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Made available in DSpace on 2022-05-01T09:30:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The construction of four large reservoirs for hydroelectric power generation in the main channel of the Paraná River and many others in the tributaries has eliminated important wetlands, except over an area of ∼2000 km2 between the reservoirs of the UHE Engenheiro Sérgio Motta (Porto Primavera) and the Itaipu. The up-river reservoirs created large changes in the river's hydrology and in its loads of suspended, bed and dissolved material. A detailed assessment of the impact of these changes requires a description and classification of the floodplain's different subunits, called macrohabitats, according to hydrological, hydromorphological, and vegetational parameters. The classification system presented herein is hierarchical and is embedded in the classifications of Brazilian wetlands. The system differentiates the Paraná River floodplain into 6 functional units, 13 subclasses, and 23 macrohabitats, which are presented in this paper. Changes in hydrology have reduced the flood amplitude, frequency and permanence, and thus confined the macrohabitats to an area currently subjected to a regular flood pulse of ∼3 m rather than the previous ∼6 m. The gradual terrestrialization of macrohabitats at the upper end of the flood gradient is expected, accompanied by a loss of macrohabitats at its lower end because of long-term flooding. The retention of sediments and dissolved nutrients in the reservoirs will lead to the oligotrophication of aquatic macrohabitats, the degradation of near-channel hydromorphic structures and their vegetation, and a general reduction of overall primary production in the floodplain, which may extend also to higher trophic levels. National Institute for Science and Development in Wetlands (INCT-INAU) Federal University of Mato Grosso (UFMT) Universidade Estadual de Maringá (UEM) Instituto SENAI de Inovação Biomassa BioLogic Consultoria Ambiental Universidade Estadual Paulista (Unesp) Universidade Estadual Paulista (Unesp)

Water and soil chemistry provide important parameters for the study of river ecology and biogeochemical cycles. Furthermore, they determine management options of rivers and connected wetlands. The first scientific classification of Amazonian water bodies was elaborated in the 1950s by Harald Sioli. He used water color, as well as physical and chemical parameters, to explain limnological characteristics of the large Amazonian rivers and related these characteristics to the geological and geomorphological properties of their catchments. Today, an increasing amount of hydrochemical data indicate that the chemical composition of Amazonian water bodies varies much more than assumed by Sioli. Nevertheless, his simplified classification is useful for describing the natural physical and chemical variability of Amazonian rivers and wetlands. The electrical conductivity, pH-value and the distribution of major cations and anions allow to distinguish well among the three classical water types and to categorize other water bodies in order to subsidize a more detailed classification system of Amazonian fresh waters. A qualidade química da água proporciona parâmetros fundamentais para o estudo da ecologia dos rios, sua biodiversidade e seus ciclos biogeoquímicos. Esses parâmetros determinam opções de gestão dos rios e das áreas úmidas associadas. A primeira classificação científica dos corpos da água da Amazônia foi elaborada pelo pesquisador Harald Sioli em meados do século passado. Ele estabeleceu 3 tipos de água: água branca, água preta e água clara. Com esta tipologia ele explicou peculiaridades limnológicas dos grandes rios da Amazônia. Além disso, ele relacionou os fatores físico-químicos dos três tipos de águas com as propriedades geológicas e geomorfológicas das suas bacias hidrográficas. Hoje em dia uma quantidade crescente de dados hidro-químicos indicam que a composição dos corpos da água na Amazônia varia muito mais do que foi assumido por Sioli. Foram usados os dados disponíveis na literatura sobre as variáveis transparência, pH, condutividade elétrica e a distribuição de cátions e ânions principais para reavaliar a antiga classificação. A nossa análise permitiu distinguir os três tipos de água clássicos e categorizar outros corpos de água em mais três tipos, a fim de subsidiar um sistema de classificação mais detalhado para as águas Amazônicas.

As áreas úmidas savânicas desempenham múltiplos serviços e produtos ambientais, portanto seu uso múltiplo deve ser incentivado. No Brasil as áreas úmidas savânicas se encontram no Pantanal, Rio Araguaia (Ilha do Bananal), Rio Guaporé e nos lavrados de Roraima. O Brasil, como signatário da Convenção Ramsar, deve compatibilizar suas políticas públicas, através do reconhecimento dos múltiplos valores das áreas úmidas, alcançando assim o uso racional dos seus recursos e contribuindo para o desenvolvimento sustentável. No Brasil, áreas úmidas savânicas não são contempladas na legislação especifica e a orientação de seu manejo uma vez reconhecida como área de uso restrito deverá atender aos princípios das Convenções Ramsar e da Diversidade Biológica. Frente as demandas por produtos florestais madeireiros e não-madeireiros fornecidos pelas áreas úmidas savânicas a adoção de planos de manejo diferenciados é necessária. Esta abordagem propõe formas de manejo ecologicamente benéficas, incorporando valores adicionais ao uso da terra e às formações florestais, além do valor comercial dos recursos madeireiros. O uso múltiplo em áreas úmidas é o tipo de manejo integrado e planejado, onde os vários usos dos recursos, devem estar interligados tornando-se uma estratégia viável para prolongar a disponibilidade dos recursos, o uso viável da terra e manter as características ecológicas desses ambientes. As principais vantagens do manejo de uso múltiplo são: uso diversificado dos recursos naturais, aumento do rendimento de produtos e serviços, desenvolvimento da produtividade florestal, envolvimento das partes interessadas na obtenção de benefícios de recursos naturais, diminuição dos conflitos sociais e degradação dos recursos florestais, o incentivo à manutenção de áreas florestadas e a proteção de sua biodiversidade, entre outros. Modelos de uso múltiplo para as áreas úmidas savânicas florestadas devem considerar seus valores múltiplos e suas interdependências, baseando-se principalmente nos princípios da sustentabilidade, sobretudo no uso integrado de recursos florestais madeireiros e não madeireiros. O conhecimento sobre as savanas florestadas de áreas úmidas e seu uso potencial devem ser divulgados e incentivados, para que seu uso seja realizado de forma sustentável garantindo seu aproveitamento por futuras gerações.

