Diversity of photosynthetic responses in the mesic and arid Mediterranean—type climate regions of southern Africa

Rutherford, M. C.

doi:10.1016/b978-0-444-89183-9.50013-7

Cited by 3 publications

(1 citation statement)

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“…Similar ‘broad‐shouldered’ temperature response curves have been noted in C 3 species of much warmer ecosystems, such as Larrea tridentata of the Mojave Desert (Mooney et al , 1978). Southern African species from temperate semi‐arid Mediterranean ecosystems display far lower temperature optima, between 20°C and 30°C, or temperature response curves with clearly defined peaks (Rutherford 1991). The expected exponential increase in R day with temperature caused dark respiration losses to increase from 4% of net CO 2 uptake at 25°C to almost 18% at 35°C.…”

Section: Discussionmentioning

confidence: 99%

Photosynthetic and gas exchange characteristics of dominant woody plants on a moisture gradient in an African savanna

Midgley

Aranibar

Mantlana³

et al. 2003

Global Change Biology

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We determined key photosynthetic gas exchange parameters, and their temperature dependence, in dominant woody plants at four savanna sites on a moisture gradient in Botswana, southern Africa. Leaf stable carbon and nitrogen (N) isotope and morphological measures were made concurrently. Sampling of these predominantly non-N-fixing species took place during an exceptional rainfall season, representing nearoptimum conditions for primary production at these sites. The mean specific leaf area and leaf size were positively related to mean annual rainfall (MAR); species with larger leaves of lower density were more abundant in wetter sites. Almost all species at all sites showed high net light-saturated photosynthetic rates (A max @ 10 lmol CO 2 m À 2 s À 1 ) due both to high CO 2 carboxylation (V c,max ) and RubP-regeneration capacity (J max ). These high rates were associated with high values of leaf [N]. Across all sites, the temperature response of A max showed no clear optimum, and a gradual drop from 25 1C to 35 1C, without notable temperature limitation at leaf temperatures in excess of 35 1C. Dark respiration rate (R day ) across all species and sites increased exponentially with increasing leaf temperature. Species sampled at selected sites revealed a negative relationship between leaf d 13 C (stable carbon isotope ratio) and MAR, suggesting higher leaf-level water-use efficiency at drier sites when integrated over the life of the leaf. At wetter sites, specific leaf [N] was lower and photosynthetic nitrogen-use efficiency increased, a pattern reflected at the ecosystem level by less 15 N enrichment of leaves at these sites. Taken together, the results suggest a switch from water-use to nitrogen-use efficiency constraints with increasing moisture availability. These constraints impact leaf form and function significantly, and may emerge at the ecosystem level in aspects of water and N cycling.

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Section: Discussionmentioning

confidence: 99%