Journal of Arachnology

Published by: American Arachnological Society

« previous article : next article »


Journal of Arachnology 33(2):269-279. 2005
doi: 10.1636/CT05-43.1

INFLUENCE OF GRAZING BY LARGE MAMMALS ON THE SPIDER COMMUNITY OF A KENYAN SAVANNA BIOME

Charles M. Warui, Martin H. Villet, Truman P. Young, and Rudy Jocqué

aDepartment of Invertebrate Zoology, National Museums of Kenya, P.O. Box 40658-00100 GPO, Nairobi, Kenya, ;

bDepartment of Zoology and Entomology, Rhodes University, 6140 Grahamstown, South Africa;

cDepartment of Plant Sciences, University of California, Davis, 95616 USA;

dInvertebrate Section, Department of African Zoology, Royal Museum for Central Africa, Leuvensesteenweg 13, B-3080 Tervuren, Belgium

Abstract

Pitfall trap and sweep net samples were taken over a period of fifteen months (2002– 2003) in the Kenya Long-term Exclosure Experiment (KLEE), in which the presence of domestic and wild herbivores have been independently manipulated since 1995. ANOVA and ANCOVA showed that the exclosure treatments significantly affected plant cover, with the presence of cattle significantly reducing the relative vegetation cover and spider diversity. Herbivory by indigenous mega- and meso–herbivores did not have a significant influence on the diversity of the spider fauna, but abundance of three dominant species (Cyclosa insulana Costa (Araneidae), Argiope trifasciata Forskål (Araneidae) and Runcinia flavida Simon (Thomisidae)) decreased in cattle-grazed plots. In contrast, Aelurillus sp. became more prevalent where cattle have been grazing. Multivariate analyses revealed that the spider community responded to grazing pressure by aggregating into three groups that reflected control, cattle grazing and non-cattle grazing clusters. It was probable that the direct effects on vegetation mediated an indirect influence of herbivores on spider diversity. The relative vegetation cover was a positive predictor of spider diversity. Spider communities were found to be an indicator of the activity of mammals and could be used as indicators of land use changes and for bio-monitoring.

