Ecophysiology of Dominant Plant Species during Old-Field Succession in a High Tropical Andean Ecosystem

Abstract We compared ecophysiological characteristics of plant species that dominate during different stages of succession in fallow fields of a traditional agroecosystem in the Venezuelan High Andes. For each species we determined during the dry and wet seasons the photosynthetic light response and photosynthesis rate at light saturation (Amax), specific leaf area (SLA), stomatal conductance at light saturation (gmax), midday water potential (ψ), and intrinsic water use efficiency (WUEi, photosynthesis rate per unit of stomatal conductance). The species studied were the forbs Rumex acetosella (early succession dominant) and Lupinus meridanus (intermediate stages), the shrubs Acaena elongata and Baccharis prunifolia (late succession), the giant rosette Espeletia schultzii, and the shrub Hypericum laricifolium (mature ecosystem dominant). Clear ecophysiological trends were identified: early and intermediate successional species had higher Amax, gmax, and SLA but lower WUEi. E. schultzii maintained a high w...