Coordinated evolution of leaf and stem economics in tropical dry forest trees

• Published in: Ecology (Durham) 2012-11, Vol.93 (11), p.2397-2406
• Main Authors: Méndez-Alonzo, Rodrigo, Paz, Horacio, Zuluaga, Rossana Cruz, Rosell, Julieta A, Olson, Mark E
• Format: Article
• Language: English
• Subjects: adaptation; Adaptation, Physiological - genetics; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biological Evolution; Cavitation flow; Drought; drought tolerance; Dry forests; dry season; ecosystems; evolution; Forest trees; Forestry; functional traits; Fundamental and applied biological sciences. Psychology; General aspects; General forest ecology; Generalities. Production, biomass. Quality of wood and forest products. General forest ecology; Hydraulics; leaf abscission; leaf deciduousness; Leaves; Mexico; plant biomechanics; Plant ecology; Plant Leaves - genetics; Plant Leaves - growth & development; Plant Stems - genetics; Plant Stems - growth & development; Plants; Species; Species Specificity; stems; trade-offs; Trees; Trees - genetics; Trees - physiology; Tropical Climate; Water; water potential; wood; wood density; Xylem; xylem hydraulic conductivity; xylem resistance to cavitation
• ISSN: 0012-9658; 1939-9170
• DOI: 10.1890/11-1213.1

With data from 15 species in eight families of tropical dry forest trees, we provide evidence of coordination between the stem and leaf economic spectra. Species with low-density, flexible, breakable, hydraulically efficient but cavitationally vulnerable wood shed their leaves rapidly in response to drought and had low leaf mass per area and dry mass content. In contrast, species with the opposite xylem syndrome shed their costlier but more drought-resistant leaves late in the dry season. Our results explain variation in the timing of leaf shedding in tropical dry forests: selection eliminates combinations such as low-productivity leaves atop highly vulnerable xylem or water-greedy leaves supplied by xylem of low conductive efficiency. Across biomes, rather than a fundamental trade-off underlying a single axis of trait covariation, the relationship between leaf and stem economics is likely to occupy a wide space in which multiple combinations are possible.