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Bestelmeyer, B.T. and J.A. Wiens. 1996. The effects of land use on the structure of ground-foraging ant communities in the Argentine Chaco. Ecological Applications, 16(4), 1225-1240. DOI:10.2307/2269603

latest article added on January 2015

ArticleFirst AuthorPublished
Beyond the least-cost path: evaluating corridor redundancy using a graph-theoretic approachPinto, Naiara2009

Beyond the least-cost path: evaluating corridor redundancy using a graph-theoretic approach

Keywords

Agroecosystems, Atlantic forest, Brazil, Functional connectivity, Corridors, Cost distance, Dispersal, Fragmentation, Graph theory, Matrix, Migration, Shortest path

Abstract

The impact of the landscape matrix on patterns of animal movement and population dynamics has been widely recognized by ecologists. However, few tools are available to model the matrix’s influence on the length, relative quality, and redundancy of dispersal routes connecting habitat patches. Many GIS software packages can use land use/land cover maps to identify the route of least resistance between two points—the least-cost path. The limitation of this type of analysis is that only a single path is identified, even though alternative paths with comparable costs might exist. In this paper, we implemented two graph theory methods that extend the least-cost path approach: the Conditional Minimum Transit Cost (CMTC) tool and the Multiple Shortest Paths (MSPs) tool. Both methods enable the visualization of multiple dispersal routes that, together, are assumed to form a corridor. We show that corridors containing alternative dispersal routes emerge when favorable habitat is randomly distributed in space. As clusters of favorable habitat start forming, corridors become less redundant and dispersal bottlenecks become visible. Our approach is illustrated using data from a real landscape in the Brazilian Atlantic forest. We explored the effect of small, localized disturbance on dispersal routes linking conservation units. Simulated habitat destruction caused the appearance of alternative dispersal routes, or caused existing corridors to become narrower. These changes were observed even in the absence of significant differences in the length or cost of least-cost paths. Last, we discuss applications to animal movement studies and conservation initiatives.

Authors

Pinto, Naiara and Keitt, Timothy H.

Year Published

2009

Publication

Landscape Ecology

Locations
DOI

10.1007/s10980-008-9303-y

Effects of Urban Development on Ant Communities: Implications for Ecosystem Services and ManagementSANFORD, MONTE P.2009

Effects of Urban Development on Ant Communities: Implications for Ecosystem Services and Management

Keywords

ants; ecosystem services; forest management; Lake Tahoe; service-providing units; water infiltration; urbanization hormigas; infiltración de agua; Lago tahoe; manejo de bosques; servicios del ecosistema; unidades proveedoras de servicio; urbanización

Abstract

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, measured vegetation characteristics, quantified human activities, and evaluated ant-community responses by grouping ants into service-providing units (SPUs), defined as a group of organisms and their populations that perform specific ecosystem services, to provide an understanding of urbanization impacts on biodiversity and their delivery of ecosystem services. Species richness and abundance peaked at intermediate levels of urban development, as did the richness of 3 types of ant SPUs (aerators, decomposers, and compilers). With increasing land development aerator and decomposer ants significantly declined in abundance, whereas compiler ants significantly increased in abundance. Competing models demonstrated that precipitation was frequently among the strongest influences on ant community structure; however, urban development and human activities also had a strong, negative influence on ants, appearing in most models with ΔAICc < 2 for species richness and abundance patterns of SPUs and generalists. Response diversity was observed within SPUs, which suggests that the corresponding ecosystem services were maintained until development reached 30–40%. Our data provide evidence that ecosystem functions, such as water infiltration and soil productivity, may be diminished at sites subject to greater levels of urbanization and that conserving ant communities and the ecosystem services they provide could be an important target in land-use planning and conservation efforts.

Authors

SANFORD, MONTE P., MANLEY, PATRICIA N. and MURPHY, DENNIS D.

