James S. Pryke

Terrestrial invertebrates as bioindicators: an overview of available taxonomic groups

Bioindicators, as taxa or functional groups, are widely used as indicators of environmental change, specific ecological factors or taxonomic diversity. The use of ecological, environmental and biodiversity indicators, is reviewed here. Although indicator taxa are considered to be generally unreliable as broad indicators of biodiversity, they may serve a useful function in identifying ecological characteristics or monitoring the effects of habitat management. Use of only a narrow range of taxa may be unreliable, and is particularly vulnerable to distortion by a small number of invasive species. Taxa also need to be selected to reflect the specific ecosystem being studied. It is recommended that isopods be used for soil systems (if there is sufficient local diversity), in some areas earthworms or mites may be useable but are generally too difficult to identify to be practically useful. In the ground layer indicator sets could include ants, millipedes, molluscs (snails in particular), ground beetles, harvestmen and gnaphosid spiders. Foliage-inhabiting indicators could comprise ants, chrysomelid leaf beetles, theridiid spiders and arctiid moths. Ants, orthopterans and butterflies may be appropriate for use in open habitats. These basic sets should be supplemented by other taxa where appropriate resources and taxonomic expertise are available.

Fungal Planet description sheets: 107–127

Novel species of microfungi described in the present study include the following from Australia: Phytophthora amnicola from still water, Gnomoniopsis smithogilvyi from Castanea sp., Pseudoplagiostoma corymbiae from Corymbia sp., Diaporthe eucalyptorum from Eucalyptus sp., Sporisorium andrewmitchellii from Enneapogon aff. lindleyanus, Myrmecridium banksiae from Banksia, and Pilidiella wangiensis from Eucalyptus sp. Several species are also described from South Africa, namely: Gondwanamyces wingfieldii from Protea caffra, Montagnula aloes from Aloe sp., Diaporthe canthii from Canthium inerne, Phyllosticta ericarum from Erica gracilis, Coleophoma proteae from Protea caffra, Toxicocladosporium strelitziae from Strelitzia reginae, and Devriesia agapanthi from Agapanthus africanus. Other species include Phytophthora asparagi from Asparagus officinalis (USA), and Diaporthe passiflorae from Passiflora edulis (South America). Furthermore, novel genera of coelomycetes include Chrysocrypta corymbiae from Corymbia sp. (Australia), Trinosporium guianense, isolated as a contaminant (French Guiana), and Xenosonderhenia syzygii, from Syzygium cordatum (South Africa). Pseudopenidiella piceae from Picea abies (Czech Republic), and Phaeocercospora colophospermi from Colophospermum mopane (South Africa) represent novel genera of hyphomycetes. Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

Conservation of invertebrate biodiversity on a mountain in a global biodiversity hotspot, Cape Floral Region

Mountains present particular challenges for biodiversity conservation. Table Mountain is a significant mountain in a global biodiversity hotspot, the Cape Floristic Region. It has outstanding angiosperm diversity and endemism. Yet, aerial and foliage invertebrates in the area have been poorly studied, despite their importance as pollinators and predators. These plant and invertebrate assemblages are under great pressure from human disturbance. Aerial and foliage invertebrates were sampled with a range of techniques. Sites were chosen to make comparisons between vegetation structure and type, elevation and aspect. In total, 216 species from 63 families and 14 orders were recorded. Vegetation structure (fynbos or forest) and elevation were the most important environmental variables for both aerial and foliage invertebrates. Peak time for aerial invertebrate abundance was spring and summer in the fynbos and spring in the forests, while the foliage invertebrates showed very little seasonal variation. There was no correlation between the diversity of aerial and foliage invertebrates. When these results were compared with others on epigaeic invertebrates, it became clear that epigaeic and aerial invertebrates are not correlated, while epigaeic and foliage invertebrates were only partially correlated, but not sufficiently so to consider one as a reliable estimator of the other. The management pointer from this study is that sites at all elevations are vital for the conservation of biodiversity on Table Mountain. Both the aerial and epigaeic/foliage invertebrate assemblages will need to be monitored separately to maintain the mountain’s conservation status.

Significant variables for the conservation of mountain invertebrates

Conserving biodiversity on mountains holds particular challenges, with topographic species beta diversity being high. In turn, conserving mountain biodiversity in the heart of a biodiversity hotspot, with intense urbanization on its lower slopes, poses further challenges. We investigate here an iconic mountain at the southern tip of Africa, which is under multiple human pressures, while receiving much conservation attention. We sought here some general principles to guide conservation management of this and other similar mountains. Our focal organisms were surface-active invertebrates, as they are abundant, diverse, and environmentally sensitive at point localities. We show that vegetation structure and elevation were the most important environmental variables determining this diversity. Type of fynbos vegetation, proximity of forest to a river, aspect, and abundance of the alien Argentine ant Linepithema humile, had no significant influence. Suburban woodland species richness and abundance had a non-significant difference to that of natural forest. Fynbos had high species beta diversity of invertebrates, suggesting that large areas of this dominant vegetation type should be conserved. However, many specialist and highly local endemic species were in forest, highlighting the irreplaceability of forest habitats. Such a mountain, with its complex topography, requires total protection, as there is no room for loss of any part of the mountain. We emphasize that, while the upper slope and summit are well protected, the lower slopes are in need of urgent attention, a situation which mirrors that in Europe.

