Mixed Pine-hardwood Forests Research Articles

Prospecting during egg laying informs incubation recess movements of eastern wild turkeys

BackgroundCentral place foragers must acquire resources and return to a central location after foraging bouts. During the egg laying (hereafter laying) period, females are constrained to a nest location, thus they must familiarize themselves with resources available within their incubation ranges after nest site selection. Use of prospecting behaviors by individuals to obtain knowledge and identify profitable (e.g., resource rich) locations on the landscape can impact demographic outcomes. As such, prospecting has been used to evaluate nest site quality both before and during the reproductive period for a variety of species.MethodsUsing GPS data collected from female eastern wild turkeys (Meleagris gallopavo silvestris) across the southeastern United States, we evaluated if prospecting behaviors were occurring during laying and what landcover factors influenced prospecting. Specifically, we quantified areas prospected during the laying period using a cluster analysis and the return frequency (e.g., recess movements) to clustered laying patches (150-m diameter buffer around a clustered laying period location) during the incubation period.ResultsThe average proportion of recess movements to prospected locations was 56.9%. Nest fate was positively influenced (μ of posterior distribution with 95% credible 0.19, 0.06–0.37, probability of direction = 99.8%) by the number of patches (90-m diameter buffer around a clustered laying period location) a female visited during incubation recesses. Females selected for areas closer to the nest site, secondary roads, hardwood forest, mixed pine-hardwood forest, water, and shrub/scrub, whereas they avoided pine forest and open-treeless areas.ConclusionsOur findings suggest that having a diverse suite of clustered laying patches to support incubation recesses is impactful to nest fate. As such, local conditions within prospected locations during incubation may be key to successful reproductive output by wild turkeys. We suggest that prospecting could be important to other phenological periods. Furthermore, future research should evaluate how prospecting for brood-rearing locations may occur before or during the incubation period.

Profiling overstory survival trends following varying thinning and burning disturbance regimes in a mixed pine-hardwood forest in the US South

Prescribed burning as a silvicultural tool may be effective for achieving various management objectives, yet some practitioners have concerns about inadvertently increasing overstory tree mortality. Using extensive data from a long-term, ongoing study in northcentral Alabama, USA, that systematically applies a variety of thinning and prescribed burning disturbances on mixed pine-hardwood stands, we assess survival trends for different groups of trees. The primary research question is whether more frequent prescribed burns adversely affects overstory survival versus infrequent or no burns; secondary questions explore whether overstory survival trends differ based on thinning level, species group, or size class. Interest is in broad groups of trees, not individual tree survival or mortality; consequently, survival analysis methods are used, including nonparametric Kaplan-Meier (KM) techniques for examining single grouping factors, and parametric accelerated failure time models for analyzing simultaneous effects of multiple covariates. Leveraging relatively recent methodological advances, the statistical techniques are adjusted for interval censored data. KM survival curves showed that more frequent prescribed fires did not result in differing survival trends. Also, trees in unthinned stands had the lowest 14-year survival compared to thinned stands, oaks had the highest survival compared to pines and the others species group, and the smallest size class of overstory trees had the lowest survival. These results support managing transitional mixed pine-hardwoods using thinning and multiple prescribed fires to restore specific species composition and structure.

Profiling Overstory Survival Trends Following Varying Thinning and Burning Disturbance Regimes in a Mixed Pine-Hardwood Forest in the Us South

Profiling Overstory Survival Trends Following Varying Thinning and Burning Disturbance Regimes in a Mixed Pine-Hardwood Forest in the Us South

Post-fire recovery of ecosystem carbon pools in a tropical mixed pine-hardwood forest

