Assessing the Invasive Potential of Acer platanoides and Viburnum opulus Cultivars
Open Access
- Author:
- Conklin, Janine Ranee
- Graduate Program:
- Horticulture
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 28, 2007
- Committee Members:
- James C Sellmer, Committee Chair/Co-Chair
Ricky M Bates, Committee Member
Robert Berghage Jr., Committee Member
William Curran, Committee Member - Keywords:
- seed production
germination
viability
norway maple
guelder rose
flowering - Abstract:
- Invasive plant species threaten the biodiversity of natural areas (Bir, 2000; Morin, 1999; U.S. Department of the Interior, 1999; Wilcove et al., 1998) and cause destructive environmental and economic affects throughout the United States (Clinton, 1999; Reichard and White, 2001). Methods for determining the invasive potential of plant species and the management concerns surrounding these plants is constantly developing to encompass a broad range of topics. Issues surrounding invasive species have both captivated and divided the attention of many environmental community members such as conservation organizations, land managers, ornamental horticulture industry groups, and public awareness groups. The Norway maple (Acer platanoides L.) and guelder rose (Viburnum opulus L.) are two species that have been used throughout the ornamental horticulture industry in the United States for years and are labeled as potentially invasive. The purpose of this study was to determine the invasive potential of A. platanoides and V. opulus cultivars. Fifteen A. platanoides cultivars including ‘Columnare’, ‘Crimson King’, ‘Emerald Queen’, ‘Erectum’, ‘Faasen’s Black’, ‘Fairview’, ‘Globosum’, ‘Greenlace’, ‘Reitenbachii’, ‘Royal Red’, ‘Rubrum’, ‘Schwedleri’, ‘Summershade’, ‘Superform’, and ‘Undulatum’ along with two hybrids A. truncatum xplatanoides ‘Norwegian Sunset’ and A. truncatum xplatanoides ‘Pacific Sunset’ and seven V. opulus cultivars including ‘Aureum’, ‘Compactum’, ‘Leonard’s Dwarf’, ‘Losely’s Compact’, ‘Nanum’, ‘Roseum’, and ‘Xanthocarpum’ were assessed over a 3 and 2 year period, respectively to document annual flower and seed production, germination, and seed viability. In addition, environmental weather and soil conditions were analyzed to determine their affect on appraised traits. Biological traits were then employed by a current analytic assessment tool which was modified to determine the invasive potential of the cultivars within each taxon. Results displayed that weather and soil conditions did affect measured traits and that differences existed among all traits for A. platanoides and V. opulus cultivars. Germination rates for V. opulus cultivars at the open site and within the forest in the absence of litter were the only exception to this in that they were similar. Most A. platanoides cultivars varied from one year to the next in flower production and seed yields; however, seed set and germination rates under optimal and field conditions did not vary. Of these traits, only germination rates under optimal conditions differed from one year to the next for many V. opulus cultivars. Such findings on these traits do not allude to invasiveness. Instead, they are useful in further describing the cultivars researched and in showing that it is necessary to research these traits over several years to accurately reveal each cultivars full potential. A modified weed risk assessment (WRA) tool was then employed. All A. platanoides and V. opulus cultivars were placed in the further evaluate category except for A. platanoides, A. truncatum xplatanoides ‘Norwegian Sunset’, A. truncatum xplatanoides ‘Pacific Sunset’, and V. opulus that were rejected. All cultivars that were placed in the further evaluate category need to be reevaluated to determine whether they should be accepted or rejected. This can be done by collecting as much information as can be reasonably gathered on these plants naturalization potential in temperate zones, invasive history, weediness, allelopathic abilities, fire hazard, capability of hybridization, seed bank longevity, and ease of control. As additional information becomes available for each cultivar, invasive potential should be reassessed by the modified WRA. From this research, it was concluded that cultivars which produce prolific seed quantities and that showed high to moderate germination or viability rates may be capable of escaping cultivation and establishing in regions where they may become invasive overtime. For this reason, A. platanoides and cultivars ‘Emerald Queen’, ‘Fairview’, and A. truncatum xplatanoides ‘Norwegian Sunset’ along with V. opulus and cultivars ‘Roseum’ and ‘Xanthocarpum’ should refrain from being used in the trade. Although A. platanoides cultivars ‘Columnare’ and ‘Faasen’s Black’ had low germination and viability rates, these cultivars should refrain from being used in cultivation because they produce many seeds that may foster invasiveness via the spread of propagules. Despite that V. opulus cultivar ‘Leonard’s Dwarf’ was low yielding and germinated at low rates, it should not be heavily used by the industry because its seeds are highly viable which may permit the establishment of this plant at unwanted locations. Cultivars that generate low seed quantities, germination rates, and viability may pose less of a threat of becoming invasive outside of the landscape. Because A. platanoides cultivars ‘Crimson King’, ‘Globosum’, and ‘Rubrum’ along with V. opulus cultivars ‘Losely’s Compact’ and ‘Nanum’ were low yielding, germinated at low rates, and had low to moderate viability rates these plants should be encouraged for use within cultivation. Although research was conducted on germination and seed viability for A. platanoides cultivars ‘Erectum’, ‘Greenlace’, A. truncatum xplatanoides ‘Pacific Sunset’, ‘Reitenbachii’, ‘Royal Red’, ‘Schwedleri’, ‘Summershade’, ‘Superform’, and ‘Undulatum’ along with V. opulus cultivars ‘Aureum’ and ‘Compactum’, to accurately assess their invasiveness it is necessary that further research be conducted on these plants seed production.