At Smith Falls State Park in northern Nebraska, a relict population of Populus × smithii, a hybrid of quaking aspen (P. tremuloides) and bigtooth aspen (P. grandidentata), has been targeted for management due to its rarity and risk of extirpation. This relict occurs under favorable microclimatic conditions in springbranch canyons along the Niobrara National Scenic River, but factors such as climate change, lack of regeneration, and competition with invasive juniper (Juniperus virginiana) make its persistence tenuous. This study was designed to assess the overall health of the Smith Falls aspen population and determine whether individual stands (n = 10) differed in condition, whether these differences in condition were related to environmental or demographic variables, and whether the condition of the stands was worsening. We found evidence of a declining aspen population, with crown loss and limb dieback documented across all size classes and worsening over a period of two y. Trees from younger, smaller size classes displayed less damage than older, larger ones, but accrued more damage over the two-y interval. At the stand level, higher levels of damage occurred in stands with larger area, more individual boles, and larger, older trees. Our findings suggest that this unique relict population of aspen is showing significant signs of decline but has potential to survive if managed with ecological principles of succession in mind.

Farmland in the Upper Midwest, USA, planted to corn has increased significantly in the past decade due to a rush toward ethanol production for fuel. Much of this increase came from fields that were previously protected under the Conservation Reserve Program (CRP), a Federal land retirement incentive. This Geographic Information Systems (GIS) study quantifies these land changes in Minnesota, a northern state in the U.S. Corn Belt, prior to the past decade using 1997 and 2008 CRP GIS data layers for individual fields. Currently available CRP enrollment data by county masks significant changes occurring on a field-level scale, data which is no longer publicly available. Results suggest that marginal lands better suited for riparian wildlife habitat and surface water protection were plowed under in favor of industrial corn production. This was especially notable with fields in close proximity to refineries or those in drinking water supply management or groundwater contamination susceptibility areas. Federal ethanol mandates, farm bill policies, and high corn prices contribute to the pressure to farm these sensitive lands. Currently, CRP enrollments are capped at 9.7 million hectares, reduced from a long-standing 13-million-hectare cap by the 2014 farm bill. Discussions are now underway in the U.S. Congress to craft the 2018 farm bill and farming and conservation interests are strongly urging the Federal government to restore the 13-million-hectare enrollment cap. Ecosystem functions and benefits are optimized when conservation efforts are maintained over long periods and not interrupted by short-term political or economic trends.

Disturbances, including wildfire, play an important role in forest maintenance, and have been modified over time. Determining the importance of historical disturbance can be complex, especially if disturbance regimes differ over a species' range. Pinus rigida (pitch pine) is associated with wildfire in the core of its range; however, the association becomes less certain toward its range margins, including at the northeast extent of its range in the Thousand Islands Ecosystem (TIE), Ontario, where the species is rare. To test for fire dependence of seedling recruitment in a natural pitch pine population at this range limit, we compared the efficiency of prescribed fire to mechanical and control treatments. We used a Before–After Control–Impact (BACI) design at two sites in the TIE, controlling for the effects of canopy cover, understory cover, and depth to mineral soil. Pitch pine seedlings were observed for the first time in decades in the TIE following treatment; only fire had a significant positive effect on recruitment. Our results suggest that prescribed fire is effective in increasing pitch pine seedling recruitment even in a marginal natural pitch pine population. We discuss what mechanisms might explain these results, as well as restoration considerations including the potential for modified mechanical disturbance treatments where prescribed fires might not be feasible.