Aim of the study: To analyze the recovery pattern of carbon pools in terms of size and the relative contribution of each pool to total ecosystem C along a fire chronosequence of tropical mixed pine-hardwood forest.Area of the study: Las Joyas Research Station (LJRS), core zone of Sierra de Manantlán Biosphere Reserve (SMBR) in the state of Jalisco, central western Mexico.Materials and methods: Carbon stored in aboveground plant biomass, standing dead trees, downed woody debris, forest floor, fine roots and mineral soil, was compared with a nested analysis of variance (ANOVA) in post-fire stands of eight-year-old, 28- and 60-year-old stands of mixed Pinus douglasiana-hardwood forest.Main results: The total ecosystem carbon in eight-year-old stands was 50% lower than that of 60-year-old stands. Carbon content in the biomass and mineral soil increased with stand age. The carbon in the biomass recovered to the undisturbed forest in the 28 years of succession. The main C storage in the eight-year-old stands were the mineral soil (64%) and downed woody debris (18%), while in the 28- and 60-year-old stands, live tree biomass and mineral soil were the two largest components of the total C pool (43% and 46%, respectively).Research highlights: We found a significant effect of high-severity fire events on ecosystem C storage and a shift in carbon distribution. The relatively fast recovery of C in ecosystem biomass suggests that mixed Pinus douglasiana hardwood forest possess functional traits that confer resilience to severe fire events.Key words: chronosequence; carbon dynamics; mineral soil; Pinus douglasiana; fire effects.Abbreviations used: LJRS, Las Joyas Research Station; DBH, diameter at breast height; DL, duff layer; LL, litter layer; DWD, downed woody debris; ANOVA, analysis of variance; CO2, carbon dioxide; SMBR, Sierra de Manantlán Biosphere Reserve; C, carbon. AGV, above ground vegetation.

Limited carbon contents of centuries old soils forming in legacy sediment

Accelerated erosion from European agriculture overwhelmed transport capacities of relatively low-gradient Piedmont watersheds and triggered widespread and massive sediment deposition on floodplains, referred to as legacy sediments. While erosion-driven soil loss on the Southern Piedmont landscape has been widely studied, the resultant legacy sediments deposited on hillslopes, floodplains, and in channels appear remarkably understudied. In the interim between deposition and future remobilization, legacy sediments are undergoing soil formation in ways that impact carbon stocks, nutrient retention, and a number of other soil-sediment functions. Here, we use a pedological framework to understand the dynamics of these legacy sediments by constraining the time since deposition and redevelopment of vegetation and the soil profile. In this study, we characterized the properties of legacy sediment and buried, pre-legacy sediment alluvium, established the timing of legacy sediment deposition and its volume in a 600-ha watershed, and analyzed the impact of accelerated sedimentation on floodplain soil carbon (SOC) storage.We found alluvial legacy sediment in the 6 km2 Holcombe's Branch watershed to range in thickness from 0.35 to 1.25 m, averaging 1.01 m in depth (n = 20, CV = 19%). Radiocarbon (14C) dates from buried wood indicate that accelerated deposition began by the mid-1800s. During the next century, deposition rates increased and peaked at levels up to 40× higher than contemporary sedimentation rates. By the mid-1900s, accelerated deposition rates had slowed significantly, as indicated by surficial distributions of 1960s fall-out 137Cs in sediments. Upstream floodplains are today less frequently flooded and function as abandoned floodplains, or terraces. In contrast, downstream sites remain active floodplains and zones of deposition. A century of pedogenesis has formed acidic, well-drained Entisols, characterized by incipient, redeveloping A horizons over coarse-textured C horizons. Buried, pre-legacy sediment alluvium have well-developed redox features, are lower in hue and chroma than legacy sediments, and occasionally have moderate to strong aggregate structure. A century-old mixed pine-hardwood forest has diminished subsoil carbon stocks and created a shallow vertical distribution of SOC stocks, that total 95 Mg C ha−1 (CV = 25%) in the upper 2 m. Legacy sediments have nearly doubled alluvial sediment in the catchment and account for 55% of soil carbon stock. Coarse texture and porous legacy sediment-soils limit accumulation of mineral-associated soil carbon. A-horizon morphology was preserved in buried A horizons underlying legacy sediment, yet these horizons did not account for significant SOC stocks at depth. Depth profiles of active, light-fraction organic carbon revealed differences in SOC preservation between upstream and downstream sites. The hydrogeomorphic change responsible for this difference - from abandoned legacy sediment terraces upstream to active sedimentation on floodplains downstream – will continue to impact soil-sediment dynamics and functioning. Time since last deposition and revegetation are dominant forces in SOC dynamics, while gradients in soil moisture may be creating subtle longitudinal patterns in SOC preservation at depth.

