Southern Appalachian Hardwood Forest Research Articles

Acorn production, climate, and tree-ring growth of five oak species in southern Appalachian forests

Oak (Quercus) are a dominant and important tree genus in the Central Hardwood Region (USA) due to their commercial timber value, and food value of their protein-rich seed – acorns – to wildlife. Acorn production is characteristic of masting, with highly variable crop sizes that are synchronized within populations, but with consideration variation among individual trees. Critical to acorn masting studies are longitudinal datasets, which are often difficult to maintain due to a host of constraints. One possible approach to extending mast datasets involves the use of dendrochronology, where tree-ring-width variability serves as a proxy for annual acorn production. In this study, we addressed the future utility of mast reconstructions by examining relationships between acorn production, climate, and tree-ring data from five common oak species in southern Appalachian hardwood forests (Bent Creek Experimental Forest). We found little evidence to suggest that acorn production influences seasonally resolved tree-ring data, even when we considered early and latewood growth separately, or when we analyzed trees with substantially higher overall investment in acorn production (i.e., super producers). Monthly climate (temperature, precipitation) correlated to acorn production was strongest when lagged, which could indicate weather conditions were more important for phases of flower production and fertilization than acorn maturation. However, relationships were relatively weak, indicating limited potential for the forecasting of acorn crops, or for reconstruction methods that combine observed weather data and tree-ring responses to masting. Overall, our findings provide some support for the role of resource dynamics in regulating masting in oaks, but relationships between radial growth and acorn production are not sufficiently strong, at least in this location, to permit tree-ring based reconstruction of masting in these oak species.

Short‐term responses of riparian salamander populations to wildfire in the Southern Appalachians

AbstractWildfire is a natural disturbance within many forest ecosystems and is rapidly becoming more frequent and severe because of the combination of historical fire suppression and climate change. In Southern Appalachian hardwood forests, there is a limited understanding of how salamander populations respond to wildfire, despite their high diversity and abundance in forest ecosystems. We expected populations of lungless, plethodontid salamanders to respond negatively to wildfire and the drier microhabitat conditions in burned habitat. We evaluated the effect of fire on 3 plethodontid salamander species (Blue Ridge two‐lined salamander [Eurycea wilderae], Ocoee salamander [Desmognathus ocoee], red‐legged salamander [Plethodon shermani]) with different life histories from 2017–2019 following a wildfire in a Southern Appalachian riparian forest in North Carolina, USA. We estimated differences in abundance, frequency of adults in the population, and terrestrial distribution in relation to streams between burned and reference riparian forest sites. Wildfire had negative effects on the abundance of semi‐aquatic species, but temporal patterns differed by species. Abundance of the Blue Ridge two‐lined salamander was lower in burn sites than reference sites immediately after fire, followed by a gradual convergence towards reference‐site densities. Conversely, Ocoee salamanders had a time‐lagged response, where we observed significantly lower densities in burn sites relative to reference sites for only 2 years after fire. We did not observe strong responses of red‐legged salamander abundance to fire. There were no consistent patterns in how the percentage of adults in reference or burn sites differed over time, suggesting that population responses to burn vary by species. Finally, we observed adults of all species and juveniles of semi‐aquatic species farther from streams in burn sites. Our findings suggest plethodontid salamander communities may tolerate riparian wildfires, although longer‐term studies are required to understand how long it takes for patterns of population size structure and habitat use to converge with those in unburned reference sites.

Prescribed fire and other fuel-reduction treatments alter ground spider assemblages in a Southern Appalachian hardwood forest

