Dispersal-limited detritivores in fire-prone environments: persistence and population structure of terrestrial amphipods (Talitridae)

2016 ◽  
Vol 25 (7) ◽  
pp. 753 ◽  
Author(s):  
L. Menz ◽  
H. Gibb ◽  
N. P. Murphy
Keyword(s):  
Population Structure ◽  
Fire Severity ◽  
Critical Role ◽  
Life History Strategies ◽  
Taxonomic Resolution ◽  
Genetic Analyses ◽  
Limited Dispersal ◽  
In Fire ◽  
The Impact

Invertebrate detritivores play a critical role in the decomposition of litter, an important component of wildfire fuel. Knowledge of invertebrate response to fire is often hampered by taxonomic resolution; however, genetic species identification can enable analysis of fine-scale assemblages and the interaction between dispersal and population recovery. In this study, we ask: do terrestrial amphipod assemblages differ following increasing fire severities and does population structure indicate in situ survival or recolonisation following severe fires? Using seven replicate sites over three fire severities, we measured amphipod abundance at the site of the catastrophic 2009 ‘Black Saturday’ fires in south-east Australia. Genetic analyses to distinguish species and population structure revealed 16 species. Populations of Arcitalitrus sylvaticus were highly structured, suggesting limited dispersal. Amphipod abundance and species richness were not affected by fire severity 3 years after fire. Localised population structure within A. sylvaticus suggests that in situ survival enabled amphipods to repopulate severely burnt sites. The genetic analyses used in this study enabled the detection of unrecognised diversity and population structure in these detritivores. With many detritivores showing similar life history strategies, studies that combine a genetic and ecological approach are essential for understanding the impact of fire on litter decomposition.

scholarly journals Effects of in situ climate warming on monarch caterpillar (Danaus plexippus) development

2015 ◽  
Author(s):  
Nathan P Lemoine ◽  
Jillian N Capdevielle ◽  
John D Parker
Keyword(s):  
Climate Warming ◽  
Host Plants ◽  
Evolutionary Dynamics ◽  
Danaus Plexippus ◽  
Developmental Rate ◽  
Life History Strategies ◽  
Lepidopteran Larvae ◽  
The Impact ◽  
Pupal Mass

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae, but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared on Asclepias tuberosa grown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1˚ C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

scholarly journals Effects ofin situclimate warming on monarch caterpillar (Danaus plexippus) development

PeerJ ◽  
2015 ◽  
Vol 3 ◽  
pp. e1293 ◽  
Author(s):  
Nathan P. Lemoine ◽  
Jillian N. Capdevielle ◽  
John D. Parker
Keyword(s):  
Climate Warming ◽  
Host Plants ◽  
Evolutionary Dynamics ◽  
Danaus Plexippus ◽  
Developmental Rate ◽  
Life History Strategies ◽  
Lepidopteran Larvae ◽  
The Impact ◽  
Pupal Mass

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae but also reduce final pupal mass and increase mortality. Usingin situfield warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared onAsclepias tuberosagrown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1 °C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

scholarly journals Wildfire and topography drive woody plant diversity in a Sky Island mountain range in the Southwest USA

2021 ◽  
Author(s):  
Andrew Barton ◽  
Helen Poulos
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Woody Plant ◽  
Fire Severity ◽  
Alpha Diversity ◽  
Fire Regimes ◽  
Mountain Range ◽  
Gamma Diversity ◽  
In Fire ◽  
The Impact