White Oak (Quercus alba) Response to Thinning and Prescribed Fire in Northcentral Alabama Mixed Pine–Hardwood Forests

AbstractStrong white oak sawtimber markets, partially attributed to the stave and cooperage industries, are encouraging forest managers to re-examine silvicultural practices for white oak (Quercus alba). We examined recruitment and retention of white oak in mixed oak–pine stands on the William B. Bankhead National Forest in northcentral Alabama. Stands were subjected to three thinning levels (residual basal areas of 75 ft2/ac, 50 ft2/ac, and no thinning) and three fire frequencies (dormant season burns of none, one, three fires) in a factorial design. Both thinning treatments reduced overstory white oak tree densities, and fire had no effect on densities. For all reproduction height classes, regardless of thinning treatment, three prescribed burns increased white oak densities; thinned and burned stands had larger white oak seedling sprouts than those thinned with no burn. However, white oak reproduction height was primarily less than 2 ft tall, and seedlings larger than 4 ft tall were reduced. Thinning with one fire resulted in the highest densities of large white oak reproduction (4 ft tall up to 1.5 in. dbh). Red maple reproduction was the dominant competitor in all treatments and is positioned to dominate the reproduction cohort without additional tending treatments.

Biology and Control of Cogongrass (Imperata cylindrica) in Southern Forests

Cogongrass (Imperata cylindrica (L.) Beauv.) is a Southeast Asian warm-season perennial grass species that has spread to all continents except Antarctica. It is considered among the worst problematic weeds on a global scale. Control of cogongrass is difficult, especially in forests. This 6-page fact sheet written by Patrick J. Minogue, Brent V. Brodbeck, and James H. Miller and published by the UF/IFAS School of Forest Resources and Conservation presents recommendations for control strategies that will work in mixed pine-hardwood forests and pine forests. http://edis.ifas.ufl.edu/fr411

Natural history of Ixodes affinis in Virginia

The ixodid tick species Ixodes affinis is expanding its range northward, changing the tick community population dynamics in the Mid-Atlantic United States. We present five years of surveillance on newly established populations of I. affinis throughout southeastern Virginia and discuss the habitat and host associations of I. affinis in this northernmost extent of its range. We found that I. affinis populations tend to persist once they are established, and populations tend to increase as ecological succession progresses, provided a vegetated understory persists. Populations of I. affinis were never found in the smallest habitat fragments or in xeric dune habitats, and the highest densities of I. affinis were found in mixed pine-hardwood forests with an herbaceous understory. We also document several new mammalian hosts for I. affinis, including house mice (Mus musculus) and coyotes (Canis latrans) and discuss how these hosts may facilitate the continued dispersal of I. affinis and the maintenance of these newly established populations.

Landscape-Scale Geospatial Assessment of Open Pine and Natural Grassland Condition for Northern Bobwhite in the Gulf Coastal Plains and Ozarks

The National Bobwhite Conservation Initiative 2.0 (NBCI) suggests >13 million acres of pine forests and >600,000 acres of grasslands have high potential for northern bobwhite (Colinus virginianus) conservation in the Southeast. The Gulf Coastal Plains and Ozarks Landscape Conservation Cooperative (LCC) identifies northern bobwhite as one of 15 indicator species for open pine/woodland/savanna and grassland/prairie ecological systems, and describes specific habitat conditions considered desirable as measurable landscape endpoints in each system as part of an Integrated Science Agenda (ISA). The ISA suggests bobwhite are limited by the habitat characteristics associated with basal area and canopy cover in pine systems, and patch size, vegetation density, bare ground, shrub cover, and warm-season grass density in grassland systems across the 180 million acre LCC. We conducted Rapid Ecological Assessments (REAs) of pine and grassland systems to describe where, how much, and in what condition the desired habitat conditions exist for each system. Using endpoint threshold values, the best available geospatial data, and a dichotomous decision tree approach, the pine and grassland REAs assigned per-pixel Condition Index Values (CIV) for the entire LCC. Results indicate 46% of the 48 million acres of pine or mixed-pine hardwood forests are in patches >600 acres with one other endpoint present, but only 0.2% (100,000 acres) reflect all desired open pine conditions. In the grassland system, 48% of the 32 million acres of grassland were characterized by the presence of at least one desired condition, with no areas meeting all desired conditions. In many cases, areas with high CIV scores overlap areas classified as high and medium land use opportunities in NBCI 2.0, suggesting continuity of these independent empirical and expert-driven assessments. Understanding the current condition of pine and grassland systems in concert with NBCI potential acreage targets can help refine management and population objectives in NBCI and LCC conservation planning.

