Forest In Ohio Research Articles

Available Organic Soil Phosphorus Has an Important Influence on Microbial Community Composition

Soil acidity can have a potent influence on soil microbial composition and function, but it remains unclear if this influence is a direct response to the concentration of H+or an indirect response caused by the influence of pH on other soil chemical properties. We hypothesized that the composition and function of soil microorganisms would shift in response to decreases in the availability of inorganic P caused by mobilized Al. We tested this hypothesis at Dysart Woods, a mosaic of old growth and second growth mixed, mesophytic forest in eastern Ohio. We evaluated microbial community composition (phospholipid fatty acid [PLFA] analysis) and function (extracellular enzyme activity) in the context of P availability and common metrics of soil fertility. We observed a threshold response where available organic P (Po, i.e., bicarbonate‐extracted, molybdate‐unreactive P) dominated (∼80%) the availability of total available P when mobilized Al was present (>0.1 cmolckg−1), but when Al was immobilized, available inorganic P (Pi, i.e., bicarbonate‐extracted, molybdate‐reactive P) content was significantly greater (∼50%). Available Posignificantly correlated (r= 0.54) with acid phosphatase activity. Using nonmetric multidimensional scaling, we observed that PLFA composition ordination was significant along a gradient of soil pH and available PoBecause the composition and function of the microbial community changes due to available Po, results suggest that microbial communities in acidic forest soils are functionally P limited. The availability of Podid not influence the microbial biomass, however, indicating that the microbial community compensates for the apparent P limitation by altering its composition.

Characteristics of downed wood across headwater riparian ecotones: integrating the stream with the riparian area

Although downed wood is a significant structural component of riparian ecotones, most studies of downed wood dynamics are conducted only within the stream bankfull channel or on the riparian forest floor. We examined downed wood structural characteristics (e.g., length, volume, and decay class) across the entire riparian ecotone of seven headwater streams in mature deciduous forests of northeastern Ohio to understand the structural relationships between downed wood and riparian ecotones. Sampling was stratified by hydrogeomorphic zones that were defined by lateral position within the riparian ecotone and correspond to differing fluvial geomorphology. Most downed wood pieces sampled were small (<1 m) and with a high decay class. Downed wood pieces within the baseflow zone (within the wetted channel) were smaller and more abundant than those within the transitional zone (within the bankfull channel excluding the wetted channel). Surface contact was inversely related to aquatic influence across the riparian ecotone, with downed wood in Zone 3 (riparian area beyond the bankfull channel) having significantly higher contact than wood within the other zones. The ecotonal approach and the incorporation of hydrogeomorphic influences is an alternative approach that moves beyond traditional approaches to more holistic management of riparian forests.

Association of Phytophthora cinnamomi with White Oak Decline in Southern Ohio.

A decline syndrome and widespread mortality of mature white oak tree (Quercus alba) associated with wet and low-lying areas has been recently observed in southern Ohio forests. Previous studies have isolated Phytophthora cinnamomi from white oak rhizospheres. In 2008 and 2009, P. cinnamomi population densities in two healthy and two declining white oak stands at Scioto Trail State Forest were quantified and potential roles of three environmental drivers of Phytophthora spp.-induced decline were assessed: soil texture, soil moisture, and topography. Significantly higher P. cinnamomi propagule densities were found in declining stands in both years but propagule densities were not associated with soil moisture content. Trends in population densities were not correlated with soil moisture or topographic position within field sites. There was a positive, exponential relationship between overall P. cinnamomi population levels and soil moisture on a seasonal scale in 2008 but not 2009. Sites with greater soil clay content were associated with greater decline. Effects of P. cinnamomi inoculum and periodic flooding on root health of 1-year-old potted white oak trees grown in native soil mixes in the greenhouse were examined. Root systems of potted oak were significantly damaged by soil inoculation with P. cinnamomi, especially under flooding conditions. Results of these studies support the hypothesis that P. cinnamomi is a contributing agent to white oak decline in southern Ohio.

