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Major threats of freshwater systems are river damming and habitat degradation, further amplified by climate change, another major driver of biodiversity loss. This study aims to understand the effects of climate change, and its repercussions on hydropower production, on the instream biota of a regulated river. Particularly, it aims to ascertain how mesohabitat availability downstream of hydropower plants changes due to modified flow regimes driven by climate change; how mesohabitat changes will influence the instream biota; and if instream biota changes will be similar within and between biological groups. We used a mesohabitat-level ecohydraulic approach with four biological elements – macrophytes, macroalgae, diatoms and macroinvertebrates – to encompass a holistic ecosystem perspective of the river system. The ecological preferences of the biological groups for specific mesohabitats were established by field survey. The mesohabitat availability in three expected climate change-driven flow regime scenarios was determined by hydrodynamic modeling. The biota abundance/cover was computed for the mesohabitat indicator species of each biological group. Results show that climate-changed flow regimes are characterized by a significant water shortage during summer months already for 2050. Accordingly, the regulated rivers' hydraulics are expected to change towards more homogeneous flow conditions where run habitats should prevail. As a result, the biological elements are expected to face abundance/cover modifications ranging from decreases of 76% up to 67% increase, depending on the biological element and indicator taxa. Diatoms seem to endure the greatest range of modifications while macrophytes the slightest (15% decrease to 38% increase). The greatest modifications would occur on decreasing abundance/cover responses. Such underlies an important risk to fluvial biodiversity in the future, indicting climate change as a significant threat to the fluvial system in regulated rivers.

Measures of functional diversity are increasingly being used in ecological research to understand and predict vegetation ecosystem changes. However, there is currently no summary of how, why and where these indicators have been used in riparian forest studies around the world. The present article addresses the key concepts and their evolution across time and reviews the relevance of the use and application of functional trait-based approaches in riparian forests in the last two decades (1997–2017; 70 SCI articles). Our overview contains five sections: I. Evolution of concepts, applications, and methods; II. Functional diversity measures: application in riparian forests; III. Plant functional traits: which traits, how many and why; IV. Functional diversity responses and drivers of change; and V. Future research directions. It would appear that the advances in functional diversity frameworks in the last 20 years have led to an increase in the number of studies using riparian plant guilds and functional diversity indices, with a widespread distribution across Europe and the USA. The use of easily measurable (‘soft’) traits is more prevalent than that of ‘hard traits’ consisting of direct measurements of individual processes. Specific Leaf Area (SLA), plant height, and seed mass were the most common traits used in riparian studies. The number of traits per case study varied greatly, ranging from 1 to 36 traits (median = 6), most of which were selected with the goal of describing ecosystem processes. Among the functional diversity indices, Functional Richness was the most common metric, usually coupled with indices that incorporate trait abundances such as Functional Evenness, Functional Divergence, Functional Dispersion, Rao, and Functional Redundancy. Future research should seek to integrate ecological networks and connectivity in such a way as to produce guidance with regard to trait selection, applications to large spatial scales, and comparable frameworks (guilds, index values) across regions. Novel approaches are emerging in this field of science, seeking to improve both the connection to both prevailing ecological networks and biotic and abiotic interactions.