Prescribed burns and understory thinnings are forest management practices aimed at reducing fuel loads to lessen wildfire threat in the Southern Appalachians, USA. Spiders play a critical role in forest ecosystems by controlling insect populations and providing an important food source for vertebrates. We used pitfall and colored pan traps to investigate how abundance, species richness, and diversity of spiders differed among three fuel reduction treatments administered repeatedly over a 15-year period and untreated controls. Additionally, we examined how spiders responded to one round (before and after) of fuel reduction treatments. We established treatments within the 15-year period as follows: mechanical understory removal (twice; M), prescribed burning (four times; B), mechanical understory removal followed one year later by high-severity prescribed burns and three subsequent burns (MB), and untreated controls (C). Our study period (2014–2016) occurred after multiple prescribed burns and two rounds of mechanical understory removal had occurred. Salticidae and Lycosidae were the two most commonly collected spider families in Southern Appalachian hardwood forests. Generally, we found increased spider abundances within all fuel-reduction treatments compared to controls. Individual spider families and species showed variable responses to treatments, but abundance of several spider families was greater in one or more fuel-reduction treatments than in controls. Additionally, abundance of several spider families and hunting/web building guilds (webs built for hunting purposes or defense) exhibited yearly differences to the last round of fuel-reduction treatments. Overall, our results suggest that changes in the overstory and understory of a forest are important drivers of regional spider abundance and assemblages, and forest management practices that modify forest structure can dramatically alter spider abundance and richness, usually in a positive manner.

Reptile and amphibian response to oak regeneration treatments in productive southern Appalachian hardwood forest

Forest restoration efforts commonly employ silvicultural methods that alter light and competition to influence species composition. Changes to forest structure and microclimate may adversely affect some taxa (e.g., terrestrial salamanders), but positively affect others (e.g., early successional birds). Salamanders are cited as indicators of ecosystem health because of their sensitivity to forest floor microclimate. We used drift fences with pitfall and funnel traps in a replicated Before-After-Control-Impact design to experimentally assess herpetofaunal community response to initial application of three silvicultural methods proposed to promote oak regeneration: prescribed burning; midstory herbicide; and shelterwood harvests (initial treatment of the shelterwood-burn method) and controls, before and for five years post-treatment. Species richness of all herpetofauna, amphibians, reptiles, frogs, salamanders, or snakes was unaffected by any treatment, but lizard species richness increased in the shelterwood harvest. Capture rate of total salamanders decreased post-harvest in shelterwood units after a 2–3year delay; Plethodon teyahalee decreased post-harvest in shelterwoods, but also in control units. In contrast, capture rate of total lizards and Plestiodon fasciatus increased in shelterwood stands within the first year post-harvest. Prescribed burn and midstory herbicide treatments did not affect any reptile or amphibian species. A marginally lower proportion of juvenile to adult P. teyahalee, and a higher proportion of juvenile P. fasciatus in shelterwood than control units suggested that heavy canopy removal and associated change in microclimate may differentially affect reproductive success among species. Our study illustrates the importance of longer-term studies to detect potential changes in herpetofaunal communities that may not be immediately apparent after disturbances, and highlights the importance of including multiple taxa for a balanced perspective when weighing impacts of forest management activities.

Songbird Use of White-Tailed Deer (Odocoileus virginianus) Food Plots in Appalachian Hardwood Forests

Abstract Food plots are commonly planted for Odocoileus virginianus (White-tailed Deer) in the eastern US, because they are known to benefit this species. We hypothesized that food plots may also provide early-successional habitat for nongame species, such as songbirds, in areas where it is normally lacking. Thus, we evaluated songbird use of food plots planted with Trifolium spp. (perennial clovers) in the northern and southern Appalachian Mountains by comparing avian species richness and abundance within plots, along their edges, and in the adjacent forest. During the breeding season on northern sites, there was no difference in avian richness or abundance among the plots, their edges, or adjacent forest. However, both species richness and abundance were greater along plot edges during breeding season on southern sites. Species richness was also greater along plot edges for a subset of southern sites sampled during winter. Thus, food plots within southern Appalachian hardwood forests enhanced habitat co...