A integração de dados remotos e de sistema de informação geográfica (SIG) tem a capacidadede fornecer informações, avaliar e monitorar sítios Ramsar e outras áreas úmidas (AUs) no tempo e no espaço. Assim, sabendo-se da necessidade que o Brasil possui de realizar, na prática, as diretrizes da Convenção Ramsar, são necessárias orientações para o planejamento de inventário, a avaliação e o monitoramento de AUs utilizando dados remotos e SIG. Neste trabalho, definiram-se passos integrados e orientações para garantir a realização de um inventário de AUs e atender às ações da atual Estratégia Nacional de Conservação e Uso Sustentável das Áreas Úmidas do Brasil.

Low-order streams and riparian wetlands are important contributors to the drainage network in the landscape. However, there has been little research into the nature of these ecosystems in Brazil. Our estimates show that riparian wetlands of low-order streams and other small associated wetlands cover at least 25% of the forested part of the Amazon basin and about 10% of the Cerrado region. Information on the semi-arid Caatinga is lacking, but ~ 3% of the area may be occupied by riparian wetlands and other small wetland types, many of which are periodically dry. Riparian vegetation includes a very large richness in tree species. The amount and species richness of herbaceous plants depend on light availability. In-streams of the semi-arid region of Brazil, hydrophytes are restricted by unpredictable flash floods and periodic drought. Aquatic food webs are largely based on the organic matter produced by the riparian vegetation. Large-scale agriculture and cattle ranching pose a serious threat to riparian wetlands, their biodiversity, and their function as a buffer in the hydrological cycle of the landscape. A nation-wide screening program would provide a more detailed picture and allow the elaboration of a national conservation and restoration program for the Brazilian riparia.

Made available in DSpace on 2021-06-25T10:22:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Fundação de Amparo à Pesquisa do Estado do Amazonas Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The Balbina hydropower dam in the Central Amazon basin, established in the Uatumã River in the 1980s, is emblematic for its socio-environmental disaster. Its environmental impacts go far beyond the reservoir and dam, however, affecting the floodplain forests (igapó) in the downstream area (dam shadow), which have been assessed using a transdisciplinary research approach, synthesized in this review. Floodplain tree species are adapted to a regular and predictable flood pulse, with high- and low-water periods occurring during the year. This was severely affected by the operation of the Balbina dam, which caused the suppression of both the aquatic phase at higher floodplain elevations and the terrestrial phase at lower floodplain elevations (termed the ‘sandwich effect’). During the period of construction and reservoir fill, large-scale mortality already occurred in the floodplains of the dam shadow as a result of reduced stream flow, in synergy with severe drought conditions induced by El Niño events, causing hydraulic failure and making floodplains vulnerable to wildfires. During the operational period of the dam, permanent flooding conditions at low topographical elevations resulted in massive tree mortality. So far, 12% of the igapó forests have died along a downstream river stretch of more than 125 km. As a result of flood suppression at the highest elevations, an encroachment of secondary tree species from upland (terra firme) forests occurred. More than 35 years after the implementation of the Balbina dam, the downstream impacts caused massive losses of macrohabitats, ecosystem services, and diversity of flood-adapted tree species, probably cascading down to the entire food web, which must be considered in conservation management. These findings are discussed critically, emphasizing the urgent need for the Brazilian environmental regulatory agencies to incorporate downstream impacts in the environmental assessments of several dam projects planned for the Amazon region. Grupo de Pesquisa Ecologia Monitoramento e uso Sustentável de Áreas Úmidas (MAUA) Instituto Nacional de Pesquisas da Amazônia (INPA) Institute of Geography and Geoecology Department of Wetland Ecology Karlsruhe Institute for Technology (KIT) Programa de Pós-graduação em Botânica Instituto Nacional de Pesquisas da Amazônia (INPA) Programa de Pós-graduação em Ecologia Instituto Nacional de Pesquisas da Amazônia (INPA) Programa de Pós-graduação em Clima e Ambiente Instituto Nacional de Pesquisas da Amazônia (INPA)/Universidade do Estado do Amazonas (UEA) Programa de Pós-graduação em Biologia de Água Doce e Pesca Interior Instituto Nacional de Pesquisas da Amazônia (INPA) Instituto de Ciências Biológicas Departamento de Ecologia Universidade de Brasília (UnB) Department of Biogeochemical Processes Max-Planck-Institute for Biogeochemistry Universidade Estadual Paulista (UNESP) Instituto de Geociências e Ciências Exatas Naturalis Biodiversity Center Systems Ecology Vrije Universiteit Amsterdam Instituto Nacional de Pesquisas da Amazônia (INPA) Laboratório de Ecofisiologia e Evolução Molecular (LEEM) Instituto Nacional de Ciência e Tecnologia em Adaptações da Biota Aquática da Amazônia (ADAPTA) Instituto Nacional de Ciência e Tecnologia em Áreas Úmidas (INAU) Universidade Federal de Mato Grosso (UFMT) Programa de Pós-graduação em Ciência Ambiental (PROCAM) Universidade de São Paulo (USP) Centro de Formação em Ciências Agroflorestais Universidade Federal do Sul da Bahia (UFSB) Faculty of Natural Sciences University of Stirling Núcleo de Estudos e Pesquisas Ambientais (NEPAM) Universidade Estadual de Campinas (UNICAMP) Universidade Estadual Paulista (UNESP) Instituto de Geociências e Ciências Exatas Fundação de Amparo à Pesquisa do Estado do Amazonas: 062.1187/2017 CNPq: 403792/2012-6 CNPq: 441462/2017-0 CNPq: 441498/2017-5 CNPq: 441590/2016-0 CNPq: 457893/2013-3 CNPq: 465540/2014-7 CAPES: Finance Code 001 Fundação de Amparo à Pesquisa do Estado do Amazonas: FIXAM 017/2914