Exploring the mesofilter as a novel operational scale in conservation planning

Summary 1. Increased emphasis is being placed on developing effective biodiversity conservation tools for practical conservation planning. The mesofilter is such a biodiversity planning tool, but has yet to be fully explored to appreciate its effectiveness. The key premise of the mesofilter is that ecosystems contain certain physical elements that are specifically associated with a diversity of species. Identifying such mesofilters could therefore complement existing conservation planning tools such as coarse and fine filters. 2. To explore the value of the mesofilter as an operational scale in conservation planning, we studied 18 remnant patches of endangered montane grassland in KwaZulu-Natal, South Africa, using the physical landscape feature of patch rockiness as an abiotic surrogate for biodiversity. The objective was to determine whether the mesofilter of rockiness can predict variation in species richness and composition for three dominant grassland taxa (plants, butterflies and grasshoppers) at the landscape scale. 3. Variable levels of rockiness had significant interactions with all three focal taxa. Higher species richness of all taxa was closely associated with higher levels of rockiness in a patch. The rocky mesofilter only predicted significant differences in species composition for butterflies. Elevation was also important, possibly another mesofilter for plants and grasshoppers in this landscape. 4. Synthesis and applications. The results indicate that the use of an abiotic surrogate such as rockiness can predict biodiversity value across multiple taxa. The mesofilter is therefore a valuable surrogacy and congruency tool for practical biodiversity conservation across this landscape and would likely have similar value if explored elsewhere. It also has value in the design and management of protected areas.

Importance of habitat heterogeneity in remnant patches for conserving dung beetles

Landscape heterogeneity affects the spatial distribution of species. This makes it an important consideration for conservation planning, particularly when designing sustainable production landscapes. We determine whether conserving landscape elements within a transformed landscape is adequate for conserving dung beetle biodiversity. Dung beetles are excellent indicators for landscape biodiversity studies as they are ecologically sensitive. Here we measure dung beetle alpha-diversity, as well as beta-diversity within landscape elements and across different landscape elements. In doing so, we assess the value of landscape elements, as well as variation within landscape elements, in determining the spatial distribution of dung beetles across a production landscape. The study was conducted in the commercial timber production area of the KwaZulu-Natal Midlands, South Africa. In this system, the different landscape elements are a mosaic of natural indigenous forests, grasslands and alien pine plantation blocks. Our results show that the only response for dung beetle alpha-diversity was higher species richness in grasslands and pine blocks compared to natural forests. The highest beta-diversity for a landscape element was the grassland, for elevational category was low elevational areas and grassland type was the Midlands Mistbelt Grassland. The compositional diversity (beta-diversity between elements) was significantly different for all pairwise variations between landscape elements, the elevational categories and grassland types. Natural forests embedded in the two different grassland types had greater differences in compositional diversity than those embedded in natural (grassland) or transformed (pine blocks) matrices. This highlights the need to conserve a range of similar remnant patches of natural vegetation regionally, in addition to conserving broad landscape elements (i.e. grasslands or natural forests) as conservation targets. Furthermore, our results are encouraging for the potential benefits from the ecosystem service provided by dung beetles across the whole landscape, even in the transformed elements.

Conservation of the insect assemblages of the Cape Peninsula biodiversity hotspot

The Cape Peninsula is an area of outstanding biological importance, not only for to its high levels of floristic diversity and endemism, but also for its number of localised endemic invertebrates. Little is known of the spatial distribution of invertebrates across the Peninsula, or how best to conserve them. Sampling by visual searches assisted by aerial and aquatic hand-nets was undertaken throughout the Peninsula. The most important areas for insect diversity on the Peninsula, and associated environmental variables, were determined. The ‘Peninsula effect’ was also investigated. Nine Red Listed species and five new species for the Peninsula were recorded. This high number of Red Listed species (for those few groups that have been assessed) emphasises the biological importance of the Cape Peninsula. Table Mountain had the most Red Listed species, while Cape Point had many species not found in the other areas. Noordhoek Wetland is very important for aquatic Coleoptera. Small hills on the Peninsula are important for overall insect diversity. Elevation, slope, aspect, distance to water and vegetation structure were the most important environmental variables in determining the insect assemblages. The Peninsula effect appears to have no influence on these particular insect assemblages of the Cape Peninsula. The high number of new Peninsula records for well-known taxonomic groups indicates that still little is known of the insect assemblages across the Peninsula. Nevertheless, areas of conservation priority identified in this study are Table Mountain (for Red Listed species), Noordhoek (for aquatic Coleoptera) and Cape Point and the small hills across the Peninsula (for their unique invertebrate assemblages). Conservation of a variety of elevations, including steep and flat areas, all aspects of mountains, as well as both the wet and dry areas, overall will contribute to the conservation of the insects.

