Leaf demography and leaf traits of temperate-deciduous and tropical evergreen-broadleaved trees in a Mexican montane cloud forest

Leaf demography of four deciduous and five evergreen broadleaved tree speci es was studied in two replicate tropical montane cloud forest fragments (12 50-1400 m elevation) in Veracruz, Mexico. The objectives were to investigat e leaf life spans, expansion rates, survivorship curves, specific leaf area (SLA) and nitrogen concentration in tree species of contrasting leaf habit s and phytogeographical affinities growing naturally in the same forest typ e. Tagged leaves were located in the mid forest canopy and were reached wit h a six-m ladder. A total of 2688 leaves from 78 trees were monitored from bud burst to death. Mean leaf longevity was 8.25 mo for deciduous tree spec ies and 15.0 mo for evergreens. Mean leaf longevity was highly variable amo ng evergreen species which included both the longest (Magnolia, 36.4 mo) an d the shortest (Hedyosmum, 6.4 mo) values. Patterns of leaf emergence were similar for eight species with a pronounced peak at the beginning of the ca lendar year. The only exception was Hedyosmum with a multiple flush pattern . More than 50% leaf expansion occurred in less than a month for three deci duous species (Carpinus, Liquidambar, Quercus) and two evergreens (Oreopana x and Magnolia), but required more than a month for Clethra (deciduous) and Cinnamomum, Hedyosmum and Turpinia (evergreen). Leaf survivorship curves w ere similar between the two study sites, but they differed between deciduou s and evergreen species. There was no significant difference between leaf h abit groups in SLA, leaf area, or nitrogen concentration, however, SLA was inversely correlated with leaf longevity. Arranging the studied taxa from p rimitive to advanced reaveled that species in more primitive groups have th e longest life-spans (Magnolia, Cinnamomum) and more advanced taxa have the shortest life spans (Carpinus, Quercus). Phylogenetic relationships betwee n species should be taken into account when studying leaf traits.