Effects of fuel reduction treatments on movement and habitat use of American toads in a southern Appalachian hardwood forest

Prescribed fire is a commonly used management technique for maintaining fire-adapted ecosystems, yet empirical data regarding its effects on amphibians are limited and contradictory. Anurans (frogs and toads) may be the amphibian taxa most negatively affected by fire due to their extensive use of the forest floor; however, short-term abundance studies suggest that terrestrial toads (e.g., Anaxyrus [Bufo] americanus) may benefit from fire-based ecosystem management. We used radio-telemetry to examine the effects of prescribed fire on movements, home range characteristics, mortality, and habitat selection of A. americanus in a southern Appalachian upland hardwood forest. We tracked 26 adult A. americanus between 27 January and 30 May 2012. Toads exhibited high non-breeding site fidelity and traveled 993.5m (±265.9m) mean (±SD) route distance between the breeding ponds and the last recorded location within their summer habitat. We found no evidence of direct mortality of A. americanus from a prescribed fire that occurred on 13 February 2012. Forward stepwise discriminant analysis (DA) revealed that the availability of coarse woody debris (CWD) was a significant discriminator between microhabitats used (i.e., location plots) and random plots (Wilk’s lambda=0.9852, F1, 661=9.9414, p=0.002). Forward stepwise DA revealed that burned and unburned location plots were significantly different (Wilk’s lambda=0.2713, F1, 221=593.6863, p<0.001) based on the percent of plot ground cover comprised of charred material (%char). When %char was excluded from the analysis due to its short-term nature, the percent of plot ground cover comprised of deciduous leaves, a cover item commonly used by toads in unburned locations, was the variable with the most discriminatory power (Wilk’s lambda=0.4243, F1, 221=299.8741, p<0.001). Toads maintained greater distances from CWD in the unburned (mean±SD=119.50±109.64cm) than in the burned locations (mean±SD=86.05±104.81cm; χ12=9.7055, p=0.002). Our results indicate that prescribed fire as implemented in this study did not cause direct mortality, nor did it appear to inhibit migratory movements of adult A. americanus. However, fire reduced the diversity and availability of refugia, especially deciduous leaves, though the availability of alternative cover objects (e.g., CWD) in burned treatments allowed toads to inhabit those areas, suggesting the importance of noncombustible or semi-permanent refugia for A. americanus in fire-managed forests.

Extending a Model System to Predict Biomass in Mixed-Species Southern Appalachian Hardwood Forests

Functions for estimating foliage, branches and nonmerchantable stem tops, merchantable stem, and total aboveground biomass for Appalachian hardwood trees were assembled and incorporated into an existing growth-and-yield simulator for mixed-species Appalachian hardwood forests. With these functions and user-defined stand table and stand characteristics, current estimates of biomass in the different aboveground tree components can be obtained by species and diameter class for a thinned or unthinned stand. In addition, future biomass estimates for a thinned stand can be obtained for a projection period of 1 to 10 years. These estimates can be used to assess forest ecosystem services of carbon sequestration and provide information that can be used to evaluate effects of different harvesting strategies on forest carbon and other nutrient pools. A comparison of these estimates to those obtained by the forest inventory and analysis (FIA) procedure, using data from eight FIA sample plots in the southern Appalachian region, indicated that estimating biomass directly from locally developed biomass equations may give biomass estimates for the tree bole and for tops and branches, that are different from those obtained by the FIA procedure.

Rhododendron thickets alter N cycling and soil extracellular enzyme activities in southern Appalachian hardwood forests

Summary Rhododendron maximum L., a spreading understory shrub, inhibits overstory regeneration and alters forest community structure in southern Appalachian hardwood forests. Using paired plots and reciprocal litter transplants in forests with and without R. maximum cover, we examined the influence of R. maximum on litter mass and quality, N cycling and soil extracellular enzymes. Standing stocks of soil organic matter, soil N, leaf litter mass and fine root biomass were greater in forests with R. maximum than those without. Tannin extracts from R. maximum foliage, and leaf litter and fine roots collected under R. maximum had a relatively high capacity to precipitate protein compared to extracts from trees. Across the growing season, soil inorganic N availability was generally lower under R. maximum , mostly due to reduced NO 3 − availability. Our data suggest that R. maximum litter alters N cycling through the formation of recalcitrant polyphenol–organic N complexes. Soil extracellular enzymes indicate the potential processing rates of organic substrates. Between forest types, polyphenol oxidase activity was greatest in R. maximum O horizons, regardless of litter type, suggesting that the local microbial community can better degrade and access protein–tannin-complexed N. Protease activity did not differ between forest types, but was greater on R. maximum leaf litter than hardwood leaf litter. The alteration of the N cycle via the formation of polyphenol–organic N complexes may contribute to hardwood seedling suppression, while the enzymatic release of these complexes by ericoid mycorrhizal fungi may increase N acquisition for R. maximum and contribute to its expansion in southern Appalachian forests.

