Lauren S. Pile

Managing an Established Tree Invader: Developing Control Methods for Chinese Tallow (Triadica sebifera) in Maritime Forests

Biological invasions by woody species in forested ecosystems can have significant impacts on forest management and conservation. We designed and tested several management options based on the physiology of Chinese tallow (Triadica sebifera [L.] Small). Specifically, we tested four treatments, including mastication, foliar herbicide, and fire (MHfolF), mastication and foliar herbicide (MHfol), dormant-stem herbicide and fire (HdorF), and dormant-stem herbicide (Hdor), to determine their efficacy in reducing the density and regeneration of this highly invasive tree species. Mastication treatments were significant in reducing density the first year but not after 3 years. Prescribed fire significantly reduced density combined with previous treatments. Regeneration coverage was highest on those sites with mastication, which was not affected by the addition of prescribed fire. Overall, we found that the most comprehensive treatment (MHfolF) was more effective in reducing density but did not result in a difference in the amount of regeneration after treatment.

Comparing morphology and physiology of southeastern US Pinus seedlings: implications for adaptation to surface fire regimes

Key messageThe suite of traits expressed as seedlings by coastal and mountain longleaf pine and south Florida slash pine suggest they can survive fire in the seedling stage. In contrast, loblolly pine and typical slash pine tolerate fire when mature but do not exhibit traits that allow them to survive fire when young, representing a different strategy for survival in frequently burned communities.ContextFire is an important driver in the distribution and abundance of southern US pine species, and seedling fire tolerance often determines individual survival under frequent fire regimes.AimsWe investigated seedling growth, biomass allocation, needle distribution, bark thickness, and total non-structural carbohydrate (TNC) storage in taproots and related them to the expression of fire-tolerance for five species or types, including loblolly pine (Pinus taeda L.), two longleaf pine (P. palustris Mill.) types representing two distinct ecological communities (coastal and mountain) and two slash pine (P. elliottii Englem.) varieties.MethodsWe analyzed the relationship of seedling growth, biomass characteristics, and total non-structural carbohydrate storage between species by using analysis of variance.ResultsBoth coastal and mountain longleaf pines had thick bark, long, densely arranged needles, and a grass-stage. South Florida slash pine shared the same suite of traits but, contrary to previous reports, displayed reduced height growth rather than a grass-stage. In contrast, loblolly pine and typical slash pine had faster height growth, more branching, lower needle density, and thinner bark. Both longleaf pines and south Florida slash pine also had higher TNC storage in taproots than either loblolly or typical slash pines.ConclusionThe relative strength of expression of these fire-adaptation traits among the five species types generally matches the fire-return intervals associated with each species’ habitat, suggesting the importance of fire regimes in determining the distribution and abundance of the studied species.

Potential for nonnative endozoochorous seed dispersal by white-tailed deer in a southeastern maritime forest.

Abstract Nonnative invasive plants (NNIP) have far-reaching effects on native ecosystems worldwide. Understanding the role of generalist seed dispersers in spreading NNIP across the landscape is important to the conservation of native ecosystems and to the management of NNIP. We studied white-tailed deer (Odocoileus virginianus) as a seed disperser in a mixed maritime pine (Pinus spp.) forests on Parris Island, SC, with particular interest in the dispersal of Chinese tallowtree [Triadica sebifera (L.) Small], a highly invasive tree species in the southeastern United States, which is a management concern on Parris Island, SC. We collected deer scat pellet groups along transects in two forest types: those that had recently been treated with silvicultural timber harvest (thinned) and those that have not been so treated (unthinned). Using two pellet-treatment methods, directly planting or rinsing and sorting, we determined that, out of 25 species grown under greenhouse conditions, 28% (n  =  7) were nonnative, small-seeded, herbaceous species. However, T. sebifera was not identified in either of the two treatment methods. Recent forest thinning significantly affected the number of species determined in deer pellet groups (F  =  8.37; df  =  1; P < 0.01), with more native plant species identified in unthinned (x̄  =  25 ± 11) than in thinned (x̄  =  3 ± 10) forest stands (F  =  5.33; df  =  1; P  =  0.02). Our results indicate that white-tailed deer are actively dispersing nonnative seeds but not those of T. sebifera or other woody NNIP. Nomenclature: Chinese tallowtree; Triadica sebifera (L.) Small; pine; Pinus spp.; white-tailed deer; Odocoileus virginianus. Management Implications: Our study investigated whether white-tailed deer (Odocoiles virginianus) were active dispersers of Chinese tallowtree (Triadica sebifera) and other nonnative invasive plants (NNIP) in mixed maritime pine (Pinus spp.) forests at Parris Island Marine Corps Recruit Depot (MCRD), Parris Island, SC. Dispersal by generalist herbivores can lead to the establishment of NNIP in new, potentially uninvaded locations resulting in changes in ecological trajectories that can directly affect management activities. We determined that white-tailed deer were not dispersing T. sebifera but were active dispersers of other nonnative plants. White-tailed deer are ubiquitous, generalist herbivores that are overabundant in many areas of the eastern United States. When overabundant, or when native plant resources are lacking during periods of nutritional stress, white-tailed deer will alter their forage choices and select alternative plant species. Forest management activities (i.e., timber harvesting operations, prescribed burning, etc.) may provide the necessary conditions for nonnative plant establishment through increased solar radiation and mineral soil exposure and should be considered if mitigating invasive species spread.