Meeting in 2003 on Fire and Invasives at the University of New Hampshire Extension in Durham, NH.
Using Fire to Control Invasive Plants: What’s New, What Works in the Northeast? was held on January 24, 2003 at the Urban Forestry Center, Portsmouth, NH. Over one hundred natural resource professionals gathered to hear from researchers and fire managers whose observations might not have been summarized elsewhere. These papers were not peer-reviewed or edited. They were compiled by Karen P. Bennett, University of New Hampshire Cooperative
Extension, Dr. Alison C. Dibble, USDA Forest Service, Northeastern Research Station, and Dr. William A. Patterson III, University of Massachusetts.
Final report to Joint Fire Science Program, 2004
Alteration of natural habitats by woody invasive plants is a concern for land managers throughout the northeastern United States. Invasive species – both native and exotic – can adversely impact plant communities and alter fire regimes. Although there is some information on the impacts of invasive species on habitats in the Northeast, few studies have addressed best management practices for controlling or eliminating these species and no studies have evaluated their impacts on fire regimes.
JULIE A. RICHBURG- UMASS
In the Northeast, land managers are combating the deleterious effects that invasive plants have on other species and natural communities with attempts to remove them or substantially reduce their density. Control methods vary depending on the target species’ growth form, the extent of the invasion, and other species and resources at the site. Mechanical treatment, prescribed fire, hand-pulling, and application of herbicides, alone or in combination, have all been used to attempt control.
Woody invasive plants are often difficult to eliminate due to their ability to sprout from stems, stumps, and roots. Successful control of these species requires understanding temporal variations in their below-ground resources. Total non-structural carbohydrate (TNC) reserves in the roots of woody species support growth following disturbance and generally follow an annual cycle of depletion and replenishment. This study evaluates the effectiveness of treatments when applied during periods of decreased TNC reserves.
Treatments were applied to seven invasive shrubs (Cornus racemosa, Rhamnus cathartica, Rosa multiflora, Berberis thunbergii, Lonicera morrowii, Smilax rotundifolia, and Cytisus scoparius) at three different sites in Massachusetts and New York. Treatments included cutting and/or burning, applied singly or in combination, in either the dormant or growing seasons.
TNC were depleted following all treatments. Dormant-season-treated plants, whether cut or burned, sprouted and replenished their reserves within the following growing season. For growing-season-treated plants TNC remained depleted longer, with a greater effect on plants that received more treatments. For most species studied, TNC recovered to pre-treatment levels by the end of one growing season without treatment.
Sprout growth was influenced by the extent of carbohydrate reserves present before treatment. Biomass and heights of sprouts were significantly lower in growing- season-treated plants than those treated in the dormant season, even when data were adjusted for different lengths of recovery time.
All treatments reduced the cover of the target invasive shrub. As the plants sprouted, they regained some of their initial cover and are expected to dominate without further treatment. Timing treatments to the cycle of TNC can increase the effectiveness of control methods, although repeated treatments may be necessary for several years.
MICHAEL C. OHMAN
Invasion of grasslands by woody shrubs can alter existing fire regimes and give rise to problem fire behavior. Invaded areas are likely to burn less often but with more intensity. Abandoned pastures on Naushon Island, Massachusetts (USA) which have been invaded by the woody vine Smilax rotundifolia follow this pattern. I evaluated the usefulness of standard and custom fuel models for predicting fire behavior observed in a 0.5-acre (0.2-ha) experimental burn. Custom fuel model development required characterizing fuel load and fuel bed depth of the experimental burn plot – a task complicated a dense mat of vines with 100 % cover to a height of 3 to 6 ft (1 to 2 m). This was done by measuring the height of fuel beds, estimating 3-dimensional cover by modified point-intercept sampling, and harvesting live vines and leaves and dead woody and non-woody litter and vines from 1 m2 cubes. From these data, I developed regression equations to estimate fuel load using fuel bed depth.
Do prescribed fires create long-term carbon losses from the forest? How about insect defoliations? How long does it take a forest to re-capture that carbon from the atmosphere? Dr. Kenneth Clark and his fellow researchers investigated all of this and more with their latest research in the pinelands of New Jersey. Click below to access the brief.