Verticillium nonalfalfae is a fungal pathogen being used as an experimental bioherbicide to control Ailanthus altissima (tree-of-heaven). Ailanthus altissima is challenging to manage due to its ability to quickly colonize disturbed areas, grow into dense monospecific stands, and prolifically sucker. Stands of A. altissima are also generally characterized by an increased number and diversity of other invasive species relative to areas without A. altissima. This study directly compares natural regeneration (passive) to active revegetation (active) on understory plant communities and quantifies the establishment of native species following application of the bioherbicide. We installed a paired experiment with six total replicates across three physiographic provinces in Virginia with a control and reference plant community at each site. We applied the bioherbicide, and in tandem with the passive treatment, implemented an active treatment meant to enhance the establishment of native species in the understory of declining A. altissima stands. After two growing seasons, active restoration communities were more similar to the references and experienced increases in native (+ 40.2 +/- 8.3%) and overall (+ 36.8 +/- 7.6%) species richness as well as overall plant cover (+ 26.2 +/- 7.7%). The passive treatment increased only in overall species richness (+ 34.7 +/- 8.6%). However, nonnative species importance indices were unchanged, and native plantings suffered poor establishment rates. Plant communities among the control, active, and passive treatments were heavily influenced by a small selection of other invasive species. Ailanthus altissima-invaded forests pose a challenge to restoration, and active revegetation will be a necessary complement to the bioherbicide alongside additional measures that mitigate other invasive plants.
Bioblitzes are increasingly popular participatory science events aimed at documenting as many species as possible over a predefined period. They enhance community engagement and increase scientific literacy, while also contributing immense amounts of biodiversity data in a relatively short time span. Yet, the value of the biodiversity data generated is rarely quantified. In this study, we used the DeLuca Bioblitz as a case study to develop a biodiversity utility framework and a list of biodiversity metrics to evaluate the biodiversity data contributions from bioblitzes. We calculated summary statistics, including the total number of observations, number of observers, and number of species from the DeLuca Bioblitz. We compared these summary statistics to random polygons of the same area across Florida to evaluate the impacts of bioblitz efforts compared to participatory science generally. Bioblitzes tend to generate more biodiversity data when compared to other random polygons of the same size throughout the state of Florida. Importantly, bioblitz data was collected over a 24-hour period for 4 y, yet it outpaced biodiversity contributions in random polygons with data collected over multiple years on iNaturalist. The bioblitz in our case study also generated key records of new invasive species, new continental records, and records of imperiled species in Florida. Together, these data can help land managers and conservation professionals collect robust data, over a short duration, to create baseline species inventories and document species of concern for both management and conservation.
Caribou (Rangifer tarandus) is an iconic North American species with significant cultural and ecological values. Yet many caribou populations are in decline, including the woodland caribou (R. t. caribou) of the boreal ecotype (hereinafter, boreal caribou) in Quebec. One recommended action to address the threats to boreal caribou is to protect lands from anthropogenic activities. In this study we evaluate whether Quebec's protected area network provides more suitable habitat for boreal caribou than similar but unprotected areas. To do so, we used an expert-based habitat suitability model to estimate relative habitat suitability for boreal caribou in Quebec across 232,480 km2, including 1079 protected areas. We compared average suitability values within each protected area to the average suitability in the surrounding (unprotected) environment. We also assessed whether differences in habitat suitability inside relative to the outside protected areas varied with latitude, time since protection, protected area size, and the level of protection from anthropogenic activities. We found that the habitat suitability for boreal caribou was significantly higher within protected areas than outside them; this was particularly the case when protected areas were recently established, large, and had strict limits on anthropogenic activities. We also found that the difference in suitability increased with latitude in the west but not east of the province. Our findings imply that Quebec's protected area network is largely functioning as intended-limiting human disturbance and preserving natural areas. We suggest that protecting additional land within the boreal caribou distribution could be a "win-win" for the province, moving them toward their target for protected areas under the Kunming-Montreal Global Biodiversity Framework and their obligations to recover boreal caribou.
