Extreme hydroclimate response gradients within the western Cape Floristic region of South Africa since the Last Glacial Maximum. (1st September 2019)

• Record Type: Journal Article
• Authors: Chase, Brian M.; Boom, Arnoud; Carr, Andrew S.; Chevalier, Manuel; Quick, Lynne J.; Verboom, G. Anthony; Reimer, Paula J.
• Is Part Of: Quaternary science reviews. Volume 219(2019)
• Page Start: 297
• Page End: 307
• Publication Date: 2019-09-01
• Subjects: Palaeoclimate -- Climate dynamics -- South Africa -- Cape Floristic region -- Biodiversity -- Rock hyrax middens -- Stable isotopes; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2019.07.006
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: The Cape Floristic Region (CFR) is one of the world's major biodiversity hotspots, and much work has gone into identifying the drivers of this diversity. Considered regionally in the context of Quaternary climate change, climate stability is generally accepted as being one of the major factors promoting the abundance of species now present in the CFR. However, little direct evidence is available from the region, and responses to changes in global boundary conditions have been difficult to assess. In this paper, we present new high-resolution stable isotope data from Pakhuis Pass, in the species-rich western CFR, and contextualise our findings through comparison with other records from the region. Combined, they indicate clear, coherent changes in regional hydroclimate, which we relate to broader forcing mechanisms. However, while these climate change events share similar timings (indicating shared macro-scale drivers), the responses are distinct between sites, in some cases expressing opposing trends over very short spatial gradients (<50 km). We describe the evolution of these trends, and propose that while long-term (10 5 yr) general climatic stability may have fostered high diversity in the region through low extinction rates, the strong, abrupt changes in hydroclimate gradients observed in our records may have driven a form of allopatric speciation pump, promoting the diversification of plant lineages through the periodic isolation and recombination of plant populations. Highlights: New high resolution δ 15 N data from rock hyrax middens from the western Cape Floristic Region. Position of the southern westerlies apparent as a strong determinant of regional hydroclimates. High amplitude, rapid changes in hydroclimate are revealed in the region. Opposing responses to shared climate change events establish highly variable climate gradients.