Increasing elephant Loxodonta africana density is a more important driver of change in vegetation condition than rainfall

• Autorzy: Hayward M. , Zawadzka B.
• Języki publikacji: EN

Abstrakty

EN

The impact of African elephantsLoxodonta africana Blumenbuch, 1797 on biodiversity is hotly debated in wildlife management circles with scientists polarised in their views. This polarisation is largely due to the individual experiences of researchers. We aimed to determine whether elephants or rainfall patterns drove changes in vegetation condition (Normalised Difference Vegetation Index; NDVI) by avoiding a site-specific approach and looking at the issue at a broader scale. We used published estimates of elephant population density from 30 sites and recorded the change in density from 1995–1999, from 1999–2002 and from 2002–2006. We also recorded the deviation of annual rainfall from the long-term mean for those periods. We modelled these variables against the change in NDVI between periods using mixed effects models. We found that elephants were more influential in driving change in vegetation condition than rainfall, and this also occurred at one of our individual test sites where long-term data were available (Kruger). Elephants and rainfall combined to drive change in vegetation condition at our other long-term test site (Amboseli). Management activities (fencing, water provision) may cause the differences between the two long-term study sites. Change in productivity driven by rainfall has ramifications for biodiversity, suggesting that elephant derived changes in vegetation productivity (NDVI) also impacts on biodiversity. Thus, this study supports previous findings from individual sites that elephants impact vegetation, however there is also a suggestion that these impacts may vary according to management actions.

Słowa kluczowe

EN

African elephant; data analysis; Loxodonta africana; biodiversity; elephant; megaherbivore; population density; population limitation; rainfall; vegetation condition; vegetation response; wildlife management

• Wydawca: -
• Czasopismo: Acta Theriologica
• Rocznik: 2010
• Tom: 55
• Numer: 4
• Opis fizyczny: p.289-299,fig.,ref.

Twórcy

autor

Hayward M.

• Mammal Research Institute, Polish Academy of Sciences, Waszkiewicza 1c, 17-230 Bialowieza, Poland

autor

Zawadzka B.

