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Vernal pools occur in the glaciated forests of northeastern North America and provide critical breeding and foraging habitat for amphibian and mammal species. Protection for these ephemeral wetlands is not federally mandated, placing them at risk for habitat fragmentation and making them more vulnerable to impacts of climate change. Unlike the northeastern United States, limited information about vernal pools exists for the Great Lakes region, and there is a lack of information about techniques to identify and classify vernal pools using remote sensing and field surveys. At Pictured Rocks National Lakeshore, Michigan, USA, our objectives were to locate vernal pools using true-color, spring leaf-off aerial photography at the 1:12,000 scale, classify vernal pools using modified geomorphological classification systems, and determine landscape associations with soil series and cover type GIS datasets. From the 214 water features identified and categorized via aerial photography, two (water with canopy, water without canopy) of the 12 categories accounted for 91.5% of the pools. The park's 51 vernal pools had a density of 0.19 km-2 and an average surface pool area of 1078.2 m2 (± 387.6). Using basin morphology and geomorphology, vernal pools were divided into the following five classes: classic, complex, kettle-kame, dune-swale, and minor ponds. Vernal pools were associated with three soil series that were characterized by slopes less than 5%, poorly to very poorly drained soils, and a clay content less than 10%. Nearly three-quarters of the vernal pools occurred in the hemlock-hardwood cover type. The conservation and protection of these discrete and small ephemeral wetlands should be considered within a landscape context, as subsets of vernal pools have specific geomorphology, soil series, and cover type associations.
Running buffalo clover (Trifolium stoloniferum) is a federally endangered plant that was historically abundant and widespread from Kansas to West Virginia. Here we describe population trends and patch-scale population characteristics of T. stoloniferum based on more than two decades of sampling at the Blue Grass Army Depot in central Kentucky, the site with the most patches of this species across its extant range. A total of 168 patches of T. stoloniferum have been discovered at the site since 1992. Beginning in 2001, we conducted counts of individual ramets and inflorescences in each patch, and observed a range of 1160–9574 ramets and 54–2054 inflorescences per year from 2001 to 2014. While the number of individual ramets and inflorescences fluctuated widely among years, patches have steadily disappeared. Of all patches known since 1992, 66% are extirpated. The size of a T. stoloniferum patch is strongly related to its probability of persistence: patches with 20 or fewer ramets had a 50% chance of disappearing over a ten year period. Population viability analysis suggests <75% probability of extinction for 9 of 11 US Fish and Wildlife Service designated populations, but confidence intervals for 5 out of 11 populations include a 95% chance of extinction within 20 years. These findings highlight the importance of conducting more intensive population studies and developing better management strategies.
Fort De Soto Park (Pinellas County, Florida) encompasses several barrier islands and is accessible to the public by road. Over 32 ha of beach are closed to the general public to allow birds to nest, loaf, and forage without human disturbance. The objective of this study was to use video monitoring of the closed area to determine when intrusions into the protected area occurred and to see if publicizing that the area is being video monitored increased compliance. We randomly chose 400 hours of daylight video from April through August, 2013, to determine the number of intruders. In the middle of the peak nesting season (July 2) we placed signs informing the public that they were being monitored. During the 349 hours where video quality was high, we had 27 hours where at least one intruder entered the area and 144 intruders total. Most of the intrusions were in the evening (1600–1900), during low tide, and on days with higher attendance. Signage communicating video recording of the bird sanctuary led to a strong negative impact on intrusion and was statistically significant (P = 0.01). The combination of using video cameras and signs informing the public about the video cameras was a highly effective method of reducing the number of people entering a closed portion of beach.