Made available in DSpace on 2019-10-04T12:30:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-11-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) FC Aguiar We developed a pilot study on the potential of aquatic plants as indicators of ecological quality in tropical rivers to provide an index of biotic integrity for monitoring, conservation, and restoration purposes. We used floristic, environmental, and anthropogenic disturbance data from a 950 km(2) river basin in the southern littoral area of Sao Paulo State, Brazil (Itanhaem River Basin), and proposed a five-step methodological framework for the development of a macrophyte index in tropical river basins. Field surveys were carried out in 137 sites (Spring 2013-2014) of Itanhaem River for the index development and in 27 sites of Itapanhad River (Spring 2015) for its validation. A total of 44 aquatic plant species were recorded in the study area, and 11 metrics were evaluated as potential core metrics of the index. Principal Component Analysis distinguished two river types mostly related to geomorphological characteristics - the Upper river type in the mountainous region (average slope 23.7 degrees) and the Middle-low river type (average slope 9.2 degrees) in the floodplain. The Upper river catchment was characterized by extensive areas occupied by banana plantations, low water conductivity, sandy substrates, and homogeneous aquatic vegetation, whereas the Middle-low river catchment had more urban settlements and displayed high nitrogen and phosphorus contents in water and sediments. The index (MIBI-ITA) is preliminary and was based on species richness and life forms (e.g. submerged hydrophytes, helophytes). MIBI-ITA could only be developed for the lowlands and displayed a high discriminatory ability for distinguishing disturbance and a good performance with external data. Bioassessment in tropical rivers require further investigation on biogeography and long-term responses of macrophyte populations to stressors, as well as knowledge-base on river typology and functional traits of macrophytes, other than morpho-anatomic traits and diversity measures. Univ Estadual Paulista, Programa Posgrad Aquicultura, BR-14884900 Jaboticabal, SP, Brazil Univ Lisbon, Inst Super Agron, Ctr Estudos Florestais, P-1349017 Lisbon, Portugal Univ Estadual Paulista, Dept Ecol, BR-13506900 Rio Claro, SP, Brazil Univ Estadual Paulista, Programa Posgrad Aquicultura, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, Dept Ecol, BR-13506900 Rio Claro, SP, Brazil CAPES: 999.009392/2014-09 FAPESP: 2012/21517-9 Fundacao para a Ciencia e a Tecnologia (FCT, Portugal): UID/AGR/00239/2013 FC Aguiar: SFRH/BPD/112417/2015

Riverine landscapes provide numerous ecosystem services, of which pollination is essential to increase the yield, quality, and stability of crops and the biodiversity of wild flora. Pollinators’ behaviour and their community dynamics are often affected by the spatial distribution of floral and nesting resources at the landscape scale, and are thus sensitive to land-use land-cover (LULC) changes and management practices. The main objective of this study is to understand how changes in riparian vegetation and LULC at River Minho affect pollination services. For this, an approach based on the temporal analysis of historical cartography (1898) and current satellite imagery (2016) was used. We developed a novel Pollination Suitability Index for Riverine Landscapes (PSIRL) using LULC data as a proxy of habitat suitability for insect pollinators. PSIRL scores were derived from expert judgment of the local habitat conditions, floral diversity and field surveys. The PSIRL values obtained for both periods were compared using pairwise T-tests. We detected an overall reduction of the pollination services in the riverine landscape of River Minho from 1898 to 2016. However, at local level we observed gains and losses of pollination suitability as a result of distinct LULC changes. There was a marked decrease in the PSIRL in the most downstream and upstream riverine sections due to generalized conversion of scrublands, broadleaved-forests and heterogeneous agricultural areas to artificial surfaces and managed forests dominated by maritime pine and eucalyptus. However, in the middle section of the river, the area occupied by scrublands, riparian and broadleaved forests increased, resulting in an increase of the foraging resources for insects, and a consequent increase of the PSIRL. This index can be used to monitor and capture changes in the pollination suitability of complex riverine landscapes and support further land and river management decisions. The historical cartography proved to be a valuable source of information to characterize LULC change and hence to assess the evolutionary trajectory of pollination ecosystem services, at global and local level.

Dams modify geomorphology, water quantity, quality and timing of stream flows affecting ecosystem functioning and aquatic biota. In this study, we addressed the structural and functional macroinvertebrate community alterations in different instream mesohabitats of two Portuguese rivers impaired by dams. We sampled macroinvertebrates in riffles, runs and pools of river sites downstream of the dams (i.e. regulated; n = 24) and in sites without the influence of the dams (i.e. unregulated; n = 7), assessing a total of 64 mesohabitats, following late spring-early summer regular flows. We found a distinct taxonomic structure and trait composition of macroinvertebrate assemblages between regulated and unregulated flow sites, and also between mesohabitats in which the differences were more evident. When analysing each mesohabitat individually, the effect of flow regulation was detected only in run-type mesohabitats for both taxonomic and trait composition, leading us to infer that a selective macroinvertebrate assessment on run mesohabitats would be a valuable contribution to detect regulated flow effects on ecosystems impaired by dams. Additionally, there is evidence that respiration and locomotion traits could be effective tools to identify damming flow alterations. This study supports that the quality assessments of rivers impacted by dams could benefit from a sampling approach focused on run mesohabitats and the detection of some key traits, which would improve assessment accuracy.

