
Colonial waterbirds have impacted forested island ecosystems throughout their breeding range, changing vegetation, and soil characteristics and bird communities. Our objectives were to (1) determine effects of three levels of colonial waterbird exclusion on overall vegetation diversity and growth, and survival of a candidate restoration species (black elderberry; Sambucus nigra canadensis ); (2) investigate effects of different planting techniques on survival and growth of black elderberry; and (3) determine effects of waterbird colonization on soil chemistry. In 2012, we investigated effects of three levels of waterbird exclusion (none control plots [ CON ]; partial, which excluded waterbirds larger than gulls [ PEX ]; and full which excluded all waterbirds [ FEX ]) on bird use, existing vegetation growth and diversity, and survival of planted black elderberry on three islands in Door County, WI , Lake Michigan. In 2013, we evaluated survival of black elderberry established with four planting treatments within three waterbird exclusion treatments on two islands in 2013. We also compared soil chemistry characteristics between islands with and without nesting waterbirds for 2 years. Overall plant growth was greater in exclosures, but elderberry survival was similar among treatments. Soil replacement and weed suppression planting treatments did not affect survival, but generally increased overall elderberry biomass. Soil from nesting islands was more acidic and had greater nutrient concentrations than reference islands. Exclusion or removal of colonial nesting waterbirds from islands may improve overall vegetation growth, but successful restoration of woody vegetation may require significant soil manipulation and planting.