Abstract

This study focuses on Green Alder (Alnus crispa) vigor in relation to high or low Blackberry (Rubus canadensis) cover at Roan Highlands along the North Carolina-Tennessee state border. Green Alder has a circumboreal distribution, but the Roan Highlands plants comprise a long-distance disjunct population that is classified as a species of special concern within North Carolina and Tennessee. Green Alders are nitrogen fixers, so it is assumed that they are improving the soil. Blackberries have been invading grassy balds and alder balds at Roan Highlands due to natural succession and are mowed in some areas to manage their population. The hypothesis of the study was that proximity to Green Alder would increase the vigor of Blackberries at Roan Highlands, and that Blackberries would compete with and decrease the vigor of Green Alder. The vigor of Green Alder was quantified by measuring crown loss, new vegetative sprouts, and stem height. Blackberry vigor was quantified by measuring the density and cane height. Results showed no impact of Green Alder on Blackberry vigor, and little impact of Blackberry cover on Green Alder vigor. However, fewer alders in high Blackberry cover plots produced vegetative sprouts, along with fewer sprouts per clump. Since Green Alder reproduction is mostly clonal, blackberry encroachment could affect its long-term persistence at Roan Highlands.

Keywords

Green Alder, Roan Highlands, Blackberry, Management

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