James T. Anderson

A COMPARISON OF PLANT COMMUNITIES IN MITIGATION AND REFERENCE WETLANDS IN THE MID-APPALACHIANS

Wetland destruction has plagued the U.S. for decades, but the need to compensate for these losses has only been embraced within the last 20 years. Because so many compensatory mitigation wetlands have been created, there is a need to assess the function of these valuable ecosystems relative to natural wetlands. The goal of this study was to evaluate the functional equivalency of mitigation wetlands in West Virginia in supporting hydrophytic plant communities. A series of nested quadrats was used to compare plant community structure among eleven mitigation and four naturally occurring reference wetlands. For all species combined, mean total percent cover across all sampling quadrats per wetland was similar between mitigation and reference wetlands. Species richness, evenness, and diversity were greater in mitigation than in reference wetlands. Mean weighted averages of plant communities calculated using cover values and wetland indicator status were similar between mitigation and reference wetlands. There were, however, major differences in species composition. Mitigation sites tended to have more pioneer species, non-native dominants, and species with relatively lower conservation quality. Ordination analyses suggested that compositional differences become smaller as mitigation sites age. Both mitigation and natural wetlands met criteria for hydrophytic vegetation according to the 1987 U.S. Army Corps of Engineers Wetland Delineation Manual. These data suggest that the mitigation wetlands investigated in this study adequately support hydrophytic vegetation and appear to be developing vegetation similar to reference standards.

Grassland songbird nest‐site selection and response to mowing in West Virginia

Abstract Grassland bird populations in the eastern United States have become increasingly dependent on human-altered grassland habitats such as former hayfields and pastures for nesting. We compared grassland bird nest success and nest placement on former hayfields (n = 3) and former pastures (n = 3) and on mowed and unmowed areas on the Canaan Valley National Wildlife Refuge (CVNWR), West Virginia, 1999–2000. We located 83 nests of the 4 dominant grassland species: bobolinks (Dolichonyx oryzivorus; 19% nest success), Savannah sparrows (Passerculus sandwichensis; 34%), red-winged blackbirds (Agelaius phoeniceus; 21%), and eastern meadowlarks (Sturnella magna; 70%). Vertical density of vegetation was taller at successful bobolink nests and maximum height was greater at successful Savannah sparrow nests than at unsuccessful nests. Eastern meadowlarks chose nest sites with more standing dead vegetation, deeper litter, and a greater maximum height of vegetation. Although there were no differences in nest success between mowed and unmowed treatments, mowing some fields at the conclusion of the breeding season may provide long-term advantages to grassland bird nesting success by maintaining former fields as grassland habitats.

Mute Swans' Impact on Submerged Aquatic Vegetation in Chesapeake Bay

Abstract Mute swans (Cygnus olor) are poorly studied despite their potential to impact submerged aquatic vegetation (SAV). We measured vegetation characteristics (i.e., percent cover, shoot density, and canopy ht) of SAV beds in controls (unfenced), 2-year exclosures, and 1-year exclosures at 18 sites in the Chesapeake Bay, Maryland, USA, to quantify the impact of herbivory by mute swans on SAV during 2003 and 2004. Mute swan herbivory had a substantial adverse impact on percent cover, shoot density, and canopy height of SAV. At the end of the study mean percent cover, shoot density, and canopy height in the controls were lower by 79%, 76%, and 40%, respectively, as compared to those in 2-year exclosures. During 2004, percent cover, shoot density, and canopy height increased by 26%, 15%, and 22%, respectively, between early and late seasons of SAV growth in exclosures, but they decreased by 36%, 41%, and 18%, respectively, in the controls. Paired mute swans predominantly occupied 6 of 7 moderate-depth sites (0.76–0.99 m), and these sites experienced less (i.e., 32–75%) SAV reduction. All (n = 7) shallow water sites (0.50–0.75 m) were predominantly occupied by mute swan flocks, and percent cover reduction of SAV was as high as 75–100% at these sites. Mute swan flocks also predominantly occupied 3 of the 5 deep-water sites (≥1 m) and 1 of 7 moderate-depth sites, wherein we recorded considerable (i.e., 77–93%) SAV reduction. Thus, considering that flocks are more detrimental to SAV as compared to paired mute swans, we recommend that initial emphasis primarily be placed on controlling mute swans in flocks and secondarily on pairs.

