scholarly journals The hummingbird and the hawk-moth: Species distribution, geographical partitioning, and macrocompetition across the United States

2017 ◽  
Author(s):  
Abdel Halloway ◽  
Christopher J. Whelan ◽  
Joel S. Brown
Keyword(s):  
United States ◽  
Species Richness ◽  
Atmospheric Pressure ◽  
Summer Precipitation ◽  
Niche Overlap ◽  
The United States ◽  
Hawk Moth ◽  
Moth Species ◽  
Richness Patterns ◽  
Summer Time

ABSTRACTWe introduce a new concept called macrocompetition – defined as the mutual suppression of diversity/species richness of competing clades – and investigate evidence for its existence. To this end, we analyzed the distribution of two convergent nectarivorous families, hawk-moths and hummingbirds, over the continental United States to determine whether there is geographic partitioning between the families and its potential causes. Using stepwise regression, we tested for latitudinal and longitudinal biases in the species richness of both taxa and the potential role of 10 environmental variables in their distribution pattern. Hawk-moth species richness increases with longitude (eastward-bias) while that of hummingbirds declines (westward-bias). Similar geographic patterns can be seen across Canada, Mexico and South America. Hawk-moth species richness is positively correlated with higher overall temperatures (especially summer minimums), atmospheric pressure, and summer precipitation; hummingbird species richness is negatively correlated with atmospheric pressure and positively correlated with winter daily maxima. The species richness patterns reflect each family’s respective anatomical differences and support the concept of macrocompetition between the two taxa. Hawk-moth species richness was highest in states with low elevation, summer-time flowering, and warm summer nights; hummingbird species richness is highest in the southwest with higher elevation, greater cool season flowering and high daytime winter temperatures. Hawk-moths and hummingbirds as distinct evolutionary technologies exhibit niche overlap and geographical partitioning. These are two of three indicators suggested by Brown and Davidson for inter-taxonomic competition. We intend the patterns revealed here to inspire further exploration into competition and community structuring between hawk-moths and hummingbirds.

scholarly journals Avian Breeding Season Diversity and Community Composition in Camden White Gum and Slash Pine Plantations

2021 ◽  
Author(s):  
Elizabeth J Messick ◽  
Christopher E Comer ◽  
Michael A Blazier ◽  
T Bently Wigley
Keyword(s):  
United States ◽  
Species Richness ◽  
Community Composition ◽  
Pinus Elliottii ◽  
The United States ◽  
Slash Pine ◽  
Planted Forests ◽  
Eucalyptus Plantation ◽  
Short Rotation Woody Crops ◽  
Eucalyptus Plantations

Abstract In the southern United States, some landowners have established plantations of eucalyptus (Eucalyptus spp.) and are managing them on short rotations (<15 years) to provide wood for fiber and other potential uses. Establishment of short-rotation woody crops dominated by nonnative species has implications for resident fauna in the United States that are largely unknown. We compared avifauna abundance, diversity, and community composition in newly established Camden white gum (Eucalyptus benthamii) plantations with slash pine (Pinus elliottii) plantations of the same age and height (one to two and six to seven years old, respectively) in southwestern Louisiana, USA. Species richness, diversity, and community composition in newly established eucalyptus plantations and six- to seven-year-old pines were similar. More birds were observed, and bird detections varied less in eucalyptus plantations. Indigo buntings (Passerina cyanea) and other shrub-associated species were detected more often in eucalyptus stands. In contrast, species that inhabit herbaceous-dominated communities, such as eastern meadowlarks (Sturnella magna), or that were associated with a dense graminoid community (e.g., Bachman’s sparrow [Peucaea aestivalis]) were detected less often in eucalyptus. Overall, breeding bird communities in eucalyptus plantations one to two years postestablishment differed little from plantations dominated by slash pine. Study Implications Compared with slash pine (Pinus elliottii Englem) plantations of similar age and height (one to two years and six to seven years old, respectively) we found one- to two-year-old eucalyptus (Eucalyptus benthamii Maiden & Cambage) plantations supported similar avian species richness and diversity to six- to seven-year-old pine stands. Furthermore, we found these eucalyptus plantations (E13) supported an avian community that was intermediate to similar aged pine (S13) and pine of similar height (S08). However, avian communities will likely change as eucalyptus plantations age (Christian et al. 1997). Continued monitoring and assessment of community composition, richness, and abundance is important for determining the magnitude of this change. Future investigations focused on nest success, fecundity, postfledging monitoring, and survivorship compared with other types of planted forests and native cover types would help us better understand eucalyptus plantation effects on avifauna demographics (Van Horne 1983, Martin 1998, Jones 2001, Wood et al. 2004, Sage et al. 2006, Riffell et al. 2011).