The Sugarloaf Mountains-Midland Peak Natural Area (SMMPNA) is a new 1191 acre natural area established by the Arkansas Natural Heritage Commission. A previous survey indicated that the SMMPNA includes uncut old-growth forests, with vegetation types classified as oak-hickory, shortleaf pine (Pinus echinata), cedar glade, and Cross Timbers. Selective increment core sampling of mature and old trees, aerial photograph interpretation, and field inspection were used to test the hypothesis that the natural area includes areas of uncut old-growth forest. Cores were extracted from 148 individuals of five target species based on external characteristics associated with longevity in trees such as heavy limbs, canopy dieback, and longitudinally twisted stems. The minimum age of the sample trees was determined with dendrochronology. The oldest sampled individuals were, at least, a 325-year-old eastern red cedar (Juniperus virginiana), a 280-year-old post oak (Quercus stellata), a 250-year-old Pinus echinata, a 119-year-old red oak (Quercus rubra), and an 83-year-old maple-leaf oak (Quercus acerifolia). The steep, dry, infertile soils of the natural area result in slow growth rates and strong ring width sensitivity to growing season climate. The presence of mature to old individuals near the longevity maximum for each species, the xeric noncommercial nature of the forest, the absence of roads, stumps, and other evidence for human disturbance all indicate that the vegetation cover in the study area on East Midland Peak is largely dominated by old-growth forests.
Grassy balds are rare herbaceous communities that occur only at high elevations in the Southern Appalachians. Their long-term persistence in the landscape has been attributed to frequent disturbance, but a lack of recent disturbance has left them susceptible to woody encroachment and colonization by blackberries (Rubus spp.). Management strategies have been initiated in some balds, but few studies have investigated the success of these efforts or their impacts on other plants. Our study evaluated the results of an active management program aimed at controlling blackberries in a grassy bald along the Blue Ridge Parkway in western North Carolina. We quantified the density of blackberries and the low-growing endemic forb mountain angelica (Angelica triquinata) in September 2000. Beginning in 2002, the bald was mowed for two decades at irregular intervals of 1-4 y, and vegetation was inventoried six additional times. The density of blackberry and mountain angelica fluctuated during the study period, but overall blackberry density declined by 40% and mountain angelica density increased by 46%. Blackberry density was a significant predictor of mountain angelica density, although the direction of this relationship varied through time. In the early years of the study, when mowing was more frequent, blackberry density declined and mountain angelica density increased. In later years, blackberry density increased and mountain angelica density declined, coinciding with a lapse in mowing frequency To maintain the herbaceous nature of this grassy bald, a more consistent mowing schedule is recommended, along with strategies to maintain overall plant species diversity.
Riparian ecosystems in the American Southwest store disproportionate amounts of carbon relative to their limited extent, yet their capacity is poorly quantified and threatened by climate and land-use change. We synthesize current knowledge of riparian carbon dynamics in Arizona and New Mexico and combine this with spatial datasets to estimate potential and current carbon storage. We review how climate, hydrology, geomorphic setting, and biota interact to control carbon stored in biomass, large wood, and floodplain soils. Using the national riparian basemap and hydroclimatic data, we map more than 3.5 million hectares of riparian area across Arizona and New Mexico and classify them into "warm & dry" and "cool & dry" climate classes. Applying carbon stock values from a global meta-analysis, we estimate that intact riparian ecosystems could store nearly 400 million Mg C, with National Forest System lands accounting for roughly 10% of this potential. We then use existing vegetation maps to show that only about 56% of mapped riparian extent currently supports riparian vegetation, and that riparian areas on National Forests and Grasslands store about 57% of their potential capacity, with substantial variation among forests. Finally, we report how climate change, water management, land use, livestock grazing, biological invasions, and fire jointly influence carbon pools, and we highlight restoration strategies that could increase or maintain carbon storage in southwestern riparian ecosystems. Together, our synthesis and spatial analysis demonstrate that restoring and conserving riparian ecosystems represents a high-leverage, yet underutilized, opportunity for climate mitigation and adaptation in the American Southwest.