The large flood pulse of the Amazon basin is a principal driver of environmental heterogeneity with important implications for ecosystem function and the assembly of natural communities. Understanding species ecological response to the flood pulse is thus a key question with implications for theories of species coexistence, resource management, and conservation. Yet these remain largely undescribed for most species, and in particular for trees. The large flood pulse and high tree diversity of the Negro River floodplain makes it an ideal system to begin filling this knowledge gap. We merged historical hydrologic data with 41 forest inventories under variable flooding conditions distributed across the Negro River basin, comprising a total area of 34 ha, to (i) assess the importance of flood duration as a driver of compositional variation, (ii) model the response curve shapes of 111 of the most frequent tree species in function of flood duration, and (iii) derive their niche properties (optima and tolerance). We found that flood duration is a strong driver of compositional turnover, although the majority site-to-site variation in forest composition still remains unexplained. About 73% of species responded to the flood duration gradient, exhibiting a diversity of shapes, but most frequently skewed. About 29% of species were clearly favored by flood durations >120 days year–1, and 44% of species favored by shorter floods. The median niche breadth was 85 flood days year–1, corresponding to approximately 30% of the flood duration gradient. A significant subset of species (27%) did not respond to flooding, but rather exhibited wide tolerance to the flood gradient. The response models provided here offer valuable information regarding tree species differential capacity to grow, survive, and regenerate along an ecologically important gradient and are spatially valid for the Amazon Negro basin. These attributes make them an appealing tool with wide applicability for field and experimental studies in the region, as well as for vegetation monitoring and simulation models of floodplain forest change in the face of hydrologic alteration.

Building bridges between environmental and political agendas is essential nowadays in face of the increasing human pressure on natural environments, including wetlands. Wetlands provide critical ecosystem services for humanity and can generate a considerable direct or indirect income to the local communities. To meet many of the sustainable development goals, we need to move our trajectory from the current environmental destructive development to a wiser wetland use. The current article contain a proposed agenda for the Pantanal aiming the improvement of public policy for conservation in the Pantanal, one of the largest, most diverse, and continuous inland wetland in the world. We suggest and discuss a list of 11 essential interfaces between science, policy, and development in region linked to the proposed agenda. We believe that a functional science network can booster the collaborative capability to generate creative ideas and solutions to address the big challenges faced by the Pantanal wetland. Made available in DSpace on 2019-09-27T00:39:34Z (GMT). No. of bitstreams: 1 SustainabilityAgenda2019.pdf: 7046678 bytes, checksum: 95e607f5662246d9f5e01cf9b656b030 (MD5) Previous issue date: 2019

Traditional water classifications for Amazonian rivers are based mainly on optical characteristics that do not fully capture their complexity. Today, an increasing amount of hydrochemical data indicates that the chemical composition of Amazonian rivers varies much more than this simple classification indicates. Revising river classification based on hydrochemical properties is proposed here. In this first comprehensive review of Amazonian river chemistry, we synthesized critical information from 168 scientific publications and distinguish unusual white, black, and clearwater rivers. It is shown the distribution of such rivers across the basin and the limitations of using generalized designations for river typologies. For example, some optically clearwater rivers draining carboniferous stripes have chemical properties similar to whitewater rivers, regardless of their high transparency. Furthermore, a clear or blackwater stream that becomes turbid because of soil erosion does not become a whitewater stream. Its hydrochemical parameters of acidity and nutrient poverty depend on the geology of the catchment area and remain relatively unaffected. These insights into Amazonian river classification provide a new understanding of their baseline limnological conditions. They have implications for sustainable management of freshwater systems and for monitoring potential impacts of large development projects and climate change on the Amazonian aquatic systems.

Adaptation to prolonged flooding was investigated using cuttings of two tree species from the Central Amazon white-water floodplain (V�rzea). Morphological features and oxygen distribution patterns were correlated with metabolic changes under hypoxia, such as alterations in alcohol dehydrogenase (ADH) activity and adenylate energy charge (AEC) of root cells. Salix martiana (Leyb.) was able to react to hypoxic growth conditions with formation of adventitious roots rich in lysigenous aerenchyma, which facilitates root aeration by longitudinal oxygen transport and rhizosphere oxidation by radial oxygen loss (ROL). The oxygen concentration on the surface of adventitious roots of S. martiana reached 2-3 mg O2 L–1. The low resistance to gas exchange in Salix roots was reflected by low ADH activities, which ranged between 0.03-0.1 μmol NADH mg –1 min–1, and AEC values of 0.8-1 under hypoxic conditions. Adventitious roots were also formed by Tabernaemontana juruana ([Markgr.] Schumann ex. J.F. Macbride) during growth under low-oxygen conditions, although at a later stage. The gas-space continuum in roots of T. juruana was less pronounced, resulting in a 10-fold lower oxygen concentration in the root cortex under oxygen stress compared with adventitious roots of Salix. The lower oxygen content was reflected in 6-fold higher ADH activities and decreased AEC values. ROL occurred only at the non-suberized root tip, suggesting that the suberized hypodermis functions as a barrier against gas exchange between the root and the rhizosphere. These findings indicate that different strategies of adaptation to low oxygen levels are realized in the two species under investigation that occur naturally in the same ecosystem but inhabit different elevation sites.

As áreas úmidas savânicas são responsáveis por múltiplos serviços e produtos ambientais; portanto, seu uso múltiplo deve ser incentivado. No Brasil, as áreas úmidas savânicas se encontram no Pantanal, no rio Araguaia (Ilha do Bananal), no rio Guaporé e nos lavrados de Roraima. Como signatário da Convenção Ramsar, o Brasil deve compatibilizar suas políticas públicas, através do reconhecimento dos múltiplos valores das áreas úmidas, alcançando, assim, o uso racional dos seus recursos e contribuindo para o desenvolvimento sustentável. No Brasil, áreas úmidas savânicas não são contempladas na legislação específica, e a orientação de seu manejo – uma vez reconhecida como área de uso restrito – deverá atender aos princípios das Convenções Ramsar e da Diversidade Biológica. Diante das demandas por produtos florestais madeireiros e não madeireiros, a adoção de planos de manejo diferenciados é necessária. Essa abordagem propõe formas de manejo ecologicamente benéficas, incorporando valores adicionais ao uso da terra e às formações florestais. O uso múltiplo em áreas úmidas é o tipo de manejo integrado e planejado em que os vários usos dos recursos devem estar interligados, tornando-se uma estratégia possível para prolongar a disponibilidade dos recursos e o uso viável da terra, e manter as características ecológicas desses ambientes. As principais vantagens do manejo de uso múltiplo são o uso diversificado de recursos naturais, o aumento do rendimento de produtos e serviços, a participação das partes interessadas na obtenção de benefícios de recursos naturais, a diminuição dos conflitos sociais e degradação dos recursos florestais, o incentivo à manutenção de áreas florestais e a proteção da sua biodiversidade, entre outros. O conhecimento sobre as áreas úmidas savânicas e seu uso potencial devem ser divulgados e incentivados, para que seu uso seja realizado de forma sustentável, garantindo seu aproveitamento por futuras gerações.

