Catherine L. Parr

Climatic drivers of hemispheric asymmetry in global patterns of ant species richness.

Although many taxa show a latitudinal gradient in richness, the relationship between latitude and species richness is often asymmetrical between the northern and southern hemispheres. Here we examine the latitudinal pattern of species richness across 1003 local ant assemblages. We find latitudinal asymmetry, with southern hemisphere sites being more diverse than northern hemisphere sites. Most of this asymmetry could be explained statistically by differences in contemporary climate. Local ant species richness was positively associated with temperature, but negatively (although weakly) associated with temperature range and precipitation. After contemporary climate was accounted for, a modest difference in diversity between hemispheres persisted, suggesting that factors other than contemporary climate contributed to the hemispherical asymmetry. The most parsimonious explanation for this remaining asymmetry is that greater climate change since the Eocene in the northern than in the southern hemisphere has led to more extinctions in the northern hemisphere with consequent effects on local ant species richness.

Tropical grassy biomes: misunderstood, neglected, and under threat

Tropical grassy biomes (TGBs) are globally extensive, provide critical ecosystem services, and influence the earth-atmosphere system. Yet, globally applied biome definitions ignore vegetation characteristics that are critical to their functioning and evolutionary history. Hence, TGB identification is inconsistent and misinterprets the ecological processes governing vegetation structure, with cascading negative consequences for biodiversity. Here, we discuss threats linked to the definition of TGB, the Clean Development Mechanism (CDM) and Reducing Emissions from Deforestation and Forest Degradation schemes (REDD+), and enhanced atmospheric CO2, which may facilitate future state shifts. TGB degradation is insidious and less visible than in forested biomes. With human reliance on TGBs and their propensity for woody change, ecology and evolutionary history are fundamental to not only the identification of TGBs, but also their management for future persistence.

Inventory and Bioindicator Sampling: Testing Pitfall and Winkler Methods with Ants in a South African Savanna

AbstractThe sampling efficiency and consistency of pitfall traps and Winkler samples for inventory, bioindicator and ecological studies in savanna habitats was compared using ants. Pitfall traps are often used for ant collecting while Winkler litter sampling has until now had rather limited use. We test Winkler sampling for the first time in a South African savanna. Pitfall traps were more efficient and productive than Winkler sampling for epigaeic ants, with a greater total species richness and higher abundance of ants recorded. Winkler samples contributed few additional species. The relative abundance of different sized ants was different with the two collection methods. Winkler sampling was found to catch greater numbers of smaller ants than pitfall trapping, whereas pitfall trapping caught more larger ants. The standard collecting Winkler quadrat size of 1 m2 did not perform as well as 2×

Cornerstones of biodiversity conservation? Comparing the management effectiveness of Kruger and Kakadu National Parks, two key savanna reserves

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Burning for biodiversity: highly resilient ant communities respond only to strongly contrasting fire regimes in Australia's seasonal tropics

m2 quadrats combined for one sample.

Contrasting species and functional beta diversity in montane ant assemblages

The mechanisms leading to structure in local assemblages are controversial. On the one hand, assemblage structure is thought to be the outcome of local interactions determined by the properties of species and their responses to the local environment. Alternatively, this structure has been shown to be an emergent property of assemblages of identical individuals or of random sampling of a regional assemblage. In ants at baits, a combination of environmental stress and interspecific competition is widely held to lead to a unimodal relationship between the abundance of dominant ants and species richness. It is thought that in comparatively adverse environments, both abundance and richness are low. As habitats become more favorable, abundance increases until the abundance of dominant ants is so high that they exclude those that are subordinate and so depress richness. Here we demonstrate empirically that this relationship is remarkably similar across three continents. Using a null model approach, we then show that the ascending part of the relationship is largely constrained to take this form not simply as a consequence of stress but also as a result of the shape of abundance frequency distributions. While the form of the species‐abundance frequency distribution can also produce the descending part of the relationship, interspecific competition might lead to it too. Scatter about the relationship, which is generally not discussed in the literature, may well be a consequence of resource availability and environmental patchiness. Our results draw attention to the significance of regional processes in structuring ant assemblages.

Does Structural Complexity Determine the Morphology of Assemblages? An Experimental Test on Three Continents

How effective are large, well-resourced protected areas at achieving biodiversity conservation goals? In this study we critically review biodiversity research and management practice in two of the world’s premier savanna reserves (Kruger National Park, South Africa and Kakadu National Park, Australia) by exploring management approaches to three shared conservation issues: fire, alien species and threatened species. These management approaches contrast sharply between the two reserves, with Kruger having notably more detailed and prescribed planning for biodiversity conservation. Overall assessment of the effectiveness of management is hampered by limited available information on trends for native species and threatening processes, but in general it is far more straightforward to understand the management framework and to measure biodiversity conservation performance for Kruger than for Kakadu. We conclude that biodiversity conservation outcomes are most likely to be related to the adequacy of dedicated resources and of monitoring programs, the explicit identification of clear objectives with associated performance indicators, and the considered application of management prescriptions. In Kakadu particularly, conflicting park objectives (e.g., biodiversity and cultural management) can reduce the effectiveness of biodiversity efforts. However, we recognize that for the long-term persistence of these large conservation areas and hence for biodiversity conservation, it is critical to include consideration of social context.

The size-grain hypothesis: a phylogenetic and field test

An understanding of contemporary and likely future biodiversity requires knowledge of how past human societies have shaped diversity patterns. Here, we use long-term pollen data sets extending from lowlands to subalpine environment in the Carpathian region (Romania) with the aim of exploring the relationship between landscape openness, anthropogenic disturbance, elevation and vegetation richness over the Holocene. We found that landscape openness represents a significant driver of pollen richness: The more open sites from mid (440–750 m) and high elevations (1550–1850 m) showed on average greater diversity than more forested upland sites (1050–1360 m). For the first time, our results show pollen richness patterns along elevation gradients that remain constant over the Holocene. Although significant only over the last 3000 cal. yr BP, these elevational patterns become accentuated with stronger evidence of anthropogenic impact. We also found a strong link between diversity change and major land use strategies of prehistoric societies, demonstrating the potential of pollen richness to be used as a tool to depict the ecological impact of human disturbance on diversity. Most distinct episodes of enhanced floristic richness are evident during the Roman Period (2000 cal. yr BP), and over the last 500 cal. yr BP. Recent anthropogenic activity negatively impacted diversity in mountainous areas mainly through plantations; the lack of sites in agriculture landscapes however limits our inference for this type of setting. The maintenance of habitat diversity is key to maintaining high levels of diversity. While there is temporal consistency in the diversity pattern in records from similar climate and vegetation settings, comparison of diversity from different vegetation assemblages and levels landscapes openness should be interpreted cautiously.