Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-27T09:52:47.687Z Has data issue: false hasContentIssue false

Patterns of mistletoe infection in four Acacia species in a semi-arid southern African savanna

Published online by Cambridge University Press:  29 August 2012

Hilton G. T. Ndagurwa*
Affiliation:
Forest Ecology Laboratory, Faculty of Applied Sciences, National University of Science & Technology, P.O. Box AC 939 Ascot, Bulawayo, Zimbabwe Department of Forest Resources and Wildlife Management, Faculty of Applied Sciences, National University of Science & Technology, P.O. Box AC 939 Ascot, Bulawayo, Zimbabwe
Peter J. Mundy
Affiliation:
Department of Forest Resources and Wildlife Management, Faculty of Applied Sciences, National University of Science & Technology, P.O. Box AC 939 Ascot, Bulawayo, Zimbabwe
John S. Dube
Affiliation:
Department of Animal Science and Rangeland Management, Lupane State University, P.O. Box AC 255 Ascot, Bulawayo, Zimbabwe
Donald Mlambo
Affiliation:
Border Timbers Limited, 1 Aberdeen Road P.O. Box 458 Mutare, Zimbabwe
*
1Corresponding author. Email: hilton.ndagurwa@nust.ac.zw

Extract

In a range of systems, studies on mistletoe distribution on the host plant have documented a number of factors that affect their occurrence and spread (Aukema & Martinez del Rio 2002a, Bowie & Ward 2004, Overton 1996, Reid et al. 1995). These patterns can be determined by host specificity, environmental conditions, host plant characteristics (Martinez del Rio et al. 1995) and the movement patterns of dispersal agents (Aukema & Martinez del Rio 2002a, 2002b). In mistletoe plants, host choice can be considerably influenced by the advantages of interacting with relatively abundant hosts (Norton & Carpenter 1998, Norton & De Lange 1999). Besides the relative abundance of host species, characteristics such as branch size, age and height can have a strong effect on mistletoe attachment resulting in size-related mistletoe infection patterns (Overton 1994). Generally positive relationships between mistletoe infection and host size have been demonstrated worldwide (Donohue 1995, Martinez del Rio et al. 1996, Norton et al. 1997, Reid & Stafford Smith 2000) and they have been interpreted in terms of the preferences by dispersing birds to perch and feed in taller trees (Aukema & Martinez del Rio 2002a) and trees accumulating infections as they age (Overton 1994). Aukema & Martinez del Rio (2002a) reported more frequent perching in taller-than-average trees by the phainopepla (Phainopepla nitens), which is the principal disperser of the desert mistletoe Phoradendron californicum. Thus, visits by mistletoe-seed-dispersing birds, and therefore mistletoe seeds received, tend to increase with tree height (Aukema & Martinez del Rio 2002a). Using a simple metapopulation model, Overton (1994) predicted the frequency of parasitized trees to increase with host age. Therefore, assuming that size is a good proxy for age, large trees are likely to be more infected than smaller trees. Reid & Stafford Smith (2000), using experimentally disinfected trees, found that larger trees were disproportionately re-infected with mistletoes. This size–intensity relationship may be used to describe mistletoe infection patterns. However, several previous studies have shown size–intensity relationships to be weak (Aukema & Martinez del Rio 2002a, Donohue 1995, Overton 1994, Reid & Stafford Smith 2000). This indicates that other factors may be important in determining mistletoe infection intensity, including that already parasitized hosts of a specific height are more likely to receive seeds than non-parasitized hosts of the same height or dispersers are likely to be attracted to trees for reasons other than size (Aukema & Martinez del Rio 2002a).

