Stomatal characteristics of ferns and angiosperms and their responses to changing light intensity at different habitats

Aims Stomata are critical in controlling the exchange of water vapour and carbon dioxide and maintaining the balance between plant water and carbon relations. Here, we investigated the effects of habitat (open and understory) and plant type (ferns and angiosperms) on stomatal morphology and stomatal responses to changing light intensity.
Methods We measured stomatal morphology and stomatal conductance in response to transitions in light intensity in five ferns and four angiosperms from different habitats. To increase the sample size, we also collected data on stomatal characteristics for 45 ferns and 70 angiosperms from published studies.
Important findings For all the nine species, the plants in open-habitat had significantly greater stomatal density, shorter stomatal length and greater sensitivity to decreasing light intensity than those in the understory, but the effect of plant type was not significant. Combined analysis with published data indicated that the effects of both habitat and plant type on stomatal morphology were significant. As stomatal sensitivity was closely linked to stomatal morphology, more and smaller stomata might enable angiosperms to respond more quickly to environmental perturbations than ferns. We conclude that both habitat and plant type affect the stomatal response to light.