Leaf structure in trees of Central Amazonian floodplain forests (Brazil)

Leaf anatomy and morphology in 23 common arboreal species representing 20 families from Central Amazonian white- (varzea) and blackwater (igapo) floodplain forests (Brazil) were analyzed with SEM microscopy. Species differed in leaf-fall behavior (evergreen. deciduous) as well as in the fate of submerged leaves (species either shed or keep their submerged leaves). Leaves of all species showed various traits generally related to leathery leaves and/or xeromorphism, e.g., large epidermal cells, thick outer epidermis walls, thick cuticula, compact spongy parenchyma with only few and small intercellular spaces, sunken stomata, and transcurrent vascular bundles with a strong sclerenchymatous bundle sheath. No trend was found to differentiate evergreen from deciduous species by leaf morphology and anatomy. Species that shed their submerged leaves showed similar characteristics than species that keep their submerged leaves, significant differences were found only in the leathery appearance and the thickness of the outer wall and cuticula. Keeping submerged leaves apparently does not require major morphological or anatomical modifications. Species from the nutrient rich varzea showed similar characteristics as species of the nutrient poor igapo. When the present data set was combined with data from a previous study (total of 34 species) the frequency of two leaf characters was significantly different between floodplain types with igapo species showing a somewhat higher degree of xeromorphism. As leathery and/or xeromorphic leaves are the typical pattern in tropical trees, leaf structures found here are unlikely to represent adaptations to floodplain conditions. The scarcity of similarities in confamiliar or congeneric species also gives further evidence for this interpretation. The relation of xeromorphism with drought resistance and nutrient deficiency in Central Amazonian floodplains is discusse

Leaf morphology and anatomy in eleven tree species from Central Amazonian floodplains (Brazil)

Leaf anatomy and morphology in eleven common arboreal species representing eleven families from Central Amazonian floodplain forests (Brazil) were analysed with SEM microscopy. Species differed in leaf-fall behaviour (evergreen, deciduous) as well as in the fate of submerged leaves (species either shed or keep their submerged leaves). Leaves of all species showed various traits generally related to leathery leaves and/or xeromorphism, e.g., large epidermal cells, thick outer epidermis walls, thick cuticula, compact spongy parenchyma with only few and small intercellular spaces, sunken stomata, and transcurrent vascular bundles with a strong sclerenchymatous bundle sheath. We found no trend to differentiate evergreen from deciduous species by leaf morphology and anatomy. Species that shed their submerged leaves showed similar characteristics than species that keep their submerged leaves. A high level of screlophylly in most species suggests that the trees might experience water stress in their floodplain habitats, independent of leaf-fall behaviour. However, as leathery and/or xeromorphic leaf are the typical pattern in tropical trees, leaf structures found here are unlikely to represent adaptations to floodplain conditions. Keeping submerged leaves apparently does not require different or additional morphological or anatomical characteristic

Chemical composition of fruits and seeds from floodplain biotopes of the Pantanal do Mato Grosso near Cuiabá, Brazil, in comparison to those from similar ones of Central Amazonia.

The chemical composition of 16 fruit species of floodplain biotopes near Cuiabá in the Pantanal do Mato Grosso were determined. Some hints concerning the morphology of the fruits, data obtained by proximate analyses (crude protein, crude fat, crude fibre, crude ash, soluble carbohydrates), content of polyphenols, phosphates and silicates, the concentrations of macro- (K, Ca, Mg, Na) and some microelement (Fe, Mn, Sr) are presented. The differences between the chemical composition of fruits of the Pantanal do Mato Grosso and those from Central Amazonia (Waldhoff et al., 1997), as well as the relationship to the respective water and soil qualities of the different biotopes are discussed

Responses of three Central Amazonian tree species to drought and flooding under controlled conditions.

The forest species in Central Amazonia are able to overcome the extreme stress of flooding and drought in the floodplains. We investigated the survival strategies of three tree species representative of the Amazonian floodplain forest, under controlled conditions in climatic chambers in the University of Kiel. We measured a) the anatomical and morphological characteristics such as adventitious roots, roots with a pneumatophore-like structure, lenticels, and stem dimorphism; and b) the growth and photosynthetic activity under different stress conditions. Two different patterns of adaptive responses to stress in the floodplain forests were observed: high-light-demanding plants grow quickly in height and shed their leaves during inundation, and the shade-tolearnt plants grow at a much slower rate and maintain their leaves during inundation. These leaves seem to perform photosynthesis underwater

Fluorescence Measurements as Indicator of Adaptation Strategies in an Abundant Tree Species from Central Amazonian Floodplain Forests

