Introduction The Wetlands Reserve Easement (WRE) program accounts for the majority of private land afforestation in the Lower Mississippi Alluvial Valley (LMAV), but consistent ecological monitoring is not often feasible after restoration activities are complete. Objectives We evaluated environmental factors influencing survival of trees planted during WRE bottomland afforestation and compared forest community composition among afforested WRE sites, pre-existing forests on WRE sites, and nearby reference forests. Methods We measured survival of trees planted during afforestation activities and evaluated planted tree survival in relation to site and stand characteristics using a generalized linear mixed-effects model (GLMM). We calculated the importance value of individual tree species to determine overall contribution to forest composition in each forest category. Using nonmetric multidimensional scaling ordination and post-hoc pairwise tests, we compared community composition among the three forest categories. Results Our community composition analysis indicated that afforested sites differed from both pre-existing and reference forests. Planted tree survival was negatively associated with local overstory tree (>10 cm) density, understory tree (<= 10 cm) density, and elevation relative to stream drainage and was lower in hydric as compared to non-hydric soils. Conclusions Based on our results, greater survival of planted trees could most likely be achieved by thinning stands if natural regeneration is abundant, stratifying planted tree species by the most extreme expected hydrologic conditions, and restoring microtopography to simulate minor elevational changes characteristic of bottomland hardwood forests.

Prescribed burning is a common management tool for both shortleaf pine and associated oak species, as they can resprout following top-kill and are adapted to frequent surface fire regimes. In Missouri, shortleaf pine often occurs with oaks in mixedwood ecosystems, though its prevalence is diminished from historic levels. With interest in restoring shortleaf pine, research is needed on specific strategies for using prescribed fire to promote shortleaf pine in mixed pine-oak ecosystems. We studied the survival and resprouting of shortleaf pine and oaks of different sizes following a prescribed burn in Missouri. Our results affirm the patterns of increasing stem size reducing the likelihood of top-kill and of greater fire intensity increasing the likelihood of top-kill for both shortleaf pine and oaks. We found that shortleaf pine can resist top-kill at a lower basal stem diameter threshold than oaks and that shortleaf pine and oaks differ in post-resprouting resource allocations, with shortleaf pine growing numerous shorter sprouts and oaks growing fewer taller sprouts. We suggest the use of well-timed prescribed burning to release shortleaf pine from oak competition and improve its viability in mixed pine-oak systems.

Due to lower site productivity and lack of aggressive competitors, oak regeneration in Missouri is often considered less problematic than in the rest of the Central Hardwoods Region. However, oak advance reproduction is scarce on more productive sites in the Missouri Outer Ozark Border Subsection where sugar maple has accumulated in the midstory. The purpose of our study was to identify barriers to accumulating competitive white oak advance reproduction in the Outer Ozark Border Subsection at different stages of the regeneration process, including seed germination, seedling establishment, and development as advance reproduction in a mature upland oak-hickory forest. We manipulated light availability through thinning of the overstory and removal of the midstory, and we controlled deer herbivory by installing fenced exclosures. We tracked the performance of sown acorns, naturally regenerated seedlings of known germination year, and underplanted bareroot seedlings. Our results demonstrate the importance of a mast year, as many sown acorns were removed by small mammals or infested with weevils. The underplanted seedlings had a low survival rate (<35%) after five years, during which time a new cohort of seedlings was established following a bumper acorn crop. Neither heavy shade nor deer herbivory limited germination of natural reproduction. Heavy shade limited the growth and persistence of white oak advance reproduction in the understory. Deer herbivory did not impact the survival of white oak but negatively impacted its size. Active management will be necessary to create adequate light for regeneration, which we achieved through either midstory removal or commercial thinning.

Mixed-species plantations are increasingly adopted as they may exhibit higher productivity and carbon sequestration potential under suitable species mixtures and management. Assessing the mixing effects typically relies on controlled biodiversity-ecosystem functioning (BEF) experiments and other forest inventory data. Often, the BEF experiments are limited to a short period (e.g., <30 years), and other forest inventory data inherit uncontrolled factors not aligned with the BEF experiments. Results from both are often inconsistent. We used a forest dynamic model to conduct simulation experiments of mixed-species forest plantations. Our simulations varied factors that may affect mixing effects, including levels of species mixture, competition control treatments for naturally regenerated species, and planting density. We informed the simulation model from the BEF experiments and validated the simulated results against forest inventory data. Our results showed that species trait dissimilarity is the primary factor affecting mixing effects, with its relative importance ranging from 20% to 40% across all simulation periods. High niche overlaps intensify competition, and distinct niches facilitate complementarity. The effects of competition control treatments are determined by functional complementarity or redundancy between the naturally regenerated and planted species. A high planting density (e.g., 4,444 stems·ha−1) enhanced interspecific interactions that amplified the effects of species trait dissimilarity up to twofold. We found that the inconsistent mixing effects from the BEF experiments and other forest inventory data are due to not including the self-thinning process, as the BEF experiments usually do not extend to this stage. Post self-thinning (at approximately 80 years after the plantation) leads to the re-optimization of stand structure that sets the basis for enhancing the mixing effects for the long term. Thus, our simulation results underscore the importance of both time span and stand development stages when assessing the mixing effects of forest plantations.