Montane longleaf pine (Pinus palustris) forests are rare and no detailed inventory exists documenting stands in North Carolina. We inventoried all longleaf pine trees (n = 403) growing in a 24-ha remnant montane longleaf pine forest in the Uwharrie Mountains of central North Carolina, USA, in autumn 2014 to (1) map their location, (2) document age/height/diameter characteristics, and (3) determine special ecological features of this rare montane population. All longleaf pine were geographically referenced via GPS, measured for height and diameter, and a subsample of trees was cored to determine age. All longleaf pine were mapped based on growth-stage categories—grass, juvenile, young adult, and mature—to determine spatial patterning of stand-age characteristics. The longleaf pine stand contains a variety of growth-stage categories, but is dominated (63%) by mature-stage trees growing on south- and southwestern-facing slopes, while nearly all regeneration-stage trees (i.e., grass and juvenile) are growing on northwest-facing slopes, suggesting environmental conditions conducive to establishment have changed. Median (maximum) tree height and trunk diameter for young adult and mature were 17 (25) m and 38 (72) cm, respectively. Median (maximum) tree age at 0.3 m height was 116 years (272 years), and at least seven trees were greater than 150 years old, with four trees establishing in the 18th century. We conclude that the stand's characteristics—400 trees of various ages including old-growth, occurring principally on steep, southerly slopes with a total relief of 85 m, and extending over 24 ha—warrant “montane” longleaf pine forest status in North Carolina.
This study examines the impacts of European fire ants on arboreal insect abundance and diversity in Acadia National Park, Maine. Abundance and diversity were quantified via arboreal pitfall traps that were checked every three days for 21 days from May to June 2009. In areas infested with European fire ants, arboreal insect abundance declined, but arboreal insect species richness remained unchanged. This study illustrates the importance of examining the ecological links between canopies and leaf litter and demonstrates the breadth of impacts that biological invasions can have in an ecosystem.
During the past decade, three previously undescribed vascular plant species have been documented growing on Mancos Shale barrens in southwest Colorado. Soil chemistry has been correlated with the presence of some rare endemics elsewhere, such as species growing on serpentine soils. However, research on shale barrens suggests that structural components, rather than unique chemistry, more strongly influence endemism on this substrate. The effect of the structural characteristics of the barrens soil was examined in connection with the presence of cushion bladderpod (Physaria pulvinata), a rare barrens endemic. The results suggest that P. pulvinata may be uniquely suited to the shallow soil and low moisture characteristic of the shale barrens habitat. The need for long-term monitoring and management is discussed.
Bigtooth maple (Acer grandidentatum Aceraceae) is found in scattered relict populations across the southern Intermountain West of North America. The quadrat procedure was used to examine the woody plant population in a mesic site (canyon bottom near stream), a thirty-year-old deer exclosure (slightly upslope), and a xeric site (more upslope with shallower soil) at Lost Maples State Natural Area in Central Texas. All woody plants were identified, categorized as trees, saplings, or seedlings, and counted. The circumference of trees was measured. Bigtooth maple had the highest density of all seedling species, with its highest density at the mesic site and lowest in the exclosure. Both sapling and tree densities were highest in the exclosure. The mesic site did not contain bigtooth maple trees. Bigtooth maple total basal area was higher in the exclosure than at the xeric site, which had larger but fewer trees. Additionally, fifteen first-year seedlings were planted inside the exclosure and at the xeric site. One-year mortality was 100% at the xeric site and 67% in the exclosure. The presence of large vertebrate herbivores seems to affect significantly the survival and density of juvenile bigtooth maple, suggesting that browsing is a primary cause of recruitment failure in Central Texas relict populations.
We identified prey items being delivered by adult Canyon Wrens (Catherpes mexicanus) to nestlings on public lands in northern Colorado using digital photography. Adult wrens delivered single invertebrate prey items from 11 orders in four classes: Insecta, Arachnida, Malacostraca, and Chilopoda. Within Insecta and Chilopoda, we describe invertebrates from four families not previously documented as Canyon Wren prey: Noctuidae, Rhaphidophoridae, Formicidae, and Scutigeridae. Our observations align with previous studies in other locations indicating that insects and spiders are key components of the Canyon Wren diet. Moreover, our data show that additional locally available invertebrates including centipedes, isopods, and winged ants are captured to provision nestlings. Prey identification from digital imagery is a nondestructive sampling technique that can effectively be implemented for songbirds, and may be suited for citizen science monitoring programs on public lands.