Year Published

2009

Publication

Conservation Biology

Locations
DOI

10.1111/j.1523-1739.2008.01040.x

Impact of Flooding on the Species Richness, Density and Composition of Amazonian Litter-Nesting AntsMertl, Amy L.2009

Impact of Flooding on the Species Richness, Density and Composition of Amazonian Litter-Nesting Ants

Keywords

Formicidae; Hymenoptera; Hypoponera; intermediate disturbance; litter ants; Pheidole; terra firme forest

Abstract

Litter-nesting ants are diverse and abundant in tropical forests, but the factors structuring their communities are poorly known. Here we present results of the first study to examine the impact of natural variation in flooding on a highly diverse (21 genera, 77 species) litter-nesting ant community in a primary Amazonian forest. Fifty-six 3 × 3 m plots experiencing strong variation in flooding and twenty-eight 3 × 3 m terra firme plots were exhaustively searched for litter-nesting ants to determine patterns of density, species richness and species composition. In each plot, flooding, litter depth, twig availability, canopy cover, plant density, percent soil nitrogen, carbon, and phosphorus were measured. Degree of flooding, measured as flood frequency and flood interval, had the strongest impact on ant density in flooded forest. Flooding caused a linear decrease in ant abundance, potentially due to a reduction of suitable nesting sites. However, its influence on species richness varied: low-disturbance habitat had species richness equal to terra firme forest after adjusting for differences in density. The composition of ant genera and species varied among flood categories; some groups known to contain specialist predators were particularly intolerant to flooding. Hypoponera STD10 appeared to be well-adapted to highly flooded habitat. Although flooding did not appear to increase species richness or abundance at the habitat scale, low-flooding habitat contained a mixture of species found in the significantly distinct ant communities of terra firme and highly flooded habitat.

Authors

Mertl, Amy L., Ryder Wilkie, Kari T. and Traniello, James F. A.

Year Published

2009

Publication

Biotropica

Locations
DOI

10.1111/j.1744-7429.2009.00520.x

Species richness, equitability, and abundance of ants in disturbed landscapesGraham, John H.2009

Species richness, equitability, and abundance of ants in disturbed landscapes

Keywords

Disturbance; Equitability; Fire; Formicidae; Military training; Spatial heterogeneity; Species richness

Abstract

Ants are used as indicators of environmental change in disturbed landscapes, often without adequate understanding of their response to disturbance. Ant communities in the southeastern United States displayed a hump-backed species richness curve against an index of landscape disturbance. Forty sites at Fort Benning, in west-central Georgia, covered a spectrum of habitat disturbance (military training and fire) in upland forest. Sites disturbed by military training had fewer trees, less canopy cover, more bare ground, and warmer, more compact soils with shallower A-horizons. We sampled ground-dwelling ants with pitfall traps, and measured 15 habitat variables related to vegetation and soil. Ant species richness was greatest with a relative disturbance of 43%, but equitability was greatest with no disturbance. Ant abundance was greatest with a relative disturbance of 85%. High species richness at intermediate disturbance was associated with greater within-site spatial heterogeneity. Species richness was also associated with intermediate values of the normalized difference vegetation index (NDVI), a correlate of net primary productivity (NPP). Available NPP (the product of NDVI and the fraction of days that soil temperature exceeded 25 °C), however, was positively correlated with species richness, though not with ant abundance. Species richness was unrelated to soil texture, total ground cover, and fire frequency. Ant species richness and equitability are potential state indicators of the soil arthropod community. Moreover, equitability can be used to monitor ecosystem change.

Authors

Graham, John H., Krzysik, Anthony J., Kovacic, David A., Duda, Jeffrey J., Freeman, D. Carl, Emlen, John M., Zak, John C., Long, W. Russell, Wallace, Michael P., Chamberlin-Graham, Catherine, Nutter, Jonathan P. and Balbach, Hal E.