Stress from low light availability and flooding can reduce photosynthesis and growth rates of trees, contributing to possible regeneration challenges in bottomland hardwood forests. This study investigated the photosynthetic light responses of pin oak (Quercus palustris Muenchh.) and swamp white oak (Quercus bicolor Willd.) seedlings growing in two light environments and across a hydrological gradient. Our findings revealed that neither light environment nor soil moisture availability had a significant impact on leaf mass per area, light compensation point, dark respiration rate, or apparent quantum yield. However, light availability strongly affected photosynthetic rates of the oak seedlings, with greatest photosynthetic rates observed in high light environments. The more light-demanding pin oak exhibited lower rate of photosynthesis in response to decreased light availability compared to swamp white oak. The different light requirements of these oak species could directly influence the length of time seedlings can remain in the understory before they can be released. Additionally, the effect of soil moisture stress on foliar nitrogen and photosynthesis was more pronounced in low light environments. We observed a direct relationship between foliar nitrogen and light availability, as well as a positive correlation between photosynthetic rate and foliar nitrogen. Thus, any decrease in foliar nitrogen resulting from low light environments and soil inundation could adversely affect photosynthetic capacity and subsequent development of oak seedlings in bottomland hardwood forests.

Shortleaf pine has the broadest range of the southern pine species, occurring in 22 states and extending north into New Jersey, Pennsylvania, and New York (Staten Island). Shortleaf pine has been understudied compared to loblolly pine and longleaf pine, typically favored for timber production and conservation value, respectively. The extensive range of shortleaf pine contributes to a high degree of variability within and among its ecosystems and contributes to the need to understand regional context in considering its ecology and management. The goal of this paper is to review and synthesize the state-of-knowledge on shortleaf pine ecosystems, emphasizing the importance of variation across its range in identifying management challenges and opportunities. We discuss the variation in growing conditions that occur across the geographic range, shortleaf pine natural community groups, and contemporary shortleaf pine forest types that occur on the landscape. We provide a review of the state-of-knowledge for topics related to shortleaf pine management, including its fire ecology, genetic considerations, economics, and others. Finally, we synthesize these into key considerations and highlight regionally specific management challenges and opportunities.

White oak (Quercus alba L.) is an ecologically and economically important tree species, common in upland hardwood forests throughout the eastern United States (US). This study examines the population dynamics of this foundational species over the past 30 years, highlighting both range-wide and regional metrics of change. Using data from the USDA Forest Service Forest Inventory and Analysis program, we analyzed changes in age and size distributions, as well as recruitment, mortality, and growth rates. We found a significant shift towards an older, mature-dominant population, with a notable decline in young age classes. Despite substantial increases in standing volume, net annual recruitment for trees with a diameter at breast height (dbh) ≥ 5 in. was negative—a concerning result for long-term sustainability if persistent. Regional analyses highlighted variation as most areas showed no signs of overutilization, but some exhibited volume reductions over the last 30 years and currently unsustainable growth-to-drain ratios. Other areas, spanning almost ¾ of the study region exhibited either seedling or sapling scarcity suggesting recruitment- or establishment-based bottlenecks that challenge long-term sustainability. Our results underscore the importance of management strategies to address challenging demographic rates. Efforts to mitigate the risks and effects of population decline and maintaining the myriad benefits white oak provides to eastern US forests, especially in the context of climate change and shifting species ranges, benefit from a deeper understanding of the ecological and socioeconomic factors driving these results.