The invasive annual grass Bromus tectorum (cheatgrass) creates multiple challenges as it spreads across the Great Basin, fueling repeated wildfires and dominating large expanses of land that were once sagebrush shrublands. The replacement of shrublands by annual grasslands has been widespread and much research has focused upon loss of wildlife habitat, altered fire regimes, and degraded ecosystem function. Monitoring of short-term plant community reassembly occurs in these systems, but considerably less is known about the long-term succession of native plant communities after fire. Using repeated measures in time over a 66-year period, we examined the species composition of two shrubland sites in the Great Basin. The sites burned completely in 1947 and density data on herbaceous species were reported one year and 41 years after the fire. At both sampling intervals, B. tectorum and other annual invasive species, dominated the sites. Our resampling 25 years later found B. tectorum no longer maintained dominance on the north-facing site and native grasses were common. The south-facing site still contained a high density of B. tectorum, but it was four times less abundant than in previous years. Our results are consistent with the few studies using historical data that show, in some instances, desert shrublands can transition out of an annual dominated state into a native perennial state over decadal time scales without intervention. This study highlights the importance of repeated long-term studies for improving development of restoration plans and state-and-transition models, as community trajectories may not be apparent for more than five decades following disturbance.
Land management practices, invasive species expansion, and changes in the fire regime greatly impact the distribution of native plants in natural areas. Wyoming big sagebrush (Artemisiatridentata ssp. wyomingensis), a keystone species in the Great Basin, has seen a 50% reduction in its distribution. For many dryland species, reestablishment efforts have focused on direct seeding but achieved only minor success due to irregular seed germination and poor survival. We investigated the effects of container volume and fertilization on the performance of nursery-grown Wyoming big sagebrush seedlings following outplanting. Additionally, to evaluate the impact of site preparation, one-year-old seedlings were outplanted into tilled and untilled field conditions. Initial seedling size increased with container volume; larger seedlings exhibited significantly higher root collar diameter (RCD) growth than smaller seedlings. As container volume increased from 108 to 251 and 336 cm3, seedling survival on the tilled plot increased from 28 to 44 and 43%, respectively, whereas no influence was observed on the untilled plot (57 to 61, and 60%, respectively). Fertilization reduced seedling survival on tilled (by 25%) and untilled (by 14%) plots. Fertilizer increased RCD growth on the untilled plot but final nutrient status was unaffected. Thus, container volume may influence seedling morphology and optimize establishment, while field fertilization, especially during spring outplanting when planting sites have low moisture availability, may hinder first-year survival.
Wilderness management objectives and wildlife conservation objectives often conflict with each other, despite conservation being one of six basic reasons for which wilderness is established. Most wilderness areas appear to have been established as the result of political or societal desires, but in the absence of critical ecological thought. In an era of increasing anthropogenic impacts to wildlife populations and to wildlife habitat outside of wilderness, those ostensibly “pristine” areas in and of themselves will become less and less effective as conservation tools, particularly for large, vagile mammals. Impacts occurring outside of wilderness areas have ramifications for wide-ranging animals that use those areas during portions of their annual cycles, thereby affecting wilderness character. Similarly, impacts occurring inside of designated wilderness also have ramifications for large, vagile mammals that also utilize proximate lands. There is a need to re-ignite the debate over the value of wilderness, both in the context of its societal role, as well as that of a conservation strategy. It is essential that wildlife conservation be elevated to the same level of importance that is accorded solitude and other subjective attributes of wilderness.
Rare species recovery presents several challenges for conservation managers, particularly when listed species interact with one another. We present a case study involving two such species: golden paintbrush (Castilleja levisecta) and Taylor's checkerspot butterfly (Euphydryas editha taylori), both of which occur in lowland prairies in the Puget Sound region and are federally protected (threatened and endangered, respectively). These two species occupy some of the same sites, and golden paintbrush likely historically served as a larval food plant for Taylor's checkerspot. Managers working to recover these species have encountered a number of challenges and opportunities—recovery efforts for one species may have no effect, positive effects, or negative effects on the other. Furthermore, sometimes rapid recovery actions are necessary on shorter time scales than those at which research typically occurs, and must proceed in spite of significant knowledge gaps. Here we share how our growing understanding of the complex ecology of these species has given rise to large-scale management questions and conflicts, and outline the strategies we are using to navigate these challenges. Our approach has included convening periodic workshops with experts on both species; designing and implementing research studies to fill knowledge gaps about the two species' relationship; and identifying “no regrets” actions that can be taken to benefit one or both species with minimal risk in the face of uncertainty. While the details of this case study are highly specific, the lessons can be applied to other systems with interacting listed species.
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