Bibliografia

• Akaike H. 1973. Information theory and an extension of the maximum likelihood principle. [In: Proceedings of the Second International Symposium on Information Theory. N. Petrov and F. Csadki, eds]. Akademiai Kiado, Budapest: 267–281.
• Akaike H. 1974. A new look at the statistical model identification. IEEE Transactions on Automatic Control AC 19: 716–723.
• Andersen R., Herfindal I., Saether B.-E., Linnell J. D. C., Odden J. and Liberg O. 2004. When range expansion rate is faster in marginal habitats. Oikos 107: 210–214. doi: 10.1111/j.0030-1299.2004.13129.x
• Barnes R. F. W., Craig G. C., Dublin H. T., Overton J. M., Simons W. and Thouless C. R. 1998. African elephant database 1998. African Elephant Specialist Group, IUCN, Gland, Switzerland.
• Baxter P. W. J. and Getz W. M. 2005. A model-framed evaluation of elephant effects on tree and fire dynamics in African savannas. Ecological Applications 15: 1331–1341. doi: 10.1890/02-5382
• Blanc J. J., Barnes R. F. W., Craig G. C., Dublin H. T., Thouless C. R., Douglas-Hamilton I. and Hart J. A. 2007. African elephant status report 2007: An update from the African elephant database. Species Survival Commission, IUCN — The World Conservation Union: Gland, Switzerland.
• Blanc J. J., Thouless C. R., Hart J. A., Dublin H. T., Douglas-Hamilton I., Craig G. C. and Barnes R. F. W. 2003. African elephant status report 2002: An update from the African elephant database. African Elephant Specialist Group (AfESG), Species Survival Commission (SSC), International Union for the Conservation of Nature and Natural Places (IUCN). Gland, Switzerland.
• Burnham K. P. and Anderson D. J. 2001. Kullback-Leibler information as a basis for strong inference in ecological studies. Wildlife Research 28: 111–119. doi: 10.1071/WR99107
• Caro T. M. and Scholte P. 2007. When protection falters. African Journal of Ecology 45: 233–235. doi: 10.1111/ j.1365-2028.2007.00814.x
• Caughley G. 1976. The elephant problem — an alternative hypothesis. East African Wildlife Journal 14: 265–283.
• Celesia G. G., Peterson A. T., Kerbis Peterhans J. C. and Gnoske T. P. 2010. Climate and landscape correlates of African lion (Panthera leo) demography. African Journal of Ecology 48: 58–71. doi: 10.1111/j.1365-2028.2009. 01082.x
• Chamaille-Jammes S., Fritz H. and Murindagomo F. 2006. Spatial patterns of NDVI-rainfall relationship at the seasonal and interannual time scales in an African savanna. International Journal of Remote Sensing 27: 5185–5200.
• Cumming D. H. and Jones B. 2005. Elephants in southern Africa: management issues and options. World Wildlife Fund (WWF) — SARPO, 11, Harare, Zimbabwe.
• Cumming D. H. M., Fenton J. B., Rautenbach I. L., Taylor R. D., Cumming G. S., Cumming M. S., Dunlop J. M., Ford A. G., Hovorka M. D., Johnston D. S., Kalcounis M., Mahlangu Z. and Portfors V. R. 1997. Elephants, woodlands and biodiversity in southern Africa. South African Journal of Science 93: 231–236.
• East R. 1984. Rainfall, soil nutrient status and biomass of large African savanna mammals. African Journal of Ecology 22: 245–270.
• Edkins M. T., Kruger L., Harris K. and Midgley J. J. 2008. Baobabs and elephants in Kruger National Park: nowhere to hide. African Journal of Ecology 46: 119–128. doi: 10.1111/j.1365-2028.2007.00798.x
• Fangfang Yu, Price K. P., Ellis J. and Shi P. 2003. Response of seasonal vegetation development to climatic variations in eastern central Asia. Remote Sensing Environment 87: 42–54.
• Flannery T. F. 1994. The future eaters: An ecological history of the australasian lands and people. Reed Books: Sydney.
• Fritz H., Duncan P. J., Gordon I. J. and Illius A. W. 2002. The influence of megaherbivores on the abundance of the trophic guilds in African ungulate communities. Oecologia 131: 620–625. doi: 10.1007/s00442-002-0919-3
• Gaylard A., Owen-Smith N. and Redfern J. F. 2003. Surface water availability: implications for heterogeneity and ecosystem processes. [In: The Kruger experience: ecology and management of savanna heterogeneity. J. T. Du Toit, K. H. Rogers and H. C. Biggs, eds]. Island Press, Washington: 171–188.
• Gill J. 2000. Generalized linear models: a unified approach. Sage University, Thousand Oaks, CA.
• GIMMS 2010. Global inventory modeling and mapping studies satellite drift corrected and NOAA-16 Incorporated normalized difference vegetation index. University of Maryland Global Land Cover Facility Data Distribution. University of Maryland, Maryland.
• Giorgi F. 1990. Simulation of regional climate using a limited area model nested in a general circulation model. Journal of Climate 3: 941–963.
• Giorgi F., Mearns L. O., Shields C. and Mayer L. 1996. A regional model study of the importance of local versus remote controls of the 1988 drought and the 1993 flood over the central United States. Journal of Climate 9: 1150–1162.
• Gough K. and Kerley G. I. H. 2006. Lack of density dependent regulation in Addo’s elephant population. Oryx 40: 464–441.
