Photoacclimation capacity in seedling and sapling of Siparuna guianensis (Siparunaeae): Response to irradiance gradient in tropical forest

Abstract

Light is a limiting factor in plant establishment and growth in the understory of forests. In this paper, we assessed acclimation capacity of Siparuna guianensis, an early secondary successional species. We used seedlings and saplings in three regeneration areas with different irradiance regimes to determine the traits that confer photoplasticity. We examined whether these traits differ at different developmental stages. Anatomical characteristics, photochemical efficiency, photosynthetic capacity, and growth were analyzed. Multivariate component analysis revealed the formation of six clusters: three for seedlings (one for each regeneration area) and three for saplings (following the same pattern of seedlings, considering the area). Increased irradiance favored photosynthetic performance, independently of the developmental stage. The same trend was observed for most data on chlorophyll (Chl) a fluorescence and the ratios of net photosynthetic rate/intercellular CO2 concentration (P N /C i ) and P N /PPFD. No parameter indicated photoinhibition stress. The CO 2 -and light-response curve data indicated that seedlings were already acclimated to tolerate variation in irradiance. Anatomical adaptations, such as thickness of leaf blade and of adaxial cuticle, were observed in individuals growing in areas with higher irradiation. Thinning of spongy parenchyma and higher investment into a plant height were observed in seedlings, possibly due to the vertical stratification of CO 2 and light in the understory; because light is a more limiting resource than CO 2 in the lower stratum of the forest. Photoplasticity in S. guianensis is associated with a set of morphological, anatomical, photochemical, and biochemical traits, whereas biochemical performance is best acclimated to variation in irradiance. These traits differed in seedlings and saplings but they were modulated mainly by irradiance in both developmental stages.

Using leaf δ13C and photosynthetic parameters to understand acclimation to irradiance and leaf age effects during tropical forest regeneration

“…The data show that the main species regenerating in the understory can increase carbon gain and tolerate more irradiance after management. These data in addition to previous studies (Evaristo et al, 2011;Lage-Pinto et al, 2012;Lage-Pinto et al, 2015;Silva et al, 2010;Teixeira et al, 2015;Vieira et al, 2015) show the photoacclimation performance of these species to more irradiance, that could explain their abundance in the open and management areas. Thus, there is a possibility that the management may affect the trajectory of forest regeneration, including potential dominance of these species.…”

“…This suggests that photodamage is reversible in young leaves. Although these species show photoacclimation capacity (Silva et al, 2010;Lage-Pinto et al, 2012;Teixeira et al, 2015;Vieira et al, 2015), dynamic photoinhibition had been observed 1 year after management for S. guianensis and X. sericea in this area (Lage-Pinto et al, 2012). All species are able to photoacclimate,, but B. sericea is the fastest species to recuperate initial conditions after forest management (Teixeira et al, 2015).…”

“…Studies concerning photosynthetic responses to irradiance, carried out in degraded or managed secondary forest, gaps or along irradiance gradients, have generally shown functional and structural acclimatation responses (Lage-Pinto et al, 2012;Rabelo et al, 2013;Silva et al, 2010;Milena Carvalho Teixeira et al, 2015;Vieira et al, 2015). Leaf functional responses to environmental variation can be evaluated as a time-integrated response of leaf carbon isotope composition (δ 13 C) (Dawson et al, 2002;Duarte et al, 2005;Leavitt and Long, 1986;Zimmerman and Ehleringer, 1990), because the supply of CO 2 at the site of carboxylation determines discrimination against 13 CO 2 relative to 12 CO 2 during photosynthesis (Farquhar and Richards, 1984).…”

Leaf phenology and morphofunctional variation in Myrcia amazonica DC. (Myrtaceae) in gallery forest and “campo rupestre” vegetation in the Chapada Diamantina, Brazil

“…Plant survival is closely linked to the capacity to adapt to varying environmental conditions (Singh and Kushwaha 2005), which, in turn, is facilitated by plasticity of their morphological (Bloor and Grubb 2004) and/or physiological traits (Sultan 2000;Valladares et al 2000;Gamage et al 2003;Vieira et al 2015;Vitória et al 2016). This plasticity facilitates the occupation of a wide variety of microhabitats and amplifies the use of ecological niches (Ganie et al 2014).…”

Morpho-physiological acclimation to canopy coverage of Araucaria angustifolia during the establishment in the Atlantic Forest, Argentina

“…However, more subtle changes in the magnitude and spatial distribution of light under closed canopies can also influence long-term survival and recruitment of seedlings (Zhang et al 2012). Plants can adjust genotype expression in response to those changes in light availability, in order to change phenotype to tolerate or optimize light interception and use (Vieira et al 2015). Thus, the survival and growth of plants in changing environments highly depend on the ability to acclimate to different micro-environmental conditions (Gianoli and Valladares, 2012) to catch the resources that limit growth.…”