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Temperate forests have a strong carbon sink capacity, although the future of this ecosystem service is uncertain in the eastern United States in light of widespread changes affecting succession. This study quantified aboveground carbon accumulation and storage in a southeastern Pennsylvania forest fragment, while assessing whether carbon storage capacity will be supported in the future. Six 0.2 ha plots were censused in 2013 and 2018 for living tree and dead wood carbon storage, as well as tree species composition. Three plots were in a 100-year-old forest, while the remainder were in a 200-year-old forest. Living tree carbon storage increased significantly over time (p < 0.05), although dead wood carbon storage did not. Living tree carbon storage, basal area, and stem density were significantly higher in the younger forest (p < 0.05). The 200-year-old forest lacked small-diameter stems (<30 cm), relative to the younger forest, although both areas contained many large-diameter trees (>60 cm). Compositional data suggest decreased future canopy tree diversity, with the native Fagus grandifolia and nonnative Acer platanoides dominating forest understories. While there is high living tree carbon storage capacity, the dead wood pool will increase over time as many large trees die. Intervention to augment regeneration and maintain sink strength in the 200-year-old forest is needed. Action to limit the spread of A. platanoides and increase native regeneration throughout the forest will support forest resilience and long-term carbon storage capacity. Assessments of understory conditions are critical in supporting forests' carbon sink capacity into the future.
Setting priorities for scarce conservation dollars requires an accurate accounting of the most vulnerable species. For many invertebrates, lack of taxonomic expertise, low detectability, and funding limitations are impediments to this goal, with conservation ranks usually based on expert opinion, the published literature, and museum records. Because of biases and inaccuracies in these data, they may not provide an accurate basis for conservation ranks, especially when compared to de novo field surveys. We assessed this issue by comparative examination of these data sources in re-ranking the conservation status of all 254 land snail taxa reported from Texas, USA. We confirmed 198 land snail taxa, including 34 new state records. Our assessment of the entire land snail fauna of Texas resulted in (1) a near doubling of recommended Species of Greatest Conservation Need (SGCN) and (2) a 79% turnover in the makeup of SGCN taxa. Field sampling strongly outperformed museum and literature data in the encounter rate of both the entire fauna and all SGCN species, with the latter two demonstrating bias toward larger-bodied species. As a result, conservation priorities based solely on expert opinion and museum and literature records may be more wrong than right, with taxon-appropriate, targeted sampling required to generate accurate rankings.
Small streams are a high priority for conservation and an important target for biomonitoring. Stream salamanders are a useful indicator for biotic integrity of headwater streams; however, assessing stream salamanders is a challenging endeavor and existing methods can cause habitat disturbance or require expensive equipment. Our goal was to develop an artificial habitat that mimics the natural habitat that salamanders prefer, leading to rapid colonization and that also (1) represents a standardized area and (2) is easy to handle for rapid assessment. After developing a new artificial habitat (the Maloney Salamander Hotel), we tested the device in a variety of streams and compared our method with other techniques. After a series of field tests in a variety of streams through multiple seasons, we found that stream salamanders will colonize the apparatus and that this method yielded results similar or superior to other methods. For efficient and relatively simple assessment, our results indicate that three devices, left in streams for 3 d, should provide a reliable assessment of salamander presence. The device is relatively inexpensive, simple to build, easily handled for efficient deployment and collection, and does not harm the salamanders. We hope the development of this device provides a useful innovation for biological consultants, land managers, and researchers interested in assessing salamander presence in streams.
Fire managers are increasingly using natural ignitions to restore and maintain fire-adapted ecosystems. Managing natural ignitions after decades of suppression, however, holds inherent ecological, economic, and personal risks. During the severe drought of 2011, fire management staff on the Ouachita National Forest used a range of strategies to manage the lightning-ignited High Peak Wildfire because full suppression was infeasible and there were potential resource benefits (e.g., restoration of desired forest structure and composition). Because of concerns that the combined effect of drought and fire could adversely affect overstory tree health and timber value, we established plots in burned and unburned areas in dry and dry-mesic pine-oak forests and loblolly pine (Pinus taeda) plantations immediately after the fire, and remeasured them 2 and 5 y post-burn. Between inferred pre-burn condition and 2 y post-burn, overstory trees across community types were resistant to fire (94% survival) while midstory trees were less resistant (35% survival). Survival between 2 and 5 y post-burn was near 100% for both overstory and midstory. Both the density and diversity of the midstory were reduced by 2 y post-burn, which had the desired effect of moving forest structure and composition toward an open woodland condition. This study provides evidence that wildfire, even in a drought, can be used in restoration efforts and that overstory trees in dry and dry-mesic pine-oak forests and pine plantations of the Ouachita Mountains can survive with little effect on resource values, provided that weather and fuel conditions are conducive to low- and moderate-severity burning.
