Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter: invasive versus non-invasive plants.

摘要

In northeastern United States, invasive plants alter forest fuels, but their combustion characteristics are largely unknown. We assessed underground samples of foliage and twigs in the cone calorimeter for 21 non-invasive, native species, paired with 21 invasive species (18 non-native). The samples for these tests were obtained from nine sites in the eastern and mid-Atlantic USA (Maine, Maryland, Massachusetts, New York and Virginia). Variables included sustained ignition, peak heat release rate, total heat release, and especially average effective heat of combustion, which is independent of initial sample mass. Heat of combustion was overall slightly lower for invasive species than for counterpart non-invasive species, and was significantly lower for Norway maple (Acer platanoides), black locust (Robinia pseudoacacia) and glossy buckthorn (Frangula alnus [Rhamnus frangula]) than for three non-invasive trees. It was low for invasive Japanese stiltgrass (Microstegium vimineum), sheep sorrel (Rumex acetosella) and glossy buckthorn, and for non-invasive whitegrass (Leersia virginica), interrupted fern (Osmunda claytoniana), grape, sphagnum moss (Sphagnum fallax) and three-lobed bazzania (Bazzania trilobata). Heat of combustion was high for invasive roundleaf greenbrier (native, Smilax rotundifolia), scotchbroom (Cytisus scoparius), tree-of-heaven (Ailanthus altissima), Japanese honeysuckle (Lonicera japonica), Japanese barberry (Berberis thunbergii), swallow-wort (Cynanchum cf. louiseae) and garlic mustard (Alliaria petiolata), and for non-invasive plants of fire-prone ecosystems: black huckleberry (Gaylussacia baccata), pitch pine (Pinus rigida), bear oak (Quercus ilicifolia), northern bayberry (Morella pensylvanica) and reindeer lichen (Cladonia rangifera). Heat content of twigs and foliage interrelates with other factors that affect fire behaviour, yet the cone calorimeter results enabled comparison of combustion properties among many species. These data have potential application as improved inputs for fire behaviour modelling.