Received: 5 April 2005; Revised: 1 September 2005

Keywords: Grazing, mammals, savanna, Kenya, spiders



LITERATURE CITED

Abensperg-Traun, G. T., G. T. Smith, G. W. Arnold, and D. E. Stevenson. 1996. The effects of habitat fragmentation and livestock-grazing on animal communities in remnants of gimlet Eucalyptus salubris woodland in the Western Australian wheatbelt. I. Arthropods. Journal of Applied Ecology 33:1281–1301. CrossRef, CSA
Abrous-Kherbouche, O., R. Jocqué, and J. P. Maelfait. 1997. Les effets du pâturage intensif sur l'aranéofaune dans la région de tala-Guilef (Parc National du Djurdjura, Algérie). Bulletin et Annales de la Société royale Belge d'Entomologie 133:71–90.
Ahn, P. M. and L. C. Geiger. 1987. Soils of Laikipia District. National Agricultural Research Laboratories, Nairobi, Kenya, 119 pp.
Blandin, P. and M-L. Célérier. 1981. Les Araignées des savanes de Lamto (Côte- d'Ivoire). Organisation des peuplements, bilans énergétiques, place dans 1′écosystème. Publications du Laboratoire Zoologie de l'Ecole normale Supérieure 21:1–586.
Caro, T. M. and G. O. Doherty. 1999. On the use of surrogate species in conservation biology. Conservation Biology 13:805–814. CrossRef
Churchill, T. B. 1998. Spiders as ecological indicators in the Australian tropics: family distribution patterns along rainfall and grazing gradients. Pp. 325—330. In Proceedings of the 17th European Colloquium of Arachnology, Edinburgh. (P.A. Selden, ed.). 14–18 July 1997.
Clarke, B. and R. Gorley. 2001. PRIMER 5 for windows version 5.24. Plymouth, PRIMER-E Ltd. [Software].
Clarke, B. and R. M. Warwick. 1994. Change in marine communities: an approach to statistical analysis and interpretation. Plymouth, Plymouth Marine Laboratory, 133 pp.
Coddington, J. A., L. H. Young, and F. A. Coyle. 1996. Estimating spiders' species richness in a Southern Appalachian cove hardwood forest. Journal of Arachnology 24:111–128. CSA
Curtis, D. J., E. J. Curtis, and D. B. A. Thompson. 1990. On the effects of trampling on montane spiders and other arthropods. Bulletin de la Société Européenne d'Arachnologie 1:103–109.
Dippenaar-Schoeman, A. S. and A. Leroy. 2003. A check list of the spiders of the Kruger National Park, South Africa (Arachnida: Araneae). Koedoe 46:91–100. CSA
Dippenaar-Schoeman, A. S., A. Leroy, M. de Jager, and A. Van den Berg. 1999. Spider diversity of the Karoo National Park, South Africa (Arachnida). Koedoe 42:31–42.
Dippenaar-Schoeman, A. S., A. M. van den Berg, and A. van den Berg. 1989. Species composition and relative seasonal abundance of spiders from the field and tree layers of the Roodeplaat Dam Nature Reserve. Koedoe 32:25–38. CSA
Dublin, H. T. 1995. Vegetation dynamics in the Serengeti-Mara ecosystem: the role of elephants, fire and other factors. Pp. 71—90. In Serengeti II: Dynamics, Management, and Conservation of an Ecosystem. (A.R.E. Sinclair & P. Arcese, eds.). Chicago: University of Chicago Press.
Fabricius, C. 1997. The impact of land use on biodiversity in xeric succulent thicket, South Africa. Ph.D. Thesis, University of Cape Town.
Fabricius, C., A. R. Palmer, and M. Burger. 2002. Landscape diversity in a conservation area and commercial and communal rangeland in xeric succulent thicket, South Africa. Landscape Ecology 17:531–537. CrossRef, CSA
Foord, S. H., A. S. Dippenaar-Schoeman, and M. van der Merwe. 2002. A check list of the spider fauna of the western Soutpansberg, South Africa (Arachnida: Araneae). Koedoe 45:35–43. CSA
Gibson, C. W. D., V. K. Brown, L. Losito, and G. C. McGavin. 1982. The response of invertebrate assemblies to grazing. Ecography 15:166–176. CrossRef
Gibson, C. W. D., C. Hambler, and V. K. Brown. 1992. Changes in spider (Araneae) assemblages in relation to succession and grazing management. Journal of Applied Ecology 29:132–142. CrossRef, CSA
Green, J. 1999. Sampling method and time determines composition of spider collections. Journal of Arachnology 27:176–182.
Greenslade, P. J. M. 1964. Pitfall trapping as a method for studying populations of Carabidae. Journal of Animal Ecology 33:301–310. CrossRef
Gunnarsson, B. 1988. Spruce-living spiders and forest decline; the importance of needle loss. Biological Conservation 43:309–319. CrossRef, CSA
Halaj, J., D. W. Ross, and A. R. Moldenke. 2000. Importance of habitat structure to the arthropod food-web in Douglas-fir canopies. Oikos 90:139–152. CrossRef
Keesing, F. 2000. Cryptic consumers and the ecology of an African savanna. BioScience 50:205–215. Abstract
Kremen, C., R. K. Colwell, T. L. Erwin, D. D. Murphy, R. F. Noss, and M. A. Sanjayan. 1994. Terrestrial arthropod assemblages. Their use in conservation planning. Conservation Biology 7:796–808. CrossRef, CSA