The effects of thinning and burning treatments on within-canopy variation of leaf traits in hardwood forests of southern Ohio

Leaf nitrogen content (N mass, %) and leaf mass per area (LMA, g m −2) are two important features that are closely linked to the photosynthetic performance of plants and, thus, the NPP of forest ecosystems. Forest management practices, such as burning and thinning, change stand structure and soil dynamics, which may result in changes in N mass and LMA. The objective of this study was to understand how N mass and LMA of seven canopy tree species/genus ( Quercus alba, Q. coccinea, Q. prinus, Q. velutina, Carya spp., Acer rubrum, and Liriodendron tulipifera) responded to (i) thinning and/or burning treatments and to (ii) different landscape and soil properties in southern Ohio. We collected leaves from the top, and bottom, of five individuals of each taxa in each treatment unit. Leave traits (N mass and LMA) were compared using analysis of variance followed by orthogonal contrasts. To further understand the factors that influence the canopy leaf traits, we used regression tree analysis (RTA) to examine how variations of LMA and N mass were linked to thinning and/or burning treatments, soil, and landscape variables. Finally, we assessed the potential ramifications of changes in these traits on canopy carbon budgets using a PnET-Day model, which is a daily time-step canopy carbon exchange model. We found significant effects of thinning, burning, and their interactions on LMA at the bottom of the crown while none of the treatments showed significant effects on LMA at the top of the crown. N mass responded significantly to only burning treatment . RTA results exhibited minor effects of landscape features and soil properties on N mass and LMA. Interspecific differences accounted for most variations of both leaf traits. Sensitivity analysis of PnET-Day model suggested these subcanopy changes in LMA increased the annual net primary production (NPP) by 8%. In summary, our results suggest that forest management can substantially influence canopy leaf traits such as N mass and LMA and that alteration of these traits can influence forest NPP. Given the role of forests as global carbon sinks, the potential influence of thinning and burning on canopy traits, and thus NPP, is an important consideration for forest management.

Effect of Bot Fly Parasitism on Vertical Habitat use byPeromyscus leucopus

Peromyscus leucopus (White-footed Mouse) use the 3-dimensional space of their habitat. We studied whether Cuterebra fontinella (Bot Fly) larvae affected rate of capture in traps set above ground compared to traps set on the ground in deciduous forests in Ohio and Georgia. Rates of infestation were nearly three-fold greater in Ohio than in Georgia. Infested animals were captured equally in traps on the ground and in traps 1.5 m above ground in Ohio, but were captured less frequently in traps on the ground than in traps 1.5 m above ground in Georgia. Sex of animals did not affect these results. Infested animals were not captured in traps 4.5 m above the ground in Georgia, suggesting a possible limit to use of vertical habitat space by infested mice.

Carbon and nitrogen pools in reclaimed land under forest and pasture ecosystems in Ohio, USA

The long-term changes of ecosystem carbon (C) and nitrogen (N) pools in reclaimed mine soils remains poorly understood. Thus, age chronosequence sites, ranging from < 1 to 25 years of reclamation, under forest and pasture land use, were identified to determine ecosystem C and N pools. Ecosystem C and N pools and selected soil properties were measured for 42 reclaimed sites across northeast Ohio. Soil organic C (SOC) was estimated by determining coal C and inorganic C, and subtracting these from the total soil C. Of the total soil C in reclaimed soil, coal C ranged from 0.2 to 15%, and inorganic C from < 1 to 42%, depending on soil depth and land use. The C sequestered in the minesoil ecosystem followed a polynomial function, with the highest rate of sequestration of 6.59 Mg ha − 1 after 14 years of reclamation in the forest and 1.61 Mg ha − 1 after 6 years under pasture. After 25-year of reclamation, C sequestration was 107 Mg ha − 1 under forest ecosystem and 21 Mg ha − 1 under pasture. In the forest ecosystem, a major portion of ecosystem C consisted of soil C (94%) during the initial period (< 1 year) and biomass C (66%) during the later period (> 14 year). In the pasture ecosystem, soil C contributed a major portion of ecosystem C throughout the reclamation period: 95% for < 1 year and 89% for > 25 years of reclamation. However, soil N contributed a significant portion of ecosystem N in both the forest and pasture ecosystems. Ecosystem C and N pools and bulk densities were strongly related with reclamation age for both forest and pasture. The rates of ecosystem C and N sequestration peaked at about 10 to 15 years of reclamation. After 10 to 15 years of reclamation, the rate of sequestration decreased as reclamation age increased.

