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We investigated abundance and community structure of soil microarthropods in three stages of a primary successional chronosequence along the Tanana River in interior Alaska: early-successional alder stands, mid-successional balsam poplar stands and late successional white spruce stands. Microarthropod abundances in alder stands were uniformly low and tended to increase in balsam popular stands where abundances were highly variable among sites. White spruce stands had the highest abundances, almost 8 times those of alder sites. Arthropod taxon and Oribatida family richness also increased (alder: 29 taxa, 6 families; balsam poplar: 34 taxa, 10 families; white spruce: 40 taxa, 14 families). Non-metric multidimensional ordination of arthropod taxa indicated microarthropod communities became more similar within stand types later in succession and environmental fit of the site characteristics found organic matter thickness, soil degree days, organic layer phosphorus (P), mineral layer concentrations of carbon (C), nitrogen (N), and manganese (Mn), and white spruce basal area were significant (p < 0.05). Regression analysis indicated prey abundance and predator abundance were positively correlated (R2 = 0.43; p< 0.001). Our findings point to the importance of vegetation, soil development and temperature, site stability, microarthropod colonization time, and possibly predator abundance in shaping these microarthropod communities.
Pre-Euro-American settlement vegetation provides information about historical ecology. I evaluated baseline conditions and novel status of current forests in Michigan using historical (1836 to 1858) and current (2010–2015) surveys and assessed quantitative and qualitative measures of novel status. Aspen (increased from 2% to 11% of all trees) and red maple (<2% to 12.5%) replaced eastern hemlock (15% to 2%) and American beech (8% to <1%) as most abundant species. Density was similar between surveys but mean diameter (trees ≥12.7 cm) decreased from 39 to 22 cm. The emerging forest type is a mix of early- to mid-successional species, particularly red maple, from eastern broadleaf forests of the central-eastern US.Openlands in southern Michigan have been replaced by agriculture and closed forests. Historical forests dominated by few tree species have transitioned to diverse eastern broadleaf forests throughout the eastern US, conforming to quantitative and qualitative measures of novel ecosystem status. Besides exceeding a quantitative threshold (e.g., squared chord distance), current forests meet novel status because they are ubiquitous, constitute a new normal, arise predictably, and unavoidably in response to disturbance or land-use change, auto-organize, and retain novelty after crossing thresholds challenging to reverse.
Distributions of the planktonic foraminifers Globigerinoides ruber (d'Orbigny) and Trilobus sacculifer (Brady) from the tropical-subtropical South Pacific Ocean are related to sea surface temperature (SST), chlorophyll-a, nitrate, phosphate, salinity and oxygen to determine whether their niches overlap. Their distributions in the ForCenS database of species in seafloor sediment are studied as proxies for upper ocean data. In the occurrence analysis (MaxEnt) SST is the strongest predictor of niche suitability followed by chlorophyll-a; environments between 0–20° S are the most suitable for both species: niches are undifferentiated. Contrarily, abundance analysis (Random Forests) identifies nitrate and chlorophyll-a as primary variables for Globigerinoides ruber, and SST and chlorophyll-a for Trilobatus sacculifer. Maximum abundances of the former are predicted in the subtropical hyper-oligotrophic zone while maxima of the latter are predicted at its margins and near the West Pacific Warm Pool. The high relative abundance of Globigerinoides ruber in the hyper-oligotrophic zone is attributed to its photosymbiotic relation with on-board dinoflagellates; this compensates for the low primary productivity in the zone. It is the best-adapted planktonic foraminifer in this huge marine ‘desert’ and is a proxy for hyper-oligotrophic environments. The photosymbiotic relation is weaker in Trilobatus sacculifer which primarily depends on particulate nutrition.
Understanding the ecology and life history of rare species is critical to assessing their conservation status and developing effective management strategies. We examined the habitat and demography of impoverished pinweed (Lechea intermedia var. depauperata), a rare, narrowly endemic post-fire coloniser native to the Athabasca Plain of Canada, using a combination of germination tests, plant community assessments, and microclimate monitoring. In addition, we monitored demographic trends over three years in five of six known extant populations to explore the temporal dynamics of impoverished pinweed populations. Areas supporting impoverished pinweed populations were found to be warmer than adjacent areas during the growing season; however, warmer temperatures did not correlate with higher seed germination. Plant community composition varied little between occupied and unoccupied areas. Demographic assessments suggest the taxon is likely a short-lived perennial, and populations appear to be self-sustaining in the short term. Based on work presented here and in a previous study, we suggest that impoverished pinweed has several characteristics of inherently vulnerable taxa, and we recommend that population trends be monitored over time. Further, we recommend directions for future work to address identified outstanding knowledge gaps.
We report leucism in groups of up to five tayras, Eira barbara, in a fish-bone human settlement in southern Roraima, centre of the Guyana shield of the Brazilian Amazonia, during systematic line transect surveys in Terra Firme forests. These tayras had much larger non-rounded ears, and much larger and robust paws compared to current descriptions of the species. The leucistic individuals were snow-white with the exception of the distal half of the forearms, front paws, and the eyes, which were black. Leucism appeared to be commoner in this region than in the rest of the Guyana shield, as it occurred in a non-isolated population. The leucistic individuals did not appear to face the disadvantages reported in the literature, such as competitive exclusion, or difficulties in intra-specific communication and recognition.
The Riverfly Partnership, launched in 2004, is a UK network of organisations and individuals working to protect river habitats and macroinvertebrate communities. The Riverfly Partnership's Anglers' Riverfly Monitoring Initiative (ARMI), launched in 2007, supports citizen science volunteers to monitor macroinvertebrates in their local rivers. In Manchester and surrounding areas, ARMI monitoring began in 2011 with volunteers from a fishing club active across the Irwell catchment. Whilst there has been mixed success establishing a robust long-term monitoring program, volunteers investigate issues raised by the local community and data provide a baseline against which river pollution events can be compared. For example, in April 2017 citizen scientists responding to a report of dead crayfish by an angler identified a pollution incident resulting in a catastrophic loss of macroinvertebrates along a 19 km reach of the River Irwell. Recognizing the limitations of the ARMI methodology for urban and degraded rivers nationwide led to the development of the Urban Riverfly index through the Riverfly Partnership so that citizen scientists can more effectively contribute to the work of government agencies mitigating urban river pollution. Citizen science has importantly been a catalyst for public engagement and environmental projects which should encourage wider public participation in river catchment management.
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