Aim: Drastic changes in fire regimes are altering plant communities, inspiring ecologists to better understand the relationship between fire and plant species diversity. We examined the impact of a 2011 megafire on woody plant species diversity in an arid mountain range in southern Arizona, USA. We tested recent fire-diversity hypotheses by addressing the impact of the fire severity, fire variability, historic fire regimes, and topography on diversity. Location: Chiricahua National Monument, Chiricahua Mountains, Arizona. USA., part of the Sky Islands of the US-Mexico borderlands. Taxon: Woody plant species. Methods: We sampled woody plant diversity in 138 plots before (2002-2003) and after (2017-2018) the 2011 Horseshoe Two Megafire in three vegetation types and across fire severity and topographic gradients. We calculated gamma, beta, and alpha diversity and examined changes over time in burned vs. unburned plots and the shapes of the relationships of diversity with fire severity and topography. Results: Alpha species richness declined and beta and gamma diversity increased in burned but not unburned plots. Fire-induced enhancement of gamma diversity was confined to low fire severity plots. Alpha diversity did not exhibit a clear continuous relationship with fire severity. Beta diversity was enhanced by fire severity variation among plots and increased with fire severity up to very high diversity, where it declined slightly. Main Conclusions: The results reject the intermediate disturbance hypothesis for alpha diversity but weakly support it for gamma diversity. Spatial variation in fire severity promoted variation among plant assemblages, supporting the pyrodiversity hypothesis. Long-term drought probably amplified fire-driven diversity changes. Despite the apparent benign impact of the fire on diversity, the replacement of two large conifer species with shrubs signals the potential loss of functional diversity, emphasizing the importance of intervention to direct the transition to a novel vegetation mosaic.

scholarly journals Multilayer observation and estimation of the snowpack cold content in a humid boreal coniferous forest of eastern Canada

2021 ◽  
Vol 15 (12) ◽  
pp. 5371-5386
Author(s):  
Achut Parajuli ◽  
Daniel F. Nadeau ◽  
François Anctil ◽  
Marco Alves
Keyword(s):  
Time Series ◽  
Snow Cover ◽  
Snow Water Equivalent ◽  
Critical Role ◽  
Coniferous Forest ◽  
Energy Deficit ◽  
Snow Density ◽  
The Impact ◽  
Snow Temperature

Abstract. Cold content (CC) is an internal energy state within a snowpack and is defined by the energy deficit required to attain isothermal snowmelt temperature (0 ∘C). Cold content for a given snowpack thus plays a critical role because it affects both the timing and the rate of snowmelt. Measuring cold content is a labour-intensive task as it requires extracting in situ snow temperature and density. Hence, few studies have focused on characterizing this snowpack variable. This study describes the multilayer cold content of a snowpack and its variability across four sites with contrasting canopy structures within a coniferous boreal forest in southern Québec, Canada, throughout winter 2017–2018. The analysis was divided into two steps. In the first step, the observed CC data from weekly snowpits for 60 % of the snow cover period were examined. During the second step, a reconstructed time series of modelled CC was produced and analyzed to highlight the high-resolution temporal variability of CC for the full snow cover period. To accomplish this, the Canadian Land Surface Scheme (CLASS; featuring a single-layer snow model) was first implemented to obtain simulations of the average snow density at each of the four sites. Next, an empirical procedure was used to produce realistic density profiles, which, when combined with in situ continuous snow temperature measurements from an automatic profiling station, provides a time series of CC estimates at half-hour intervals for the entire winter. At the four sites, snow persisted on the ground for 218 d, with melt events occurring on 42 of those days. Based on snowpit observations, the largest mean CC (−2.62 MJ m−2) was observed at the site with the thickest snow cover. The maximum difference in mean CC between the four study sites was −0.47 MJ m−2, representing a site-to-site variability of 20 %. Before analyzing the reconstructed CC time series, a comparison with snowpit data confirmed that CLASS yielded reasonable bulk estimates of snow water equivalent (SWE) (R2=0.64 and percent bias (Pbias) =-17.1 %), snow density (R2=0.71 and Pbias =1.6 %), and cold content (R2=0.93 and Pbias =-3.3 %). A snow density profile derived by utilizing an empirical formulation also provided reasonable estimates of layered cold content (R2=0.42 and Pbias =5.17 %). Thanks to these encouraging results, the reconstructed and continuous CC series could be analyzed at the four sites, revealing the impact of rain-on-snow and cold air pooling episodes on the variation of CC. The continuous multilayer cold content time series also provided us with information about the effect of stand structure, local topography, and meteorological conditions on cold content variability. Additionally, a weak relationship between canopy structure and CC was identified.