Invasional meltdown hypothesizes that invasive species facilitate the establishment of subsequent invaders, with cascading consequences for ecosystem structure and function, including the extirpation of native species. However, meltdown has rarely been tested empirically with large regional data sets, leading to somewhat equivocal support. Recently, the USDA Forest Service initiated sampling of nonnative plants within a subset of their Forest Inventory and Analysis (FIA) plots, presenting an ideal dataset to evaluate meltdown and its consequences across large geographies. We used FIA data from 963 plots across 11 northeastern states to test the predictions of invasional meltdown and to examine the mechanism through which invasion impacts native tree seedling richness. Remeasured plots showed a significant increase in the number and cover of invasive species over time. We provide support for invasional meltdown, finding a pattern of accelerating invasive species richness over 4–5 y in plots with higher initial invasive species richness. Also, we found that plots with higher levels of invasive abundance corresponded to decreased native tree species richness at one point in time and that the magnitude of the relationship appeared to be stronger after 4–5 y. Our results suggest that evidence of invasional meltdown is more clearly evident when examining invasive plant species richness over time; further, invader abundance (measured as cover) is a better predictor of impacts than invader richness, which supports growing evidence that invasive abundance is an important driver of ecological impact.
Physaria kingii subsp. kaibabensis, the Kaibab bladderpod (Brassicaceae), is endemic to the Kaibab Plateau, in Coconino County, Arizona. Due to its limited distribution, state and federal agencies are concerned about its conservation status. However, limited information is available regarding the ecology of this species. To better understand several aspects of its ecology, in 2015 and 2017 the following parameters were assessed at six sites: plant density, habitat assessment (characteristics/disturbances), reproductive ecology (pollination biology, reproductive output, and flower visitors), pre-dispersal seed predators, and seed germination. Overall we found that plant density and habitat characteristics/disturbances varied across time and among sites for Physaria kingii subsp. kaibabensis. In addition, this species requires pollinators for fruit and seed production. At the site level, fruit set, seed set, and seed germination, can be up to 73%, 39%, and 93%, respectively. Also, evidence was found for the presence of pre-dispersal seed predators and gall formers. These studies provide much-needed information to assist with the conservation and management of this endemic species and will assist the US Fish and Wildlife Service with any future listing decisions for the species.
Anthropogenic modifications to the environment have had damaging effects on the wildlife that depend on those natural ecosystems. Specific to Upper Mississippi River fishes, channelization, dams, and loss of floodplain connectivity have all been purported as deleterious. In the face of these habitat modifications, understanding habitat requirements of native species is needed to help guide management and restoration efforts. Furthermore, bluegill (Lepomis macrochirus) are an important indicator species that may provide insight to habitat needs of the broader fish community (e.g., “canary in a coal mine”). Prior research suggests bluegill require a mosaic of habitats throughout all life stages (e.g., main channel to backwater connection). As such, the objective of this study was to identify the habitat needs of bluegill in the Upper Mississippi River. We evaluated bluegill habitat use via electrofishing conducted by the U.S. Army Corps of Engineers’ Long-Term Resource Monitoring (LTRM) element. Electrofishing events (n = 4868) were conducted at three field sites throughout the Upper Mississippi River from 1993 to 2017. Our analysis of catch data (n = 83,352) indicates that bluegill prefer backwater macrohabitat over main channel and side channel habitats. Bluegill abundance varied between microhabitat characteristics. Bluegill catch rates were highest in low-flow areas, with velocities ranging from 0 to 0.09 m/sec. In general, catch rates were highest across all pools in moderately shallow depths (0–1.5 m) and in silty substrates. Management efforts that focus on the preservation of backwater habitat and connectivity to the main channel should help to sustain bluegill populations in the Upper Mississippi River. The information garnered in this study can be used to help direct management efforts that not only favor bluegill, but also other members of the Upper Mississippi River fish community.
Amphibians are under threat from many drivers resulting in declining populations. Restoration and creation of habitat is a method used to reverse amphibian declines. The green and golden bell frog (Litoria aurea) is distributed in southeastern Australia, and is threatened by the fungal pathogen Batrachochytrium dendobatidis (chytrid), an introduced fish (the plague minnow, Gambusia holbrooki), and habitat loss. There have been numerous wetland restoration attempts to combat population declines in this species, which have been largely unsuccessful in producing persisting populations. Here we present a robust model for the creation of breeding habitat for the L. aurea population on Kooragang Island, New South Wales, which is based off thorough review of the literature and past pilot studies and experiments. We describe in detail the habitat, land use history, and wetland habitat design formulation and construction so that the context of the habitat creation is understood and so construction can be repeatable and the design can be further refined. The habitat features passive controls for chytrid and G. holbrooki, and contains the most optimum breeding habitat for L. aurea based upon current knowledge. This is the first attempt in our knowledge to create wetlands in an open system that have the potential to passively manage chytrid.
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