Year Published

2009

Publication

Ecological Indicators

Locations
DOI

10.1016/j.ecolind.2008.10.003

Uncoupling the effects of shade and food resources of vegetation on Mediterranean ants: an experimental approach at the community levelArnan, Xavier2007

Uncoupling the effects of shade and food resources of vegetation on Mediterranean ants: an experimental approach at the community level

Keywords

No keywords available

Abstract

Vegetation is one of the main factors affecting the composition and structure of ant communities. The effect of vegetation is both by offering food resources and by modifying the proportion of ground cover exposed to shade conditions. However, it is difficult in field studies to uncouple the effects of food resources and shade on animal communities. The goal of this study was to analyze experimentally the effects of vegetation through food and shade supply on the structure and composition of a Mediterranean ant community. We have crossed these two factors in a factorial design where we have eliminated vegetation in experimental treatments and we have simulated the effects of vegetation by manipulating separately the supply of food resources and shade. The expected decrease in ant abundance and richness in plots without food resources but with shade was only partially confirmed by the results, because there was a decrease in the number of ant species but not a significant decrease in overall ant abundance in plots without food resources. We did not confirm the second hypothesis that the decrease in shade while maintaining food resources resulted in an increase of heat-tolerant, subordinate species and, consequently, ant richness. Species composition differed in the different experimental treatments. Stress-tolerant species were abundant in areas without shade and without food resources. Heat-tolerant species were mainly present in plots without shade but with food resources. Finally, species with high requirements of shade and/or food resources were associated to control plots with both shade and food resources from vegetation. Overall, this study provides an experiment that uncouples experimentally shade and food resources and dissects their effects on the whole ant community, and shows that the effects of the two factors are independent and affect different components of ant community structure and composition.

Authors

Arnan, Xavier, Rodrigo, Anselm and Retana, Javier

Year Published

2007

Publication

Ecography

Locations
DOI

10.1111/j.0906-7590.2007.04796.x

Contrasting fire-related resilience of ecologically dominant ants in tropical savannas of northern AustraliaAndersen, Alan N.2007

Contrasting fire-related resilience of ecologically dominant ants in tropical savannas of northern Australia

Keywords

Biogeography; fire experiment; Iridomyrmex; Oecophylla; rain forest; savanna/rain forest dynamics

Abstract

This paper examines the role of fire in mediating the relative abundance of two of the world's major ecologically dominant ant genera, Iridomyrmex and Oecophylla, where they coexist across the tropical savanna landscapes of northern Australia. These taxa have contrasting biogeographical histories, which are predicted to lead to contrasting responses to fire. Iridomyrmex is an autochthonous Australian genus that has radiated primarily in the arid zone; as such, its abundance is predicted to be promoted by frequent fire because this maintains an open habitat. In contrast, Oecophylla is a genus of leaf-nesting ants occurring in the canopies of Old World tropical rainforest, and is a recent arrival to Australia in geological time; the abundance of these ants is predicted to decline under frequent fire. We test these predictions using results from a landscape-scale fire experiment, where three experimental fire regimes (including no fire) were applied to replicated subcatchments over a 5-year period. Using sweep nets, ants were sampled in the grass layer (the habitat layer of greatest overlap between Iridomyrmex and Oecophylla) in eucalypt woodland (canopy cover < 30%) and open eucalypt forest (canopy cover about 50%) habitats. A total of 27 species from 11 genera were collected during the study; eight were common enough for statistical analysis, and the abundances of four of these were significantly affected by fire treatment. As predicted, the abundance of Iridomyrmex was promoted by fire, whereas that of Oecophylla declined. These changes occurred only under late-season (relatively high intensity) fires, and for Oecophylla occurred only in open forest (not woodland) habitat. This fire-mediated relationship between Iridomyrmex and Oecophylla mirrors the much broader, ecosystem-wide dynamic between eucalypt-dominated savanna and rainforest in tropical Australia, with savannas dominated by fire-resistant sclerophyll elements of Australian origin, and rainforest dominated by fire-sensitive mesophyll elements of South-East Asian origin.

