Stefan H. Foord

Micro-scale heterogeneity of spiders (Arachnida: Araneae) in the Soutpansberg, South Africa : a comparative survey and inventory in representative habitats

ABSTRACT Coarse-scale studies that focus on species distributions and richness neglect heterogeneity that may be present at finer scales. Studies of arthropod assemblage structure at fine (1 × 1 km) scales are rare, but important, because these are the spatial levels at which real world applications are viable. Here we investigate fine-scale variation in spider assemblages, comparing five representative vegetation types in the western Soutpansberg, Limpopo Province, South Africa. We assess these vegetation types in terms of their family and species composition, as well as levels of endemicity, relating these differences with vegetation structure. We inventoried 297 species (49 families) in an area less than 450 ha, as part of South African National Survey of Arachnida. Analysis of the results suggests that endemic taxa are associated with Tall Forest and, to a lesser extent, Woodland. The Woodland had the highest species diversity, and much of the variation observed in spider assemblage structure is explained by these two vegetation types. Based on vegetation structure variables that explained significant variation in spider assemblages, human influence through bush encroachment will result in a change of spider assemblages to that of Short Forest and Mosaic Woodland vegetation types, with implications for biodiversity maintenance and heterogeneity.

Towards a standardized and optimized protocol for rapid biodiversity assessments: spider species richness and assemblage composition in two savanna vegetation types

A semi-quantitative inventory of spider diversity was done in the Blouberg Nature Reserve (BNR) and Western Soutpansberg Conservancy (WSC) situated in the Savanna Biome of the Limpopo Province, South Africa. Two hundred and ninety-six samples of one person-hour work each, comprised of five methods (vegetation beating, sweep netting, aerial hand collecting, ground hand collecting and leaf litter sifting) were divided between four relatively homogenous sites (plant communities) within a vegetation type of the BNR and WSC, respectively, an average of 37 per site. In addition, 25 pitfall traps were left open for a total of 20 days in each of the eight plant communities, 200 in total. We collected 1328 adult spiders representing 186 species of which 31% were singletons in the BNR vegetation type and 909 spiders in 222 species of which 41% were singletons in the WSC vegetation type. The number of species present was estimated using six estimators. The estimates varied between 233 and 307 for the BNR and 302 and 386 for the WSC. Inventory completeness was more than 70%. However, the fit to a lognormal distribution suggests that there are 370 species (750 000 individuals) and 445 (850 000 individuals) species in the universes (16 ha) sampled within the two vegetation types. Collector experience had no effect on the results of the inventory, whereas time of day had a very small yet significant effect. Seasonality only affected abundance and richness, but not assemblage composition. Sampling methods used had the biggest effect on our results. These results are used to design an optimized sampling protocol for standardized inventories in the Savanna Biome.

South African Spider Diversity: African Perspectives on the Conservation of a Mega-Diverse Group

Any field of endeavour requires retrospection after a period of substantial activity. This process provides a measure of what has been achieved and identifies future directions. Studies of spider diversity in South Africa have gone through an intense growth phase over the past ten years and reached a stage in its development where reflections on patterns and processes observed could provide meaningful input into the identification of further work. This chapter establishes the background and framework for such a discussion on the path to a more holistic conservation planning that includes invertebrates. Invertebrate conservation and diversity pose a significant challenge to planners and managers (Engelbrecht, 2010), and in spite of the central role that insects and arachnids play in terrestrial biodiversity, they still remain peripheral to decision-making processes. The reality is that, for Africa in particular, there are very few conservation areas that have both the resources and expertise to include invertebrates as part of their monitoring and management initiatives (however, see South African River Health Programme1). The advent of adaptive management, with a strong emphasis on experimental implementation of alternative management options (Johnson, 1999), has informed much of recent thinking and has cast a dim light on classical inventory studies that generate species lists. However, records of the numbers of species and their distribution provides a fundamental starting point for the conservation of biodiversity (Pullin, 2002). This view also ignores the contribution that basic inventories and alpha taxonomy make to the initial development of a field. This chapter will show that South African spider systematics and ecology are in an exploratory phase, and that traditional approaches to mapping diversity has enabled spider ecology in the country to generate species lists that are often resolved up to species level. Very few other studies on mega-diverse invertebrate groups in Africa can match this taxonomic resolution (see e.g. Formicinae). This descriptive phase will provide the

South African National Survey of Arachnida (SANSA): review of current knowledge, constraints and future needs for documenting spider diversity (Arachnida: Araneae)