[LWF] Laikipia Wildlife Forum.1996. A total count of herbivores in Laikipia District, preliminary results. Laikipia (Kenya), Laikipia Wildlife Forum, unpublished report.
Lotz, L. N., M. T. Seaman, and D. J. Kok. 1991. Surface-active spiders (Araneae) of a site in a semi-arid central Africa. Navorsinge van die Nasionale Museum Bloemfontein 7:529–540. CSA
Mbugua, S. W. 1986. Monitoring livestock and wildlife in Kenya. Pp. 413—430. In Range Development and Research in Kenya. (R.M. Hansen, B.M. Woie & R.D. Child, eds.). Morrilton, Arizona: Winrock International Institute for Agriculture Development.
New, T. R. 1999. By-catch ethics and pitfall traps. Journal of Insect Conservation 3:1–3. CrossRef
Rambo, J. L. and S. H. Faeth. 1998. Effects of vertebrate grazing on plant insect community structure. Conservation Biology 13:1047–1054. CrossRef
Rivers-Moore, N. A. and M. J. Samways. 1996. Game and cattle trampling, and impacts of human dwellings on arthropods at a game park boundary. Biodiversity and Conservation 5:1545–1556. CrossRef, CSA
Russell-Smith, A. 1981. Seasonal activity and diversity of ground-living spiders in two African savanna habitats. Bulletin of British Arachnological Society 5:145–154.
Russell-Smith, A. 1999. The spiders of Mkomazi Game Reserve. Pp 197—222. In Mkomazi: the Ecology, Biodiversity and Conservation of a Tanzanian Savanna. (Coe, M., N. McWilliam, G. Stone & M. Parker, eds.). Royal Geographic Society, London.
Russell-Smith, A., J. M. Ritchie, and N. M. Collins. 1987. The surface active spider fauna of arid bushland in Kora Reserve, Kenya. Bulletin of British Arachnological Society 7:171–174. CSA
Rypstra, A. L. 1983. The importance of food and space in limiting web-spider densities: a test using exclosures. Oecologia 59:312–316. CrossRef, CSA
Rypstra, A. L., P. E. Carter, R. A. Balfour, and S. D. Marshall. 1999. Architectural features of agricultural habitats and their impact on the spider inhabitants. Journal of Arachnology 27:371–377.
Scharff, N. and C. E. Griswold. 1996. Biodiversity and biogeography of the spider fauna of the Eastern Arc Mountains, Tanzania. Preliminary report, 10 pp.
Seymour, C. 1998. Different grazing intensities in arid rangelands: effects on invertebrates on a communal farm in the succulent Karoo, South Africa. MSc. Thesis, University of Cape Town.
Seymour, C. L. and W. R. J. Dean. 1999. Effects of heavy grazing on invertebrate assemblages in the Succulent Karoo, South Africa. Journal of Arid Environments 43:267–286. CrossRef
Skarpe, C. 1991. Impact of grazing in savanna ecosystems. Ambio 20:351–356. CSA
Spence, J. R. and J. K. Niemelä. 1994. Sampling carabid assemblages with pitfall traps: the madness and the method. The Canadian Entomologist 126:881–894. CSA
StatSoft, Inc.1999. STATISTICA for Windows. Computer program manual. Oklahoma, Tulsa.
Taiti, S. W. 1992. The vegetation of Laikipia district, Kenya. Laikipia-Mt. Kenya Papers, B-2. Laikipia Research Programme, Universities of Nairobi and Bern, pp 21.
Uetz, G. W. 1991. Habitat structure and spider foraging. Pp 325—348. In Habitat Structure. The Physical Arrangement of Objects in Space. (Bell, S.S., E.D. McCoy & H.R. Mushinsky, eds.). Chapman & Hall, London.
Uetz, G. W. and J. D. Unzicker. 1976. Pitfall trapping in ecological studies of wandering spiders. Journal of Arachnology 3:101–111.
Van den Berg, A. and A. S. Dippenaar-Schoeman. 1991. Ground-living spiders from an area where the harvester termite Hodotermes mossambicus occurs in South Africa. Phytophylactica 23:247–253.
Warui, C. M., M. H. Villet, and T. P. Young. 2004. Spiders (Araneae) from black cotton soils of a highland savanna in Laikipia, central Kenya. Journal of Afrotropical Zoology 1:13–24.
Western, D. 1989. Conservation without parks: wildlife in the rural landscape. Pp 158—165. In Conservation for the twenty-first century. (D. Western & M.C. Pearl, eds.). Oxford: Oxford University Press.
Whitmore, C., R. Slotow, T. E. Crouch, and A. S. Dippenaar-Schoeman. 2001. Checklist of spiders (Araneae) from a savanna ecosystem, Northern Province, South Africa: including a new family record. Durban Museum Novitates 26:10–19.
Wise, D. H. 1993. Spiders in Ecological Webs. Cambridge, Cambridge University Press, pp 328.
Woldu, Z. and M. A. Saleem. 2000. Grazing induced biodiversity in the highland ecozone of E. Africa. Agriculture, Ecosystems and Environment 79:45–52. CrossRef
Young, T. P., N. Patridge, and A. Macrae. 1995. Long term glades in Acacia bushland and their edge effects in Laikipia, Kenya. Ecological Applications 5:98–108. CrossRef
Young, T. P., B. D. Okello, D. Kinyua, and T. M. Palmer. 1998. KLEE: A long-term multi-species herbivore exclusion experiment in Laikipia, Kenya. African Journal of Range and Forage Science 14:94–102.