Tree Basal Growth Response to Flooding in a Bottomland Hardwood Forest in Central Ohio1

Abstract: Tree basal growth in response to flooding regime was evaluated at a 5.2‐ha bottomland forest along the Olentangy River in central Ohio. Tree‐ring analysis was used to develop a 14‐year basal area increment (BAI) (cm2/year) series for 42 canopy trees (representing 10 species) throughout the bottomland. Mean annual BAI was evaluated relative to the frequency and duration of bankfull (&gt;70 m3/s) and high‐flood (&gt;154 m3/s) river discharge for a given water year (October 1‐September 30) and growing season (April 1‐September 30). A significant polynomial relationship was detected between the number of days of high‐flood river discharge over a combined two‐year period (Year i + Year i − 1) and mean annual BAI. No significant relationships were detected when only the concurrent‐year or previous‐year flood regimes were considered or when growing season was considered. A similar relationship was detected when duration of high‐flood discharge days and BAI were both evaluated in two‐year increments (Year i + Year i − 1). Mean annual BAI was most influenced by boxelder (Acer negundo) which was the dominant species and exhibited strong agreement with the overall BAI series. In each case, the resulting parabolic curve of tree basal growth in response to flooding suggests an optimal number of flooding days, a response to perturbation consistent with the subsidy‐stress model. Dendrochronology may be a useful tool for managers looking to restore environmental flows to regulated rivers.

Forest Management and Curculionid Weevil Diversity in Mixed Oak Forests of Southeastern Ohio

Abstract Weevils (Coleoptera: Curculionidae) may play a role in the reduced regenerative ability of oak (Quercus L.) species in the hardwood forests of eastern North America. Presently, because of biome-wide regeneration failure, silvicultural treatments of prescribed fire and mechanical thinning are being implemented as a means to enhance natural oak regeneration. The effect that these treatments may have on the diversity and population structure of non-target organisms like weevils (oak seed predators) remains unclear. This study provides an evaluation of the weevil populations of two experimentally managed, mixed-oak forests in southeastern Ohio. Each of the two sites used in this study was divided into four 20 ha treatment plots consisting of: (1) untreated control, (2) thin only, (3) thinning followed by prescribed burning, and (4) prescribed burning only plots. Pyramid style traps (N = 48) were placed in each treatment unit to sample weevils. Overall, we identified 26 species of Curculionid weevils ...

Effect of Hydrologic Restoration and Lonicera maackii Removal on Herbaceous Understory Vegetation in a Bottomland Hardwood Forest

Abstract Amur honeysuckle (Lonicera maackii (Rupr.) Herder), a large deciduous shrub from China, has invaded many forests in eastern/central United States. The species was removed by cutting and herbicide application from a recently hydrologically restored section of a bottomland hardwood forest in central Ohio, and the response of understory plants, especially herbaceous species, was measured. Plots were established in uncleared and cleared sections, and percent cover of each herbaceous understory species was estimated monthly. One season after several years of Lonicera removal efforts, no significant association was discovered between percentage of Lonicera cover and total understory species abundance. There was, however, a direct correlation between elevation and honeysuckle abundance; L. maackii abundance was negatively associated with low elevations, likely due to hydrologic factors. Plant species diversity (H) and richness (s) increased with elevation but were not significantly different on plots with honeysuckle removal (H = 0.86 ± 0.08 vs. 0.78 ± 0.09 and s = 4.4 ± 0.19 vs. 4.2 ± 0.2 species/m2, respectively) despite the fact that understory light levels measured by densiometer were significantly higher (α= 0.003) in cleared versus uncleared sections. Native and invasive species were found in similar proportions in the two sections, and significant sprouting and regrowth of L. maackii were observed throughout the cleared section. Although the removal of L. maackii altered the characteristics of the plant species assemblage, the value of this management remains questionable in the years immediately following treatment.