Large floodplains are complex ecosystems at the land–water boundary. Because of rainy and dry seasons, most tropical floodplains are subjected to annual water-level fluctuations. During typical low-water periods, extensive areas of the floodplains are dry. However, relatively small geomorphological differences within the boundaries of the floodplains result in comparatively large differences in the length and depth of inundation and, in turn, the establishment of distinct plant communities, called macrohabitats. The specific ecological conditions of these macrohabitats have to be taken into consideration in the development of sustainable management methods and protection measures. Extreme floods and droughts have very strong effects on flora and fauna. The low hydrological buffer capacity of floodplains makes them vulnerable to anthropogenic changes in hydrology and to the impacts of global climate change. This study presents a macrohabitat classification system that has been applied to three large Brazilian floodplains: the forested Amazonian varzeas and igapos, and the savanna floodplains of the upper Paraguai River (Pantanal of Mato Grosso). Examples are provided to demonstrate the applicability of this system in comparative inter- and intra-wetland studies and therefore its utility in assessing environmental changes, including those arising from global climate change. Our approach can also be used to guide the implementation of sustainable management methods and as a focal point for the development of environmental legislation.

Site-specific growth modeling based on tree-ring data is demonstrated to be an efficient tool for conservation and sustainable forest management of an economically important tropical tree species, Calophyllum brasiliense. One of the main challenges in the sustained management of natural tropical forests is obtaining reliable data on tree growth, which is prerequisite information for determining harvesting volumes and felling cycles. In this study, we apply growth models based on tree-ring data and allometric equations to estimate site-specific management options for timber resources of the commercial species Calophyllum brasiliense (Calophyllaceae) comparing 16 wetland sites across different Brazilian ecoregions, the Amazon, Cerrado (savannah), Pantanal and Mata Atlântica (Coastal Atlantic Rainforest). By modeling diameter, height, and volume growth parameters, we estimate site-specific minimum logging diameters (MLD) and felling cycles analyzing a total of 341 trees. Between ecoregions, the mean diameter increments varied slightly between 4.3 ± 1.6 mm year−1 in the Amazon region (average of six sites), 4.0 ± 0.8 mm year−1 in the Cerrado and Pantanal (average of seven sites), and 4.5 ± 1.2 mm year−1 in the Mata Atlântica (average of three sites). However, between sites, we observed significant differences in diameter and volume increment rates, resulting in felling cycles varying from 14 to 63 years and MLDs in the range of 35–81 cm. This clearly indicates that forest management practices in Brazil, which generally applies a feeling cycle of 25 years and a diameter-cutting limit of 50 cm cannot guarantee a sustainable timber harvest. Timber resource management of this species requires site-specific criteria and should be restricted at sites with a low wood productivity. Moreover, long-term monitoring of the population structure and dynamics is necessary for a better understanding of the relationship between environmental factors and population dynamics, especially concerning the regeneration processes.

The Araguaia River floodplain is a large wetland in the tropical savanna belt (cerrado) in the southern Amazon basin. Studies using multitemporal satellite Landsat 5 TM images with a spatial resolution of 30 m indicate a surface area at maximum flood level of 88,119 km2. During the low-water period, only 3.3 % of the area is covered by water. Flooding is the result of the annual rise in the water level of the Araguaia River and of local rainfall and insufficient drainage during the rainy season. Sedimentology studies have distinguished between an active recent and sub-recent floodplain, which covers ~20 % of the area, and a paleo-floodplain probably several hundreds of thousand years in age. Paleo-floodplain sediments are strongly weathered and marked by the clay mineral association of kaolinite, gibbsite, goethite, and Al-chlorite, predominantly formed from feldspars and micas. The active paleo-floodplain participates in the hydrological cycle but does not receive recent sediments from the river. Higher-lying, not flooded areas (inactive paleo-floodplain) are probably the remnants of paleo-levees, now in an advanced stage of erosion. A hypothesis to explain the genesis of the floodplain is proposed herein.

Knowledge about the distribution and diversity of wetlands has become an essential tool for environmental management and policy-making. Yet, while recent estimates indicate that 27% of the area of Colombia is covered by wetlands and despite a number of regional studies, information about the diversity of wetlands nationally is scarce. In response, we present a national wetland classification system that is based on an ecological approach, from the perspective of wetland scientists, and which builds upon the assumptions underlying the flood pulse concept and hydrogeomorphic approach. Thus, the approach and structure of the Brazilian wetland classification system are used, with geomorphological adjustments made according to Colombia’s topography. The classification is hierarchical, multi-scale, functional, and organized according to four levels (system, macroregion, subsystem, and class), with the wetland diversity of Colombia represented nationally by 89 macrohabitats across marine-coastal, inland, and anthropogenic systems. The primary purpose of this classification is to provide integrated and organized information on the distribution and diversity of Colombian wetlands that will serve as a baseline for transparent environmental policy-making.

