6.2 at 1 Camp Cozy Park_NRMP_2023

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78 Friends of the Mississippi River Camp Cozy Park NRMP The elms and ash at Camp Cozy are at risk of dying in the near future, and many dead crowns of green ash can be seen when viewing the canopy of the forested areas. When such large trees die, it will have a pronounced effect on the understory vegetation and the water in the river. These trees act to shade the water and provide habitat and improve water quality for fish and other species. When large trees die, they open the canopy and create gaps, which releases the understory that was formerly suppressed by the shade from such trees. If desirable species like native forbs, grasses, sedges, and shrubs exist in the understory, then this can have a positive effect since the result will probably be a net increase in bank stability and diversity. In the case of this property, these canopy gaps will likely be filled by buckthorn and Tatarian honeysuckle, which are poised to take advantage of such a situation. To avoid this undesirable scenario, active management is recommended. Removal of undesirable shrub species and replacement with desirable native shrubs and herbaceous plant species is a recommended management strategy. For green ash in particular, the situation is particularly important, as this species makes up over 50% of the canopy in many areas of the floodplain forest. The principle of risk is highly applicable here; risk is often defined as the probability of a negative event weighted by its consequences. In the case of EAB, the consequences will be large and quite negative, as a loss of half the canopy on the property could have cascading consequences for invasive species, water quality, and wildlife. The probability that EAB arrives is high, though it is unclear when this will occur. While we plan to remove invasive species prior to this occurring, which will reduce some of the negative consequences, another potential strategy is to proactively remove the ash from the property. This would be a large undertaking, as the ash would have to be removed and replaced by other floodplain species. Removal could be contracted to logging firms, which could potentially fund the work, though the market for ash in the county is relatively sparse and this technique unlikely to create any profit for the city. Ultimately, removal should occur once invasive species are removed, and could occur in stages (10-20% per year) to minimize disturbance to the community. However, removal will realistically have a large negative impact on the property, especially in floodplain areas and to neighboring trees. The removal would also have to be timed to minimize impacts on the prairie restoration process. Advice from the city or county should be solicited when making these decisions. Oak Wilt and Bur Oak Blight Oak wilt is an increasingly common tree disease caused by the fungus Ceratocystis fagacearum. While the disease is present in many eastern US states, it is most prevalent in the Midwestern US. Within Minnesota, it is an issue of serious concern in and around the seven-county metro area, including in Sherburne County. Oak wilt affects all of Minnesota’s most common oak species (red oak [Quercus rubra], pin oak [Q. ellipsoidalis], bur oak [Q. macrocarpa], and white oak [Q. alba]), though it does not affect these species equally. Red and pin oak are the most susceptible species, with infected individuals wilting in six weeks or less. Bur and white oaks may take years to wilt completely and may only do so one branch at a time. The fungus can be transported from tree to tree by sap beetles, but most commonly spreads through root grafts. The beetles are attracted to the fungal mats created when mature oaks die from oak wilt, and also to wounds on uninfected oaks, providing a convenient pathway of spread for the fungus.