Biodiversity is one of the most important concepts in contemporary biology, with a broad range of applications. In November 1995, South Africa ratified the Convention on Biological Diversity (CBD). Signatories are obligated to develop a strategic plan for the conservation and sustainable use of biodiversity. To meet the requirements of the CBD, the South African National Survey of Arachnida (SANSA) was initiated in 1997. This national project has several aims: to document and describe the arachnid fauna of South Africa; to consolidate all the available data on South African arachnids into one relational database and to make this biodiversity information available to science; and to address issues concerning their conservation and sustainable use. Extensive sampling took place and the SANSA database contains a wealth of biodiversity data that are used to provide answers to ecological questions. Presently 71 spider families, 471 genera and 2170 species are known from South Africa, representing approximately 4.8% of the world fauna. This paper presents the current state of spider biodiversity information and how it is managed. It demonstrates the importance of running a national inventory; emphasises the significance of using a good database application; and the importance of capacity development to improve the quality and integration of biodiversity information. Further, it shows the role SANSA has played in unifying and strengthening arachnid research, with the major thrust to discover the spider diversity in South Africa. We discuss the present status of knowledge, constraints to improving this, and the future directions for research. SANSA has provided the foundations for a more integrative approach to spider diversity research. Future research should build on this legacy by linking taxonomic diversity with that of functional diversity, predicting the response of this diversity to global change drivers. Functional approaches will link these studies to ecosystem processes. Global collaborative studies at several sites following standardised sampling protocols and focused research questions would add value to the SANSA collection and the importance of spiders for the health of ecosystems.

Temporal patterns of ant diversity across a mountain with climatically contrasting aspects in the tropics of Africa.

Factors that drive species richness over space and time are still poorly understood and are often context specific. Identifying these drivers for ant diversity has become particularly relevant within the context of contemporary global change events. We report on a long-term bi-annual (wet and dry seasons), standardized sampling of epigeal ants over a five year period on the mesic and arid aspects of an inselberg (Soutpansberg Mountain Range) in the tropics of Africa. We detail seasonal, annual and long-term trends of species density, test the relative contribution of geometric constraints, energy, available area, climate, local environmental variables, time, and space in explaining ant species density patterns through Generalized Linear Mixed Models (GLMM) where replicates were included as random factors to account for temporal pseudo-replication. Seasonal patterns were very variable and we found evidence of decreased seasonal variation in species density with increased elevation. The extent and significance of a decrease in species density with increased elevation varied with season. Annual patterns point to an increase in ant diversity over time. Ant density patterns were positively correlated with mean monthly temperature but geometric constraints dominated model performance while soil characteristics were minor correlates. These drivers and correlates accounted for all the spatio-temporal variability in the database. Ant diversity was therefore mainly determined by geometric constraints and temperature while soil characteristics (clay and carbon content) accounted for smaller but significant amounts of variation. This study documents the role of season, elevation and their interaction in affecting ant species densities while highlighting the importance of neutral processes and temperature in driving these patterns.

The faunistic diversity of spiders (Arachnida: Araneae) of the South African Grassland Biome

ABSTRACT As part of the South African National Survey of Arachnida (SANSA), all available information on spider species distribution in the South African Grassland Biome was compiled. A total of 11 470 records from more than 900 point localities were sampled in the South African Grassland Biome until the end of 2011, representing 58 families, 275 genera and 792 described species. A further five families (Chummidae, Mysmenidae, Orsolobidae, Symphytognathidae and Theridiosomatidae) have been recorded from the biome but are only known from undescribed species. The most frequently recorded families are the Gnaphosidae (2504 records), Salticidae (1500 records) and Thomisidae (1197 records). The last decade has seen an exponential growth in the knowledge of spiders in South Africa, but there are certainly many more species that still have to be discovered and described. The most species-rich families are the Salticidae (112 spp.), followed by the Gnaphosidae (88 spp.), Thomisidae (72 spp.) and Araneidae (52 spp.). A rarity index, taking into account an endemicity index and an abundance index, was determined to give a preliminary indication of the conservation importance of each species. The endemicity index indicates that 58 species are endemic to the biome, while 38 species could be considered to be introduced, cosmopolitan, or having a distribution extending beyond the Afrotropical Region. Levels of endemism are highest for mygalomorph trapdoor spiders (7.14–50%) and selected araneomorph families with restricted dispersal capabilities (i.e. Archaeidae, Sicariidae and Scytodidae). A brief review of the published data of surveys from the biome and the patterns of spider assemblage structure in each is presented, together with information on the most species-rich spider families occurring in the biome.

