Flooding of tropical forests in central Amazonia: what do the effects on the photosynthetic apparatus of trees tell us about species suitability for reforestation in extreme environments created by hydroelectric dams?

Abstract

Brazil plans to construct many new hydroelectric dams in the Amazon region. The new conditions of flooding promoted by reservoirs can alter photosynthetic processes, and the study of physiological responses of trees can be used for selected suitable species to reforest these altered areas. The present study analyzed changes in pigment content and photosynthetic performance in floodtolerant and flood-intolerant species that are common in the floodplains along the Uatumã River and on islands in the reservoir of the Balbina Hydroelectric Dam. Their photosynthetic responses were tested using chloroplast pigment content and chlorophyll a fluorescence. Flooding caused a significant reduction in pigment content in all of the three flood-intolerant species and in one of the seven flood-tolerant species studied. Flood-tolerant species were unaffected and neither a change in their chlorophyll contents nor a decrease in the efficiency of energy use in the photosynthetic process was observed. From chlorophyll a fluorescence transients (OJIP transients) was calculated the performance index (PI ABS ), a parameter derived from the OJIP transient by means of the JIP-test (translation of original fluorescence measurements into biophysical expressions quantifying the stepwise flow of energy through photosystem II). This parameter was a very sensitive indicator of the physiological status of trees under field and was shown to be a particularly sensitive indicator of stress tolerance in flood-intolerant species during inundation, whereas flood-tolerant species had only minor reductions in their photosynthetic performance. We suggest that tree species selection for reforestation around reservoirs can benefit from species-specific measurements of photosynthetic response using the JIP-test.

Causes of reduced leaf‐level photosynthesis during strong El Niño drought in a Central Amazon forest

“…Leaves were dark adapted for 30 min, then exposed to a saturated light pulse of 3000 lmol m À2 s À1 with a wavelength-of 650 nm during 1 s using a portable fluorimeter (PEA, MK2 -9600 -Hansatech, Norfolk, UK). Chlorophyll a fluorescence parameters (Maximum quantum yield of photosystem II-F v /F m , Performance index-PI ABS, and Total performance index--PI total ) were calculated by the JIPtest (Santos, Gonc ßalves, Strasser, & Fearnside, 2015;Strasser, Srivastava, & Govindjee, 1995;Strasser, Tsimilli-Michael, Qiang, & Goltsev, 2010). For detailed information about the fluorescence parameters used in this paper see Strasser et al (1995Strasser et al ( , 2010; Stirbet and Govindjee (2011)…”

Special issue in honour of Prof. Reto J. Strasser - Chlorophyll a fluorescence of Bertholletia excelsa Bonpl. plantations under thinning, liming, and phosphorus fertilization

“…Changes in the curvature of OJIP transient reflect the alteration in the energy flux in leaves. Plants subjected to stressful conditions may increase effective dissipation (DI0) of an active reaction center (RC) as a strategy to reduce excessive absorbed energy and enhance protective quenching of photosynthetic apparatus, thus they may also reduce other steps of the energy flux, such as absorption (ABS), trapped energy (TR0), and electron transport (ET0) (Strasser et al 2004, dos Santos Junior et al 2015. The increase in nonphotochemical dissipation, in general, results in the decrease of FV/FM and a decrease in PIABS (Strasser et al 2004, Kalaji et al 2012, Stirbet and Govindjee 2012.…”

Growth and functional leaf traits of coppice regrowth of Bertholletia excelsa during an El Niño event in the central Amazon

“…The selected leaves were submitted to a 30 min period of adaptation to darkness. Subsequently, the leaves were exposed to saturated light at an intensity of 3,000 µmol m -2 s -1 and a wavelength of 650nm for 5 s (dos Santos Junior et al 2015). The parameters related to polyphasic chlorophyll a fluorescence transient were obtained from specific software (Handy PEA software -v 1.30), and quantum efficiency of PSII (Fv/F M ) and the performance indicators PIabs and total PI were calculated according to the JIP-test (Strasser et al 1995).…”