scholarly journals Understory Vegetation Richness and Diversity of Eucalyptus benthamii and Pinus elliottii Plantations in the Midsouth US

2019 ◽  
Author(s):  
Andrea De Stefano ◽  
Michael A Blazier ◽  
Christopher E Comer ◽  
Thomas J Dean ◽  
T Bently Wigley
Keyword(s):  
United States ◽  
Species Richness ◽  
Soil Ph ◽  
Pinus Elliottii ◽  
The United States ◽  
Slash Pine ◽  
Understory Vegetation ◽  
Understory Species ◽  
Species Richness And Diversity ◽  
The Impact

Abstract In the Western Gulf region of the United States cold-tolerant eucalyptus have been explored as pulpwood feedstock. However, non-native plantations may alter understory species diversity, modifying environmental conditions and soil characteristics. Few studies have compared eucalyptus plantations with native ecosystems to understand the impact on understory vegetation in the United States. In this study, we compared understory plant species richness and diversity during 2014–2016 in (1) slash pine (Pinus elliottii) established in 2008, (2) slash pine established in 2013, and (3) and Camden white gum (Eucalyptus benthamii) established in 2013. Overstory characteristics, soil pH, and soil nutrient concentrations were measured to understand factors that affected understory species richness and diversity. Results indicated a decline in understory species richness over time, with Camden white gum in an intermediate condition between same-age slash pine (highest richness) and older slash pine (lowest richness). Leaf area index, soil pH and K, and tree height were the most important factors influencing understory species richness and diversity. The adoption of fast-growing eucalyptus on these sites will probably accelerate the deterioration of natural habitats and reduce open-condition species in favor of shade-tolerant species, overturning the conservation efforts already put in place by governmental agencies and conservation groups.

scholarly journals Impact of Sea Surface Temperature and Soil Moisture on Summer Precipitation in the United States Based on Observational Data

2011 ◽  
Vol 12 (5) ◽  
pp. 1086-1099 ◽  
Author(s):  
Rui Mei ◽  
Guiling Wang
Keyword(s):  
United States ◽  
Soil Moisture ◽  
Correlation Analysis ◽  
Surface Temperature ◽  
Precipitation Amount ◽  
Summer Precipitation ◽  
The United States ◽  
Sea Surface ◽  
Precipitation Prediction ◽  
The Impact

Abstract This study examines the impact of sea surface temperature (SST) and soil moisture on summer precipitation over two regions of the United States (the upper Mississippi River basin and the Great Plains) based on data from observation and observation-forced model simulations (in the case of soil moisture). Results from SST–precipitation correlation analysis show that spatially averaged SST of identified oceanic areas are better predictors than derived SST patterns from the EOF analysis and that both predictors are strongly associated with the Pacific Ocean. Results from conditioned soil moisture–precipitation correlation analysis show that the impact of soil moisture on precipitation differs between the outer-quartiles years (with summer precipitation amount in the first and fourth quartiles) and inner-quartiles years (with summer precipitation amount in the second and third quartiles), and also between the high- and low-skill SST years (categorized according to the skill of SST-based precipitation prediction). Specifically, the soil moisture–precipitation feedback is more likely to be positive and significant in the outer-quartiles years and in the years when the skill of precipitation prediction based on SST alone is low. This study indicates that soil moisture should be included as a useful predictor in precipitation prediction, and the resulting improvement in prediction skills will be especially substantial during years of large precipitation anomalies. It also demonstrates the complexity of the impact of SST and soil moisture on precipitation, and underlines the important complementary roles both SST and soil moisture play in determining precipitation.