Mesophytic species invasion and the loss of oaks from previously oak-dominated forest communities are two well-documented changes currently affecting the deciduous forests of the Appalachian Mountains. Several previous assessments of these changes prescribe active management to maintain oak. Currently, historically white oak (Quercus alba) dominated mesic stands documented in both the Allegheny Plateau and Ridge and Valley regions show increasing dominance of mesophytic species such as red maple (Acer rubrum) and black birch (Betula lenta). We describe a unique near-xeric, 72-ha tract of old-growth forest within the Ridge and Valley Region. This upland oak-pine, formerly oak-chestnut community, has maintained oak dominance without silvicultural management, despite being greatly impacted from the loss of American chestnut (Castanea dentata), fire suppression, high deer densities, and European gypsy moth (Lymantria dispar) defoliation. A dendroecological analysis of these 200-year-old stands shows persistence of oak through centuries of documented disturbances. These unmanaged old-growth stands have resisted mesophytic species invasion and therefore may provide insight into future compositional patterns and changes of similar upland and ridgeline forests within the Ridge and Valley. The combination of low site quality of ridgelines and ecological disturbances such as defoliation events, which may act as a moderate basal area reduction, allows oaks to persist and maintain dominance without silvicultural intervention. However, fire is recommended for the maintenance of co-dominant fire-dependent species such as Table Mountain pine (Pinus pungens) and herbaceous diversity along these ridge forests.

Nonnative species are a threat to biodiversity as their numbers are increasing in protected areas globally, impacting many ecological processes such as hydrological cycles, fire regimes, and competition. These species possess traits that ease their progression into alpine habitats, which could be a threat to rare and endemic plants in these areas. A prime example of this is in the Gaspésie National Park (Québec) where many nonnative species, such as Poa annua, are progressing in elevation, establishing in alpine habitats inhabited by rare and endemic species. In the case of this study, the impacts of elevation on parental plants and date of collection on seed germinability was determined for mature seeds of P. annua on three mountains in the Gaspésie National Park. Elevation as well as the date of collection did not influence germination of seeds of P. annua, and total germination remained very high (>80%) at high elevations. Therefore, because seed germination is not affected by maternal plant elevation, we assume that the abundance of P. annua may increase in disturbed alpine areas, and management strategies should be developed to counter or mitigate the effects of these invasions.

Kuenzler's hedgehog cactus (Echinocereus fendleri var. kuenzleri [Castetter, P. Pierce & K.H. Schwer.] L.D. Benson) is a federally listed threatened species found in pinyon-juniper habitats in south-central New Mexico, USA. Little is known about effects of prescribed fire on this species. First- and second-year responses of plants burned in the field indicated that fire did not affect frequency of flowering, number of flowers produced, or mortality. In a controlled-burning experiment with a burn barrel there was 100% apparent mortality three mo post-burning; however, plants burned with the equivalent of 1344 kg ha^-1 of excelsior had higher mortality than plants burned with 672 kg ha^-1 of fuel or control plants and there was no difference in mortality between control plants and plants burned with 672 kg ha^-1 of excelsior. There was a negative relationship between plant size and mortality of plants burned with 672 kg ha^-1 of fuel; there was no relationship between mortality and plant size for plants burned with 1344 kg ha^-1 of fuel. Results suggest that fire does not negatively impact plants burned under typical fuel loads in field settings. The use of prescribed fire in habitat where Kuenzler's hedgehog cacti are present should consider fine fuel load.

Genetic analyses can provide important insights for the successful reestablishment or augmentation of populations of endangered plant species. Tiedemannia canbyi (Apiaceae) is an endangered southeastern US coastal plain species whose natural range extends from southwestern Georgia to southeastern North Carolina with a disjunct (approximately 600 km) population in Maryland. T. canbyi currently has only approximately 40 known populations. Thirty nuclear allozyme loci were employed to determine the levels and distribution of neutral genetic diversity within and among 14 populations of T. canbyi and eight populations of its more common and widespread congener, T. filiformis. Both species exhibited relatively high levels of genetic diversity (H_e = 0.185 and 0.284 for T. canbyi and T. filiformis, respectively). The Maryland population of T. canbyi had the lowest overall level of genetic diversity (H_e = 0.089). Genetic differentiation among populations of both species was similar (G_ST = 0.250 and 0.254). Populations of T. canbyi formed two genetically distinct groups, southwest and south-central Georgia vs. eastern Georgia, South Carolina, and Maryland. Six T. filiformis populations from southern and coastal Georgia and coastal South Carolina formed one genetically similar group while an inland population from Georgia and an inland South Carolina population were genetically distinct from each other and from the six coastal populations. Patterns of genetic variation observed for these two Tiedemannia species are most consistent with the different groups of populations having originated from genetically discrete glacial refugia. The value of these results for the restoration and/ or augmentation of T. canbyi populations is discussed.