Introduction Sericea lespedeza (Lespedeza cuneata) is a nitrogen-fixing legume that is native to Asia and was promoted in the central United States for forage, wildlife habitat, and to mitigate erosion and mine spoils. It has since become a high-impact invasive plant, especially in tallgrass prairie ecosystems. Traditionally, herbicide is the common tool to control Sericea lespedeza's spread and manage its impact; however, herbicide treatments come at a cost to other restoration efforts.Objectives This research was conducted to evaluate the effectiveness of management to control Sericea lespedeza populations within a chronosequence of reconstructed tallgrass prairies.Methods We compared the difference in Sericea lespedeza coverage across 98 (25 m2) paired plots from 2019 to 2023 representing (1) managed and (2) management-excluded treatments along with differences in the Sericea lespedeza seed bank after 4 years.Results Findings from this study suggest that Sericea lespedeza populations continue to grow in the absence of management, increasing to 13 times their original densities, while populations in areas of sustained management remained stable around 2-5% coverage with year-to-year variation. Without management, the Sericea lespedeza soil seed bank was also five times more abundant. Older prairie reconstructions were more resistant to increases in Sericea lespedeza abundance but were not immune. Results also suggest that management may negatively impact forb populations, but without management both forb and graminoid populations declined.Conclusions This study highlights the importance of maintaining and prioritizing resources for the long-term control of aggressive invasive plants.

Increasing spatial complexity is a restoration goal for many frequent fire forests. Regeneration of longleaf pine often occurs in patches within canopy gaps, where resource availability is higher and canopy-derived fuels are lower. Once established, dense patches of regeneration may alter fuel composition and fire behavior, but the magnitude of this change and its resulting effect on the survival of the regenerating longleaf pine trees is unknown. To better understand spatial patterns of vegetation–fire feedbacks and inform restoration efforts, we studied how regeneration patches altered fuels, fire behavior, and fire effects in longleaf pine forests. We found fuel loading, fire behavior, and fire effects were reduced within regeneration patches compared to areas with regeneration occurring as single trees within the overstory matrix. Fire effects were reduced in patch centers and opposite the direction (downwind) of fire movement. The spatial pattern of naturally occurring and planted longleaf pine can influence fire behavior, and ultimately survival and recruitment into the overstory. Understanding spatial dynamics of vegetation–fire feedbacks provides new insights on regeneration processes in longleaf pine forests. These results can inform restoration and management efforts that seek to enhance structural complexity in natural forest systems.

Research on sapling recruitment and age structure in mature longleaf pine (Pinus palustris Mill.) woodlands is needed to inform silvicultural treatments that maintain or enhance stand structural diversity. To address this issue, we quantified sapling age structure within and across dense patches of longleaf pines that established from natural regeneration in canopy gaps of mature uneven-aged stands. We determined the age when trees emerged from the grass stage (i.e., effective age) of 475 saplings and then developed a diameter-age model to predict the ages of another 1,606 saplings. We found that the interquartile range of sapling effective ages within patches was relatively narrow, averaging 4.8 years. This provides support for the commonly held view that longleaf pine sapling patches are even-aged. We also found that there were significant differences in mean sapling effective age among patches. The means for sapling patches ranged from 20.8 to 25.9 years. Cone crop and prescribed fire records provided further support to there being multiple years in which different locations across our study area were regenerated to longleaf pine. Stands with sapling patches that have a range of mean ages could enhance stand structural diversity, which could have the co-benefit of meeting wildlife habitat objectives.

In bottomland forests, managing oak regeneration is challenging due to competition with other species. Low understory light levels in mature stands favor more shade-tolerant tree species, whereas harvest often results in release of fast-growing competitors. In the late 1990s, a study was initiated in northeastern Missouri to evaluate the effects of overstory harvests on stand development of bottomland forests, with particular interest in oak regeneration. Canopy removal resulted in rapid growth of undesired soft-mast species without increasing the abundance of oak reproduction. In 2017, bare-rooted pin oak (Quercus palustris Muenchh.) and swamp white oak (Quercus bicolor Willd.) seedlings were planted, to increase the oak component through enrichment planting in the stands that had previously been harvested and underplanting in the stands that had received no regeneration harvest. For all planted seedlings, three levels of midstory release treatments were applied after planting in 2017, including a control (no release), and light release, and a heavy release. This study tested the effects of the original overstory harvests and the subsequent midstory release on survival and development of planted oak advance reproduction over 5 years. Our results suggest that establishing oak advance reproduction prior to overstory harvest is more efficient than enrichment planting after overstory harvest. A prior midstory release is important to develop competitive oak advance reproduction before a later overstory harvest to ensure successful oak regeneration.

