Exotic trees modify the thermal landscape and food resources for lizard communities
- 420 Downloads
Increasing numbers of invasive plant species are establishing around the globe, and these species frequently form dense stands that alter habitat structure in critical ways. Nevertheless, little is known about the mechanisms underlying the impacts of invasive alien plant species on native fauna. We first ask whether alien pine trees impact lizard species richness in the Cape Floristic Region of South Africa, a world-renowned biodiversity hotspot, by examining differences in lizard species richness, abundance, and diversity between native mountain fynbos and exotic pine tree-dominated habitats. We then examine two mutually non-exclusive processes: (i) changes in the thermal quality of the habitat and (ii) changes in the availability of food resources, to explain differences in lizard assemblages among habitat types. Lizard richness, abundance, and diversity were greater in fynbos habitat than in fynbos heavily invaded by pine and in pine plantations. The thermal quality of the environment and food resources was consistently higher in native fynbos than in pine forests, but these responses were more varied when comparisons were made along an invasion gradient and among seasons. Our results suggest that management strategies must consider spatially and temporally detailed measurements of thermal regimes and resources to assess the impacts of invasive vegetation on reptile diversity.
KeywordsEctotherm Thermoregulation Operative temperatures Preferred body temperature Pinus radiata
Funding for this project was provided by the DST-NRF Centre of Excellence for Invasion Biology (C.I.B), Stellenbosch University, South Africa, and E.S. was supported by a C.I.B bursary. All applicable institutional guidelines for the care and use of animals were followed (# SU-ACUM12:00023) and Cape Nature granted collection permits (# 0056-AAA041-00006). The authors thank M. Logan, A.E. Magurran and an anonymous referee for useful comments on the manuscript, and the Speirs family and G. Williams for access to field sites.
Author contribution statement
SCT formulated the idea, ES conducted the fieldwork, and ES and SCT developed methodology, performed statistical analyses, and wrote the manuscript.
- Armstrong AJ, van Hensbergen HJ, Scott DF, Milton SJ (1996) Are pine plantations ‘inhospitable seas’ around remnant native habitat within South-western Cape forestry areas? S Afr For J 176:1–9Google Scholar
- Begon M, Harper JL, Townsend CR (1990) Ecology: individuals, populations and communities, 2nd edn. Blackwell Scientific, LondonGoogle Scholar
- Branch WR (1998) Field guide to snakes and other reptiles of Southern Africa. Ralph Curtis Books Publishing, FloridaGoogle Scholar
- Clarke KR, Gorley RN (2006) Primer v6: user manual/tutorial. PRIMER-E, PlymouthGoogle Scholar
- Clarke KR, Warwick RM (2001) Change in marine communities: an approach to statistical analysis and interpretation. PRIMER-E, PlymouthGoogle Scholar
- Colwell RK (2009) EstimateS—statistical estimation of species richness and shared species from samples. Version 9.10. http://viceroy.eeb.uconn.edu/estimates
- Heatwole HF, Taylor J (1987) Ecology of reptiles. Surrey Beatty and Sons, Chipping NortonGoogle Scholar
- Krebs CJ (1989) Ecological methodology. Harper and Row, New YorkGoogle Scholar
- Magurran AE (2004) Measuring biological diversity. Blackwell Publishing, OxfordGoogle Scholar
- Magurran AE, McGill BJ (2011) Biological diversity: frontiers in measurement and assessment. Oxford University Press, OxfordGoogle Scholar
- Mucina L, Rutherford MC (eds) (2006) The vegetation of South Africa, Lesotho and Swaziland. Strelitzia 19. South African National Biodiversity Institute, PretoriaGoogle Scholar
- Oksanen J, Blanchet GF, Kindt R, Legendre P, Minchin PR, O’Hara RB, Simpson GL, Solymos P, Stevens MHH, Wagner H (2013) vegan: community ecology package. R package version 2.0-10Google Scholar
- Picker M, Griffiths C, Weaving A (2002) Field guide to insects of South Africa. Struik Publishers, Cape TownGoogle Scholar
- R Core Team (2014) R: a language and environment for statistical computing. R foundation for statistical computing, Vienna, Austria. http://www.R-project.org/
- Samways MJ, McGeoch MA, New TR (2010) Insect Conservation: a handbook of approaches and methods. Techniques in ecology and conservation series. Oxford University Press, OxfordGoogle Scholar
- Simpson GL (2014) permute: functions for generation restricted permutations of data. R package version 0.8-3Google Scholar