Symmeria paniculata is a common, evergreen tree species in the lowest part of the flooding gradient in black water inundation forests in Central Amazonia (Brazil) which does not shed submerged leaves. Chlorophyll a fluorescence was measured in aerial and submerged leaves in 1999-2000. Measurements were performed at up to 8 m under water. The Fm/Fv values ('current photochemical capacity' of photosystem II) in leaves submerged at 0-1 m depth were above the lower limit of natural variation of healthy leaves (>0.7), indicating an undamaged photochemical apparatus. Leaves submerged at 1-8 m depth (up to 175 days inundation at the time of measuring) showed Fv/Fm values between 0.6 and 0.4. The recovery of these Fv/Fm values to ³0.7 during falling water levels apparently took place still under water. Rapid light curves (RLC) of leaves submerged at >1 m depth revealed that PS II started with electron transport when lighted. However, the electron transport was apparently inhibited shortly after the start. A negative correlation was found between the inhibition of electron transport and the depth/duration of inundatio

Fluorescence parameters, chlorophyll concentration, and anatomical features as indicators for flood adaptation of an abundant tree species in Central Amazonia: Symmeria paniculata

Symmeria paniculata is a common, evergreen tree species from the lowest part of the flooding gradient in blackwater inundation forests in Central Amazonia (Brazil) which does not shed submerged leaves. Chlorophyll a fluorescence was measured regularly in non-submerged and submerged leaves of different age classes in 1999-2000. Measurements at up to 8 m under the water were performed in both years. Chlorophyll concentration was determined in the leaves of different age classes; the older leaves having experienced submergence of several months. The F-v/F-m values (''current photochemical capacity'' of photosystem II (PSII)) in non-submerged leaves and in those submerged at 0-1 m depth were not correlated with the changing water levels and remained above the lower limit of natural variation of healthy leaves (>0.66), indicating an undamaged photochemical apparatus. Younger leaves showed higher F-v/F-m values than older leaves which in turn showed higher values than in currently submerged leaves. Leaves submerged in darkness (1-7 m depth, up to 163 days of submergence at the time of measuring) showed F-v/F-m values between 0.7 and 0.4, showing a negative correlation with the duration of submergence. The recovery of these F-v/F-m values to mostly greater than or equal to0.7 during falling water levels apparently took place when still underwater. ''Rapid light curves'' of leaves submerged at >1 m depth revealed that the PSII started with electron transport when illuminated. However, the electron transport was apparently inhibited shortly after the start. A negative correlation was found between the inhibition of electron transport and the depth/duration of submergence. Chlorophyll concentration was significantly correlated with leaf age, i.e. long-term submergence did not affect this pattern. Comparison of anatomical and morphological leaf structures with other Polygonaceae revealed that S. paniculata follows the general pattern of the family, i.e. they did not appear to be related to particular floodplain conditions. However, several features such as thick epidermis cells and cuticula, cuticular wrinkles, epicuticular waxes, raised stomatal rims, and sunken stomata should facilitate the survival under floodplain conditions. (C) 2002 Elsevier Science B.V. All rights reserved

Value of fruits and seeds from the floodplain forests of Central Amazonia as food resource for fish.

Floodplain forests of Central Amazonia are heavily influenced by the period fluctuation of the water level. The regular change between terrestrial and aquatic phase in the forests has an impact on friut-shedding as well as on many fish species: during inundation, which lasts for months, they migrate into flooded forests to feed on fruits and seeds shed by trees and bushes in an area more than 300 000 km² in size. For the region near Manaus, Amazonia, Brazil, we report on: (1) the nutritional value and further chemical details of 19 fruits and seeds of those species used by fish as food, furthermore on an additional 11 species which probably serve or could serve as fish food, (2) the amount of fruits-shed in one bioto for 4 selected species, and (3) the percentage of different fish catches with fruits as stomach content. Total annual production of the whole inundated forest can be estimated to be 16-53 million tons of fruits, corresponding to a monetary value of the fish production from the floodplains in the range of US$ 320 to 530 million. The idea is discussed that since some of the fruits which are preferred by frugivorous fish are abundant in three different biotae, it could be possible to use them to feed farmed fish

Central amazonian floodplain forests: Tree adaptations in a pulsing system

Amazonian floodplain forests are characterized by an annual flood pulse with changes of the water table that exceed 10 meters. Seedlings and adult trees are waterlogged or submerged for continuous periods lasting up to seven months per year. The monomodal flood pulse of the rivers causes drastic changes in the bioavailability of nutrients, oxygen levels, and concentrations of phytotoxins. The aquatic phase occurs during a period in which temperature and light conditions are optimal for plant growth and development, implying the need for adaptations. Not only do trees persist in a dormant state, they grow vigorously during most of the year, including the aquatic period. The regularity of flooding may have enhanced the evolution of specific traits, which partially are well known from floodplain trees in other tropical and in temperate regions. Different kinds of adaptations are found at the level of structural, physiological, and phenological traits. Combinations of adaptations regarding seed germination, seedling development, and traits of roots, shoots, and leaves result in a variety of growth strategies among trees. These lead to specific species distributions and zonations along the flooding gradient and within Amazonian floodplain systems (nutrient-rich white-water várzea and nutrient-poor black-water igapó). © 2004 The New York Botanical Garden