Conservation translocations are an increasingly common and often necessary component of recovering species that have become extirpated from portions of their range. Understanding and ameliorating potential threats that reduce the likelihood of successful population establishment at recipient sites is a key component of successful translocation planning. We examined multiple potential threats, including pathogens, contaminants, and invasive species, as well as habitat suitability and food resources, to assess the feasibility of reintroducing threatened, streamobligate foothill yellow-legged frogs, Rana boylii, to Pinnacles National Park. Foothill yellow-legged frogs were extirpated from this protected area more than half a century ago. Although invasive species, disease, contaminants, food resources, and water temperatures are unlikely to inhibit foothill yellow-legged frog population establishment, potential recipient streams at Pinnacles National Park had shorter hydroperiods and much higher canopy cover than reference streams with extant foothill yellow-legged frog populations. Although the exact cause of extirpation of foothill yellow-legged frogs from Pinnacles National Park is unknown, translocations of foothill yellow-legged frogs to the park are more likely to succeed if riparian canopy cover is reduced and stream hydroperiods increased to better match those at nearby populations. Thoroughly understanding the threats to and characteristics of potential recipient sites could improve the likelihood of success of translocation outcomes in natural areas.
As of 2020, North Dakota was the second largest oil producing and oil reserve state in the country, resulting in extensive land disturbances across its western half. Currently, no federally mandated guidelines exist for the reclamation of oil and gas extraction sites, leaving states to regulate and monitor site recovery, often with limited staff capacity. Inconsistent reclamation requirements and limited oversight make the effectiveness of reclamation activities uncertain. This study aimed to (1) determine if soil properties recover as time since reclamation increases; (2) assess how long reclaimed soil properties take to reach values similar to adjacent undisturbed soil; and (3) evaluate how reclamation influences vegetation growth and presence compared to the surrounding undisturbed areas. To address these objectives, soil bulk density (BD), pH, electrical conductivity (EC), microbial biomass carbon (MBC), permanganate oxidizable carbon (POXC), and gravimetric water content (GWC) were measured, along with conducting vegetation surveys to assess vegetation establishment and ground cover across seven sites reclaimed between 4 and 37 y ago. Results show that the BD, GWC, pH, EC, MBC, and POXC values are more similar to undisturbed areas in older reclamation sites. While the results of this study provide insight into reclamation effectiveness, they reflect only a snapshot of conditions rather than a site's recovery process. More frequent monitoring would help clarify the soil and vegetation recovery process over time and how long it takes for reclamation sites to reflect undisturbed areas in western North Dakota. This information could assist in shaping reclamation methodology in the future.
Managing plant biodiversity in tallgrass prairie ecosystems under changing environmental conditions requires a better understanding of the mechanisms that control and maintain species' distributions. In a landscape with a clear spatial gradient of soil moisture, the concept of "hydrological niche" segregation states that the partitioning of water availability across space significantly explains the pattern of plant community composition and distribution. We evaluated the applicability of this concept to a tallgrass prairie remnant (the Faville Prairie in southern Wisconsin) with a 70-year monitoring history, the Faville Prairie Wisconsin State Natural Area (43.1486N, 88.8779W). We tested the hypothesis that plants occupy distinct hydrological niches by partitioning the soil moisture availability gradient generated by topographic heterogeneity. Using a permanent array of 180 plots across the prairie, we collected plant occurrences in 2022 and topsoil moisture contents monthly from May to August in 2023. We made continuous soil moisture maps with spatial interpolation in ArcGIS Pro. Our results suggest that fine-grained topographic heterogeneity generates significant spatial and temporal variation in soil moisture at Faville. The distribution of plant species differed significantly along the spatial gradient of soil moisture. We describe these species-specific patterns of segregation and posit explanations for each. These results support the conclusion that plants at Faville coexist at a landscape level by segregating based on distinct hydrological niches. This study provides more insight into understanding the mechanisms that govern plant distribution in a tallgrass prairie by taking hydrological affinities of species into account.