Effects of Repeated Growing Season Prescribed Fire on the Structure and Composition of Pine–Hardwood Forests in the Southeastern Piedmont, USA

We examined the effects of repeated growing season prescribed fire on the structure and composition of mixed pine–hardwood forests in the southeastern Piedmont region, Georgia, USA. Plots were burned two to four times over an eight-year period with low intensity surface fires during one of four six-week long periods from early April to mid-September. Density of saplings (0.25–11.6 cm diameter at breast height) was significantly reduced after one or two fires during the first four-year period. Sapling density declined with additional burning over the next four years, but density of mesic hardwoods including sweetgum (Liquidambar styraciflua) and red maple (Acer rubrum) remained relatively high (~865 stems ha−1). Repeated burning had little effect on density or basal area of trees (≥11.7 cm dbh) and changes in overstory structure were limited to small increases in the quadratic mean diameter of all trees and pines. We found little evidence to suggest differential effects on structure or composition due to timing of burn within the growing season. Although repeated growing season burning alters midstory structure and composition, burning alone is unlikely to result in immediate shifts in overstory composition or structure in mixed pine–hardwood forests of the southeastern Piedmont region.

A Presence-Only Model of Suitable Roosting Habitat for the Endangered Indiana Bat in the Southern Appalachians.

We know little about how forest bats, which are cryptic and mobile, use roosts on a landscape scale. For widely distributed species like the endangered Indiana bat Myotis sodalis, identifying landscape-scale roost habitat associations will be important for managing the species in different regions where it occurs. For example, in the southern Appalachian Mountains, USA, M. sodalis roosts are scattered across a heavily forested landscape, which makes protecting individual roosts impractical during large-scale management activities. We created a predictive spatial model of summer roosting habitat to identify important predictors using the presence-only modeling program MaxEnt and an information theoretic approach for model comparison. Two of 26 candidate models together accounted for >0.93 of AICc weights. Elevation and forest type were top predictors of presence; aspect north/south and distance-to-ridge were also important. The final average best model indicated that 5% of the study area was suitable habitat and 0.5% was optimal. This model matched our field observations that, in the southern Appalachian Mountains, optimal roosting habitat for M. sodalis is near the ridge top in south-facing mixed pine-hardwood forests at elevations from 260–575 m. Our findings, coupled with data from other studies, suggest M. sodalis is flexible in roost habitat selection across different ecoregions with varying topography and land use patterns. We caution that, while mature pine-hardwood forests are important now, specific areas of suitable and optimal habitat will change over time. Combining the information theoretic approach with presence-only models makes it possible to develop landscape-scale habitat suitability maps for forest bats.

Comparison of snag densities among regeneration treatments in mixed pine–hardwood forests

Standing dead trees (snags) are an important component of forest ecosystems, providing foraging, nesting, and roosting substrate for a variety of vertebrates. We examined the effects of four forest regeneration treatments on residual snag density and compared those with densities found in unharvested, naturally regenerated forests (controls) during the second, fourth, and sixth year after timber harvest in mixed pine–hardwood forests of Arkansas and Oklahoma. Regeneration treatments were clearcut with snag creation, shelterwood, single-tree selection, and group selection. Density of large snags (≥25.0 cm DBH) differed only during the sixth year after harvest, with shelterwoods having a lower density of large snags (1.0 snags/ha) than the control or group selection stands (4.0 and 4.2 snags/ha, respectively). Density of small snags (10.0–24.9 cm DBH) mirrored residual basal area, with controls and group-selection stands having the greatest snag densities. Creation of snags in clearcuts by injection with herbicides caused initial snag density in these areas to be greater than other treatments, but density in clearcuts declined sharply by 6 years after harvest. In the absence of snag creation, treatments such as shelterwoods that remove most trees may have snag densities below that required to address some management objectives without additional snag creation.