Response of white-footed mice ( Peromyscus leucopus) to fire and fire surrogate fuel reduction treatments in a southern Appalachian hardwood forest

An experiment conducted as part of the multidisciplinary National Fire and Fire Surrogate Study was designed to determine effects of three fuel reduction techniques on small mammals and habitat structure in the southern Appalachian mountains. Four experimental units, each >14-ha were contained within each of three replicate blocks at the Green River Game Land, Polk County, NC. Treatments were (1) prescribed burning (B); (2) mechanical felling of shrubs and small trees (M); (3) mechanical felling + burning (MB); (4) controls (C). Mechanical understory felling treatments were conducted in winter 2001–2002, and prescribed burning was conducted in March 2003. After treatment, there were fewer live trees, more snags, and greater canopy openness in MB than in other treatments. Leaf litter depth was reduced by burning in both B and MB treatments, and tall shrub cover was reduced in all fuel reduction treatments compared to C. Coarse woody debris pieces and percent cover were similar among treatments and controls. We captured 990 individuals of eight rodent species a total of 2823 times. Because white-footed mice composed >79% of all captures, we focused on this species. Populations in experimental units increased 228% on average between 2001 and 2002, but there was no evidence of an effect of the mechanical treatment. From 2002 to 2003, all units again showed an average increase in relative population size, but increases were greater in MB than in the other treatments. Age structure and male to female ratio were not affected by the fuel reduction treatment. Average adult body weight declined from 2001 to 2002, but less so in M than in units that remained C in both years. The proportion of mice captured near coarse woody debris was similar to the proportion captured in open areas for all treatments, indicating that white-footed mice did not use coarse woody debris preferentially or change their use patterns in response to fuel reduction treatments. Land managers should understand possible effects of different fuel reduction treatments on white-footed mouse populations, as they are an important component of the fauna and food chain of deciduous southern Appalachian forests.

Gap size and succession in cutover southern Appalachian forests: an 18 year study of vegetation dynamics

We used clearcut logging in establishing four replicated sizes of canopy openings (0.016, 0.08, 0.4, and 2.0 ha) in a southern Appalachian hardwood forest in 1981 to examine the long-term effects of disturbance size on plant community structure, biomass accumulation, aboveground net primary productivity (NPP), and mode of recovery. The reestablishment of NPP and biomass following logging was 6–7-fold greater in large than small openings by 17 years. Total biomass in the 2.0 ha openings (127.3 Mg ha−1) recovered 59.5% as NPP (19.7 Mg ha−1 yr−1) reached 225% of precut forest levels. Biomass accumulation was 2.6–3.6-fold greater in interior than edge locations of all but the 0.016 ha gaps. The absence of significant patch size or edge vs. interior differences in tree densities suggests that growth rates of individual trees were enhanced in more insolated microenvironments. Sprouting (86–95% of tree NPP) was much more important than advance regeneration (4–10%) or seedling germination (<2%) during early recovery in all opening sizes. Canopy dominant Quercus and Carya trees exhibited limited sprouting following disturbance. Instead, shade-intolerant Robinia pseudoacacia and Liriodendron tulipifera were major sprouters that used N-fixation (Robinia) and rapid growth (Liriodendron) in attaining 7.4 and 5.9 fold greater biomass accumulation, respectively in 2.0 ha than 0.016 ha opening sizes. Seedling germination and understory production were extensive in all openings following logging, but declined rapidly as the young tree canopy began closing by 4–6 years. The relative importance of shade-intolerant tree biomass approximately doubled over 17 years as shade-tolerant tree seedlings, herbs, and shrubs gradually regained importance under the emerging canopy. Sprouting caused the persistence of a tree species composition in all openings that remained relatively similar to the precut forest. Large disturbances on mountain slopes of the southern Appalachians generally promote sprouting and rapid recovery, whereas small disturbances in low-elevation cove forests lead to a gradual recovery through seedling germination and/or advance regeneration. Continued logging in the southern Appalachians will increase the relative size and frequency of large disturbances, further the importance of sprouting of shade-intolerant species, and lead to more even-aged forest stands throughout the region.