Persistence and colonization strategies of playa wetland invertebrates

Wetland invertebrates have evolved numerous means of inhabiting spatially and temporally flooded wetland environments. The ability of invertebrates to either colonize from other sources and/or to persist in dry wetlands through diapause has seldom been simultaneously studied. We compared strategies of colonization and persistence by invertebrates in variable environments (playa wetlands on the Southern High Plains of Texas). We also examined emergence response time, following flooding, of taxa that persist in playa soil using field experiments and microcosms. At least 26 of 87 invertebrate taxa survive seasonal drying of playas through aestivation in soil. More invertebrate taxa only colonized flooded playas (70.1%) than only persisted in dry soil (29.9%) (P < 0.05). Of the invertebrate taxa that persisted in dry soil, more (P < 0.05) of these were active colonists or relied strictly on diapause rather than a combination of aestivation and colonization. Invertebrate densities were not statistically different among taxa that practiced colonization and persistence (5.2 invertebrates/m2, SE = 2.0) or that only persisted (1.5 invertebrates/m2, SE = 0.5) in playas (P=0.918). The average amount of time for a taxon to first appear in a microcosm was about 3 weeks less in 1995–96 than 1994–95, which was likely due to greater precipitation during 1995–96. We found that both colonization and persistence was practiced more often than a single strategy for those invertebrates sampled in microcosms. Conservation efforts for playa invertebrates should be implemented at the landscape level and focus on playas with intact watersheds, because these playas have relatively undisturbed hydroperiods.

Comparison of Two Double‐Observer Point‐Count Approaches for Estimating Breeding Bird Abundance

Abstract Point counts are one of the most widely used and efficient approaches to survey land-bird populations. A new approach to point-count surveys involves the use of 2 observers, which allows the calculation of a detection probability for each bird species. Detection probabilities derived from 2 observers permit investigators to calculate a corrected abundance estimate that accounts for birds present but not detected. We evaluated 2 double-observer point count approaches: the dependent-observer approach and the independent-observer approach. The dependent-observer approach involves 2 observers recording data together on a single data sheet with one observer designated the primary observer and the other designated as the secondary observer. The primary observer verbally dictates the number of each species detected while the secondary observer records this information; the secondary observer also records birds that the primary observer did not detect. The independent-observer approach involves 2 observers recording data independently on separate data sheets without verbal communication between observers. This study compares the detection probabilities and associated levels of precision generated by both double-observer approaches to ascertain which technique generates data that are more accurate and more feasible to apply in the field. We conducted point counts at 137 point locations in northern West Virginia during the spring of 2000 and 2001 using both double-observer approaches. We generated detection probabilities and abundances from data collected using both double-observer approaches using program DOBSERV. The dependent-observer approach resulted in higher observer-specific and joint detection probabilities, as well as lower standard errors of detection probability across most cover types. Species-specific detection probabilities were higher across all cover types under the dependent-observer approach. Given the higher detection probabilities and associated precision combined with fewer logistical constraints, we suggest that the dependent-observer approach be used when investigators are interested in surveying birds using point counts.

Effects of habitat on small-mammal diversity and abundance in West Virginia

Abstract The importance of riparian habitat in small-mammal sampling and conservation is unknown in the central Appalachian region, and the little research available has produced mixed results. In addition, studies have produced varied results when comparing small-mammal communities in edge and interior locations. We compared relative abundance and diversity of small mammals from pitfall trap arrays (per 100 trap-nights) between riparian (<100 m from water source) and upland (≥100 m from water source) habitats and between edge (<100 m from habitat edge) and interior (≥100 m from habitat edge) locations in northern West Virginia. Shannon diversity (P=0.010) and Pielou evenness (P=0.012) were higher in edge than interior trapping locations but similar between riparian and upland habitats. Meadow voles (Microtus pennsylvanicus; P=0.012) and southern bog lemmings (synaptomys cooperi; P=0.001) were more abundant in edge than interior sites. We found no difference in abundance or diversity of small mammals between riparian and upland habitats. We suggest that sampling for inventory and monitoring purposes should be stratified by edge and interior locations to provide an accurate representation of diversity and abundance of small-mammal populations.

Effects of highway construction on stream water quality and macroinvertebrate condition in a Mid-Atlantic Highlands watershed, USA.