• Guldemond R. and Van Aarde R. J. 2008. A meta-analysis of the impact of African elephants on savanna vegetation. Journal of Wildlife Management 72: 892–899. doi: 10.2193/2007-072
• Guy P. R. 1976. The feeding behaviour of elephant (Loxodonta africana) in the Sengwa area, Rhodesia. South African Journal of Wildlife Research 6: 55–63.
• Hayward M. W. 2009a. Conservation management for the past, present and future. Biodiversity and Conservation Online early: doi: 10.1007/s10531-008-9436-y.
• Hayward M. W. 2009b. The need to rationalize and prioritize threatening processes used to determine threat status in the IUCN Red List. Conservation Biology 23: 1568–1677. doi: 10.1111/j.1523-1739.2009.01260.x
• Hayward M. W., Hayward G. J. and Kerley G. I. H. 2010. The impact of upgrading roads on the conservation of the threatened flightless dung beetle,Circellum bacchus (F.) (Coleoptera: Scarabaediae). The Coleopterists Bulletin 64: 75–83. doi: 10.1649/0010-065X-64.1.75
• Holdo R. M., Holt R. D. and Fryxell J. M. 2009. Grazers, browsers, and fire influence the extent and spatial pattern of tree cover in the Serengeti. Ecological Applications 19: 95–109. doi: 10.1890/07-1954.1
• Jędrzejewska B. and Jędrzejewski W. 2005. Large carnivores and ungulates in European temperate forest ecosystems: bottom-up and top-down control. [In: Large carnivores and the conservation of biodiversity. J. C. Ray, K. H. Redford, R. S. Steneck and J. Berger, eds]. Island Press, Washington: 230–246.
• Kerley G. I. H. and Landman M. 2006. The impacts of elephants on biodiversity in the Eastern Cape subtropical thickets. South African Journal of Science 102: 395–402.
• Kerley G. I. H., Landman M., Kruger L., Owen-Smith N., Balfour D., De Beer Y., Gaylard A., Lindsay K. and Slotow R. 2007. Effects of elephants on ecosystems and biodiversity. [In: 2007 South African assessment of elephant management]. South African Government, Pretoria: 1–71.
• Kerr J. T. and Ostrovsky M. 2003. From space to species: ecological applications for remote sensing. Trends in Ecology and Evolution 18: 299–305.
• Kidwell K. B. 1990. Global vegetation index user’s guide. U.S. Department of Commerce/National Oceanic and Atmospheric Administration/National Environmental Satellite Data and Information Service/National Climatic Data Centre/Satellite Data Services Division: Houston, USA.
• Laws R. M. 1970. Elephants as agents of habitat and landscape change in East Africa. Oikos 21: 1–15.
• Levinsky I., Skov F., Svenning J.-C. and Rahbek C. 2007. Potential impacts of climate change on the distributions and diversity patterns of European mammals. Biodiversity and Conservation 16: 3803–3816.
• Lombard A. T., Johnson C. F., Cowling R. M. and Pressey R. L. 2001. Protecting plants from elephants: botanical reserve scenarios within the Addo Elephant National Park, South Africa. Biological Conservation 102: 191–203.
• Loucks C., Ricketts T. H., Naidoo R., Lamoreux J. F. and Hoekstra J. M. 2008. Explaining the global pattern of protected area coverage: relative importance of vertebrate biodiversity, human activities and agricultural suitability. Journal of Biogeography 35: 1337–1348. doi: 10.1111/j.1365-2699.2008.01899.x
• Madelli F., Romanelli S., Bottai L. and Zipoli G. 2003. Use of NOAA-AVHHR NDVI images for the estimation of dynamic fire risk in Mediterranean areas. Remote Sensing Environment 86: 187–197.
• Makhabu S. W., Skarpe C. and Hytteborn H. 2006. Elephant impact on shoot distribution on trees and on rebrowsing by smaller herbivores. Acta Oecologica 30: 136–146. doi: 10.1016/j.actao.2006.02.005
• Mapaure I. and Campbell B. M. 2002. Changes in miombo woodland cover in and around Sengwa Wildlife Research Area, Zimbabwe, in relation to elephants and fire. African Journal of Ecology 40: 212–219. doi: 10.1046/ j.1365-2028.2002.00355.x
• Moss C. J. 2001. The demography of an African elephant (Loxodonta africana) population in Amboseli, Kenya. Journal of Zoology 255: 145–156. doi: 10.1017/S095283 6901001212
• Murwira A. and Skidmore A. K. 2005. The response of elephants to the spatial heterogeneity of vegetation in a southern African agricultural landscape. Landscape Ecology 20: 217–234. doi: 10.1007/s10980-004-3159-6
• Nelder J. A. and Wedderburn R. W. M. 1972. Generalized linear models. Journal of the Royal Statistical Society, Series A 135: 370–385.
• Nemani R. R., Keeling C. D., Hashimoto H., Jolly W. M., Piper S. C., Tucker C., Myneni R. B. and Running S. W. 2003. Climate-driven increases in global terrestrial net primary production from 1982 to 1999. Science 300: 1560–1563. doi: 10.1126/science.1082750
• NOAA 2008. WMO Resolution 40 Climate Data Webpage. National Climatic Data Centre, U.S. Department of Commerce, Washington, USA.
• Owen-Smith N. 1988. Megaherbivores: The influence of very large body size on ecology. Cambridge University Press: Cambridge, U.K.