Authors

Andersen, Alan N., PARR, CATHERINE L., Lowe, Lyn M. and Muller, Warren J.

Year Published

2007

Publication

Diversity And Distributions

Locations
DOI

10.1111/j.1472-4642.2007.00353.x

Effects of feral horses in Great Basin landscapes on soils and ants: Direct and indirect mechanismsBeever, E.A.2006

Effects of feral horses in Great Basin landscapes on soils and ants: Direct and indirect mechanisms

Keywords

Equus caballus; Formica; Pogonomyrmex; Nevada; Disturbance; Conservation

Abstract

We compared soil-surface penetration resistance and abundance of ant mounds at 12 western Great Basin sites (composed of 19 plots) either grazed by feral horses (Equus caballus) or having had horses removed for the last 10–14 years. Across this broad spatial domain (3.03 million ha), we minimized confounding due to abiotic factors by selecting horse-occupied and horse-removed sites with similar aspect, slope, fire history, grazing pressure by cattle (minimal to none), and dominant vegetation (Artemisia tridentata). During both 1997 and 1998, we found 2.2–8.4 times greater abundance of ant mounds and 3.0–15.4 times lower penetration resistance in soil surfaces at horseremoved sites. In 1998, thatched Formica ant mounds, which existed predominately at high elevations, were 3.3 times more abundant at horse-removed sites, although abundance varied widely among sites within treatments. Several types of analyses suggested that horses rather than environmental variability were the primary source of treatment differences we observed in ecosystem components. Tests of several predictions suggest that alterations occurred through not only direct effects, but also indirect effects and potentially feedback loops. Free-roaming horses as well as domestic grazers should be considered in conservation planning and land management in the Great Basin, an ecoregion that represents both an outstanding conservation opportunity and challenge.

Authors

Beever, E.A. and Herrick, J.E.

Year Published

2006

Publication

Journal of Arid Environments

Locations
DOI

10.1016/j.jaridenv.2005.11.006

Ants, altitude and change in the northern Cape Floristic RegionBotes, A.2006

Ants, altitude and change in the northern Cape Floristic Region

Keywords

Ants; climate change; conservation; myrmecochores; spatial autocorrelation; species–environment relationships; South Africa; species richness

Abstract

Aim  Climate-modelling exercises have demonstrated that the Cape Floristic Region is highly sensitive to climate change and will apparently lose much of its northern limits over the next few decades. Because there is little monitoring of diversity in this area, ant assemblage structure was investigated within the main vegetation types in the Greater Cederberg Biodiversity Corridor. In particular, we sought to determine how ant assemblage structure differs between the main vegetation types, how restricted ants – and in particular the major myrmecochores – are to the major vegetation types, and which environmental variables might underlie differences in the ant assemblages and in the specificity of species to particular areas. Location  Northern Cape Floristic Region, Western Cape, South Africa. Methods  Sampling was undertaken during October 2002 and March 2003 across an altitudinal gradient ranging from sea level (Lambert's Bay) to c. 2000 m a.s.l. (Sneeukop, Cederberg) and down again to 500 m a.s.l. (Wupperthal) in the Western Cape, South Africa. Pitfall traps were used to sample ants at 17 altitudinal bands, stretching over three vegetation types (Strandveld, Mountain Fynbos and Succulent Karoo). Biotic and abiotic environmental variables were collected at each sampling site. Generalized linear models were used to determine the relationships between species richness, density, abundance and the abundance of the major myrmecochores, and the environmental variables. Redundancy analysis was used to determine the relationship between ant assemblage structure and the environmental variables. The Indicator Value Method was used to identify characteristic ant species for each vegetation type and altitudinal site. Results  Temperature explained significant proportions of the variation in species density and abundance, and, together with area and several vegetation variables, contributed significantly to the separation of the assemblages in the major vegetation types and biomes. Four major myrmecochores were identified [Anoplolepis sp. (cf. custodiens), Anoplolepis sp. (cf. steinergroeveri), Camponotus niveosetosus, Tetramorium quadrispinosum]. The abundances of the two Anoplolepis species were related to vegetation variables, while the abundance of the other two species showed opposite relationships with temperature variables. Fourteen ant species were characteristic of certain vegetation types and altitudes. Several of these species contributed to the differences between the assemblages. Main conclusions  There are likely to be substantial and complex changes to ant assemblages as climates change in the northern Cape Floristic Region. Moreover, the importance of ants for ecosystem functioning suggests that these responses are not only likely to be a response solely to vegetation changes, but might also precipitate vegetation changes. The changes that are predicted to take place in the next 50 years in the Cape Floristic Region could be substantially exacerbated by such synergistic effects, which have major implications for long-term conservation plans. Ongoing monitoring of this transect will reveal the nature and pace of the change as it unfolds.