Carbon limitation leads to suppression of first year oak seedlings beneath evergreen understory shrubs in Southern Appalachian hardwood forests

Inhibition of canopy tree recruitment beneath thickets of the evergreen shrubs Rhododendron maximum L. and Kalmia latifolia L. has long been observed in Southern Appalachian forests, yet the mechanisms of this process remain unresolved. We present a first-year account of suppression of oak seedlings in relation to Rhododendron and Kalmia basal area, light and resource availability, seedling performance and the rates of seedling damage i.e., herbivory. We found no evidence of first-year seedling suppression or significant resource deficiencies beneath thickets of K. latifolia in mature mixed hardwood stands. Suppression beneath R. maximum was apparent during the first growing season. We found that seedling biomass, light availability prior to canopy closure, and seedling tissue C:N ratios were negatively correlated with R. maximum basal area. Basal area of R. maximum was positively correlated with seedling mortality rates, soil Al, and early-growing season leaf herbivory rates. Seedling growth was positively correlated with light and tissue C:N, while negatively correlated with soil Al. Overall, our results support the inhibition model of shade-mediated carbon limitation beneath dense understory shrubs and indicate the potential importance of herbivory and aluminum toxicity as components of a suppression mechanism beneath R. maximum thickets. We present a causal model of first year inhibition beneath R. maximum in the context of our findings and the results of prior studies.

Response of white-footed mice ( Peromyscus leucopus) to coarse woody debris and microsite use in southern Appalachian treefall gaps

The influence of treefall gaps and coarse woody debris (CWD) on white-footed mouse ( Peromyscus leucopus) abundance was tested experimentally during 1996–1999 in a southern Appalachian hardwood forest. I compared the relative abundance and body size of P. leucopus among unsalvaged gaps that were created by wind disturbance and retained high CWD levels, salvage logged gaps where fallen and damaged tree boles had been removed, and closed-canopy controls. I also tested the relative use by mice of four microsite types: CWD, pits, woody brush, and open ground. One-hundred and forty-one P. leucopus were captured 310 times during the study. There were no differences in capture success, body size, or sex ratio among treatments before or after salvage logging, but abundance varied among years. Capture success was higher at traps set adjacent to CWD ( P<0.05) and in pits ( P<0.10) than at traps set under brush or on open ground. In the southern Appalachians, windthrow-created canopy gaps and associated microsites do not affect habitat use by P. leucopus at a landscape level (as measured by relative abundance among treatments), but CWD influences the microdistribution of P. leucopus where it is present.

NICHE RELATIONSHIPS OF TWO SYNTOPIC SPECIES OF SHREWS,SOREX FUMEUSANDS. CINEREUS,IN THE SOUTHERN APPALACHIAN MOUNTAINS

Abstract The smoky shrew (Sorex fumeus) and the masked shrew (S. cinereus) are common soricids in mature southern Appalachian hardwood forests. To better understand the role of body size and niche relationships in these syntopic species, 12 50- by 50-m plots were established in the Pisgah National Forest of western North Carolina. Trapping was conducted from August through November 1996 and from March through August 1997 using Y-shaped drift fences with associated pitfalls. Prey items and microhabitat components were measured to examine correlations with abundance of shrew species. Total shrew captures (n = 176) included 105 (59.7%) Sorex fumeus and 41 (23.3%) S. cinereus. Smoky shrews were significantly larger than masked shrews in both mass and body length. Stepwise multiple regression analyses determined that a combination of litter moisture, class 5 coarse woody debris (CWD), and number of invertebrates and mountain dusky salamanders (Desmognathus ochrophaeus) was the best predictor of S. fumeus abund...