Oil Pipeline Corridor Through an Intact Forest Alters Ground Beetle (Coleoptera: Carabidae) Assemblages in Southeastern Ohio

Litter-dwelling ground beetle (Coleoptera: Carabidae) assemblages were monitored 1 yr after the construction of a corridor for installation of an oil pipeline along a xeric ridge-top forest in southeastern Ohio. After the creation of the corridor, three distinct habitats were evident in these sites: open corridor, ecotone areas around the corridor, and undisturbed forest interior. Carabidae were collected using directional pitfall traps that were placed parallel and perpendicular to the corridor in each of the three habitats. Results indicate that more carabids were present in the ecotone than in the other two habitats. Carabid diversity as estimated by rarefaction was highest in the corridor followed by ecotone and forest interior. Generalist and forest specialists such as Synuchus impunctatus (Say), Carabus goryi Dejean, and Pterostichus trinarius (Casey) were present in greater numbers in the forest interior and ecotone assemblages. In contrast, open-habitat specialists such as Harpalus pensylvanicus (DeGeer) and Selenophorus opalinus (LeConte) were present in greater numbers in the corridor assemblages. Carabid assemblages of the corridor were distinct from those of the ecotone and forest interior, whereas the latter two habitats had very similar assemblages. The successional pathway of the corridor carabid assemblage will therefore be likely different from that of the forest interior and ecotone. Overall, results indicate that construction of the oil pipeline corridor had significant short-term effects on the carabid numbers, diversity, and species composition because of ensuing habitat changes and fragmentation of the forest.

Shifts in morphological traits, seed production, and early establishment ofDesmodium nudiflorumfollowing prescribed fire, alone or in combination with forest canopy thinning

Reintroduction of periodic dormant-season fire and overstory thinning are currently being employed for forest ecosystem management in deciduous forests of eastern North America. These manipulations usually alter the flux of light and the availability of soil nutrients to the perennial herbaceous plants that dominate the understory. We utilized Bayesian statistical methods to examine the effects of prescribed burning (B) and the combination of burning and overstory thinning (T+B) on the morphology, seed production, and early establishment of Desmodium nudiflorum (L.) DC. (Fabaceae) in mixed-oak ( Quercus spp.) forests in southern Ohio. During the fourth growing season after the first fire, plants from thinned and burned (T+B) plots were 62% larger than plants from control plots (C). Both burning alone (B) and T+B treatments decreased specific leaf area (SLA). T+B also resulted in significantly decreased root mass ratio (RMR), and increased leaf mass ratio (LMR), and specific root length (SRL). During the first growing season after a second fire, both B and T+B resulted in significantly increased plant biomass, LMR, individual seed mass, and total seed production, as well as decreased SLA and plant height; in contrast, neither B nor T+B had significant impacts on leaf area ratio or seedling establishment. Prescribed fire, especially when combined with thinning, can result in increases in total biomass, seed size, and seed production, and hence enhance the fitness of this perennial herb in these mixed-oak forests.

Silvicultural treatment effects on oak seed production and predation by acorn weevils in southeastern Ohio

Oak regeneration failure in the hardwood forests of eastern North America has been well documented. Silvicultural treatments of prescribed burning and canopy thinning (fire surrogate) are being studied as possible management tools to promote oak regeneration in oak dominated forests. We examined oak seed production and predation by acorn weevils (Coleoptera: Curculionidae) from two experimental forests in southeastern Ohio, under four different silvicultural treatments. Treatments consisted of replicate stands that received a prescribed burning, thinning, and thinning followed by a prescribed burn, in addition to an untreated control. Initial thinning and prescribed burning treatments were conducted in winter/spring of 2000–2001, with a second prescribed burn in spring 2005. Within each treatment unit, nine black oak and nine chestnut oak trees were selected for study and two 0.25 m 2 seed fall traps were placed beneath each tree. Seed collections were completed for five seasons from 2001 to 2005. Data were analyzed using a randomized complete block design, utilizing a mixed-model repeated measures analysis. Overall, stand level treatments resulted in only a slight increase in acorn production (in the burn and thin + burn stands) relative to the control; however, this response was species specific. Masting, the intermittent production of large seed crops, was evident in our study though occurrence of a mast event was not influenced by the treatments. Chestnut oak displayed greater yearly, as well as individual variation in seed production than did black oak. Treatments had no effect on predation by acorn weevils. Predation percentages were lowest during mast years for chestnut oak; however, percentages were mostly stable for black oak across all 5 years. Our data suggest that variation due to climate and genotype are more influential in affecting seed production and masting cycles than are stand level disturbances. Thus, stand level management activities are not likely to have a large influence on oak seed production and oak regeneration must be more strongly influenced at other stages of its life history.