Too hot to trot? Evaluating the effects of wildfire on patterns of occupancy and abundance for a climate-sensitive habitat specialist

2015 ◽  
Vol 24 (7) ◽  
pp. 921 ◽  
Author(s):  
Johanna Varner ◽  
Mallory S. Lambert ◽  
Joshua J. Horns ◽  
Sean Laverty ◽  
Laurie Dizney ◽  
...  
Keyword(s):  
Fire Severity ◽  
Individual Species ◽  
Small Animals ◽  
Habitat Specialist ◽  
Burned Areas ◽  
Disturbance Regimes ◽  
Thermal Refuge ◽  
Habitat Factors ◽  
In Fire

Wildfires are increasing in frequency and severity as a result of climate change in many ecosystems; however, effects of altered disturbance regimes on wildlife remain poorly quantified. Here, we leverage an unexpected opportunity to investigate how fire affects the occupancy and abundance of a climate-sensitive habitat specialist, the American pika (Ochotona princeps). We determine the effects of a fire on microclimates within talus and explore habitat factors promoting persistence and abundance in fire-affected habitat. During the fire, temperatures in talus interstices remained below 19°C, suggesting that animals could have survived in situ. Within 2 years, pikas were widely distributed throughout burned areas and did not appear to be physiologically stressed at severely burned sites. Furthermore, pika densities were better predicted by topographic variables known to affect this species than by metrics of fire severity. This widespread distribution may reflect quick vegetation recovery and the fact that the fire did not alter the talus microclimates in the following years. Together, these results highlight the value of talus as a thermal refuge for small animals during and after fire. They also underscore the importance of further study in individual species’ responses to typical and altered disturbance regimes.

scholarly journals Multilayer observation and estimation of the snowpack cold content in a humid boreal coniferous forest in eastern Canada

2021 ◽  
Author(s):  
Achut Parajuli ◽  
Daniel F. Nadeau ◽  
François Anctil ◽  
Marco Alves
Keyword(s):  
Time Series ◽  
Snow Cover ◽  
Snow Water Equivalent ◽  
Critical Role ◽  
Coniferous Forest ◽  
Energy Deficit ◽  
Snow Density ◽  
The Impact ◽  
Snow Temperature

Abstract. Cold content (CC) is an internal energy state within a snowpack and is defined by the energy deficit required to attain isothermal snowmelt temperature (0 °C). For any snowpack, fulfilling the cold content deficit is a pre-requisite before the onset of the snowmelt. Cold content for a given snowpack thus plays a critical role because it affects both the timing and the rate of snowmelt. Estimating the cold content is a labour-intensive task as it requires extracting in-situ snow temperature and density. Hence, few studies have focused on characterizing this snowpack variable. This study describes the multilayer cold content of a snowpack and its variability across four sites with contrasting canopy structures within a coniferous boreal forest in southern Québec, Canada, throughout winter 2017–18. The analysis was divided into two steps. In the first step, the observed CC data from weekly snowpits for 60 % of the snow cover period were examined. During the second step, a reconstructed time series of CC was produced and analyzed to highlight the high-resolution temporal variability of CC for the full snow cover period. To accomplish this, the Canadian Land Surface Scheme (CLASS; featuring a single-layer snow model) was first implemented to obtain simulations of the average snow density at each of the four sites. Next, an empirical procedure was used to produce realistic density profiles, which, when combined with in situ continuous snow temperature measurements from an automatic profiling station, provides a time series of CC estimates at half-hour intervals for the entire winter. At the four sites, snow persisted on the ground for 218 days, with melt events occurring on 42 of those days. Based on snowpit observations, the largest mean CC (−2.62 MJ m−2) was observed at the site with the thickest snow cover. The maximum difference in mean CC between the four study sites was −0.47 MJ m−2, representing a site-to-site variability of 20 %. Before analyzing the reconstructed CC time series, a comparison with snowpit data confirmed that CLASS yielded reasonable estimates of the snow water equivalent (SWE) (R2 = 0.64 and percent bias (Pbias) = −17.1 %), bulk snow density (R2 = 0.71 and Pbias = 1.6 %), and bulk cold content (R2 = 0.90 and Pbias = −2.0 %). A snow density profile derived by utilizing an empirical formulation also provided reasonable estimates of cold content (R2 = 0.42 and Pbias = 5.17 %). Thanks to these encouraging results, the reconstructed and continuous CC series could be analyzed at the four sites, revealing the impact of rain-on-snow and cold air pooling episodes on the variation of CC. The continuous multilayer cold content time series also provided us with information about the effect of stand structure, local topography, and meteorological conditions on cold content variability. Additionally, a weak relationship between canopy structure and CC was identified.