The Pantanal is subjected to a monomodal and predictable flood pulse of low amplitude which is the main driver of ecological processes and patterns of biodiversity in one of the largest wetlands in the world. Nevertheless, little is known about how the plant communities of this wetland respond to predicted climate changes. In this paper, we used tree-ring analyses of Vochysia divergens Pohl (Vochysiaceae), a light-demanding pioneer species that occurs in periodically or short-term flooded areas in the Cerrado and Pantanal. We evaluated the influence of precipitation and water level on the growth rates of this species, where it occurs, to determine how local climatic variables (precipitation and water level) influence tree growth and how a large-scale climatic driver in the tropical eastern Pacific (El Niño events) could affect both tree growth and local climate in the northern region of the Pantanal. The indexed tree-ring chronology of eight individuals had a significant relationship with annual precipitation (r = 0.22). Interannual variations of the water level did not affect tree growth. Sea surface temperature anomalies of the El Niño 1 + 2 region lead to decreased precipitation in the northern region of the Pantanal, resulting in decreased diameter increments of V. divergens. Our results demonstrated the dendrochronological potential of V. divergens for analyzing climate–growth relationships for developing climate-sensitive proxies for reconstructing past climatic conditions. © 2018, Botanical Society of Sao Paulo.

The Amazon River and its large tributaries are bordered by floodplains covering tens of thousands of square kilometers. Studies on the structure, function, and species composition have allowed a classification of the macrohabitats of Amazonian white-water floodplains, rich in suspended matter and nutrients and of neutral pH (varzea). Here we describe the use of a similar approach to classify the macrohabitats of the black-water floodplains, rich in humic substances, poor in nutrients and acidic (igapo) of the Negro River and its black-water tributaries. With 12 subclasses and 25 macrohabitats, the igapo is less complex than the varzea. Although white-water and black-water rivers are subjected to similar flood regimes, the low sediment load and shallower declivity of the Negro River lead to reduced sedimentation and erosion processes. Differences in nutrient levels between both ecosystems influence species composition, richness, and growth rates of higher plant communities. Species richness is lower in igapo than in varzea, and wood increment and litter production of igapo trees is about half that reported for varzea trees. In addition, igapo lacks highly productive herbaceous plant communities that are common in varzea. The classification of igapo macrohabitats provides a valuable tool for the elaboration of sustainable management strategies and conservation. While many varzea macrohabitats are suitable for small-scale agriculture, animal husbandry, forestry and commercial fisheries, the carrying capacity of igapo is limited and allows only for subsistence-level fishery and agriculture, the capture of ornamental fishes, and ecotourism. We argue that the biota of most igapo macrohabitats is highly sensitive to changes in hydrological cycles as caused by river damming and/or by climate change.

Flores et al. (1) suggest that large Amazonian floodplains are vulnerable to fire and that a future, drier climate will trigger wide-spread conversion of floodplain forests into fire-dominated savanna. Furthermore, the authors argue that fires in fluvial networks will cascade through nonflooded communities and spearhead fire-induced change in the wider basin. We disagree with the reasoning, which we argue lacks a nuanced understanding of habitat diversity in Amazonian floodplains. In their modeling approach, Flores et al. (1) do not distinguish between highly dynamic varzea and oligotrophic igapo floodplains. Estimates based on remote-sensing in the Amazon basin indicate that varzea covers a larger area (456 × 10 … [↵][1]1To whom correspondence should be addressed. Email: jochen.schongart{at}inpa.gov.br. [1]: #xref-corresp-1-1

Today, an increasing amount of hydrochemical data indicate that the chemical composition of Amazonian rivers varies much more than the traditional classification indicates. In this first comprehensive review of Amazonian river chemistry, we synthesized critical information from 400 scientific publications and distinguish the types: white, black, clear, intermediate type A and type B. We show the distribution of such rivers across the Amazon basin and the limitations of such approach. These insights into Amazonian river classification provide a new understanding of their baseline limnological conditions. They have implications for sustainable management of Amazonian freshwater systems.

Although 20% of Brazilian territory is covered by wetlands, wetland inventories are still incomplete. In 1993, Brazil signed the Ramsar Convention but a coherent national policy for the sustainable management and protection of wetlands has yet to be established. Major gaps in the definition of a specific wetland policy are twofold: (1) the lack of standardized criteria by which wetlands are defined and delineated that reflects the specific ecological conditions of the country and (2) the lack of a national classification of wetlands that takes into account specific hydrological conditions and respective plant communities. In recent years, efforts have been made at a regional level to improve public awareness of the ecology of Brazilian wetlands, their benefits to society, and the major threats endangering them. Studies have shown that wetlands play a crucial role in the regional hydrological cycle and provide multiple benefits for local populations. Furthermore, Brazilian wetlands contribute significantly to South American biodiversity. Therefore, wetland conservation and sustainable management should be given high legislative priority. This article provides a synthesis of the current body of knowledge on the distribution, hydrology, and vegetation cover of Brazilian wetlands. Their definition, delineation, and classification at the national level are proposed in order to establish a scientific basis for discussions on a national wetland policy that mandates the sustainable management of Brazil's extremely diverse and complex wetlands. This goal is particularly urgent in the face of the continuing and dramatic deterioration of wetlands resulting from large-scale agro-industrial expansion, and hydroelectric projects as well as the projected impact of global climate change on hydrological cycles.

Water resources in Amazonia affect all natural and human-altered ecosystems in the region, including their human populations. Evapotranspiration by the Amazon forest provides water vapor that is transported by wind to other regions of Brazil and to neighboring countries. The enormous quantities of water involved in hydrological processes in Amazonia give great importance to the region’s water resources and to potential impacts if these cycles are altered. The diversity of fish and other aquatic organisms is enormous, as is the importance of this fauna as economic and food resources for the human population. There are impacts from pollution, including mercury methylation in hydroelectric reservoirs. Dams also block migration of fish and alter the flooding cycles of rivers. Hydroelectric dams release methane, thereby contributing to global warming. The chemical characteristics of different types of water affect processes such as the transport of organic carbon, the supply of nutrients to the plankton that are the base of the food chain in aquatic ecosystems, and the quantity of bio-available ions that affect sensitivity of organisms to copper and other toxic elements. Several of the major rivers in the region drain more than one country, as is the case for the Madeira River, whose basin drains parts of Bolivia and Peru, in addition to Brazil. International treaties require protecting the rights of other countries that share aquatic resources in trans-border watersheds. The hydroelectric dams under construction in Brazil on the Madeira River imply a variety of impacts in the neighboring countries, including blocking the migration of large catfish. One of the priorities for rational decision making on aquatic resources in Amazonia is expansion of scientific knowledge on aquatic systems in the region. A series of national and international projects are engaged in improving this knowledge, and masters and PhD programs are increasing the capacity for research in the area. The human population in the region depends on the functioning of aquatic ecosystems. People share the fate of these ecosystems, in which they constitute a central component.

