The Mississippi Sandhill Crane National Wildlife Refuge (MSCNWR) has conducted prescribed burning and vegetation management since early 1980s to restore the native habitat for the endangered Mississippi sandhill crane (Grus canadensis pulla). Prescribed fire and timber management which tend to clear overstory trees have created an avenue for biological invasion. Chinese tallow (Triadica sebifera) has invaded the landscape and become a serious ecological threat to native ecosystems. A spatially random sample of 56 0.04-ha monitoring plots were established in 2015 and measured in 2015 and 2018. Tallow presence, abundance and stand characteristics, mean fire intervals, distance to road (seed source) were recorded and calculated for each plot to estimate the invasibility (susceptibility) of two ecosystem types: pine savanna and pine flatwood and contributing factors at the landscape level using the spatial regression model.
Results/Conclusions
The invasion probability (0.30) of pine flatwood is doubled that (0.15) of pine savanna, but the difference is statistically marginal (0.085) at the level of significance of 0.05. Compared to pine savanna, pine flatwood has more tallow seedlings (< 1m) saplings (1m<height<3m), but the abundance of large tallows (> 3m) has no statistical difference. Considering both invasion probability and population size of invasive tallows, pine flatwood is more susceptible to tallow. Factors that affect ecosystem invasibility (susceptibility) include distance to road, seed tree, canopy cover, understory cover and mean fire intervals. Restoration practices should consider these factors in habitat restoration and mitigation of the invasion and impact of invasive Chinese tallow.