Invasive species, management for conservation and remote sensing

The paper chosen for the award by the Chief Editors of Applied Vegetation Science, from among those published in 2007 is that by Hartman & McCarthy (2007). Exotic (alien, non-indigenous) species are a concern for their impact on native communities, as well as fascinating probes into community structure: natural experiments. Recent research has tried to measure their impact by examining invaded and non-invaded sites. This approach has the flaw that the non-invaded sites may not have been invaded because they were different in the first place. Examining sites before and after an invasion is difficult because invasions are not normally noticed until after they have happened, and anyway there might have been an allogenic environmental change, or one caused by the reaction of the other species. The ideal would be to go backwards in time in both invaded and non-invaded sites. Impossible? But Hartman & McCarthy (2007) did this by dendrochronology. Working in deciduous hardwood forest in Ohio, USA, they shewed that the exotic understorey shrub Lonicera maackii (Rupr.) Herder reduced the growth of native trees in the overstorey.

The effects of prescribed fire and silvicultural thinning on the aboveground carbon stocks and net primary production of overstory trees in an oak-hickory ecosystem in southern Ohio

More than 70 years of fire suppression has influenced forest dynamics and led to the accumulation of fuels in many forests of the United States. To address these changes, forest managers increasingly seek to restore historical ecosystem structure and function through the reintroduction of fire and disturbance processes that mimic fire such as silvicultural thinning. In oak forests of eastern North America, prescribed fire and thinning are important tools used to facilitate oak ( Quercus spp.) regeneration and recruitment. The global scientific community is increasingly raising concerns about the accumulation of atmospheric CO 2, and its potential to impact global climate; therefore, activities such as prescribed fire and thinning that can influence the carbon balance of terrestrial ecosystems should be evaluated. We used field measurements and modeling with the PnET-II carbon balance model in oak forests of southern Ohio, USA, to (1) assess the efficacy of prescribed fire and silvicultural thinning in facilitating oak recruitment and regeneration, and (2) quantify the impacts of these treatments on aboveground carbon stocks and net primary production. Silvicultural thinning increased recruitment of maples, but oak recruitment was minimal. Prescribed burning caused an increase in the mortality rate of oaks’ major competitor ( Acer rubrum L.) in the overstory (stems ≥10 cm DBH), but oak mortality also increased following the burn treatments. Our measurements of stem growth suggest that the timing of the prescribed fires coincided with the initiation of growth in oaks, which may have created vulnerability in these species that are generally considered fire-resistant. The pre-treatment aboveground biomass of overstory trees was approximately 233 Mg/ha (Mg = 1 × 10 6 g). Prescribed burning had significant impacts on the mortality of stems; however, it had no significant effects on the aboveground net primary production (ANPP). Thinning removed approximately 30% of the aboveground biomass and resulted in significant but transient (1 year) reduction of ANPP (386 and 560 g C m −2 year −1 for thinned and non-thinned stands, respectively). In sum, thinning created recruitment opportunities in our study area, but these opportunities were captured by maples, and oak recruitment was minimal. Prescribed fire caused mortality in oaks and maples, and the oak mortality may have been related to the coincidence of the burn treatment and the initiation of oak stem growth. Finally, our data suggest that there is a transient impact of thinning on ANPP, but that there is no long-term effect of thinning and/or burning treatments on the aboveground carbon uptake in oak forests.

Fuel reduction treatments affect stand structure of hardwood forests in Western North Carolina and Southern Ohio, USA

Prescribed fire and mechanical treatments were tested at the two hardwood sites of the National Fire and Fire Surrogate Study (southern and central Appalachian regions) for impacts to stand structure. After two fires and one mechanical treatment, no treatment or treatment combination restored stand structure to historical levels. Burning alone had little impact on overstory vegetation the first year after treatment but mortality continued for 4–5 years thus opening canopies. Thinning at the Ohio Hills site reduced stand basal area, but not to levels desired for restoration objectives. Chainsaw removal of the shrub layer at the southern Appalachian site reduced the midstory temporarily but promoted abundant regeneration. The combination of mechanical and burning treatments opened these dense forests the most, especially at the southern Appalachian site where hot fires killed overstory trees and promoted oak regeneration. Results from both study sites emphasize the rapid sprouting and growth of undesirable eastern species and the need for frequently-repeated treatments during the restoration phase.