The Amazon basin is covered by the most species-rich forests in the world and is considered to house many endemic tree species. Yet, most Amazonian ecosystems lack reliable estimates of their degree of endemism, and causes of tree diversity and endemism are intense matters of debate. We reviewed the spatial distribution of 658 of the most important floodtolerant Amazonian white-water (varzea) tree species across the entire Neotropics by using data from herbaria, floras, inventories and checklists. Our results show that 90% of the varzea tree species are partially or widely distributed across neotropical macro-regions and biomes. Chi-square analyses indicated that varzea species richness in non-varzea macro-regions was dependent on the flooding gradient and the longitudinal position. Cluster analysis combined with association tests indicated four significant patterns of varzea species distributions depending on species flood-tolerance (low vs high) and spatial distribution (restricted vs widespread). We predict that the predominance of Andean substrates is the most important factor that determines the distribution of varzea tree species within and beyond the Amazon basin and explains the high floristic similarity to the Orinoco floodplains. Distribution patterns in other extra-Amazonian macro-regions are more likely linked to climatic factors, with rainforest climates housing more varzea species than savanna climates. 130 tree species were restricted to South-American freshwater floodplains, and 68 ( 10%) were endemic to Amazonian varzea. We detected two centers of endemism, one in the western Amazon characterized by low and brief floods, and one in the central Amazon, characterized by high and prolonged floods. Differences in taxonomic composition of endemic centers in the western and central Amazon are the result of different abiotic factors (i.e. flood regimes), as well as the regional species pools from where the species are recruited from. We hypothesize that numerous morphological, physiological and biochemical adaptations permit survival of trees in flooded environments. Furthermore, these adaptations are independently derived across many taxa and result in a highly specialized flora. We attribute higher than expected levels of endemism to the great spatial extent and age of floodplain ecosystems in the Amazon basin, and highlight the role of Amazonian varzea as an potential driver in speciation and diversification processes. Freshwater floodplains cover an area of approximately 1.7

Wetlands cover at least 6 % of the Earth’s surface. They play a key role in hydrological and biogeochemical cycles, harbour a large part of the world’s biodiversity, and provide multiple services to humankind. However, pressure in the form of land reclamation, intense resource exploitation, changes in hydrology, and pollution threaten wetlands on all continents. Depending on the region, 30–90 % of the world’s wetlands have already been destroyed or strongly modified in many countries with no sign of abatement. Climate change scenarios predict additional stresses on wetlands, mainly because of changes in hydrology, temperature increases, and a rise in sea level. Yet, intact wetlands play a key role as buffers in the hydrological cycle and as sinks for organic carbon, counteracting the effects of the increase in atmospheric CO2. Eight chapters comprising this volume of Aquatic Sciences analyze the current ecological situation and the use of the wetlands in major regions of the world in the context of global climate change. This final chapter provides a synthesis of the findings and recommendations for the sustainable use and protection of these important ecosystems.

Most countries sharing the Amazon basin have signed the Ramsar Convention on Wetlands of International Importance but still lack complete wetland inventories, classification systems, and management plans. Amazonian wetlands vary considerably with respect to hydrology, water and soil fertility, vegetation cover, diversity in plant and animal species and primary and secondary productivity. Here, we propose a classification system of major natural habitats of Amazonian white-water river floodplains (varzeas) based on hydrological, water and soil chemistry and biological parameters. The Amazonian varzea is one of the largest Amazonian wetlands. It is exceptionally rich in plant and animal species and plays important roles in landscape history, evolution, hydrology and biogeochemical cycles of the Amazon basin. Most of Amazonia’s rural population lives in or along the varzea, emphasizing the economic importance of its natural resources. Our classification indicates five major systems, which are subdivided into 10 main habitats and up to 40 functional (vegetation) units of which the most important mesohabitats are described. We understand this classification as a dynamic system, as it is open to the inclusion of future research attempts and habitats without affecting the entire classification system. Our classification may be used for scientific purposes, such as comparative studies on biomass, productivity, biogeochemical cycles and biodiversity. Also, because the classification builds on habitat types and/or vegetation and functional units already distinguished by the local population it may be especially useful in guiding intelligent use of varzea habitat for specific management activities, such as agriculture, animal husbandry, forestry, fisheries, and conservation.

With a total area of 160,000 km2, the Pantanal is one of the largest wetlands in South America and certainly the most famous. It is essential for the maintenance of biodiversity and is highly ranked in national and international protection plans. The ecology of the Pantanal is influenced by the annual inundation, frequent fires during the dry period, and multiple human activities. To maintain traditional low density cattle ranching, which is the economic basis for the Pantanal’s human population, the spread of woody vegetation into former pasture areas requires pasture clearing. Legal restrictions, however, have led to the confusion of pasture clearing with the illegal deforestation that has accompanied Brazil’s rapid economic development, thus creating serious conflicts between the Pantanal’s ranchers and the governmental environmental agency. This dichotomy of interests, i.e., the need to maintain habitat and species diversity while guaranteeing the livelihoods of the ranchers but warding off deforestation, can only be resolved through modern management plans that reconcile the requirements of environmental protection with the economic needs of the ranchers, who are the owners of most of the Pantanal. The key to any such plan’s successful implementation is to consider the Pantanal not as a pristine wetland, but as a valuable cultural landscape. Over the last two and a half centuries, the vegetation in large parts of the Pantanal has been altered due to the presence of cattle ranches. This has maintained its habitat diversity and multiple services to humans and to the environment, including the enhancement of species diversity. This management practice corresponds to modern approaches in other parts of the world, where low density animal grazing, sometimes in combination with mechanical removal of woody vegetation are considered powerful management tools for the maintenance of valuable cultural landscapes.

