Photoinhibition in Atlantic Forest native species: short-term acclimative responses to high irradiance

Abstract

Forest management in a biological reserve is removing eucalyptus. Siparuna guianensis (early secondary), Xylopia sericea and Byrsonima sericea (pioneers) are the three most abundant native species in the eucalyptus understory. Chlorophyll a fluorescence and photosynthetic pigments were analyzed every 2 weeks for 120 days after clearcutting to answer: (i) Will the three species recover their photosynthetic performance after 120 days? (ii) Will recovery time be similar across these species? (iii) Does photosynthetic performance vary with time of the day (8:00 am, 12:00 pm, and 4:00 pm)? All the three species recovered photosynthetic performance after 120-days. Non-photochemical quenching (NPQ) increased approximately 40, 30 and 20 % for S. guianensis, X. sericea, and B. sericea, respectively, between days 45 and 75 after clearcutting. However, photosynthetic performance fell only in the first 45 days (Fv/Fm: 0.73, 0.71, and 0.75 and ΔF/Fm′ 0.56, 0.70 and 0.68 for S. guianensis, X. sericea, and B. sericea, respectively). The higher NPQ in S. guianensis is associated with the lower ΔF/Fm′ and qP, suggesting that this species may be more shade-tolerant, compared to the others. The PCA showed that B. sericea recovers more quickly and/or is less affected by irradiance, when compared to the other species analyzed. Photosynthetic performance was lower at 12:00 and 4:00 pm, highlighting the nocturnal recovery capacity of these species and dynamic photoinhibition. These species presented high potential to prevail in the area managed. However, it is necessary to prevent the dominance of these species to prevent environmental issues.