• Owen-Smith N., Kerley G. I. H., Page B., Slotow R. and Van Aarde R. J. 2006. A scientific perspective on the management of elephants in the Kruger National Park and elsewhere. South African Journal of Science 102: 389–394.
• Owen-Smith N. and Mills M. G. L. 2006. Manifold interactive influences on the population dynamics of a multispecies ungulate assemblage. Ecological Monographs 76: 73–92. doi: 10.1890/04-1101
• Pamo E. T. and Tchamba M. N. 2001. Elephants and vegetation change in the Sahelo-Soudanian region of Cameroon. Journal of Arid Environments 48: 243–253.
• Parker I. S. C. 1982. The Tsavo story: an ecological case history. [In: Management of large mammals in African conservation areas. N. Owen-Smith, ed]. Haum, Pretoria: 37–50.
• Penzhorn B. L., Robbertse P. J. and Olivier M. C. 1974. The influence of the African elephant on the vegetation of the Addo Elephant National Park. Koedoe 17: 137–158.
• Pettorelli N., Vik J. O., Mysterud A., Gaillard J.-M., Tucker C. and Stenseth N. C. 2005a. Using the satellite-derived NDVI to assess ecological responses to environmental change. Trends in Ecology and Evolution 20: 503–510.
• Pettorelli N., Weladji R., Holand O., Mysterud A., Breie H. and Stenseth N. C. 2005b. The relative role of winter and spring conditions: linking climate and landscapescale plant phenology to alpine reindeer body mass. Biology Letters 1: 24–26.
• Pinzon J., Brown M. E. and Tucker C. 2005. Satellite time series correction of orbital drift artifacts using empirical mode decomposition. [In: Hilbert-Huang, transform: introduction and applications. N. Huang, ed]. NASA, Colorado: 167–186.
• Richard Y. and Poccard I. 1998. A statistical study of NDVI sensitivity to seasonal and interannual rainfall variations in southern Africa. International Journal of Remote Sensing 19: 2907–2920.
• Roerink G. J., Menenti M., Soepboer W. and Su Z. 2003. Assessment of climate impact on vegetation dynamics by using remote sensing. Physics and Chemistry of the Earth 28: 103–109.
• Said M. Y., Chunge R. N., Craig G. C., Thouless C. R., Barnes R. F. W. and Dublin H. T. 1995. African Elephant Database 1995. African Elephant Specialist Group of the Species Survival Commission, International Union for the Conservation of Nature, Gland, Switzerland.
• Sankaran M., Ratnam J. and Hanan N. P. 2008. Woody cover in African savannas: the role of resources, fire and herbivory. Global Ecology and Biogeography 17: 236–245. doi: 10.1111/j.1466-8238.2007.00360.x
• Scholte P., Adam S. and Kadiri Serge B. 2007. Population trends of antelopes in Waza National Park (Cameroon) from 1960 to 2001: the interacting effects of rainfall, flooding and human interventions. African Journal of Ecology 45: 431–439. doi: 10.1111/j.1365-2028.2007. 00774.x
• Sellers P. J., Berry J. A., Collatz G. J., Field C. B. and Hall F. G. 1992. Canopy reflectance, photosynthesis, and transpiration. III: a reanalysis using improved leaf models and a new canopy integration scheme. Remote Sensing Environment 42: 187–216.
• Singh R. P., Roy S. and Kogan F. 2003. Vegetation and temperature condition indices from NOAA AVHRR data for drought monitoring in India. International Journal of Remote Sensing 24: 4393–4402.
• Stoner C. J., Caro T. M., Mduma S., Mlingwa C., Sabuni G., Borner M. and Schelten C. 2007. Changes in large herbivore populations across large areas of Tanzania. African Journal of Ecology 45: 202–215. doi: 10.1111/j.1365-2028.2006.00705.x
• Tucker C., Pinzon J., Brown M. E., Slayback D., Pak E. W., Mahoney R., Vermote E. and Saleous N. 2005. An extended AVHRR 8-km NDVI data set compatible with MODIS and SPOT vegetation NDVI data. International Journal of Remote Sensing 26: 4485–4498.
• van Aarde R. J. and Jackson T. P. 2007. Megaparks for metapopulations: addressing the causes of locally high elephant numbers in southern Africa. Biological Conservation 134: 289–297.
• van Aarde R. J., Whyte I. J. and Pimm S. L. 1999. Culling and the dynamics of the Kruger National Park African elephant population. Animal Conservation 2: 287–294.
• Waldram M. S., Bond W. J. and Stock W. D. 2008. Ecological engineering by a mega-grazer: white rhino impacts on a South African savanna. Ecosystems 11: 101–112.
• Wang Q., Watanabe M., Seiji H. and Shogo M. 2003. Using NOAA AVHRR data to assess flood damage in China. Environmental Monitoring and Assessment 82: 119–148.
• Western D. 1989. The ecological role of elephants in Africa. Pachyderm 12: 42–45.
• Western D. 2006. A half a century of habitat change in Amboseli National Park, Kenya. African Journal of Ecology 45: 302–310.
• Western D. and Maitumo D. 2004. Woodland loss and restoration in a savanna park: a 20-year experiment. African Journal of Ecology 42: 111–121.
• Zhou L., Kaufmann R. K., Tian Y., Myneni R. B. and Tucker C. 2003. Relation between interannual variations in satellite measures of northern forest greenness and climate between 1982 and 1999. Journal of Geophysical Research 108: 4004. doi: 10.1029/2002JD002510.