Amphibian and reptile responses to thinning and prescribed burning in mixed pine-hardwood forests of northwestern Alabama, USA

We evaluated the response of amphibians and reptiles to two levels of prescribed burning and three levels of thinning using a field experiment consisting of a before–after, control-impact, and factorial complete block design over a four year period in the William B. Bankhead National Forest located in northwestern Alabama. We captured 2643 individuals representing 47 species (20 amphibians and 27 reptiles) during 3132 trap nights. Pre-treatment captures varied widely for both amphibians and reptiles among the stands designated for management, which was likely due to forest structural changes caused by tree mortality resulting from Southern Pine Beetle (Dendroctonus frontalis) infestations. Within each amphibian and reptile species assemblage, we observed species-specific associations with specific treatments and environmental characteristics. In regards to individual species responses, Eastern Fence Lizards (Sceloporus undulatus) increased in thin-with-burn treatments and Green Anoles (Anolis carolinensis) tended to increase in all thinned stands. North American Racers (Coluber constrictor) increased in thin-only plots primarily during the second post-treatment year. Mississippi Slimy Salamander (Plethodon mississippi) captures tended to decrease in all treatment stands throughout the study period, which may been due to either drier environmental conditions during post-treatment sampling or natural population cycling. Pool-breeding amphibian captures were more likely related to the hydroperiod of aquatic breeding environments within 290m of survey locations rather than forest treatments. Our results illustrate that forest restoration through tree thinning can positively influence certain reptile species with limited impacts on amphibians in upland, pine-dominated forests of northern Alabama. However, as our forest stands are scheduled to be burned every 3–5years, continued monitoring is necessary to understand the impacts of repeated disturbances.

Evaluation of regeneration potential of Pinus koraiensis in mixed pine-hardwood forests in the Xiao Xing’an Mountains, China

Large scale harvest of Korean pine (Pinus koraiensis) seeds as a food product in the mixed Korean pine-hardwood forest of northeastern China poses a serious threat to the sustainability and restoration of this endangered regional ecosystem. Seed collection over past decades greatly reduced the seed bank and subsequent seedling and sapling recruitment, and impacting a wide array of granivorous animals that rely on the pine seeds. We surveyed Korean pine seeds, including solid seeds (SS), insect consumed seeds (ICS) and other (animal) consumed (OCS) kernels, of the seed bank (forest floor and the top 10 cm of mineral soil), the seedlings and saplings from 1 m2 sample plots in five forest types in Liangshui Nature Reserve (LNR) of the southern Xiao Xing’an Mountains in northeastern China to provide accurate information for assessing the Korean pine regeneration potential. The average number of pine seeds in the seed bank were 11.2 seeds/m2, 9.1 seeds/m2, 4.6 seeds/m2, 1.1 seeds/m2, and 0.2 seeds/m2 in Korean pine-basswood forest, mixed Korean pine-hardwood forest, mixed conifer-hardwood forest, white birch forests, and oak forests, respectively. In the first three forest types, percentages of SS (potentially viable seeds) were 11.2%, 3.5% and 27.8%, respectively. The percentages of ICS (not viable seeds) were consistent at around 35%. The higher but variable percentages of OCS (not viable seeds) indicated high seed predation in these forests. Compared with other studies, we recorded higher percentages of seed damage, probably due to our survey approach and the increased depth of seed bank sampled in our study. Depletion of pine seeds in the seed bank greatly reduced seedling and sapling recruitment. Densities of pine seedlings varied from about 180 trees/ha in the mixed Korean pine-hardwood forest to about 5,400 trees/ha in the mixed conifer-hardwood forests and showed a high degree of spatial variation. Saplings were rare in the mixed Korean pine-hardwood forest, but ranged in the thousands in other forests. Large scale pine seed harvest has seriously threatened the sustainability of the mixed Korean pine-hardwood forest ecosystem. Scaling down the seed harvest or supplemental planting of pine saplings are urgently needed to maintain the health of the existing Korean pine forests and to restore this endangered ecosystem.