Effects of fragmentation on juvenile morphology of Acer saccharum Marsh. (sugar maple) in temperate forests of northeastern Ohio, USA

The influence of forest fragmentation on population and community dynamics of woody plants has been well established worldwide, but rarely at the level of an individual plant. We evaluated the influence of fragmentation on juvenile stem morphology of Acer saccharum Marsh. (sugar maple), while also examining light levels and considering possible confounding effects attributed to elevation gradients in temperate forests of northeastern Ohio, USA. At two sites, plant stem dimensions, canopy openness, and relative ground level elevation were measured using randomly positioned plots in forest edge and interior habitats that were within 25 and 60–100 m from a forest edge, respectively. Ratios of stem length to stem basal diameter were greater in forest interiors than near forest edges. These differences in stem morphology between habitats were likely a result of stem elongation in relation to a shade avoidance response in forest interiors that were consistently darker than forest edge areas across study sites. By contrast, such morphological differences were likely not related to variation in relative ground level elevation since a subtle elevation gradient was detected at only one site. We encourage experimentation to identify mechanisms that affect plant stem morphology of young individuals and its influence, in turn, on plant population dynamics in fragmented forests.

Improving the budburst phenology subroutine in the forest carbon model PnET

The timing of leaf expansion in spring and leaf senescence in fall determines growing season length; hence leaf phenology is important in modelling carbon production. Previous work monitoring net ecosystem exchange using eddy flux technology found phenological timing to be a key factor determining ecosystem carbon balance. Growing degree days (GDD; the sum of daily mean temperature above 0 °C) have long been used to track tree phenological behavior. Ecosystem carbon balance simulations should employ models that reliably track leaf phenological activities. Our goals for this study were to evaluate the GDD-based phenological algorithm for the forest carbon simulation model PnET and to develop a robust budburst model for the implementation of PnET in the forests of Ohio. We obtained 11 years (1990–2000) of leaf budburst phenology data from Harvard Forest, MA and found large inter-annual variations on the date of budburst. Contrary to the previous sensitivity analysis on GDD, we used the observed range in the data to inform our new GDD sensitivity analyses. In fact the broad inter-annual variation of the budburst phenology had substantial impacts on the annual net primary production. Moreover, GDD did not provide reliable prediction on the date of budburst although it was employed by the PnET family of models. The predictions of budburst dates were largely improved by incorporating a chilling factor, with 16 of 17 deciduous tree species showing significant linear relationships between predicted and observed dates of budburst. However, this updated phenology model showed geographic specificity that is not suitable for our simulations in southern Ohio. For successful development of a more comprehensive phenological model, locally developed and long-term leaf phenology records are required.

Ecophysiological responses of two herbaceous species to prescribed burning, alone or in combination with overstory thinning

The oak-rich deciduous forests of the central Appalachian Mountains of eastern North America have changed significantly since the onset of effective fire suppression early in the 20th century. Those changes have resulted in progressively decreasing light and nutrient supplies to herbaceous perennial understory species. Application of ecological restoration treatments such as reintroduction of frequent dormant-season fire and overstory thinning to pre-suppression density often increase light, soil temperature and moisture, and short-term nutrient availability to pre-suppression levels. To persist in this environment, perennial understory herbs must be able to acclimate phenotypically to the very different resource supply combinations present with and without fire suppression. As part of a larger study of the response of the long-lived herbaceous perennials Desmodium nudiflorum and Panicum boscii to ecosystem restoration treatments in Ohio mixed-oak forests, this study examined the ecophysiological effects of prescribed burning (B) and the combination of burning and thinning (T + B) in mixed-oak forests in southern Ohio. Control (C) plants had significantly lower maximum photosynthetic rate (A(max)) than those in the treated plots. The enhancement of A(max) averaged 26.7% and 52.7% in the B and T + B treatments, respectively. Plants from the T + B plots had higher quantum yield, stomatal conductance, and photosynthetic nutrient use efficiency than B and C plants. B plants had greater intrinsic water use efficiency (WUE) than plants in the C or T + B treatments. Light saturation point (LSP), light compensation point (LCP), and "dark" respiration (DR) did not differ among treatments. Photosynthetic parameters did vary significantly between the species, but no significant treatment × species interactions were detected. Our results support the hypothesis that prescribed burning, especially when combined with overstory thinning, in these perennial herbs can result in phenotypic acclimation characterized by enhanced photosynthetic performance.