Authors

Botes, A., McGeoch, M. A., Robertson, H. G., Niekerk, A., Davids, H. P. and Chown, S. L.

Year Published

2006

Publication

Journal of Biogeography

Locations
DOI

10.1111/j.1365-2699.2005.01336.x

Different responses of plants and herbivore insects to a gradient of vegetation height: an indicator of the vertebrate grazing intensity and successional agePöyry, Juha2006

Different responses of plants and herbivore insects to a gradient of vegetation height: an indicator of the vertebrate grazing intensity and successional age

Keywords

No keywords available

Abstract

Empirical studies have suggested that species richness of grassland insects usually decreases under grazing management. By contrast, grazing has been shown to increase the species density and richness of vascular plants, especially on productive soils. In order to test the suggested differences in response to management between plants and insects, we simultaneously studied species richness of vascular plants and their insect herbivores, butterflies and moths, in 68 semi-natural grasslands with varying grazing intensity and frequency in SW Finland. Species richness of plants and insects was for the first time related to a quantitative measure of disturbance intensity and successional age, mean vegetation height, by using generalized additive models (GAM). The effects of soil nutrients on vegetation height were accounted for by using phosphorus concentration as a productivity surrogate. The results showed that species richness of butterflies and moths peaked in taller vegetation compared with vascular plants, corresponding to a lower disturbance intensity and increasing time since abandonment. These patterns are discussed in the light of two hypotheses, the “structural diversity hypothesis” and “dynamic equilibrium model” of Huston, both suggesting a weaker disturbance tolerance of insects compared with plants. Butterflies and moths which are specialists in their larval host-plant use (monophagous and oligophagous species) preferred lower vegetation (higher disturbances) compared with generalists (polyphagous species), as predicted by Huston's model. This difference indicates a stronger relationship with plant species richness for specialist than for generalist butterflies and moths. Our results support the application of regionally and temporally varying grazing intensities in grassland conservation management.

Authors

Pöyry, Juha, Luoto, Miska, Paukkunen, Juho, Pykälä, Juha, Raatikainen, Katja and Kuussaari, Mikko

Year Published

2006

Publication

Oikos

Locations
DOI

10.1111/j.2006.0030-1299.15126.x

Post-fire recovery of Mediterranean ground ant communities follows vegetation and dryness gradientsArnan, Xavier2006

Post-fire recovery of Mediterranean ground ant communities follows vegetation and dryness gradients

Keywords

Ants; diversity; dryness gradient; fire; forest type; Mediterranean communities; post-fire recovery; resilience; species richness