Effects of seven silvicultural treatments on terrestrial salamanders

We compared the relative abundance of terrestrial salamanders before and after application of seven regeneration treatments in a low-elevation, southern Appalachian hardwood forest in southwest Virginia. Treatments included understory removal, group selection, two shelterwoods, leave-tree, clearcut, and a control. Salamander relative abundance was significantly lower after harvest on the group selection ( p=0.005), shelterwoods ( p=0.007 and p=0.015), leave-tree ( p=0.001), and clearcut treatments ( p=0.001). There was no significant difference in relative abundance during the same period on the control ( p=0.788) or understory removal ( p=0.862) treatments.

Stemflow nutrient inputs to soil in a successional hardwood forest

Stemflow and throughfall from a regenerating (8-year-old) southern Appalachian hardwood forest were collected to examine the relative importance of tree bole nutrient leaching in response to acid deposition. Samples from nine (2 m2) stemflow collection plots were analyzed for four dormant season and 11 growing season rainstorm events. Results showed that, relative to throughfall fluxes, stemflow accounted, on average, for approximately 8.5% of total water reaching the forest floor during both dormant and growing season storms. Relative to foliar leaching, K-, SO4-, and PO4 ions appear to be the most easily leached ions from young tree stems. Proportional nitrate and base cation stemflow fluxes increased significantly (p<0.05) with growing-season storm-event duration, suggesting that the stemsurface nutrient pool is depleted by precipitation more slowly than the foliar pool. On average, proportional stemflow fluxes of SO4 (12%) and K (14%) were consistently higher than reported maximum values for more mature forest stands, which indicates that small-scale stemflow inputs of ions such as these to the forest floor may be important in early successional ecosystems.

Litter Decomposition, Nitrogen Dynamics and Litter Microarthropods in a Southern Appalachian Hardwood Forest 8 Years Following Clearcutting

.' SUMMARY (1) Litter decomposition rates, nitrogen dynamics and litter microarthropods on the xeric slopes of a watershed 8 years after clearcutting (WS 7) and on an adjacent reference watershed (WS 2) at the Coweeta Hydrologic Laboratory were measured using litterbags. Litter of Comusflorida L., Acer rubrum L. and Quercusprinus L. was used as experimental substrates in three plots on adjacent areas of both watersheds. Results from this study were compared with those obtained before and after cutting to assess the longer-term changes induced by canopy removal. (2) Reduced litter decomposition rates were associated with clearcutting. Litter nitrogen dynamics were also affected. Net immobilization of nitrogen in litter substrates was lower on WS 7. Lower net nitrogen immobilization was related to slower increases in nitrogen concentration per unit mass lost in litter on WS 7. (3) Mean annual densities of total litter microarthropods remained 28% lower on WS 7 than on WS 2, 8 years after cutting. Previous studies indicated clearcutting initially reduced mean annual densities of litter microarthropods by>50%. Mesostigmata and Oribatei densities averaged 50 and 54% lower, respectively, than on WS 2. Prostigmata and Collembola densities averaged 20 and 24% lower, respectively, than on WS 2. This differential response changed the relative abundances of major groups. Changes in litter decomposition rates and nitrogen dynamics were consistent with effects associated with lower microarthropod densities and suggest that reduced microarthropod densities may be important. (4) Results of this study differ from those at northern hardwood forest sites where clearcutting caused increased decomposition rates. This suggests that generalizations from northern hardwood forests may not apply to other regions. Instead the effects of canopy