A dendro‐ecological study of forest overstorey productivity following the invasion of the non‐indigenous shrub Lonicera maackii

AbstractQuestion: Will a non‐indigenous, invasive, understorey shrub, such as Lonicera maackii (Amur honeysuckle) have an impact on the productivity of overstorey trees in hardwood forests?Location: Trees from 12 invaded and four non‐invaded sites were sampled in hardwood forests of southwestern Ohio, US.Methods: Changes in radial and basal area tree growth in the ten years prior to L. maackii invasion vs. ten years after invasion were examined using dendrochronological techniques. Intervention analysis was used to detect growth changes 25 years prior to and 25 years following invasion, and estimates of load impacts for L. maackii population and biomass were also calculated.Results: We found that the rate of radial and basal area growth of overstorey trees was reduced significantly in eleven out of twelve invaded sites. Non‐invaded sites did not exhibit this consistent pattern of reduced growth. For invaded vs. non‐invaded sites, the mean basal area growth was reduced by 15.8%, and the overall rate of basal area growth was reduced by 53.1%. Intervention analysis revealed that the first significant growth reductions were 6.25 ± 1.24 (mean ± SE) years after invasion with the greatest frequency of negative growth changes occurring 20 years after invasion. In invaded stands, 41% of trees experienced negative growth changes. In terms of invasive load estimates per 1000 L. maackii individuals, radial tree growth was reduced by 0.56 mm.a−1, and basal area growth was reduced by 0.74 cm2.a−1, Given these findings, significant economic losses could occur in hardwood forests of Ohio.Conclusions: To our knowledge, this is the first study using dendrochronological techniques to investigate the impact of a non‐indigenous, understorey plant on overstorey tree growth. Active management will likely be needed to maintain forest productivity in L. maackii impacted landscapes.

A dendro-ecological study of forest overstorey productivity following the invasion of the non-indigenous shrub Lonicera maackii

Question: Will a non-indigenous, invasive, understorey shrub, such as Lonicera maackii (Amur honeysuckle) have an impact on the productivity of overstorey trees in hardwood forests? Location: Trees from 12 invaded and four non-invaded sites were sampled in hardwood forests of southwestern Ohio, US. Methods: Changes in radial and basal area tree growth in the ten years prior to L. maackii invasion vs. ten years after invasion were examined using dendrochronological techniques. Intervention analysis was used to detect growth changes 25 years prior to and 25 years following invasion, and estimates of load impacts for L. maackii population and biomass were also calculated. Results: We found that the rate of radial and basal area growth of overstorey trees was reduced significantly in eleven out of twelve invaded sites. Non-invaded sites did not exhibit this consistent pattern of reduced growth. For invaded vs. non-invaded sites, the mean basal area growth was reduced by 15.8%, and the overall rate of basal area growth was reduced by 53.1%. Intervention analysis revealed that the first significant growth reductions were 6.25 ± 1.24 (mean ± SE) years after invasion with the greatest frequency of negative growth changes occurring 20 years after invasion. In invaded stands, 41% of trees experienced negative growth changes. In terms of invasive load estimates per 1000 L. maackii individuals, radial tree growth was reduced by 0.56 mm.a−1, and basal area growth was reduced by 0.74 cm2.a−1, Given these findings, significant economic losses could occur in hardwood forests of Ohio. Conclusions: To our knowledge, this is the first study using dendrochronological techniques to investigate the impact of a non-indigenous, understorey plant on overstorey tree growth. Active management will likely be needed to maintain forest productivity in L. maackii impacted landscapes.