Assessing longleaf pine (Pinus palustris) restoration after southern pine beetle kill using a compact experimental design

A compact experimental design and analysis is presented of longleaf pine (Pinus palustris) survival and growth in a restoration project in the Piedmont region of Georgia, USA. Longleaf pine seedlings were planted after salvage logging and broadcast burning in areas of catastrophic southern pine beetle (Dendroctonus frontalis) attacks on even-aged mixed pine–hardwood forests. The split-plot design with randomized complete blocks was replicated on four sites. Main treatments were: chemical control of competing vegetation with herbicides; mechanical mowing to remove above-ground competition; and an untreated control. Nested within fixed-area treatment plots were single-tree plots centered on longleaf pine seedlings where adjacent vegetation was assessed immediately before treatment in years 1 and 2. Treatments applied to single-tree plots comprised three sizes of sprayed area around seedlings in chemical treatment plots. Logistic mixed-effects models indicated that initial survival was impacted by herbaceous vegetation but remained unaffected by the various vegetation control treatments applied later in year 1. Control of above- and below-ground competition around planted seedlings by mowing in conjunction with herbicide treatments resulted in significantly greater frequency of emergence from the grass stage, accelerating development of longleaf pine planted to restore beetle-killed areas in the Piedmont region of Georgia.

Soil Properties in 35 y old Pine and Hardwood Plantations after Conversion from Mixed Pine-hardwood Forest

Abstract Past management practices have changed much of the native mixed pine-hardwood forests on upland alluvial terraces of the western Gulf Coastal Plain to either pine monocultures or hardwood (angiosperm) stands. Changes in dominant tree species can alter soil chemical, biological, and physical properties and processes, thereby changing soil attributes, and ultimately, soil functions. Restoring these forests may be slow or difficult if soil function is altered appreciably. We studied the soil properties and processes in pine or hardwood-dominated stands after 35 y since conversion from a mixed pine-hardwood stand. The pine forest floor biomass was about twice as great as that of the oak stands, the oak soils were 20–30% wetter than the pine soils throughout the sampling period, the oak soils released more CO2 through respiration and had higher rates of N mineralization in the summer. We observed few differences between pine and oak stands in soil chemistry or microbial biomass. Since the difference i...

Climate-Radial Growth Relationships of Northern Latitudinal Range Margin Longleaf Pine (Pinus palustrisP. Mill.) in the Atlantic Coastal Plain of Southeastern Virginia

Climate and longleaf pine (Pinus palustris P. Mill.) radial growth relationships have been documented within its southern and western distribution. However, knowledge of this relationship is lacking along its northern latitudinal range margin (NLRM). Based on the principles of ecological amplitude, limiting factors, and studies of coniferous species in eastern temperate forests of the U.S., we hypothesized that the radial growth of longleaf pine in mixed pine-hardwood forests is responding to winter temperatures in southeastern Virginia. Two longleaf pine chronologies were developed to determine the relationship between radial growth and monthly temperature, precipitation, and Palmer Drought Severity Index (PDSI) via response function analysis (RFA). Results at the 0.05 level yielded significant response function coefficients with a positive response to current winter temperature and precipitation and a negative response to prior August PDSI. In studies of climate and longleaf pine radial growth in other parts of its range, winter temperature and precipitation have not shared a significant positive association with radial growth. Instead current spring and summer precipitation usually share this positive association. These findings add more evidence to an emerging pattern suggesting that winter temperatures contribute to limiting the radial growth of temperate conifers at northern range margins in the Northern Hemisphere.

