Benjamin O. Knapp

Early Stump Sprout Development after Two Levels of Harvest in a Midwestern Bottomland Hardwood Forest

Sprouting is an important source of regeneration for hardwood trees but has not been studied extensively in bottomland hardwood forests. We quantified the sprouting responses of 11 bottomland hardwood species or species groups after two levels of overstory harvest, including clearcutting with reserves (CCR) (residual basal area ∼2.0 m2/ha) and basal area retention (BAR) (residual basal area ∼8.0 m2/ha), in northern Missouri. The probability of sprout presence after one growing season decreased with increasing parent tree dbh for boxelder, river birch, hickories, hackberry, and American elm, as well as for eastern cottonwood and pin oak after three growing seasons. Harvest treatment affected the probability of sprout presence after three growing seasons for silver maple and American elm, with higher probabilities in CCR than BAR. After three growing seasons, height of the dominant sprout per stump was greater in CCR than in BAR across species. The sprouting probabilities and subsequent survival and growth of sprouts suggest that promoting coppice regeneration would favor silver maple, American elm, and American sycamore at the expense of oak species, river birch, and eastern cottonwood.

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.