The interplay between hydrological flushing and biogeochemical cycling in a 3rd order stream

2021 ◽  
Author(s):  
Magdalena Bieroza ◽  
Ann Louise Heathwaite
Keyword(s):  
Water Quality ◽  
High Resolution ◽  
Critical Role ◽  
Biogeochemical Cycling ◽  
Quality Data ◽  
Storm Event ◽  
Order Stream ◽  
Water Quality Data ◽  
The Impact

<p>High-resolution water quality data obtained with <em>in situ</em> sensors and analysers coupled to flow discharge records can reveal critical information on hydrochemical and biogeochemical functioning of aquatic ecosystems. In this study we explore a rich high-resolution hydrochemical dataset to synthesise the impact of hydrological flushing and biogeochemical cycling on water quality in a 3<sup>rd</sup> order groundwater-fed stream draining an agricultural catchment dominated by grassland.Our results show that despite large storm to storm diversity in hydrochemical responses, storm event magnitude and timing have a critical role in controlling the type of mobilisation, flushing and cycling behaviour. These results can be used to evaluate pollution risks in streams and their effects on freshwater quality.</p>

scholarly journals Effects of in situ climate warming on monarch caterpillar (Danaus plexippus) development

2015 ◽  
Author(s):  
Nathan P Lemoine ◽  
Jillian N Capdevielle ◽  
John D Parker
Keyword(s):  
Climate Warming ◽  
Host Plants ◽  
Evolutionary Dynamics ◽  
Danaus Plexippus ◽  
Developmental Rate ◽  
Life History Strategies ◽  
Lepidopteran Larvae ◽  
The Impact ◽  
Pupal Mass

Climate warming will fundamentally alter basic life history strategies of many ectothermic insects. In the lab, rising temperatures increase growth rates of lepidopteran larvae, but also reduce final pupal mass and increase mortality. Using in situ field warming experiments on their natural host plants, we assessed the impact of climate warming on development of monarch (Danaus plexippus) larvae. Monarchs were reared on Asclepias tuberosa grown under ‘Ambient’ and ‘Warmed’ conditions. We quantified time to pupation, final pupal mass, and survivorship. Warming significantly decreased time to pupation, such that an increase of 1˚ C corresponded to a 0.5 day decrease in pupation time. In contrast, survivorship and pupal mass were not affected by warming. Our results indicate that climate warming will speed the developmental rate of monarchs, influencing their ecological and evolutionary dynamics. However, the effects of climate warming on larval development in other monarch populations and at different times of year should be investigated.

The Laryngeal Epithelium in Reflux

2011 ◽  
Vol 21 (3) ◽  
pp. 112-117 ◽  
Author(s):  
Elizabeth Erickson-Levendoski ◽  
Mahalakshmi Sivasankar
Keyword(s):  
Laryngopharyngeal Reflux ◽  
Critical Role ◽  
Structure And Function ◽  
Laryngeal Disease ◽  
Health And Disease ◽  
And Function ◽  
The Impact

The epithelium plays a critical role in the maintenance of laryngeal health. This is evident in that laryngeal disease may result when the integrity of the epithelium is compromised by insults such as laryngopharyngeal reflux. In this article, we will review the structure and function of the laryngeal epithelium and summarize the impact of laryngopharyngeal reflux on the epithelium. Research investigating the ramifications of reflux on the epithelium has improved our understanding of laryngeal disease associated with laryngopharyngeal reflux. It further highlights the need for continued research on the laryngeal epithelium in health and disease.

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