Type
Short Communication
Copyright
Copyright © Cambridge University Press 2012

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

LITERATURE CITED

AUKEMA, J. E. & MARTINEZ DEL RIO, C. 2002a. Variation in mistletoe seed deposition: effects of intra- and interspecific host characteristics. Ecography 25:139144.Google Scholar
AUKEMA, J. E. & MARTINEZ DEL RIO, C. 2002b. Where does a fruit-eating bird deposit mistletoe seeds? Seed deposition patterns and an experiment. Ecology 83:34893496.Google Scholar
BOWIE, M. & WARD, D. 2004. Water and nutrient status of the mistletoe Plicosepalus acaciae parasitic on isolated Negev Desert populations of Acacia raddiana differing in level of mortality. Journal of Arid Environments 56:487508.Google Scholar
DONOHUE, K. 1995. The spatial demography of mistletoe parasitism on a Yemeni Acacia. International Journal of Plant Science 156:816823.Google Scholar
DYE, P. J. & WALKER, B. H. 1987. Patterns of shoot growth in a semi-arid grassland in Zimbabwe. Journal of Applied Ecology 24:633644.Google Scholar
GODSCHALK, S. K. B. 1983. Mistletoe dispersal by birds in South Africa. Pp. 117128 in Calder, M. & Bernhardt, P. (eds.). The biology of mistletoes. Academic Press, Sydney.Google Scholar
LÓPEZ, DE, BUEN, L., ORNELAS, J. F. & GARCÍA-FRANCO, J. G. 2002. Mistletoe infection of trees located at fragmented forest edges in the cloud forests of Central Veracruz, Mexico. Forest Ecology and Management 164:293302.Google Scholar
MAPAURA, A. & TIMBERLAKE, J. 2004. A checklist of Zimbabwean vascular plants. Southern African Botanical Diversity Network Report No. 33. SABONET, Pretoria and Harare.Google Scholar
MARTINEZ DEL RIO, C., HOURDEQUIN, M., SILVA, A. & MEDEL, R. 1995. The influence of cactus size and previous infection on bird deposition of mistletoe seeds. Australian Journal of Ecology 20:571576.Google Scholar
MARTINEZ DEL RIO, C., MEDEL, R. S. A. & HOURDEQUIN, M. 1996. Seed dispersers as disease vectors: bird transmission of mistletoe seeds to plant hosts. Ecology 77:912921.Google Scholar
NORTON, D. A. & CARPENTER, M. A. 1998. Mistletoes as parasites: host specificity and speciation. Trends in Ecology and Evolution 13:101105.Google Scholar
NORTON, D. A. & DE LANGE, P. J. 1999. Host specificity in parasitic mistletoes (Loranthaceae) in New Zealand. Functional Ecology 13:552559.Google Scholar
NORTON, D. A., LADLEY, J. J. & SPARROW, A. D. 1997. Development of non-destructive age indices for three New Zealand loranthaceous mistletoes. New Zealand Journal of Botany 35:337343.Google Scholar
OVERTON, J. M. 1994. Dispersal and infection in mistletoe metapopulations. Journal of Ecology 82:711723.Google Scholar
OVERTON, J. M. 1996. Spatial autocorrelation and dispersal in mistletoes: field and simulation results. Vegetation 125:8398.Google Scholar
RATTRAY, J. M. 1957. The grasses and grass associations of southern Rhodesia. Rhodesia Agriculture Journal 54:197234.Google Scholar
REID, N. & STAFFORD SMITH, M. 2000. Population dynamics of an arid zone mistletoe (Amyema preissii, Loranthaceae) and its host Acacia victoriae (Mimosaceae). Australian Journal of Botany 48:4558.Google Scholar
REID, N., SMITH, M. S. & YAN, Z. 1995. Forest canopies. Pp. 285310 in Lowman, M. D. & Nadkarni, N. M. (eds.). Ecology and population biology of mistletoes. Academic Press, San Diego, CA.Google Scholar
ROXBURGH, L. & NICOLSON, S. W. 2005. Patterns of host use in two African mistletoes: the importance of mistletoe–host compatibility and avian disperser behavior. Functional Ecology 19:865873.Google Scholar
ROXBURGH, L. & NICOLSON, S. W. 2008. Differential dispersal and survival of an African mistletoe: does host size matter? Plant Ecology 195:2131.Google Scholar
ULLMANN, I., LANGE, O.L., ZIEGLER, H., EHLERINGER, J., SCHULZ, E. D. & COWAN, I. R. 1985. Diurnal courses of leaf conductance and transpiration of mistletoes and their hosts in central Australia. Oecologia 67:577587.Google Scholar
WARD, H. K., RICHARDSON, F. D., DENNY, R. P. & DYE, P. T. 1979. Matopos Research Station: a perspective. Rhodesia Agriculture Journal 76:518.Google Scholar
ZAR, J. H. 1984. Biostatistical analysis. Simon and Schuster, Englewood Cliffs. 718 pp.Google Scholar