available online at httpj//www.idealibrary.com on I BE bl 0 @ Four sites with contrasting environmental stress in southeastern Brazil: relations of species, life form diversity, and geographic distribution to ecophysiological parameters Some ecophysiological parameters related to plant performance and fitness (carbon and nitrogen isotope composition and total C and N concentrations; in situ chlorophyll fluorescence measurements) were determined for over 30 species in four habitats bordering the montane Atlantic rain forest of Brazil, along a gradient of altitude and rainfall: a dry coastal forest, two areas of sandy coastal plain vegetation (restingas), and a high altitude campo. There was a considerable diversity of ecophysiological behaviour within and between the functional groups we created based on plant life-forms. For instance, both crassulacean acid metabolism (CAM) and C3 species were found in most life-forms sampled and throughout all habitats. Despite the variation in rainfall regimes, average overall water-use efficiency was similar between sites, particularly for C., species, while no clear pattern regarding nitrogen-use emerged in this respect. Acute and chronic photoinhibition were found in many species across this gradient, even in CAM plants. However, on average, chronic photoinhibition and lower energy dissipation capacity were more characteristic of plants from the restinga habitats. This suggests that, although plants colonizing these habitats have evolved features to deal with water shortage, adaptation to high light levels has not been fully achieved yet. The ecophysiological performance of some individual species in distinct habitats and in distinct microhabitats within habitats is also discussed. ! C 2001 The Linnean Society of London ADDITIONAL KEY WORDS: Atlantic forest -carbon isotopes -chlorophyll a fluorescence -dry forest -high altitude vegetation -nitrogen isotopes -sandy coastal vegetation.

The clonal tank‐bromeliad Aechmea bromeliifolia (Rudge) Baker was found in four different habitats in a restinga (vegetation mosaic on sandy coastal plains), of south‐eastern Brazil. These habitats (swamp forest, dry forest, dry shrubland and herbaceous marsh) lie within a few hundred metres of each other along a gradient extending inland from the coast, and differ markedly in terms of light and flood regime. We compared ramet morphology, leaf anatomy and physiology, and population parameters to examine the amplitude of trait variation of this widespread species in the studied restinga. This integrated approach allowed us to examine which variation conferred acclimation and which was merely a stress symptom. A. bromeliifolia showed site‐specific differences in abundance, distribution, rosette size and shape, leaf anatomical arrangement and photochemical efficiency (potential quantum yield; Fv/Fm) during the day. Most of the variation found seemed to be related to the interaction of light and flooding. The lowest number and size of ramets at the exposed, dry shrubland was matched by a marked leaf photoinhibition, which suggested poor acclimation to local levels of light intensity and limited water supply. In the other habitats, the morpho‐physiological parameters measured suggested adequate foraging behaviour and site acclimation. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 140, 391‐401.

Three species of Clusia, namely two CAMspecies (C. hilariana Schlecht. and C. fluminensis Planch. et Triana) and a C 3 -species (C. parviflora Saldanha et Engl.) were studied in different plant communities at the periphery of the Atlantic Forest in the state of Rio de Janeiro, Brazil. The sites chosen were an inselberg (C. parviflora), a range of wet restinga -dry restinga -semideciduous dry forest (C. fluminensis), and a gradient from the sea shore inland with a first sand dune beach ridge -a dry forest -a second beach ridge (C. hilariana). Analyses comprised C and N contents, soluble carbohydrates, soluble nonprotein N compounds and carbon isotope ratios (δ 13 C) in leaves, roots, phloem and wood. Photosynthetic performance was assessed by chlorophyll fluorescence with measurements of instant photosynthetic yield as well as light dependence and potential quantum-use efficiency of photosystem II.The data allow, first, to discuss differences between the ecophysiological performance of C 3 -and CAM-species of Clusia. The C 3 -species, C. parvifolia, had an overall weaker performance than the two CAM-species, where, however, the effects of mode of photosynthesis may have been overlaid by site conditions. Second, it was studied whether ecophysiological performance relates to patterns of local abundance, which was confirmed by showing that the dominant Clusia species of the restingas, C. hilariana, showed the strongest performance overall.Finally, it was studied whether the ecophysiological performance varied in response to site-dependent gradients of environmental water relations, which was confirmed for functions such as photosynthetic capacity, photoinhibition and solute accumulation of C. hilariana and C. fluminensis in relation to moisture of sites.