Our estimates indicate that about 30% of the seven million square kilometers that make up the Amazon basin comply with international criteria for wetland definition. Most countries sharing the Amazon basin have signed the Ramsar Convention on Wetlands of International Importance but still lack complete wetland inventories, classification systems, and management plans. Amazonian wetlands vary considerably with respect to hydrology, water and soil fertility, vegetation cover, diversity of plant and animal species, and primary and secondary productivity. They also play important roles in the hydrology and biogeochemical cycles of the basin. Here, we propose a classification system for large Amazonian wetland types based on climatic, hydrological, hydrochemical, and botanical parameters. The classification scheme divides natural wetlands into one group with rather stable water levels and another with oscillating water levels. These groups are subdivided into 14 major wetland types. The types are characterized and their distributions and extents are mapped.

Coring and acoustic surveying (3·5 kHz) in both rivers and lakes in Central Amazonia provide additional insights into the Late Quaternary hydrological and sedimentological development of the Amazon River and its tributaries. Erosion and accumulation phases were found to be linked to Quaternary sea level changes. The low sea level phase during the last glacial maximum caused deep incision of the Amazon River and erosion in major tributaries such as the Rio Negro, 1500 km upstream from the Amazon mouth. A 3·5-kHz profiling suggests a lowering of the water level by at least 30 m at Manaus. During that phase, the slope of the Amazon valley must have increased, resulting in an increase in bed load transport capacity. The subsequent sea level rise caused a backwater effect far upstream, with silting up of the Amazon valley and the tributary inflows. Former river systems changed into Ria lakes. The floodplains of the Amazon River, the varzea, were formed approximately 5000 years ago when the sea level approached its present-day level. Copyright © 2009 John Wiley & Sons, Ltd.

Long-term flooding imposes a strong selection pressure on plants for the development of protective mechanisms to alleviate the harmful effects of hypoxic and anoxic conditions. This is particularly critical in the Amazonian floodplains where plants withstand annual periods of flooding lasting 7 months and mean flooding amplitude reaching 10 m or more. Himatanthus sucuuba (Apocynaceae) is a tree that is found in the varzea (VZ) floodplains and non-flooded terra firme (TF) forests. It was examined whether individuals from these two contrasting habitats respond differently when subjected to extreme flooding conditions. TF and VZ seedlings were experimentally well-watered, waterlogged (roots and parts of the stems flooded), or submerged (whole plant flooded) during a 4-month period. Anaerobic respiration, evaluated by measuring alcohol dehydrogenase (ADH) activity, and root carbohydrate reserves were quantified, given that the availability of readily fermentable carbohydrates is essential to sustain an active fermentative metabolism. We also assessed changes in morphoanatomy, seedling survival, biomass accumulation and distribution. VZ seedlings had greater root concentrations of soluble sugars and starch, larger seedling mass and accumulated more biomass in roots and stems while TF seedlings allocated more towards stem and leaves. ADH activity was low in seedlings of both populations before exposure to flooding. Waterlogging induced an increase in ADH activity that reached a maximum value in 15 days. Thereafter activity decreased slowly, meanwhile a rapid formation of lenticels, adventitious roots and aerenchyma was observed. Submergence induced leaf shedding and the development of aerenchyma in the root cortex. While VZ seedlings maintained high levels of ADH activity throughout the whole 4-month period, ADH activity in TF seedlings peaked about 15 days after submersion followed by a continuous decrease and death of all the plants. Thus, VZ and TF seedlings differed considerably in terms of tolerating long-term exposure to flooding, especially under total submersion. These results suggest that the predictability and long-term duration of flooding in Central Amazon rivers can impose a selective pressure that is strong enough to result in large phenotypic differences between the two populations of H. sucuuba in the two habitat types.

Wetlands perform many essential ecosystem services—carbon storage, flood control, maintenance of biodiversity, fish production, and aquifer recharge, among others—services that have increasingly important global consequences. Like biodiversity hotspots and frontier forests, the world's largest wetlands are now mapped and described by an international team of scientists, highlighting their conservation importance at the global scale. We explore current understanding of some ecosystem services wetlands provide. We selected four of these wetlands (the largest peatland, West Siberian Lowland; the largest floodplain, Amazon River Basin; the least-known wetland, Congo River Basin; and the most heavily developed wetland, Mississippi River Basin), and we illustrate their diversity, emphasizing values and lessons for thinking big in terms of conservation goals. Recognizing the global significance of these wetlands is an important first step toward forging global conservation solutions. Each of the world's largest ...

Herbaceous species in the Amazon floodplains particularly C4 plants may exhibit NPP values about three times those of the floodplain forest. Although restricted to relatively small areas, they show high diversity and are very important in the carbon and nutrient budgets of the region, enriching the aquatic system and associated floodplains through their decomposition, both during the aquatic and terrestrial phases of the hydrologic cycle. Sustainable management systems for Amazon floodplains should consider the importance of herbaceous vegetation in the nutrient budget of the region. Because of favorable nutrient conditions várzea forests are frequently replaced by farms and pasture lands for cattle and buffalo ranching. The substitution of the forest by herbaceous plant communities has little effect on total primary production because these communities are often more productive than the forest itself, but it affects strongly biomass. On the other hand, massive removal of herbaceous plants for the introduction of less adapted crops w ill reduce species diversity and the fertility of the várzea, and w ill require additional fertilization. Susceptibility of these degraded systems to fire increases during the terrestrial phase, resulting in losses of crops and pastures, and leading to further degradation of the natural plant communities and associated animals of the floodplains, w ith fare reaching negative consequences for human life.

