Phenotypic plasticity to light of two congeneric trees from contrasting habitats: Brazilian Atlantic Forest versus cerrado (savanna)

Abstract

The Brazilian Atlantic Forest is a typically multi‐layer tropical forest, while cerrado (savanna) is a patchy habitat with different physiognomy. Despite these differences, both habitats have high light heterogeneity. Functional traits of Dalbergia nigra and D. miscolobium from the Atlantic Forest and cerrado, respectively, were evaluated under shade (25% of full sunlight) and full sunlight in a nursery experiment. We hypothesised that both species should benefit from high phenotypic plasticity in relation to light. Plasticity was estimated using the relative distance phenotypic index (RDPI). D. miscolobium had lower shoot growth under both light conditions, suggesting it has low competitive capacity in the forest environment, which could explain its limited ability to expand over areas of Atlantic Forest. The studied species exhibited photoprotection strategies under high light and improved light capture under low light. Stomatal conductance, ETRmax (maximum electron transport rate), PPFDsat (saturating photosynthetically active photon flux density), chlorophyll and carotenoid content had higher RDPI than stem morphological traits. Although both species showed considerable phenotypic plasticity, D. miscolobium had higher RDPI for eight of 11 evaluated traits. This high plasticity could be one of the factors that explain the occurrence of this species in a wide range of environmental conditions, from open grassland to dense woodlands, and it could also reflect its adaptation to high light. D. nigra also had considerable plasticity and good growth performance in both shade and full sunlight, but its absence in areas of cerrado suggests that factors other than light limit its occurrence in these habitats.

How does Cariniana estrellensis respond to different irradiance levels?

“…The highest Carot levels under 1400 and 2000 lmol m -2 s -1 PAR compared with lower irradiance, confirms the participation of Carot in photo-protection of the photosynthetic apparatus (Laisk et al 2005). This high level of Carot also could protect the PSII of the high sunlight incidence through the canopy (Barros et al 2012) as observed on C. estrellensis plants in partial shade and full sun. These results suggest the ecological importance of these accessory pigments in the modulation of light absorption and energy dissipation (Barros et al 2012).…”

“…This high level of Carot also could protect the PSII of the high sunlight incidence through the canopy (Barros et al 2012) as observed on C. estrellensis plants in partial shade and full sun. These results suggest the ecological importance of these accessory pigments in the modulation of light absorption and energy dissipation (Barros et al 2012).…”

“…This suggests inhibiting rubisco activity due to higher leaf temperatures associated with elevated irradiance (Law and Crafts-Brandner 1999), as observed with other tropical species when exposed to high luminosity (Dias and Marenco 2007;Magalhães et al 2009) or to photo-damage of the lower chloroplastidics pigments concentration and higher dissipation of light energy (DI 0 / RC). The photo-protection strategies of C. estrellensis under low and high light intensities suggest that it has high competitive capacity in the different forest environment, which could explain its ability to expand over areas of Atlantic Forest (Barros et al 2012).…”

“…Phenotypic plasticity of C. estrellensis may be interpreted as an adaptive response to the changes in light intensity inside the forest as suggested by Barros et al (2012) for the climax species Dalbergia nigra (Vell.) Allemão ex Benth.…”

Adaptações estruturais de sete espécies ciófitas arbustivas de Floresta Ombrófila Densa

“…ex Reissek (Celastraceae) ). Da mesma forma como o observado neste estudo, vários trabalhos têm mostrado que a razão clorofila a/b para espécies heliófitas é maior que 3, enquanto que em espécies ciófitas esta razão cai para valores pouco superiores a 1 (Almeida et al 2005, Lichtenthaler 2007, Dousseau 2009, Barros et al 2012, Li et al 2014, Nery et al 2016, o que pode ser explicado por variações nos níveis de luz dentro do sobosque em função da movimentação das copas pelos ventos (Fermino 2004). Outro aspecto a ser considerado é a variação luminosa no subosque provocada pela proximidade das espécies ciófitas às clareiras na floresta, situação esta observada neste estudo.…”