SST–North American Hydroclimate Links in AMIP Simulations of the Drought Working Group Models: A Proxy for the Idealized Drought Modeling Experiments

2010 ◽  
Vol 23 (10) ◽  
pp. 2585-2598 ◽  
Author(s):  
Alfredo Ruiz-Barradas ◽  
Sumant Nigam
Keyword(s):  
United States ◽  
Great Plains ◽  
Working Group ◽  
Climate Model ◽  
Linear Trend ◽  
Summer Precipitation ◽  
The United States ◽  
Precipitation Variability ◽  
Drought Severity ◽  
Model Experiments

Abstract The present study assesses the potential of the U.S. Climate Variability and Predictability (CLIVAR) Drought Working Group (DWG) models in simulating interannual precipitation variability over North America, especially the Great Plains. It also provides targets for the idealized DWG model experiments investigating drought origin. The century-long Atmospheric Model Intercomparison Project (AMIP) simulations produced by version 3.5 of NCAR’s Community Atmosphere Model (CAM3.5), the Lamont-Doherty Earth Observatory’s Community Climate Model (CCM3), and NASA’s Seasonal-to-Interannual Prediction Project (NSIPP-1) atmospheric models are analyzed; CCM3 and NSIPP-1 models have 16- and 14-ensemble simulations, respectively, while CAM3.5 only has 1. The standard deviation of summer precipitation is different in AMIP simulations. The maximum over the central United States seen in observations is placed farther to the west in simulations. Over the central plains the models exhibit modest skill in simulating low-frequency precipitation variability, a Palmer drought severity index proxy. The presence of a linear trend increases correlations in the period 1950–99 when compared with those for the whole century. The SST links of the Great Plains drought index have features in common with observations over both the Pacific and Atlantic Oceans. Interestingly, summer-to-fall precipitation regressions of the warm Trend, cold Pacific, and warm Atlantic modes of annual mean SST variability (used in forcing the DWG idealized model experiments) tend to dry the southwestern, midwestern, and southeastern regions of the United States in the observations and, to a lesser extent, in the simulations. The similarity of the idealized SST-forced droughts in DWG modeling experiments with AMIP precipitation regressions of the corresponding SST principal components, evident especially in the case of the cold Pacific pattern, suggests that the routinely conducted AMIP simulations could have served as an effective proxy for the more elaborated suite of DWG modeling experiments.

scholarly journals Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

2016 ◽  
Vol 113 (15) ◽  
pp. 4086-4091 ◽  
Author(s):  
Samuel M. Simkin ◽  
Edith B. Allen ◽  
William D. Bowman ◽  
Christopher M. Clark ◽  
Jayne Belnap ◽  
...  
Keyword(s):  
United States ◽  
Species Richness ◽  
Plant Species ◽  
Plant Species Richness ◽  
The United States ◽  
N Deposition ◽  
Soil Conditions ◽  
Atmospheric Nitrogen ◽  
General Response ◽  
Negative Relationships

Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these environmental factors. We assessed the effect of N deposition on herbaceous richness for 15,136 forest, woodland, shrubland, and grassland sites across the continental United States, to address how edaphic and climatic conditions altered vulnerability to this stressor. In our dataset, with N deposition ranging from 1 to 19 kg N⋅ha−1⋅y−1, we found a unimodal relationship; richness increased at low deposition levels and decreased above 8.7 and 13.4 kg N⋅ha−1⋅y−1 in open and closed-canopy vegetation, respectively. N deposition exceeded critical loads for loss of plant species richness in 24% of 15,136 sites examined nationwide. There were negative relationships between species richness and N deposition in 36% of 44 community gradients. Vulnerability to N deposition was consistently higher in more acidic soils whereas the moderating roles of temperature and precipitation varied across scales. We demonstrate here that negative relationships between N deposition and species richness are common, albeit not universal, and that fine-scale processes can moderate vegetation responses to N deposition. Our results highlight the importance of contingent factors when estimating ecosystem vulnerability to N deposition and suggest that N deposition is affecting species richness in forested and nonforested systems across much of the continental United States.

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