Effects of a fast-burning spring fire on the ground-dwelling spider assemblages (Arachnida: Araneae) in a central South African grassland habitat

Fire is widely used as a management strategy in grasslands to maintain vegetation structure and improve grazing quality for large herbivores. The impacts of burning on invertebrates in South Africa remain poorly understood. A study was initiated in spring 2005 to determine the impact of a fast hot burn on ground-dwelling spider assemblages in a grassland habitat in the central Free State. Pitfall traps were set out at six sites in the reserve, with three sites each in the burnt and unburnt areas, to sample spiders over a 12-month period. A total of 5 253 spiders were collected, representing 33 families and 120 species. Spider abundance was significantly lower in the burnt (n = 1 956) than unburnt sites (n = 3 297), and burnt sites had, on average, considerably fewer species than unburnt sites. The dominant families in the burnt sites were Lycosidae (29.5%), Gnaphosidae (16.9%), Ammoxenidae (9.6%) and Zodariidae (5.7%), whereas Ammoxenidae (22.7%), Lycosidae (20.6%), Gnaphosidae (15.3%) and Amaurobiidae (10.2%) dominated the unburnt sites. Of the nine most abundant families collected, only Caponiidae were more abundant in the burnt than unburnt sites. Our data suggest that fast-burning hot spring fires cause a considerable initial post-fire decline in spider abundance, and have a negative influence on the abundance as well as the resistance of assemblages to disturbances other than fire (e.g. rain). However, most of the dominant families had abundances comparable to unburnt areas within a year post-burn.

A review of three Tusitala (Araneae: Salticidae) species from southern Africa, with a new synonymy and description of a new species from Botswana

ABSTRACT Two species of Tusitala Peckham & Peckham, 1902, largely sympatric throughout southern Africa, T. barbata Peckham & Peckham, 1902 and T. hirsuta Peckham & Peckham, 1902, are redescribed. One subspecies, T. barbata longipalpis syn. n., is synonymised with T. barbata. One new species, T. ansieae sp. n., is described from Botswana based on both sexes.

Deciding on an appropriate scale for conservation activities : partitioning alpha and beta ant diversity in North-West Province, South Africa (Formicidae : Hymenoptera)

1. Hierarchical partitioning of diversity is an effective tool in determining at what spatial scales diversity is generated. 2. This has important implications for managing diversity as we may wish to determine the appropriate scale for conservation activities. 3. We studied whether ant assemblages are compositionally distinct between different vegetation units and at which hierarchical scale (regional vs local) diversity is being generated. We did this in an attempt to determine at what spatial scales land use management and conservation activities for ants (and therefore invertebrates) should take place. 4. We sampled ants in 4 vegetation units in North West Province, South Africa, as part of a research expedition for the South African National Survey of Arachnida (SANSA); 92 ant species (Formicidae) were sampled in 25 genera within 6 subfamilies. 5. Partitioning of diversity showed that alpha diversity was high for points (sampling units) and extremely high for sites, but both were not significantly different from the random model. Although small relative to alpha diversity, beta diversity among points contributed significantly more than expected to overall diversity whereas turnover among vegetation units was significantly lower than expected from the null model. 6. These results indicate that turnover between points within vegetation units is relatively high; turnover at a regional scale was however very low, supported by the few number of species that were site specific. The lack of any spatial structure within sites might suggest that the studies’ grain was too fine or that ant assemblages in a vegetation unit are homogenous in space. 7. The high turnover observed in the study between points may be exactly that, and if so may well be attributed to habitat quality and ant dispersal mechanisms – supported by other studies. It may, however, simply be an artefact of incomplete sampling. The low beta diversity observed between vegetation types may be attributed to the fact that ants are extremely good dispersers. 8. Different colony founding mechanisms could explain why some species contributed more to the turnover between points. 9. Our results indicate that management activities for conservation of ants are sufficient at scales as fine as 400 m×400 m, yet we caution that small conservation areas should be nested within larger reserves in order to maintain landscape connectedness.

Changes in landuse alter ant diversity, assemblage composition and dominant functional groups in African savannas

Africa’s savannas are undergoing rapid conversion from rangelands into villages and croplands. Despite limited research, and evidence of deleterious effects to biodiversity, international organisations have earmarked this system for cropland. Invertebrates, and ants in particular, are sensitive indicators of habitat fragmentation, and contribute to ecosystem services at a range of scales. We investigated how rangelands, villages and croplands differ in ant species and functional diversity, and assemblage composition. We sampled ants using pitfall traps at 42 sites (14 replicates each in rangeland, cropland, and village) in northern South African savannas. We investigated the impact of landuse, season, and multiple soil and vegetation habitat variables on ant species diversity, assemblages and functional diversity. Rangelands had the greatest ant species richness, particularly in the wet season. Richness declined with increasing soil clay content. Ant assemblages were distinctly different between landuse types. Rangeland harboured the widest diversity of indicator species, and contained greatest functional diversity. Rangelands accommodated more scavengers, granivores, and plant-matter feeders than cropland, and representation of these groups varied with season. Ants play essential roles in soil nutrient cycling, plant and seedling recruitment, and impact other arthropods through predation and aphidoculous behaviour that in turn influences entire food webs. Thus, the reduced species richness, changes in assemblage composition and the loss of functional groups in ant assemblages found in cropland and villages is potentially problematic. Left unchallenged, these new forms of landuse threaten to characterise the entire African savanna system, impacting not only future ecological, but possibly also human wellbeing.