V Mohammadi - Former M. Sc. Student. Department of silviculture and forest ecology, Faculty of Forest Science, Gorgan university of natural resources and agricultural sciences, Iran
D Azadfar - Associate Professor. Department of silviculture and forest ecology, Faculty of Forest Science, Gorgan University of natural resources and agricultural sciences, Iran

Guard cell length and stomatal density can both beconsidered important ecophysiological parameters because bothstomatal size and density affect stomatal conductance. In the presentstudy, we examine trends in these anatomical traits in two elevation onShastkolateh forest (the east of Iran s Hyrcanian mixed forest).Samples were collected from two broadleaf tree species (Acervelutinom and Acer cappadocicum). Guard cell length and stomatalwidth increased with elevation in two species, but there were no clearelevational trends in stomatal density in any of two species. Apotential conductance index was positively correlated with elevationfor A. cappadocicum. Results are discussed in the context ofprevailing theories to explain changes in stomatal traits with elevationthat changes in stomatal traits with elevation may therefore be aresponse to changes in water relations and CO2 signal.

elevation, guard cell, stomatal density, potentialconductance index, Acer species