Abstract

Aim  In the Mediterranean Basin, the main forest communities vary in their ability to recover after fire. In this study we analyse the effects of fire on ant communities occurring in various vegetation types distributed along a geographical gradient in the western Mediterranean region. Location  The study was carried out in burned and unburned habitats of 22 sites corresponding to eight vegetation types distributed along a gradient of dryness throughout Catalonia (north-east Spain). Methods  We placed five pairs of plots (one plot located in the burned area and the second one placed in the unburned margin) per site. We compared ant communities in these unburned and burned plot types 8 years after fire using pitfall traps. Traps were set out in mid-May and mid-July. We analysed the structure and composition of ant communities in the burned and unburned areas of these vegetation types using anova tests, correspondence analysis (CA) and linear regression. Results  The resilience of ant communities varies with vegetation type. Ant communities in forests with high resilience also recover rapidly after fire, while those in forests that do not recover after fire show the lowest resilience. Species richness does not depend on burning or vegetation type. The resilience of these Mediterranean ant communities to fire is related to the environmental characteristics of the region where they live. Accordingly, differences between burned and unburned habitats are smaller for ant communities in areas with higher water deficit in summer than for those in moister ones. Main conclusions  The structure and composition of ant communities after fire depends on the level of direct mortality caused by the fire. It affects ant species differently, as determined by the habitats used for nesting and foraging. The reestablishment of vegetation cover depends on forest composition before the fire. As vegetation cover determines resource and microhabitat availability and competitive relationships among species, forest composition before the fire also affects post-fire recovery of ant communities to the medium-term. Finally, ant communities living in drier areas recover more quickly after fire than those living in moister ones. This pattern might be because in areas with higher water deficit there are more species characteristic of open environments, which are habitats similar to those generated after fire.

Authors

Arnan, Xavier, Rodrigo, Anselm and Retana, Javier

Year Published

2006

Publication

Journal of Biogeography

Locations
DOI

10.1111/j.1365-2699.2006.01506.x

Recent Articles

Beyond the Least-Cost Path: Evaluating Corridor Redundancy Using a Graph-Theoretic Approach

by Pinto, Naiara and Keitt, Timothy H.

The impact of the landscape matrix on patterns of animal movement and population dynamics has been widely recognized by ecologists. However, few tools are available to model the matrix’s influence on the length, relative quality, and redundancy of dispersal routes connecting habitat patches. Many GIS software packages can use land use/land cover maps to identify the route of least resistance be...

published 2009 in Landscape Ecology

Effects of Urban Development on Ant Communities: Implications for Ecosystem Services and Management

by SANFORD, MONTE P., MANLEY, PATRICIA N. and MURPHY, DENNIS D.

Research that connects the effects of urbanization on biodiversity and ecosystem services is lacking. Ants perform multifarious ecological functions that stabilize ecosystems and contribute to a number of ecosystem services. We studied responses of ant communities to urbanization in the Lake Tahoe basin by sampling sites along a gradient of urban land development. We sampled ant communities, me...

published 2009 in Conservation Biology


Impact of Flooding on the Species Richness, Density and Composition of Amazonian Litter-Nesting Ants

by Mertl, Amy L., Ryder Wilkie, Kari T. and Traniello, James F. A.

Litter-nesting ants are diverse and abundant in tropical forests, but the factors structuring their communities are poorly known. Here we present results of the first study to examine the impact of natural variation in flooding on a highly diverse (21 genera, 77 species) litter-nesting ant community in a primary Amazonian forest. Fifty-six 3 × 3 m plots experiencing strong variation in flooding...

published 2009 in Biotropica

Species Richness, Equitability, and Abundance of Ants in Disturbed Landscapes

by Graham, John H., Krzysik, Anthony J., Kovacic, David A., Duda, Jeffrey J., Freeman, D. Carl, Emlen, John M., Zak, John C., Long, W. Russell, Wallace, Michael P., Chamberlin-Graham, Catherine, Nutter, Jonathan P. and Balbach, Hal E.

Ants are used as indicators of environmental change in disturbed landscapes, often without adequate understanding of their response to disturbance. Ant communities in the southeastern United States displayed a hump-backed species richness curve against an index of landscape disturbance. Forty sites at Fort Benning, in west-central Georgia, covered a spectrum of habitat disturbance (military tra...

published 2009 in Ecological Indicators