Initial investigation of seasonal flammability of three invasive East Texas forest understory fuels using thermogravimetric analysis

East Texas forest understory fuels have become increasingly infested with invasive species which have contributed to greater hazardous fuel loads when combined with decades of fire exclusion and passive management. This study focused on estimating seasonal changes in flammability parameters of invasive yaupon (Ilex vomitoria), Chinese privet (Ligustrum sinense), and Chinese tallow (Triadica sebifera) using thermogravimetric analysis. Foliage and stem samples were collected in the dormant (February) and growing (August) seasons. Differential thermogravimetric (DTG) and proximate analyses were used to estimate species specific flammability parameters related to relative spontaneous ignition temperature (RSIT), gas-phase maximum mass loss rate (GP-MMLR), and combustion duration (GP-CD). Seasonality played a significant role among species RSIT (pRSIT) and combustibility (>GP-MMLR) followed by Chinese privet and tallow. Consequently, yaupon poses a significant year round wildfire and fire management risk. Chinese privets’ greater dormant season ignitability may improve prescribed fire control efforts in mid-winter, but may also pose a significant wildfire risk during drought and windy conditions. Chinese tallow stems’ greater growing season flammability may enhance integrated control measures using prescribed fire in late summer and early fall. In summary, these data further local knowledge related to seasonal and relative plant flammability and may be useful as additional inputs into custom fuel models, as well as assigning flammability hazard ratings for ornamental vegetation within the wildland-urban interface.