Landscape ecological networks are successful in supporting a diverse dragonfly assemblage

Ecological networks (ENs) are able to mitigate the negative effects of commercial forestry on terrestrial biodiversity, yet this remains untested for the aquatic fauna. Understanding the anthropogenic and natural variables that drive dragonfly diversity at the landscape and habitat scales, allows the design and implementation of ENs that minimise biodiversity loss across production landscapes. Here, we determine the relative contribution of anthropogenic disturbances and natural environmental variables to dragonfly assemblages within ENs. Sixty sites, of various freshwater body types, were sampled for adult dragonflies across ENs in a commercial forestry landscape. Overall, species richness was significantly influenced by river width, water turbidity, water depth and the presence of invasive plants. Nevertheless, overall species composition was influenced by water body type, flow rate and substrate type. Further differences were found when analyses were conducted separately for Anisoptera and Zygoptera. Counter‐intuitively, anthropogenic disturbances had less effect on dragonfly species richness and composition than did natural environmental variables, emphasising the importance of conserving natural heterogeneity. Overall, dragonfly diversity can be successfully conserved in ENs provided that conservation planning incorporates appropriate local scale variables. These results also suggest that impacts on water quality and dragonfly diversity are minimised by well‐designed ENs within this production landscape.

Grasshopper assemblage response to surface rockiness in Afro-montane grasslands

Grasshoppers are often an important functional component of ecosystems, and many species show high levels of endemism. Evidence exists that percentage surface rock cover within a landscape can predict diversity of grasshopper species. Nevertheless, the reason why grasshopper species are responding to rocky landscapes has not been established. Here, we explore whether grasshoppers are responding to physical rockiness per se, or rather to specific correlates of higher surface rock exposure within a landscape. We also determine if this response varies between grasshopper taxonomic groups. We sampled grasshoppers in Afro‐montane grasslands in KwaZulu‐Natal, South Africa, and recorded 10 environmental variables. We explored the influence of these variables on grasshopper community composition and grasshopper family composition. We also determined the vegetation characteristics, which significantly correlate with percentage surface rock cover in this landscape (geophyte richness, perennial grass richness and vegetation density), and then measured the similarity of species composition across these correlates. Overall, grasshopper assemblage composition, as well as familial composition, responded strongly to an elevation gradient, and not to the correlates of surface rock cover. In turn, the higher species richness in such areas is more likely a function of the significant vegetation correlates of higher surface rock cover. Across taxonomic groups, there are specialist species within each group which are associated with environmental conditions related to surface rockiness through its underlying correlates. Rock exposure across this grassland landscape is therefore an important contributor to grasshopper dispersion patterns, and has important implications for conservation planning for this taxon.

Positive effects of burning and cattle grazing on grasshopper diversity

Grasshoppers constitute a significant proportion of invertebrate diversity in grasslands, but little is known about how fire and grazing, two of the main drivers of grassland dynamics, influence them. Here, we determine how these disturbances influence grasshopper diversity in remnant grassland ecological networks (ENs) among commercial forestry compartments in Afromontane grassland, South Africa. Sites differed in fire frequency (annual vs. longer rotation burning), time since last fire (<12 months vs. >12 months ago), and presence or absence of domestic cattle grazing. Reference sites were in an adjacent protected area (PA). We also recorded bare ground, vegetation cover, and vegetation height. Grasshopper abundance significantly benefitted from annual burning, cattle grazing, short grass, and when the last fire was <12 months prior to sampling. Fire frequency was the only disturbance with a significant effect on grasshopper species composition, but without significantly affecting species richness. In the PA, heterogeneity of dispersion was smaller in annually burned firebreaks than in sites with longer fire‐return intervals, which points to homogenisation of resident grasshopper assemblages. Although most grasshopper species favoured recently burned or grazed grassland, some preferred low or no disturbance. This illustrates a considerable range of habitat preferences in the grasshopper assemblage. Management recommendation: Burning and grazing at moderate levels should be integral to local landscape management, as these impacts benefit grasshoppers in grassland ENs. Some areas should be left undisturbed to create a mosaic of different successional stages at the landscape spatial scale, providing diverse habitat for a wide range of species.