Legislation: Conservation – Invasive Species
Citation and link to full text: Wisconsin Statutes, 23.22
Responsible agency and link to landing page: Wisconsin Department of Natural Resources (WDNR)
Related regulations: Wisconsin Administrative Code, Chapter NR 40
Advisory body and link to landing page: Wisconsin Invasive Species Council
Roles of legislation and related regulations: In 2001, an amendment to the Wisconsin statutes directed the WDNR to develop a state-wide invasive species control program, and to promulgate rules to identify, classify and control invasive species. The statute also authorizes the Wisconsin Invasive Species Council to advise WDNR. The WDNR rule establishes classifications and lists of species under each classification. It describes prohibited acts relative to each classification.
Key definition(s): A Prohibited Invasive Species is likely to survive and spread if introduced to Wisconsin, potentially causing environmental, economic or human health harm. It is not found in the state or in the portion of the state where it is listed as prohibited, with the possible exception of isolated individuals or pioneer stands. Eradication or containment may be feasible. WDNR may require landowners to control prohibited species on their property in accordance with a control plan.
Invasive species control means to cut, remove, destroy, suppress, or prevent the spread of the species and refers to preventing both sexual and vegetative propagation.
A Restricted Invasive Species is established in Wisconsin or in the portion of the state where it is listed as restricted. It causes or is likely to cause environmental, economic, or human health harm. Eradication or containment may not be feasible.
The Wisconsin Invasive Species Council makes recommendations to WDNR regarding a statewide program for classifying and controlling invasive species. Its four subcommittees cover education, research, regulation, and interagency coordination. Its membership includes representation from five state agencies (including WDNR) and seven seats representing public and private interests.
Prohibited Invasive Species, woody plant species only (full list can be found in WDNR link above):
| Fiveleaf akebia Akebia quinata |
Japanese honeysuckle Lonicera japonica |
Himalayan blackberry Rubus armeniacus |
| Porcelain berry Ampelopsis brevipedunculata |
Amur bush honeysucklea Lonicera maackii |
Wineberry Rubus phoenicolasius |
| Common barberry Berberis vulgaris |
Princess tree Paulownia tomentosa |
Japanese wisteria Wisteria floribunda |
| Oriental loeseneri bittersweet Celastrus loeseneri |
Amur cork treeb,c Phellodendron amurenseb,c |
Chinese wisteria Wisteria sinensis |
| Scotch broom Cytisus scoparius |
Sawtooth oak Quercus acutissima |
Restricted Invasive Species, woody plant species only (full list can be found in WDNR link above):
| Amur mapled,e Acer tatarica subsp. ginnala |
Autumn olive Elaeagnus umbellata |
White mulberryb,e Morus alba |
| Tree-of-heaven Ailanthus altissima |
Burning bushe,f Euonymus alatuse |
White poplare Populus alba |
| Black alderd,e Alnus glutinosad |
Glossy buckthorng Frangula alnus syn. Rhamnus frangula |
Common buckthorn Rhamnus cathartica |
| Japanese barberrye,f Berberis thunbergii |
Amur bush honeysucklea Lonicera maackii |
Bristly locuste Robinia hispida |
| Siberian peashrube,g Caragana arborescens |
Morrow’s bush honeysuckle Lonicera morrowii |
Black locustd,e Robinia pseudoacacia |
| Oriental bittersweet Celastrus orbiculatus |
Tatarian bush honeysuckle Lonicera tatarica |
Multiflora rosec,h Rosa multiflora |
| Russian olive Elaeagnus angustifolia |
Bell’s bush honeysuckle Lonicera x bella |
Siberian elmc,e,i Ulmus pumila |
- a Species is prohibited in the northern counties of the state and restricted in the southern counties. For status by county, see WDNR Amur honeysuckle webpage.
- b Species is dioecious; male (fruitless) cultivars are exempt.
- c Use as a seedling understock or rootstock is exempt.
- d Cultivars are broadly exempt.
- e Prohibited actions allowed through 5/1/2020 without a permit.
- f Named cultivars are regulated, all others are exempt. For regulated cultivars, see WDNR Japanese barberry and Burning bush webpages.
- g Named cultivars are exempt, all others are regulated. For exempt cultivars, see WDNR Siberian peashrub and Glossy buckthorn webpages.
- h Prior to becoming a Restricted Invasive Species, Multiflora rose was made a “nuisance weed” under statute (23.23). As such, sale and distribution of this species was banned beginning in 1987.
- i Hybrids are broadly exempt.
Prohibited acts:
- Transportation, possession, transfer or introduction of a Prohibited Invasive Species.
- Transportation, transfer or introduction of a Restricted Invasive Species.
Exemptions: Prohibited acts done incidentally or accidentally are generally exempt. Transportation and transfer done in the course of identifying or disposing of a prohibited or regulated species are generally exempt, though for prohibited species the location of a positively identified prohibited species must be reported to WDNR within 30 days. WDNR can issue individual permits for prohibited related to prohibited and restricted species for research, public display/education, and other purposes specifically stated in the permit provided specific stated criteria are met. For Restricted Invasive Species, prohibited acts for woody vines (and herbaceous plants) are allowed for 3 years beyond the listing date, and prohibited acts for trees and shrubs are allowed for 5 years beyond the listing date (see footnote e above). For Restricted Invasive Species, plant parts that are incapable of reproducing may be transported, transferred, or introduced without a permit.
Cultivar exemptions: For Berberis thunbergii and Euonymus alatus, any cultivar other than those specifically listed is not included in the restriction (see footnote f above). For Frangula alnus and Caragana arborescens, only the specifically listed cultivars are exempt from restriction (see footnote g above). For certain other species, cultivars or types of cultivars/hybrids are broadly exempted (see footnotes b, d and h above). For all other species all cultivars, hybrids, and varieties are included in the listing.
Process for species selection/addition: WDNR can add or remove species from the prohibited and restricted lists or move species between lists by formally amending the NR 40 rule. This would be done with input from the Wisconsin Invasive Species Council.
Photo Credit: A forest trail at Chequamegon-Nicolet National Forest (Photo: U.S. Forest Service)
