Novel Ecosystems Hobbs, Richard J; Higgs, Eric S; Hall, Carol
2013, 2012., 2013-01-07, 2013-01-04
eBook
Land conversion, climate change and species invasions are contributing to the widespread emergence of novel ecosystems, which demand a shift in how we think about traditional approaches to ...conservation, restoration and environmental management. They are novel because they exist without historical precedents and are self-sustaining. Traditional approaches emphasizing native species and historical continuity are challenged by novel ecosystems that deliver critical ecosystems services or are simply immune to practical restorative efforts. Some fear that, by raising the issue of novel ecosystems, we are simply paving the way for a more laissez-faireattitude to conservation and restoration. Regardless of the range of views and perceptions about novel ecosystems, their existence is becoming ever more obvious and prevalent in today’s rapidly changing world. In this first comprehensive volume to look at the ecological, social, cultural, ethical and policy dimensions of novel ecosystems, the authors argue these altered systems are overdue for careful analysis and that we need to figure out how to intervene in them responsibly. This book brings together researchers from a range of disciplines together with practitioners and policy makers to explore the questions surrounding novel ecosystems. It includes chapters on key concepts and methodologies for deciding when and how to intervene in systems, as well as a rich collection of case studies and perspective pieces. It will be a valuable resource for researchers, managers and policy makers interested in the question of how humanity manages and restores ecosystems in a rapidly changing world.
We provide an updated analysis of instrumental Greenland monthly temperature data to 2019, focusing mainly on coastal stations but also analysing ice‐sheet records from Swiss Camp and Summit. ...Significant summer (winter) coastal warming of ~1.7 (4.4)°C occurred from 1991–2019, but since 2001 overall temperature trends are generally flat and insignificant due to a cooling pattern over the last 6–7 years. Inland and coastal stations show broadly similar temperature trends for summer. Greenland temperature changes are more strongly correlated with Greenland Blocking than with North Atlantic Oscillation changes. In quantifying the association between Greenland coastal temperatures and Greenland Ice Sheet (GrIS) mass‐balance changes, we show a stronger link of temperatures with total mass balance rather than surface mass balance. Based on Greenland coastal temperatures and modelled mass balance for the 1972–2018 period, each 1°C of summer warming corresponds to ~(91) 116 Gt·yr−1 of GrIS (surface) mass loss and a 26 Gt·yr−1 increase in solid ice discharge. Given an estimated 4.0–6.6°C of further Greenland summer warming according to the regional model MAR projections run under CMIP6 future climate projections (SSP5‐8.5 scenario), and assuming that ice‐dynamical losses and ice sheet topography stay similar to the recent past, linear extrapolation gives a corresponding GrIS global sea‐level rise (SLR) contribution of ~10.0–12.6 cm by 2100, compared with the 8–27 cm (mean 15 cm) “likely” model projection range reported by IPCC in 2019 (SPM.B1.2). However, our estimate represents a lower limit for future GrIS change since fixed dynamical mass losses and amplified melt arising from both melt‐albedo and melt‐elevation positive feedbacks are not taken into account here.
We present an updated analysis of coastal and inland Greenland surface air temperature records, focusing on seasonal temperature trends and correlations with key indices of atmospheric circulation change and changes in ice‐sheet mass balance, and the 2019 high‐melt summer. By quantifying the relation between observed and projected Greenland surface air temperature changes and modelled ice‐sheet mass balance changes, we underscore the likely high sensitivity of the ice sheet to continued global warming, and provide predictions of GrIS surface mass balance change.
ABSTRACT
We present an extended monthly and seasonal Greenland Blocking Index (GBI) from January 1851 to December 2015, which more than doubles the length of the existing published GBI series. We ...achieve this by homogenizing the Twentieth Century Reanalysis version 2c‐based GBI and splicing it with the NCEP/NCAR Reanalysis‐based GBI. For the whole time period, there are significant decreases in GBI in autumn, October and November, and no significant monthly, seasonal or annual increases. More recently, since 1981 there are significant GBI increases in all seasons and annually, with the strongest monthly increases in July and August. A recent clustering of high GBI values is evident in summer, when 7 of the top 11 values in the last 165 years – including the two latest years 2014 and 2015 – occurred since 2007. Also, 2010 is the highest GBI year in the annual, spring, winter and December series but 2011 is the record low GBI value in the spring and April series. Moreover, since 1851 there have been significant increases in GBI variability in May and especially December. December has also shown a significant clustering of extreme high and low GBI values since 2001, mirroring a similar, recently identified phenomenon in the December North Atlantic Oscillation index, suggesting a related driving mechanism. We discuss changes in hemispheric circulation that are associated with high compared with low GBI conditions. Our GBI time series should be useful for climatologists and other scientists interested in aspects and impacts of Arctic variability and change.
Body condition metrics are widely used to infer animal health and to assess costs of parasite infection. Since parasites harm their hosts, ecologists might expect negative relationships between ...infection and condition in wildlife, but this assumption is challenged by studies showing positive or null condition–infection relationships. Here, we outline common condition metrics used by ecologists in studies of parasitism, and consider mechanisms that cause negative, positive, and null condition–infection relationships in wildlife systems. We then perform a meta‐analysis of 553 condition–infection relationships from 187 peer‐reviewed studies of animal hosts, analysing observational and experimental records separately, and noting whether authors measured binary infection status or intensity. Our analysis finds substantial heterogeneity in the strength and direction of condition–infection relationships, a small, negative average effect size that is stronger in experimental studies, and evidence for publication bias towards negative relationships. The strongest predictors of variation in study outcomes are host thermoregulation and the methods used to evaluate body condition. We recommend that studies aiming to assess parasite impacts on body condition should consider host–parasite biology, choose condition measures that can change during the course of infection, and employ longitudinal surveys or manipulate infection status when feasible.