The Role of Black Locust (Robinia Pseudo-Acacia) in Forest Succession

(1) Early forest regeneration in southern Appalachian hardwood forests is dominated by the woody nitrogen-fixing legume, black locust (Robinia pseudo-acacia). Although it grows most prevalently on clear-felled areas, abandoned pastures, or disturbed roadsides, it may have historically been an important colonizer of burned sites. Although it commonly reproduces from seed germination, sprouting from stumps and roots is its most prevalent means of regeneration. Early sprout growth is rapid, attaining heights up to 8 m in 3 years. (2) Except for stands on high-nutrient sites, growth decreases after 10-20 years. In less vigorous stands, stem mortality may be high due to attacks by the locust stem borer (Megacyllene robiniae). The high mortality of black locust is an early successional mechanism that releases cpdominant species such as Liriodendron tulipifera, and creates canopy gaps favourable for growth of longer-lived individuals. (3) Total biomass accretion in 4, 17 and 38-year-old black locust stands growing on fertile, mesic sites was 33, 174 and 399 t ha-', respectively, in comparison to 198 t ha-' for an older, uneven-aged mixed oak forest with a history of disturbance. (4) Biomass accumulation was the predominant fate of fixed N in all three stands, with an addition to total soil N apparent only in the 38-year-old stand. (5) Symbiotic N fixation by black locust apparently increased the concentration of NO3 in the soil. The source of elevated soil NO3 is hypothesized to be high fluxes of N from leaf and root litter mineralization and nitrification, and perhaps from canopy insect frass. (6) Total stand N increased at a net average annual rate of 48, 75 and 33 kg ha-' year-', respectively, for ages 4, 17 and 38. Nodule biomass was 8, 106 and 4 kg ha-' in the 4, 17 and 38-year-old stands, respectively. (7) These patterns of N accretion are similar to those reported for other woody nitrogen-fixing species on secondary successional sites. They indicate that peak N fixation occurred from early to intermediate stages of forest succession, and declined with later successional development.

The Relation of Sodium and Water Balance to Survival in Sea Water of Estuarine and Freshwater Races of the Snakes Nerodia fasciata, N. sipedon and N. valida

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The Litter Arthropod Community in a Southern Appalachian Hardwood Forest: Numbers, Biomass and Mineral Element Content

The biomass, numbers of individuals and mineral content of the arthropod fauna in the litter of a mixed hardwood forest were examined. The biomass values of the litter arthropods were generally higher than in other forests. Possible reasons for higher biomass values are discussed. Potassium and calcium standing crops are compared to those of a Liriodendron forest in Tennessee. With few exceptions the potassium values are comparable. However, there appear to be great differences in the calcium values. INTRODUCTION The forest constitutes an ecosystem in which organic and inorganic elements interact. The basic mineral nutrition of forest vegetation is provided by rock weathering and mineral-laden rain. The forest is charged and recharged by organic products from the vegetation (Spurr, 1964). The nutrient recharging is accomplished to a great extent by litter decomposition which releases the nutrients bound up in the dead plant structural material. Decomposition is accomplished by the activities of both the forest floor microflora and fauna. As organic materials reach the forest floor, they are attacked by the microflora and fauna, releasing nutrient substances, and 40 to 90% of the initial weight may be lost during the 1st year, the actual amount varying with species and locality (Edwards et al., 1970). Witkampl and Olson (1963) showed a nonlinear rate of weight loss by leaf litter during the 1st year, often with an initial rapid loss of weight, possibly due to leaching of soluble materials. This is followed by a slower loss rate during the winter months and subsequent acceleration during spring and summer (Crossley, 1970). Fresh leaf litter may remain unpalatable to soil fauna until the polyphenols in the stem and leaf material are removed (Edwards and Heath, 1963; Satchell and Lowe, 1966), and this may delay faunal attack on the litter for some time. Several studies on the dynamics of litter breakdown by fauna have been reported. Satchell (1967) suggested there may be extensive incorporation of litter into the mineral soils by the feeding of earthworms. 'Research supported in part by the Eastern Deciduous Forest Biome, US/IBP, funded by the National Science Foundation under Interagency Agreement AF-199, 40-193-69, with the U.S. Atomic Energy Commission Oak Ridge National Laboratory, and in part by U.S. Atomic Energy Commission Contract AT-(38-1)-641 with the University of Georgia (D. A. Crossley, Jr.). Contribution No. 147 from the Eastern Deciduous Forest Biome, US/IBP. 2 Present address: Ecology Center, Utah State University, Logan, Utah.