ObjectiveTrees are the material basis for forest or landscape fires, and also the inevitable factor for fires. Reasonable selection and allocation of landscape plants is the basic work of constructing biological fire-resistant forest belts. At present, the researches on pyrolysis and flammability are mostly about forest fuels, but there are few studies on pyrolysis kinetics of landscape tree species. In this paper, the pyrolysis kinetics of 21 landscape tree species in Hohhot of northern China were studied and the fire-resistant landscape tree species were chosen to provide a theoretical basis for urban ecological security and tree planting in fire-resistant green space.

MethodThermogravimetric analysis was used to study the thermogravimetric behavior of landscape tree species under the conditions of high purity oxygen as carrier gas, air as ventilation atmosphere, gas flow rate of 10 mL/min and heating rate of 60 ℃/min. The TG-DTG curve was used to analyze the pyrolysis process and pyrolysis parameters of landscape tree species.

ResultThe pyrolysis of 21 landscape tree species in air atmosphere experienced dehydration, rapid pyrolysis and carbonization stages. The corresponding parameters of the sample in the rapid pyrolysis stage were obtained by the Coats-Redfem integration method of the first-order reaction kinetic model.

ConclusionThe order of thermal stability of leaf parts of each tree species from low to high was: Sambucus williamsii, Berberis xinganensis, Amygdalus triloba, Buxus sinica, Viburnum mongolicum, Sabina vulgaris, Rosa xanthina, Buddleja alternifolia, Tamarix chinensis, Amygdalus davidiana, Spiraea pubescens, Morus mongolica, Amygdalus persica, Syringa reticulata, Sorbaria kirilowii, Flueggea suffruticosa, Acer stenolobum, Weigela florida, Cotoneaster acutifolius, Elaeagnus angustifolia, Lycium chinense. The P-value of the pyrolysis characteristics index of leaf part of each tree species from large to small was: Lycium chinense, Cotoneaster acutifolius, Syringa reticulata, Weigela florida, Rosa xanthina, Elaeagnus angustifolia, Sorbaria kirilowii, Morus mongolica, Amygdalus davidiana, Amygdalus persica, Acer stenolobum, Tamarix chinensis, Buddleja alternifolia, Sabina vulgaris, Buxus sinica, Berberis xinganensis, Flueggea suffruticosa, Amygdalus triloba, Spiraea pubescens, Viburnum mongolicum, Sambucus williamsii. Based on the comprehensive analysis of thermal stability, ignition temperature and pyrolysis characteristics index,Flueggea suffruticosa, Acer stenolobum, Elaeagnus angustifolia, Lycium chinense and Weigela florida are strong fire-resistant landscape tree species. The results can provide a theoretical basis for the prevention and control of urban forest fires by landscape tree species.