Stomatal frequency and gas exchange differs in two Blechnum species (Pteridophyta, Blechnaceae) with contrasting ecological breadth

Abstract

In Chilean temperate forest, the fern Blechnum chilense has a wide ecological breath, but occur mainly in full sun habitats,
while Blechnum mochaenum is restricted only to shady sites. We evaluated if the species with different ecological breath
behave similarly in their anatomical and physiological traits. Maximal photosynthetic rate (Amax), Stomatal conductance
(gs), evapotranspiration (E), and SLA (specific leaf area) were measured in situ in 20 individuals of each fern species.
Additionally, we estimated the stomatal density (SD), stomatal index (SI), and stomatal size in leaves of each sampled
individual. B. mochaenum, the shade-tolerant species, had lower SD, SI, A, and E, and higher stomatal size and SLA than B.
chilense. Higher stomatal frequency could result in greater gas exchange in open sites for B. chilense. The leaf physiology
of these fern species seems to depend partially on their stomatal traits.