The effect of root inundation on the leaf emissions of ethanol, acetaldehyde and acetic acid in relation to assimilation and transpiration was investigated with 2–3 years old tree seedlings of four Amazonian floodplain species by applying dynamic cuvette systems under greenhouse conditions. Emissions were monitored over a period of several days of inundation using a combination of Proton Transfer Reaction Mass Spectrometry (PTR-MS) and conventional techniques (HPLC, ion chromatography). Under non-flooded conditions, none of the species exhibited measurable emissions of any of the compounds, but rather low deposition of acetaldehyde and acetic acid was observed instead. Tree species specific variations in deposition velocities were largely due to variations in stomatal conductance. Flooding of the roots resulted in leaf emissions of ethanol and acetaldehyde by all species, while emissions of acetic acid were only observed from the species exhibiting the highest ethanol and acetaldehyde emission rates. All three compounds showed a similar diurnal emission profile, each displaying an emission burst in the morning, followed by a decline in the evening. This concurrent behavior supports the conclusion, that all three compounds emitted by the leaves are derived from ethanol produced in the roots by alcoholic fermentation, transported to the leaves with the transpiration stream and finally partly converted to acetaldehyde and acetic acid by enzymatic processes. Co-emissions and peaking in the early morning suggest that root ethanol, after transportation with the transpiration stream to the leaves and enzymatic oxidation to acetaldehyde and acetate, is the metabolic precursor for all compounds emitted, though we can not totally exclude other production pathways. Emission rates substantially varied among tree species, with maxima differing by up to two orders of magnitude (25–1700 nmol m−2 min−1 for ethanol and 5–500 nmol m−2 min−1 for acetaldehyde). Acetic acid emissions reached 12 nmol m−2 min−1. The observed differences in emission rates between the tree species are discussed with respect to their root adaptive strategies to tolerate long term flooding, providing an indirect line of evidence that the root ethanol production is a major factor determining the foliar emissions. Species which develop morphological root structures allowing for enhanced root aeration produced less ethanol and showed much lower emissions compared to species which lack gas transporting systems, and respond to flooding with substantially enhanced fermentation rates and a non-trivial loss of carbon to the atmosphere. The pronounced differences in the relative emissions of ethanol to acetaldehyde and acetic acid between the tree species indicate that not only the ethanol production in the roots but also the metabolic conversion in the leaf is an important factor determining the release of these compounds to the atmosphere.

Trees of Central Amazonian whitewater floodplain forests are subjected to extended flood periods lasting several months. They must therefore be highly adapted to long-term flooding and to oxygen shortage in the soil and roots which is expected to be the main stress factor in this environment. The improvement of oxygen transport to the roots by pressurized gas transport, known for some tree species of the temperate zone, is one specific adaptation to flooding. To evaluate its significance, gas transport measurements were carried out under experimental conditions with saplings of five Amazonian tree species. Internal aeration of the roots was improved under conditions of pressurized gas transport as shown by polarographical measurements of oxygen exchange between root and rhizosphere. Tracer gas measurements using sulphur hexafluoride (SF 6 ) showed gas permeability of transport pathways between stem base and roots. Based on the data, we suppose that pressurized gas transport significantly contributes to internal aeration of roots in Amazonian floodplain saplings growing on the higher levels in the flooding gradient, with low water columns, and is an important adaptation for establishment in these temporarily inundated habitats also in the weeks of rising and lowering water levels.

Among globally important wetlands, the Pantanal stands out because of it's a history of harmonious coexistence of man and biodiversity. In the recent years, however, severe human impacts have emerged, which are capable of disintegrating Pantanal's natural characteristics. This paper contributes to the development of a sustainable management concept considering ecological and socioeconomical demands. Use of natural resources in the highly productive catchment of the tributaries have direct effects on the floodplains of the Pantanal. A careful planning of hydropower plants is needed to maintain (a) some of the tributaries remaining open for fish spawning migration, and (b) the natural flood pulse as the overriding ecological factor. The traditional human population of the Pantanal is threatened by the developments of global change. Their knowledge to use floodplain-specific species is very important for developing sustainable use strategies. Several positive initiatives are highlighted, including the development of a green seal for Pantanal beef and the re-establishment of gallery forests along tributaries. The sustainable use of the fish ressources requires a precise analyis of the stock dynamics. For the further development of the sustainable use, a classification system is needed, which specifies the use potential and conservation demands of the individual habitats.

International audience; Question: The encroachment of woody species has been globally reported over much of arid and semi-arid biomes, and has been associated with a decrease in cover and number of herbaceous species. How does the encroachment of a woody shrub affect herbaceous community structure and species composition in grasslands of a wetland ecosystem? Location: Seasonally flooded grasslands in a Neotropical Hyperseasonal Savanna, the Pantanal wetland, Brazil. Methods: We investigated the effect of the encroaching plant Combretum laxum on a herbaceous community from seasonally flooded grasslands in the Pantanal wetland using 29 vegetation samples representing encroachment at different spatio-temporal stages. The point quadrat method was used to acquire vegetation data, as plant cover, species richness (S) and Shannon-Wiener diversity index (H'). We evaluated the existence of stages of encroachment related to differences in vegetation structure and species composition using non-metric multidimensional scaling ordination and analysis of similarity. The response of the herbaceous community to shrub advance was analysed using linear and quadratic polynomial regression models. Model fitness was tested using the ACI. Results: The advance of the woody encroaching plant C. laxum over the seasonally flooded grassland occurs in three stages: grassland stage, shrub islands stage and shrubland stage. The initial advance of C. laxum over the grassland, represented by the shrub islands stage was correlated to an increase in species richness and a decrease in important native forage grasses. Critical changes in the herbaceous community were observed when the encroaching plant covered > 30% of the periodically flooded grassland, when the richness of herbaceous species dropped from 22 to four. Conclusions: Woody encroachment causes impoverishment and simplification of the herbaceous community. The shift from a grass-to a shrub-dominated state is related to the reduction in important grassland-obligate species, forage resources for herbivore livestock and wild animals, affecting the ecological dynamics and the economy of rangelands. Conservation of these grassland ecosystems depends on rangeland management practices guided by scientific knowledge on the causes and consequences of plant community changes.