Ser o no ser tolerante a la sombra: economía de agua y carbono en especies arbóreas del Bosque Atlántico (Misiones, Argentina)

in tropical and subtropical moist forests the most important factor limiting plant growth is solar radiation. on this basis, tree species had traditionally been classified into two functional groups based on their requirements for germination, establishment and growth. while shade-tolerant species germinate, grow and establish in places with low solar radiation, intolerant species require high irradiances for development. however, spatio-temporal variations in solar radiation exist within forests and most species show intermediate characteristics between the two extreme categories, forming a continuous gradient of ecophysiological responses. in this work we analyze the adaptations related to water and carbon economy (e.g., wood density, water transport efficiency and photosynthetic capacity) of atlantic forest tree species with the assumptions that evolutionary pressures have selected species-specific characteristics which enable them to optimize and coordinate the capture of solar radiation with the water transport to the leaves. we show that wood density is a trait that can be used to predict the behavior of tree species in relation to growth rates and properties related to transport efficiency and water use. less shadetolerant species have low wood density and high efficiency in water transport from soil to leaves. in environments with high solar radiation and evaporative demand, plants that have a low wood density and high water transport efficiency from the soil to the leaves can maintain high levels of leaf water potential (and experience less water deficit), increased stomatal conductance and, consequently, a higher rate of assimilation and growth. drastic changes in solar radiation produced by a gap opening in the forest can also impose drastic environmental changes for plant growth. the development of the individuals in the new conditions depends on its phenotypic plasticity, which can vary widely among different species. saplings of less tolerant species c