title: Diverse functional responses to drought in a Mediterranean-type shrubland in South Africa.
abstract: • 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.
authors.affiliation: Botany Department, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.|Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: A G
authors.initials: AG
authors.lastname: West
authors.affiliation: Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Dawson
authors.affiliation: Botany Department, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: E C
authors.initials: EC
authors.lastname: February
authors.affiliation: Climate Change and Bioadaptation, South African National Biodiversity Institute, Rhodes Drive, P/bag x7, Kirstenbosch 7735, South Africa.
authors.forename: G F
authors.initials: GF
authors.lastname: Midgley
authors.affiliation: Botany Department, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: W J
authors.initials: WJ
authors.lastname: Bond
authors.affiliation: Botany Department, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
authors.forename: T L
authors.initials: TL
authors.lastname: Aston
mesh_terms: D002980:Climate; D055864:Droughts; D017753:Ecosystem; D035264:Flowers / Q000502:physiology / Q000528:radiation effects; D005740:Gases / Q000378:metabolism; D006813:Humidity; D008027:Light; D019083:Mediterranean Region; D010103:Oxygen Isotopes; D010788:Photosynthesis / Q000528:radiation effects; D018521:Plant Physiological Phenomena / Q000528:radiation effects; D018517:Plant Roots / Q000254:growth & development / Q000528:radiation effects; D018520:Plant Shoots / Q000254:growth & development / Q000528:radiation effects; D012987:Soil; D013019:South Africa; D013045:Species Specificity; D014867:Water / Q000502:physiology
chemical_list: D005740:Gases; D010103:Oxygen Isotopes; D012987:Soil; D014867:Water