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Three legume tree species (Fabaceae) occurring abundantly in a semi-deciduous tropical dry forest of the Atlantic forest complex in southeastern Brazil were subjected to a comparative ecophysiological study at the end of the dry season/beginning of the wet season. The trees chosen were morphologically very similar: Caesalpinia echinata Lam. and Caesalpinia ferrea Mart. ex. Tul., both 10-20 m of height, of the sub-family Caesalpinioideae, and the somewhat smaller, 2-4 m tall, Machaerium obovatum Kuhlm. & Hoehne of the sub-family Faboideae. Despite their similarities with respect to their geographic distribution restricted to Brazilian dry forests, their comparable abundance in the study site and their phylogenetic proximity, the three species display distinctly different ecophysiological behaviour. Compared to the other two species, C. ferrea had the highest photosynthetic capacity (maximum apparent photosynthetic electron transport rate, ETR max ) and higher saturation light-intensity, was less subject to photoinhibition as indicated by potential quantum yield of photosystem II (F v /F m ) and had the lowest bulk N content of which soluble non-protein N compounds were only 1.5%. It showed stronger sun plant characteristics. C. echinata had lower photosynthetic capacity, was under chronic A. Geßler · M. Nahm · H. Rennenberg photoinhibition and had high bulk N content of which 6.1% were soluble N compounds with high concentrations of proline. In addition to proline, high concentrations of sugars may serve as osmoprotectants. M. obovatum also showed lower photosynthetic capacity and was under chronic photoinhibition. Here, arginine may have a function as osmoprotectant. The ecophysiological differences between the three species are not related to local abundance. However, the observations presented highlight a contrasting behaviour of the otherwise very similar compatriot species.

In continuous light, leaves of the Crassulacean acid metabolism (CAM) plant Kalanchoë daigremontiana Hamet et Perrier exhibit a circadian rhythm of CO2 uptake, stomatal conductance and leaf-internal CO2 pressure. According to a current quantitative model of CAM, the pacemaking mechanism involves periodic turgor-related tension and relaxation of the tonoplast, which determines the direction of the net flux of malate between the vacuole and the cytoplasm. Cytoplasmic malate, in turn, through its inhibitory effect on phospho enolpyruvate carboxylase, controls the rate of CO2 uptake. According to this mechanism, when the accumulation of malate is disrupted by removing CO2 from the ambient air, the induction of a phase delay with respect to an unperturbed control plant is expected. First, using the mathematical model, such phase delays were observed in numerical simulations of three scenarios of CO2 removal: (i) starting at a trough of CO2 uptake, lasting for about half a cycle (ca. 12 h in vivo); (ii) with the identical starting phase, but lasting for 1.5 cycles (ca. 36 h); and (iii) starting while CO2 increases, lasting for half a cycle again. Applying the same protocols to leaves of K. daigremontiana in vivo did not induce the predicted phase shifts, i.e. after the end of the CO2 removal the perturbed rhythm adopted nearly the same phase as that of the control plant. Second, when leaves were exposed to a nitrogen atmosphere for three nights prior to onset of continuous light to prevent malate accumulation, a small, 4-h phase advance was observed instead of a delay, again contrary to the model-based expectations. Hence, vacuolar malic acid accumulation is ruled out as the central pacemaking process. This observation is in line with our earlier suggestion [T.P. Wyka, U. Lüttge (2003) J Exp Bot 54:1471-1479] that in extended continuous light, CO2 uptake switches gradually from a CAM-like to a C3-like mechanism, with oscillations of the two CO2 uptake systems being tightly coordinated. It appears that the circadian rhythm of gas exchange in this CAM plant emerges from one or several devices that are capable of generating temporal information in a robust manner, i.e. they are protected from even severe metabolic perturbations.

Andira legalis Vell. Toledo (Leguminosae, Papilionoideae) is a deciduous tree of the coastal vegetation of Brazil. It was studied in the restinga ecosystems of the Atlantic coast along a moisture gradient of open dry restinga (annual precipitation 800 mm, water table high at 0.9-1.2 m but partially saline), intermediate restinga (annual precipitation 1164 mm, water table low at 2-3 m) and wet restinga (annual precipitation 1000 mm, water table high at 0.5-1 m). In addition, a comparison of the ecophysiological performance was made of A. legalis in the wet restinga and a dune forest (water table low at 2-6 m). Plants of A. legalis at a given site and even within clonal stands show considerable phenological plasticity, where especially timing of leaf shedding and new bud break, leaf expansion and maturation varies between neighbouring individuals and all stages can be observed at the same time. We used analyses of soluble carbohydrate carbon compounds, soluble non-protein nitrogen compounds, stable isotope signatures (δ 13 C, δ 15 N) and parameters of fluorescence of chlorophyll a for describing metabolic relations A. Geβler · M. Nahm · H. Rennenberg