Experimental test of the impacts of feral hogs on forest dynamics and processes in the southeastern US

The foraging activities of nonindigenous feral hogs (Sus scrofa) create widespread, conspicuous soil disturbances. Hogs may impact forest regeneration dynamics through both direct effects, such as consumption of seeds, or indirectly via changes in disturbance frequency or intensity. Because they incorporate litter and live plant material into the soil, hogs may also influence ground cover and soil nutrient concentrations. We investigated the impacts of exotic feral hogs in a mixed pine-hardwood forest in the Big Thicket National Preserve (Texas, USA) where they are abundant. We established sixteen 10m×10m plots and fenced eight of them to exclude feral hogs for 7 years. Excluding hogs increased the diversity of woody plants in the understory. Large seeded (>250mg) species known to be preferred forage of feral hogs all responded positively to hog exclusion, thus consumption of Carya (hickory nuts), Quercus (acorns), and Nyssa seeds (tupelo) by hogs may be causing this pattern. The only exotic woody species, Sapium sebiferum (Chinese tallow tree), was more than twice as abundant with hogs present, perhaps as a response to increased disturbance. Hogs increased the amount of bare soil by decreasing the amounts of plant cover and surface litter. Plots with hogs present had lower soil C:N, possibly due to accelerated rates of nitrogen mineralization. These results demonstrate that hogs may influence future overstory composition and reduce tree diversity in this forest. Management of hogs may be desirable in this and other forests where large-seeded species are an important component of the ecosystem. Further, by accelerating litter breakdown and elevating nitrogen in the soil, hogs have the potential to impact local vegetation composition via nitrogen inputs as well.

Management and Social Indicators of Soil Carbon Storage in a Residential Ecosystem, Midlothian, VA

Soil carbon storage - defined here as carbon mass per unit ground area - is an important ecosystem service, sequestering carbon that might otherwise exist 2 in atmospheric CO . Significant attention has focused on the effects that humans have on carbon cycling, but little is known about how human behaviors and attitudes relate to lawn carbon storage. The objectives of this study were to conduct household surveys in concert with soil carbon sampling in a 10-yr-old exurban neighborhood near Richmond, Virginia to quantify differences in soil carbon storage between residential lawns and mixed pinehardwood forest fragments, and to determine how lawn management and environmental attitudes relate to soil carbon storage. Lawns stored significantly less carbon than forest fragments in the top 10 cm of soils. A significant negative relationship was observed between watering and fertilizer frequency and soil carbon storage, but the goodness-of-fit was sensitive to intra-lawn variability in soil carbon mass. Survey respondents that claimed to be environmentalists stored significantly more carbon and spent one hour less per week managing their lawns, suggesting that environmental attitudes may affect how households manage their lawns and, in turn, the quantity of soil carbon stored in residential soils.

Pedologic and geomorphic impacts of a tornado blowdown event in a mixed pine-hardwood forest

Abstract Biomechanical effects of trees on soils and surface processes may be extensive in forest environments. Two blowdown sites caused by a November 2005 tornado in the Ouachita National Forest, Arkansas allowed a case study examination of bioturbation associated with a specific forest blowdown event, as well as detailed examination of relationships between tree root systems, soils, and underlying bedrock. The sites occur within mixed shortleaf pine and hardwood forests. More than 95% of trees in the severe blowdown areas were either uprooted or suffered trunk break, with uprooting more common than breakage. Within the most heavily damaged areas all uprooted trees were pines, while all trees left standing were hardwoods. Root wads of uprooted trees had a mean surface area of about 3 m 2 and volume of about 2 m 3 , though individual sizes were quite variable. Nearly 4% of the ground surface area was affected by uprootings, with a soil volume equivalent to a disturbance of the entire surface area to a depth of 2.4 cm. Tree size (as measured by diameter at breast height) was significantly related to the area and volume of root wads ( R 2 = 0.55, 0.71, respectively), with volume of uprooted soil varying as diameter to the ~ 3 power, suggesting that the timing of blowdown events relative to tree age or growth stage significantly influences the area of disturbance and the mass and volume of material involved. In 93% of cases the roots of the uprooted trees contacted or penetrated the underlying bedrock, and in all those cases bedrock was quarried by uprooting. Only 11% of the tree throws showed evidence of general lateral root turning at the soil–bedrock interface; in most cases roots penetrated bedrock along joints. The propensity for tree roots to penetrate bedrock joints, facilitate weathering, and excavate bedrock during uprooting supports the idea that tree roots play a predominant role in locally deepening soils.