Michael J. Samways

Quantifying the Contribution of Organisms to the Provision of Ecosystem Services

Research on ecosystem services has grown rapidly over the last decade. Two conceptual frameworks have been published to guide ecological assessments of organisms that deliver services—the concepts of service-providing units (SPUs) and ecosystem service providers (ESPs). Here, we unite these frameworks and present an SPU-ESP continuum that offers a coherent conceptual approach for synthesizing the latest developments in ecosystem service research, and can direct future studies at all levels of organization. In particular, we show how the service-provider concept can be applied at the population, functional group, and community levels. We strongly emphasize the need to identify and quantify the organisms and their characteristics (e.g., functional traits) that provide services, and to assess service provision relative to the demands of human beneficiaries. We use key examples from the literature to illustrate the new approach and to highlight gaps in knowledge, particularly in relation to the impact of species interactions and ecosystem dynamics on service provision.

The search for common anthropogenic impacts on biodiversity: a global network

We introduce an initiative to assess and compare landscape changes related to human activities on a global scale, using a single group of invertebrates. The GLOBENET programme uses common field methodology (pitfall trapping), to appraise assemblages of ground beetles (Coleoptera, Carabidae) in visually-similar land-mosaics (urban-rural gradients). Carabids were selected as the focal taxon as they are sufficiently varied (both taxonomically and ecologically), abundant and sensitive to the environment. However, work on other taxa is comparable with the GLOBENET framework. The continuum of decreasing human pressure from city centres into the surrounding countryside was selected to represent human-caused disturbance for this initial stage of GLOBENET because these gradients can be found virtually all over the world. Through the broad-scale assessment envisioned in the GLOBENET programme, we seek to separate general, repeated effects on biodiversity from those that depend on local environments or particular biotic assemblages. Based on this understanding we aim to develop simple tools and protocols for assessing ecological effects of human-caused landscape changes, which could help to sustainably manage landscapes for biodiversity and for human requirements. For instance, the response of different functional groups of carabids to these landscape changes may help guide management practices. Further GLOBENET developments and information are available at our website: http://www.helsinki.fi/science/globenet/

Dragonfly (Odonata) distribution patterns in urban and forest landscapes, and recommendations for riparian management

Odonata species are particularly sensitive to human disturbances. Their diversity relative to four landscape types (plantation forest, parkland, residential area, industrial area) along a small river (the Dorpspruit) that runs through Pietermaritzburg, South Africa, is described. Individual species-environment relations were investigated using the multivariate analysis package CANOCO. Four biotope types were identified and characterised. The analysis also illustrated the extent to which the urban, suburban and forestry environments affected the Odonata species. Multispecies assemblages were good environmental indicators. Individual indicator species included Chlorolestes tessellatus and Crocothemis erythraea. Chlorolestes tessellatus is a good indicator of the minimal width (> 30 m) of the indigenous strip of riparian vegetation between the stream edge and commercial plantations. This study suggests that there should be a riparian strip between the waters edge and plantation trees of at least 20 m (preferably 30 m). This finding is integrated with earlier ones to arrive at a general conservation management recommendation, at least for dragonflies, for rivers in South Africa.

Ground-living invertebrate assemblages in native, planted and invasive vegetation in South Africa

Abstract Invasive plants and plantations may be detrimental to native, ground-living, invertebrate fauna. Using pitfall traps at 20 sites in Pietermaritzburg, South Africa, an assessment was made of the distribution of epigaeic fauna under stands of the exotic invader plants: Acacia longifolia (long-leaved wattle), Acacia mearnsii (black wattle), Lantana camara (lantana) and Solanum mauritianum (bugweed), and also under a canopy of two major plantation trees: Eucalyptus grandis and Pinus patula. Control plots were minimally disturbed grassland and woodland in the same area. The effects of the invasive and cultured plants suggest that the impact is a complex interaction of factors. In general, there was a lower (but not significantly so) species richness, and also diversity, of invertebrates in exotic compared with indigenous vegetation. Certain individual species rather than whole families were affected most by these types of vegetation. There was a different assemblage of species associated with exotic compared with indigenous vegetation, with some species being good indicators for exotic or for indigenous vegetation. Although the weeds and vegetation caused a few species to increase in abundance, many other species decreased or even disappeared locally. Whereas different species assembled according to whether vegetation was exotic or indigenous, families and orders assembled along a gradient of closed to open canopy vegetation irrespective of origin. Although a few species were restricted to exotic vegetation (presumably having invaded at some time in the past from somewhere apart from the control sites), many others were restricted to indigenous vegetation. Vegetation management should be sensitive to the needs of certain invertebrate species so as to conserve them when native vegetation is replaced by exotics. Some management recommendations for conserving local invertebrate diversity are made.

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.