Figure 1. Schematic representation of the experimental design of the KLEE study plots at Laikipia, Kenya. Letters in each plot represent the herbivores allowed in: C = cattle, W = meso-herbivores, M = mega-herbivores, O = control (all large mammalian herbivores excluded). N, C and S represent north, central and south blocks respectively. Each plot measures 200 × 200 m. The distance between the furthest placed plots (between north and south block) is approximately 2 km. Adapted from Young et al. (1998)

Figures 2–3.—2. Effects of ‘cattle’ (levels: absent [treatmentsW and MW] vs. present [WC and MWC]) and ‘megaherbivores’ (levels: absent [W and WC] vs. present [MW and MWC]) on relative vegetation cover (mean + SE). Two treatments (O and C) were omitted from the data set so that the analysis was fully crossed. The interaction term was not significant (P = 0.28). 3. Effects of ‘cattle’ (levels: absent [O and W] vs. present [C and WC]) and ‘mesoherbivores’ (levels: absent [O and C] vs. present [W and WC]) on relative vegetation cover (mean + SE). Two treatments (MW and MWC) were omitted from the data set so that the analysis was fully crossed. The interaction term was not significant (P = 0.79)

Figure 4. Effects of ‘cattle’ (levels: absent [O, W and MW] vs. present [C, WC and MWC]) and ‘herbivores’ (levels: herbivores absent [O and C], only mesoherbivores present [W and CW], and both meso- and megaherbivores present [MW and MWC]) on total number of spider species from sweep-netting samples (mean + SE). No treatments were omitted from the data set. The interaction term was not significant (P = 0.81)

Figure 5. Multidimensional scaling (MDS) ordination of the spider community in the sweep-netting samples of spiders collected at Laikipia, Kenya in 2001–2002, with convex hulls superimposed to enclose regions characteristic of control, cattle and non-cattle treatments. In all cases the first letter of any code represents the three study blocks, namely north (N), central (C) and south (S). All other letters represent the animals present, where O = control, C = cattle, W = meso-herbivores, and M = mega-herbivores

table

Table 1. Results of ANOVA on effects of the factors ‘cattle’ (levels: absent [treatments O, W and MW] vs. present [C, WC and MWC]) and ‘herbivores’ (levels: herbivores absent [O and C], only meso-herbivores present [W and CW], and both meso- and mega-herbivores present [MW and MWC]) on relative vegetation cover. The codes for the treatment abbreviations are (cf. Fig. 1): O = control (no large mammalian herbivores); W = meso-herbivores; M = mega-herbivores and C = cattle. No treatments were omitted from the data set. * = Significant at α = 0.05

table

Table 2. Correlations between relative vegeta tion cover and four measures of diversity (Shannon-Wiener diversity index [H′], Margalef's richness in dex [d], Pielou's evenness index [J′] and total spider species [S]) for data sets generated at Laikipia, Kenya in 2001–2002 using sweep-netting and pit fall-trapping samples. df = 18. * = Significant at α = 0.05

table

Table 3. Analysis of covariance (ANCOVA) to establish the effects of the factors ‘meso-herbivores’ (levels: absent [O and C] vs. present [W and WC]) and ‘cattle’ (levels: absent [O and W] vs. present [C and WC]) and two covariates, relative vegetation cover and total monthly rainfall, on the abundance of Cyclosa insulana, Argiope trifasciata, Runcinia flavida and Aelurillus sp recorded at Laikipia in 2001– 2002. The codes for the above abbreviations are such that O = control (no large mammalian herbivores); (W) = meso-herbivores; (M) = mega-herbivores and (C) = cattle. * = Significant at α = 0.05

Cited by

Mayura Takada, Yuki G. Baba, Yosuke Yanagi, Saeko Terada, Tadashi Miyashita. (2008) Contrasting Responses of Web-Building Spiders to Deer Browsing Among Habitats and Feeding Guilds. Environmental Entomology 37:4, 938-946
Online publication date: 1-Aug-2008.

Abstract & References : Full Text : PDF (216 KB) : Rights & Permissions 

 
BioOne is the product of innovative collaboration between scientific societies, libraries, academe and the private sector.
 
21 Dupont Circle NW, Suite 800, Washington, DC 20036 • Phone 202.296.2296 • Fax 202.872.0884
 
Copyright © 2009 BioOne All rights reserved