ABSTRACT
UK seasonal mean temperature and precipitation conditions are extremely variable from one year to the next but in the last decade have featured several cool, wet summers and mild, wet ...winters interspersed with some notable cold winter episodes. Jet stream variability is a major determinant of these fluctuations and is often represented by the North Atlantic Oscillation (NAO) index. Recent work has shown some evidence of promising predictability in the winter NAO from 1 to 2 months ahead, while summer predictability remains very limited. Although the phase and magnitude of the NAO influences total UK rainfall, there are regional variations which it does not explain. Here we examine the relationship between UK regional summer and winter precipitation and temperature and a range of North Atlantic atmospheric circulation indices. While the NAO shows a significant relationship with temperature in both seasons and summer rainfall over most of the UK, the picture in winter is more complicated, with other circulation indices such as the East Atlantic pattern explaining rainfall anomalies in southern England. Other indices also show significant relationships with precipitation in regions where the NAO does not. Because UK weather is determined by the interplay between different circulation indices, attention should be given to developing seasonal forecasts of other circulation indices to complement the NAO forecasts. We also find that some potential drivers of jet stream variability are significantly associated with UK temperature and rainfall variability, particularly in summer. This provides further scope for producing seasonal forecasts based directly on these drivers. Improved seasonal forecasts will be useful to a range of end users in agriculture, energy supply, transport and insurance industries and can be extended to other UK weather variables such as extreme rainfall events and storm frequency, and related metrics such as wind power capacity and solar energy.
The winter North Atlantic Oscillation is predictable from a few months ahead, but does not explain all regional UK precipitation and temperature anomalies. We examine associations between a number of circulation indices and UK summer and winter temperature and rainfall patterns. The East Atlantic and Scandinavian patterns explain significant regional variations in UK weather, and some drivers of summer jet stream variability are directly associated with summer temperature and precipitation variability. There is potential to develop improved regional seasonal forecasts.
Recent studies note a significant increase in
high-pressure blocking over the Greenland region (Greenland Blocking Index,
GBI) in summer since the 1990s. Such a general circulation change, indicated
...by a negative trend in the North Atlantic Oscillation (NAO) index, is
generally highlighted as a major driver of recent surface melt records
observed on the Greenland Ice Sheet (GrIS). Here we compare reanalysis-based
GBI records with those from the Coupled Model Intercomparison Project 5
(CMIP5) suite of global climate models over 1950–2100. We find that the
recent summer GBI increase lies well outside the range of modelled past
reconstructions and future GBI projections (RCP4.5 and RCP8.5). The models
consistently project a future decrease in GBI (linked to an increase in NAO),
which highlights a likely key deficiency of current climate models if the
recently observed circulation changes continue to persist. Given
well-established connections between atmospheric pressure over the Greenland
region and air temperature and precipitation extremes downstream, e.g. over
northwest Europe, this brings into question the accuracy of simulated North
Atlantic jet stream changes and resulting climatological anomalies over
densely populated regions of northern Europe as well as of future projections
of GrIS mass balance produced using global and regional climate models.
In this trial, 1-year GVHD-free, relapse-free survival after stem-cell transplantation was 52.7% in the cyclophosphamide–tacrolimus–mycophenolate mofetil group and 34.9% in the ...tacrolimus–methotrexate group.
Landfills provide seasonally reliable food resources to many bird species, including those perceived to be pest or invasive species. However, landfills often contain multiple habitat types that could ...attract diverse species, including those of conservation concern. To date, little is known about the characteristics and composition of bird communities at landfills relative to local and regional pools. Here we used the community science database eBird to extract avian species occurrence data at landfills across the US. We compared species richness and community similarity across space in comparison to similarly-sampled reference sites, and further quantified taxonomic and dietary traits of bird communities at landfills. While landfills harbored marginally lower species richness than reference sites (respective medians of 144 vs 160), landfill community composition, and its turnover across space, were similar to reference sites. Consistent with active waste disposal areas attracting birds, species feeding at higher trophic levels, especially gulls, were more frequently observed at landfills than reference sites. However, habitat specialists including two declining grassland species, Eastern Meadowlark (Sturnella magna) and Savannah Sparrow (Passerculus sandwichensis), as well as migratory waterfowl, were more frequently encountered at landfills than reference sites. Together, these results suggest that landfills harbor comparable avian diversity to neighboring sites, and that habitats contained within landfill sites can support species of conservation concern. As covered landfills are rarely developed or forested, management of wetlands and grasslands at these sites represents an opportunity for conservation.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Individuals experience heterogeneous environmental conditions that can affect within-host processes such as immune defense against parasite infection. Variation among individuals in parasite ...shedding can cause some hosts to contribute disproportionately to population-level transmission, but we currently lack mechanistic theory that predicts when environmental conditions can result in large disease outbreaks through the formation of immunocompromised superspreading individuals. Here, I present a within-host model of a microparasite’s interaction with the immune system that links an individual host’s resource intake to its infectious period. For environmental scenarios driving population-level heterogeneity in resource intake (resource scarcity and resource subsidy relative to baseline availability), I generate a distribution of infectious periods and simulate epidemics on these heterogeneous populations. I find that resource scarcity can result in large epidemics through creation of superspreading individuals, while resource subsidies can reduce or prevent transmission of parasites close to their invasion threshold by homogenizing resource allocation to immune defense. Importantly, failure to account for heterogeneity in competence can result in under-prediction of outbreak size, especially when parasites are close to their invasion threshold. More generally, this framework suggests that differences in conditions experienced by individual hosts can lead to superspreading via differences in resource allocation to immune defense alone, even in the absence of other heterogeneites such as host contacts.
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