Dragonflies (Odonata) as indicators of biotope quality in the Kruger National Park, South Africa

1. Monitoring programmes that assess ecosystem changes depend on indicator species or assemblages. Indicators should be sensitive and their response easily measured. This study assessed the suitability of adult male Odonata as indicators of biotope quality along the Sabie River in the Kruger National Park (KNP). 2. Odonate diversity was investigated at 25 sites along the Sabie River using univariate statistical procedures. The KNP supports 81 species, 59 recorded during this study (16 for the first time). 3. Sampling sites were classified by Two Way INdicator SPecies Analysis (TWINSPAN) and ordinated by DEtrended CORrespondence ANAlysis (DECORANA), based on the abundance of adult male Odonata. A predictive model relating Odonate species-groups to biotope variables, was formulated. 4. Classification led to the recognition of 10 ecologically meaningful biotope groups, each with an indicator species and a characteristic assemblage of associated species. 5. Multiple Discriminant Analysis (MDA) indicated that shade cover, permanency and flow rate could discriminate between biotope types defined by TWINSPAN. Variation in site membership between MDA and TWINSPAN suggests interaction between variables in determining species membership. 6. Biotope variables were incorporated into a model which predicted the membership of 82% of sites to the TWINSPAN groups; shade cover alone correctly predicted 44% of the sites. 7. The suitability of the Odonata as indicators of biotope quality, and its consequences for management are discussed.

Insect species richness tracking plant species richness in a diverse flora: gall-insects in the Cape Floristic Region, South Africa

Abstract The Cape Floristic Region (CFR) is one of the most plant-species-rich regions in the world. It is also a warm temperate region and hypothetically should have high gall-insect species richness, making it interesting to investigate the relationship between the insects of the region and the rich flora. The relationship between gall-insect species richness (GSR) and plant richness was investigated for the Fynbos and for representatives of vegetation of the whole CFR. Samples (of up to 600 plants per transect for Fynbos) of woody shrubs were investigated for the presence of galls. The species richness of these insects was quantified, as well as plant species richness for each transect. GSR for Fynbos was compared to global figures for GSR. Fynbos harboured significantly more gall-insect species than other CFR vegetation types. GSR was positively correlated with CFR plant richness. GSR also closely tracked plant richness in Fynbos. GSR was not significantly influenced by other variables (elevation and aspect), suggesting that plant richness per se was an important factor in generating GSR. Fynbos GSR is comparable to other sclerophyllous regions of high GSR globally, corroborating that this vegetation type is conducive to gall-insect diversification. There is likely to be a high percentage of gall-insect endemism in the Fynbos, as might be expected from the high host fidelity of this insect group.

Faunal diversity and endemicity of the Cape Peninsula, South Africa — a first assessment

A total of 322 records were available from the literature on faunal taxa endemic to the Cape Peninsula, South Africa. Excluding possible pseudoendemics, dubious records and many invertebrate groups for which little or no information exists, these records represent 112 species (1 vertebrate and the rest invertebrates) in 47 families. This number excludes many other potential endemics having distributions that extend just off the Peninsula. When mapped according to a 590 1 km×1 km grid, these endemics were clustered in several, largely montane nodes and palaeogenic (palaeoclimatically stable) zones typically located in upper reach forest streams, riverine forest and caves (the latter supported 14 endemics). Endemics were over-represented on steep slopes. For many taxa, a very high percentage of the Peninsula representatives were endemics. There were more plant than animal endemics per 1 km2 cell, although in total there were more animal than plant endemics. A significant correlation existed between the distribution of plant and animal endemics on the Peninsula, and especially on Table Mountain. The relationship, however, appears not to be causal, and is possibly related to parallel responses to historical isolation and topography. As the endemic fauna is mostly relictual, conservation of umbrella plant communities and the sandstone caves is essential. This may avert further extinction (some invertebrate endemics are likely to be extinct at this stage). Others have suffered declines in population numbers through development, invasion of alien vegetation, and possibly through predetion by the introduced Argentine ant.

Influence of exotic conifer patches on grasshopper (orthoptera) assemblages in a grassland matrix at a recreational resort, Natal, South Africa

Abstract With the scarcity of extensive, pristine land for new nature reserves it has become increasingly important to reconcile mans activities with nature conservation. Midmar Dam, Natal, South Africa, is a recreational resort that is also a nature conservation area. The impact of specific landscape elements (conifer patches) on grasshopper (mostly Acridoidea) assemblages within a mixed grassland matrix was investigated at this location. Grasshoppers are good indicator species for general grassland insect communities, and are relatively sensitive to landscape disturbance. Microclimatic temperature and humidity bore no significant relationship to grasshopper assemblage trends, although irradiance did at some sites. There was a strong, positive correlation between grasshopper and grass species richness. Exotic cypress Cupressus arizonica Greene patches increased orthopteran species richness and abundance, while exotic pine Pinus roxburghii Sargent and P. elliotti Engelmann patches are detrimental for grasshoppers far into the grass matrix. This impoverishing effect was great enough to be influential in future conservation management decisions relating to the planting of trees for recreational shade.

Ecosystem services and biodiversity conservation: concepts and a glossary.

The RUBICODE project draws on expertise from a range of disciplines to develop and integrate frameworks for assessing the impacts of environmental change on ecosystem service provision, and for rationalising biodiversity conservation in that light. With such diverse expertise and concepts involved, interested parties will not be familiar with all the key terminology. This paper defines the terms as used within the project and, where useful, discusses some reasoning behind the definitions. Terms are grouped by concept rather than being listed alphabetically.