Original Article

International Journal of Biometeorology

, Volume 48, Issue 3, pp 119-127

Stomatal conductance in a tropical xerophilous shrubland at a lava substratum

  • Víctor L. BarradasAffiliated withInstituto de Ecología, UNAM, Apartado Postal 70-275, Circuito Exterior, Ciudad Universitaria, 04510 México, D.F., México Email author 
  • , Alfredo Ramos-VázquezAffiliated withInstituto de Ecología, UNAM, Apartado Postal 70-275, Circuito Exterior, Ciudad Universitaria, 04510 México, D.F., México
  • , Alma Orozco-SegoviaAffiliated withInstituto de Ecología, UNAM, Apartado Postal 70-275, Circuito Exterior, Ciudad Universitaria, 04510 México, D.F., México

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Abstract

Diurnal variation in leaf stomatal conductance (g s) of three xerophilous species (Buddleia cordata, Senecio praecox and Dodonaea viscosa) was measured over a 10-month period during the dry and wet seasons in a shrubland that is developing in a lava substratum in Mexico. Averaged stomatal conductances were 147 and 60.2 (B. cordata), 145 and 24.8 (D. viscosa) and 142.8 and 14.1 mmol m–2 s–1 (S. praecox) during the wet and dry season respectively. Leaf water potential (Ψ) varied in a range of –0.6 to –1.2 (S. praecox), –0.6 to –1.8 (B. cordata) and –0.9 to –3.4 MPa (D. viscosa) during the same measurement periods. Stomata were more sensitive to changes in irradiance, air temperature and leaf–air vapour pressure difference in the rainy season than the dry season. Although stomatal responses to Ψ were difficult to distinguish in any season (dry or rainy), data for the entire period of measurement showed a positive correlation, stomata tending to open as Ψ increased, but there is strong evidence of isohydric behaviour in S. praecox and B. cordata. A multiplicative model relating g s to environmental variables and to Ψ accounted for 79%–83% of the variation of g s in three sites (pooled data); however, the performance of the model was poorer (60%–76%) for individual species from other sites not included in the pooled data.

Keywords

Buddleia cordata Dodonaea viscosa Isohydric behaviour Leaf water potential Senecio praecox