Diverse functional responses to drought in a Mediterranean-type shrubland in South Africa
Article first published online: 17 MAY 2012
© 2012 The Authors. New Phytologist © 2012 New Phytologist Trust
Volume 195, Issue 2, pages 396–407, July 2012
How to Cite
West, A. G., Dawson, T. E., February, E. C., Midgley, G. F., Bond, W. J. and Aston, T. L. (2012), Diverse functional responses to drought in a Mediterranean-type shrubland in South Africa. New Phytologist, 195: 396–407. doi: 10.1111/j.1469-8137.2012.04170.x
- Issue published online: 15 JUN 2012
- Article first published online: 17 MAY 2012
- Received: 19 January 2012, Accepted: 5 April 2012
- functional types;
- hydraulic strategies;
- rainfall manipulation;
- rooting depth
- •Mediterranean-type ecosystems contain 20% of all vascular plant diversity on Earth and have been identified as being particularly threatened by future increases in drought. Of particular concern is the Cape Floral Region of South Africa, a global biodiversity hotspot, yet there are limited experimental data to validate predicted impacts on the flora. In a field rainout experiment, we tested whether rooting depth and degree of isohydry or anisohydry could aid in the functional classification of drought responses across diverse growth forms.
- •We imposed a 6-month summer drought, for 2 yr, in a mountain fynbos shrubland. We monitored a suite of parameters, from physiological traits to morphological outcomes, in seven species comprising the three dominant growth forms (deep-rooted proteoid shrubs, shallow-rooted ericoid shrubs and graminoid restioids).
- •There was considerable variation in drought response both between and within the growth forms. The shallow-rooted, anisohydric ericoid shrubs all suffered considerable reductions in growth and flowering and increased mortality. By contrast, the shallow-rooted, isohydric restioids and deep-rooted, isohydric proteoid shrubs were largely unaffected by the drought.
- •Rooting depth and degree of iso/anisohydry allow a first-order functional classification of drought response pathways in this flora. Consideration of additional traits would further refine this approach.