Poster Session # 15: Plant Ecology.

Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Woody species leaf traits: Changes from the desert to the tropical deciduous forest in Sonora, Mexico.

Gomez-Sapiens, Martha*,1, Martinez-Yrizar, Angelina1, 1 Instituto de Ecologia, UNAM-Mexico, Hermosillo, Sonora

ABSTRACT- Leaf structure, morphology and nutrient content have been used to establish relations that can provide information about different plant strategies of resource use in the ecosystem. In this study sun leaves of five perennial woody species present along a precipitation gradient in Sonora, Mexico were analyzed to test the relationship between leaf trait variability and precipitation and nutrient availability patterns from a desertscrub to a tropical deciduous forest ecosystem. We expected i) a positive correlation between leaf nutrient concentration (total N y P) and available N and P soil forms, and ii) the lowest specific leaf area (SLA) values in arid or low nutrient availability sites. Fully expanded randomly selected leaves from 15 adult trees of each species were measured for thickness, total length, leaf area, SLA, dry matter content (DMC) and total N and P content. Also, ion exchange resin bags were used to determine the relative availability of soil NH4, NO3 and PO4. We found that intraspecific differences in leaf length and leaf area were significant across the sites, with the longest and largest leaves in the tropical deciduous forest. Also, leaves with the highest SLA and lowest DMC ratios were found in the deciduous forest. The trend of change in total P and N concentrations along the gradient varied depending on the species. Relative availability of soil nutrients did not correlate with foliar nutrient concentrations. The variation in SLA seems to have a strong relation with precipitation than with the relative nutrient availability patterns.

Key words: specific leaf area, precipitation gradient, leaf structure, leaf nutrients