The US Fish and Wildlife Service (USFWS) uses the five-leaf developmental stage as a signal to the initiation of elongation in smooth brome (Bromus inermis Leyss.). In areas where certain plant community criteria are met, conducting a prescribed burn at elongation onset has reduced smooth brome populations. However, leaf stage identification presents USFWS managers with challenges due to the variability of smooth brome development in tallgrass prairies of the Northern Great Plains. The objective of this research was to develop an alternative method to determine when smooth brome populations reach the targeted 50% elongation by linking accumulated growing degree days and population-level plant phenological stages (mean stage count). We determined smooth brome phenological stages at sites in North Dakota, South Dakota, and Minnesota and calculated the corresponding number of growing degree days (using the base temperature of 0 °C). Linear regression models, correlating phenological stage and growing degree days, determined onset of elongation in the smooth brome population, regardless of leaf stage variation. The average accumulated growing degree days (1256 AGDD) and corresponding standard deviation (±155 AGDD) can be used to predict when 95% of smooth brome populations in northern tallgrass prairies reach 50% elongation. As part of USFWS Native Prairie Adaptive Management program, results will be used to assist management decisions regarding the timing of defoliation in an effort to enhance native plant communities where smooth brome is the dominant invader.

Arum italicum (Italian arum) is a perennial herbaceous geophyte native to parts of Europe, Russia, and northern Africa. It has spread outside of cultivation in northern Europe, Oceania, and the Americas. Leaves emerge in the fall and are shed in the early summer; inflorescences form in the spring and fruits ripen in mid-summer. Successful documented treatment options are limited. To test new chemical control methods, we treated plants in a Washington, D.C., natural area in mid-March with three chemical treatments (triclopyr + metsulfuron methyl, triclopyr alone, glyphosate + metsulfuron methyl), and a control. Cover estimates in the spring and fall showed a decline in cover for treatments that included metsulfuron methyl but not for the triclopyr alone treatment.

Panax quinquefolius, American ginseng, is one of the most valuable non-timber forest products providing provisioning and cultural ecosystem services in eastern temperate forests. Although ginseng has a broad distribution range, populations are declining due to several factors including overharvesting and habitat degradation. We designed experiments to study the effects of soil and aspect on ginseng to better identify potential reintroduction sites. We hypothesized soil and aspect would have a significant effect on ginseng performance. Performance included growth (leaf area, height, number of prongs) and reproduction (inflorescence presence). We predicted ginseng would have greatest performance in calcium-rich loam soil, on north-facing slopes. After four growing seasons, we found only soil had a significant effect on growth. This was a consistent result over four growing seasons. On average, ginseng grown in limed loam soil were 55-mm taller with 20,000 mm² more leaf area and more prongs than ginseng grown in soils lower in calcium. Aspect did not affect any measured variables. Given these results, we suggest identifying soils with higher levels of calcium regardless of aspect as potential ginseng habitat. This experimental study contributes to a more complete understanding of the ecology of ginseng. Further, these results can be incorporated into developing strategies for restoration and management of this valuable species.

After almost a century of absence, gray wolves (Canis lupus) are beginning to recolonize California. Based on current knowledge of wolf habitat use, we developed an expert opinion model to explore the prospects for wolf recovery in Northern California. In our model, we consider the following variables: ungulate prey availability, forest canopy cover, human population density, road density, and livestock distribution. The resulting maps predict favorable wolf habitat and identify areas with high potential for wolf–human conflict in Northern California. Validation and refinement of our model will be possible once California-specific wolf distribution data becomes available. Until then, the preliminary findings from this study can inform management of this endangered species.