Background Shortleaf pine is a fire-adapted tree species, and prescribed fire is commonly used to increase its regeneration success, improve wildlife habitat, and reach conservation objectives associated with open forest ecosystems. We studied direct effects of heat and smoke on shortleaf pine germination in a greenhouse study and effects of season of burning on the number of new germinants in a field study. Improved understanding of fire effects on shortleaf pine seed and regeneration success can help refine burn prescriptions to better meet specific management objectives. Results Temperatures ≥ 120 °C eliminated germination of shortleaf pine seeds in a greenhouse trial, and exposure of seeds to 60 °C resulted in no reduction in germination compared to the unheated control regardless of duration of exposure. At 80 °C, duration of heat exposure mattered, with exposure for 10 min reducing germination compared to unheated controls. Smoke exposure had no effect on germination. A field experiment showed that fall burns (prior to seedfall) resulted in greater initial germinant counts than early spring burns (after seedfall but before germination) or unburned controls, which both resulted in greater initial germinant counts than late spring burns (after germination). Conclusions Season of prescribed burning can affect the success of shortleaf pine germination. Late spring burning resulted in high mortality of young germinants. Burning in early spring likely resulted in direct damage to some seeds due to heating but may have also had indirect benefit by exposing mineral soil. Fall burning, before the dispersal of shortleaf pine seed, yielded the highest germinant count and is recommended if improving natural regeneration from seed is the primary objective.

Invasive plants can significantly impact the diversity of understory ground flora and forest regeneration in eastern North America. However, managing invasive plants has resulted in positive, negative, or neutral effects on key ecosystem components depending on treatment type, duration, and intensity. Management may also result in short-term control, but legacy effects from prior land use or secondary invasions may hamper desired long-term outcomes. We conducted a systematic review of the invasive plant management literature for eastern North American forests to examine treatment outcomes for invasive and native plants, tree regeneration, and secondary invasions. Our review included 165 articles with few papers published in the 1980s but the number of papers increasing through time thereafter. A variety of control methods were used, including herbicide applications, prescribed burning, torching, girdling, clipping, mastication, soil amendments, flooding, enrichment plantings, and biocontrol, as well as combinations of these treatments. Species included some of the most common forest invaders, such as the privets (Ligustrum spp.), honeysuckles (Lonicera spp.), autumn olive (Elaeagnus umbellata), buckthorns (Rhamnus cathartica and Frangula alnus), garlic mustard (Alliaria petiolata), Japanese stiltgrass (Microstegium vimineum), cogongrass (Imperata cylindrica), tree-of-heaven (Ailanthus altissima), and Chinese tallow (Triadica sebifera). The literature also included recent invaders in eastern North America, such as Callery pear (Pyrus calleryana) and fig buttercup (Ficaria verna). Findings suggest that invasive plant control efficacy is highly variable and context dependent. Information on long-term effects is limited because most studies reported on findings occurring within a few years of treatment. However, long-term success may be limited without additional management (e.g., enrichment plantings, artificial tree regeneration, re-establishing historic fire regimes, reducing herbivore densities) that ameliorates impacts from past land-use, disturbance history, or other factors. We suggest that future studies and the development of control tactics consider comprehensive approaches to building resilience in forest communities where invasive plants are only one aspect of the forest management continuum.

Developing competitive oak advance reproduction prior to canopy disturbance is understood to be important for oak regeneration success. In the early 2000s, a study was installed in southeastern Missouri to examine the effects of midstory and understory release on natural and artificial sources of pin oak (Quercus palustris Muenchh.) advance reproduction. The findings obtained three years after midstory and understory release indicated photosynthetically active radiation increased from 3 to 15 % and a corresponding increase in density of pin oak reproduction as well as the survival and growth of both natural and artificial pin oak reproduction compared to control. In 2010, eight years after the midstory and understory was removed, three different overstory harvests were applied to release the established pin oak advance reproduction. Here, we investigated the effects of the midstory and understory removal and the subsequent overstory harvests on underplanted and naturally regenerated oak advance reproduction. We also tested effects of a later midstory release on the density of natural pin oak advance reproduction. Results indicate that the survival of bareroot pin oak seedlings increased with increasing initial basal diameter. The survival of Root Production Method (RPM (R)) container pin oak seedlings, however, was not dependent on the size at the time of planting. The early understory removal with triclopyr herbicide was ineffective in ensuring survival of planted pin oak seedlings. Shelterwood increased the growth of oak advance reproduction but did not eliminate competition from other species. A late release also failed to increase the growth of oak advance reproduction. Given shelterwood also favored oak competitors in our study, multiple applications of midstory and understory competition control treatments following the shelterwood treatment will be imperative for successful oak regeneration.