Physiological parameters and plasticity as key factors to understand pioneer and late successional species in the Atlantic Rainforest

Abstract

Although there has been a long tradition in plant ecology of grouping species into functional groups, there is a lack of consensus regarding both the successional status of species and the dynamics of forest recovery. Therefore, plant species are commonly classified into two groups: early successional pioneers and late successional or even climax species. Here, we aimed to answer the following question: if pioneer and late successional species have different photosynthetic characteristics, will these differences be translated to improved performance when plants are grown under similar conditions, particularly high irradiance and different water regimes? To this end, we investigated gas exchange, photoprotection, plasticity, and nutritional traits in ten native species that were subject to natural variations in photosynthetically active radiation, rainfall, and air temperature throughout the year. Our results provided evidence that photosynthesis is directly dependent on nitrogen and phosphorus. Remarkably, this characteristic increased in importance when the species were grouped into pioneer and late successional species compared with each species separately. Furthermore, principal component analysis demonstrated that physiological traits are excellent parameters for characterizing the pioneer and late successional plants growing in situ under the same irradiance. Our findings indicate that the responses of trees to seasonal variations depend on their ability to absorb nutrients to meet the mineral requirements to sustain long-term growth. We further analyzed the mechanisms that allow woody species to cope with drought stress.