Refining best management practices (BMPs) for future highway construction depends on a comprehensive understanding of environmental impacts from current construction methods. Based on a before-after-control impact (BACI) experimental design, long-term stream monitoring (1997-2006) was conducted at upstream (as control, n = 3) and downstream (as impact, n = 6) sites in the Lost River watershed of the Mid-Atlantic Highlands region, West Virginia. Monitoring data were analyzed to assess impacts of during and after highway construction on 15 water quality parameters and macroinvertebrate condition using the West Virginia stream condition index (WVSCI). Principal components analysis (PCA) identified regional primary water quality variances, and paired t tests and time series analysis detected seven highway construction-impacted water quality parameters which were mainly associated with the second principal component. In particular, impacts on turbidity, total suspended solids, and total iron during construction, impacts on chloride and sulfate during and after construction, and impacts on acidity and nitrate after construction were observed at the downstream sites. The construction had statistically significant impacts on macroinvertebrate index scores (i.e., WVSCI) after construction, but did not change the overall good biological condition. Implementing BMPs that address those construction-impacted water quality parameters can be an effective mitigation strategy for future highway construction in this highlands region.

Decomposition Trends of Five Plant Litter Types in Mitigated and Reference Wetlands in West Virginia, USA

Decomposition of organic matter in wetlands is linked to numerous wetland processes, making it a useful metric to assess wetland function. We measured plant litter decomposition rates in three mitigated and three reference wetlands located in the Allegheny Mountains of West Virginia, from 2007 to 2009. Four common wetland species were used: broadleaf cattail (Typha latifolia L.), common rush (Juncus effusus L.), brookside alder (Alnus serrulata (Ait.)Willd.), and reed canary grass (Phalaris arundinacea L.). A fifth litter type was created from a mixture of common rush, brookside alder, and reed canary grass. Decomposition rates, based on percent of mass remaining, were similar between mitigated and reference wetlands. Percent mass remaining for reed canary grass was lower than all other litter types at the end of the study, and was significantly lower than cattail, which had the largest percent mass remaining on eight of the 14 collection dates. Linear decomposition rate constants for common rush, reed canary grass, and the mixed litter were similar, but were significantly larger than broadleaf cattail and brookside alder. Though some previous studies have found differing decomposition rates in mitigated and reference wetlands, this study observed similar environmentally mediated decomposition rates of a homogenized plant litter.

Yeasts in mound soil of the red imported fire ant.

Soil yeast occurrence and abundance was studied in brood chambers within mounds of the red imported fire ant, Solenopsis invicta , and adjacent non-mound soil from Texas. Ten yeast species were isolated from fire ant brood chamber soil and 13 from non-mound soil. Relative frequencies of Candida parapsilosis and C. lipolytica were greater in brood chamber soil, and Cryptococcus terreus occurred more frequently in non-mound soil. Rhodoturula rubra, R. minuta , and Candida vini only occurred in non-mound soil. Mean cfu g −1 of soil was greater in brood chamber soil. Fire ants alter the community composition and relative abundance of yeasts within mounds due to creation of unique microhabitat patches.

Effects of Prebaiting on Small Mammal Trapping Success in a Morrow's Honeysuckle–Dominated Area

Abstract Researchers have obtained mixed results in studies that use prebaiting to enhance small mammal trapping success. In 2004–2005 we tested the effects of prebaiting on small mammal trapping success in an exotic and invasive shrub community, Morrows honeysuckle (Lonicera morrowii), using 4 80 × 120-m live trapping grids at Fort Necessity National Battlefield in Fayette County, Pennsylvania, USA. We randomly assigned traps to 1 of 3 trapping methods: we prebaited one-third of the traps 2 nights (n = 3,508 trap-nights), one-third one night (n = 3,492 trap-nights), and one-third had no prebaiting (n = 3,509 trap-nights). We compared small mammal richness, diversity, and relative abundance (no. captures/100 trap-nights) of white-footed mice (Peromyscus leucopus; n = 462 captures), meadow voles (Microtus pennsylvanicus; n = 89 captures), meadow jumping mice (Zapus hudsonius; n = 221 captures), masked shrews (Sorex cinereus; n = 87 captures), and shorttail shrews (Blarina brevicauda; n = 78 captures) among prebaited traps and non-prebaited traps. On the first day of trapping, as well as all 4 days combined, richness, diversity, and relative abundance for all species were similar among traps that we had prebaited for 2 nights, one night, and zero nights (P = 0.856). Moreover, total number of captures was similar among prebaiting treatments (P = 0.197). These results suggest that prebaiting does not enhance trapping success for small mammals in a landscape dominated by a dense, exotic shrub. We recommend that managers do not employ prebaiting in areas with similar small mammal species composition in an attempt to increase trapping success, as we did not record a difference in trapping success in prebaited traps compared to non-prebaited traps.