River hydromorphology has long been subjected to huge anthropogenic pressures with severe negative impacts on related ecosystems’ functioning and water quality. Therefore, improving river hydromorphological conditions represents a priority task in sustainable river management and requires proper assessment tools. It is well known that riparian vegetation plays a crucial role in sustaining river hydromorphological conditions. However, it has been nearly neglected in most hydromorphological assessment protocols, including the European Water Framework Directive (WFD). This paper reviews and synthesizes the relevance of riparian vegetation for river hydromorphology, focusing on its contribution to streamflow and sediment regime conditions. We also examine how riparian vegetation is considered in the WFD and how it is included in national hydromorphological protocols currently in use. Our findings point to a temporal mismatch between the date when the WFD came into force and the emergence of scientific and technologic advances in riparian vegetation dynamism and bio-geomorphic modeling. To overcome this misalignment, we present promising approaches for the characterization and assessment of riparian vegetation, which include the identification of vegetation units and indicators at multiple scales to support management and restoration measures. We discuss the complexity of riparian vegetation assessment, particularly with respect to the establishment of river-type-based reference conditions and the monitoring and management targets, and propose some attributes that can serve as novel indicators of the naturalness vs. artificiality of riparian vegetation. We argue that the hydromorphological context of the WFD should be revisited and offer guidance to integrate riparian vegetation in river hydromorphological monitoring and assessment., The work leading to this paper was developed within the COST Action (CA16208) – CONVERGES (Knowledge Conversion for Enhancing Management of European Riparian Ecosystems and Services), supported by COST (European Cooperation in Science and Technology; www.cost. eu). Vanesa Martínez-Fernández was funded by a “Juan de la Cierva” research contract (Spanish MINECO grant no. FJC2018-035451-I at National Museum of Natural Sciences, CSIC, Spain. Francisca C.Aguiar is supported by national funds via FCT under the contracts Norma Transitoria - DL57/2016/CP1382/CT0028. The Portuguese Foundation for Science and Technology (FCT) supported Patricia María Rodríguez- González through FCT investigator programme IF/00059/2015 and the Forest Research Centre through grants UID/AGR/00239/2019 and UIDB/00239/2020.

Dams strongly impair the fluvial environment by altering downstream flows. We analysed riverscapes downstream of three dams and hypothesized that different dam types in rivers with diverse history of land-use and land cover (LULC) change have significant riparian cover differences at diverse biogeomorphic units (banks, riverbanks, islands). We performed a temporal comparison using pre-dam (1965) and post-dam (2013) high-resolution airborne imagery. A new approach was devised to correct the spatial offset between historical and contemporary imagery. Riparian vegetation and LULC (200 m-buffer) were mapped in three rivers of Portugal regulated by the dams Touvedo (run-of-river), Vilarinho das Furnas and Fronhas (storage reservoirs). Five landscape metrics, measures of shape complexity, area and edge effect of riparian patches were computed, including the Weighted Class Area, a metric developed to better interpret the landscape variation. Our findings provide support for the hypothesis of highly altered riverscapes in the post-dam period. For all case studies riparian patches are presently larger, but with less complex shapes and smaller edges. In the present study riparian patches encroach into the river channel, occupy more area and are larger at the two reservoir rivers than at the run-of-river setting. Riparian growth trajectory at the latter is mainly outwards from the active channel and non-vegetated areas in riverbanks and banks are significantly larger; likely due to the washing flows. Redundancy analyses indicated that riparian change was driven by both LULC (agricultural land abandonment and unmanaged forests) and hydrological alterations that jointly determine the structure and spatial trajectories of riparian expansion.

Large rivers on the Iberian Peninsula reflect a long-history of human interventions and natural disturbances in the fluvial corridors and on the surrounding valleys. In this study we aim to characterize the river morphology in pre-regulation times and understand the morphological changes of the large river Tagus (Central Portugal), across space and time. For this, we used comparable military thematic maps from three dates (1855, 1940 and 2000) and evaluated the river landforms, including sinuosity, aquatic, geomorphic and riparian aspects, in three geomorphological zones (Upland, Middle, and Lowland) using a Geographic Information System (GIS). We related the landform variations to the hydrological alterations and to Land-use Land-Cover (hereinafter LULC) changes at valley level. Hydrological data were achieved by simulating river flow regime using the Soil and Water Assessment Tool (SWAT) model. LULC data was obtained by on-screen digitizing of the military thematic maps complemented with ancillary bibliographic information. Metrics for channel form, aquatic and riparian features were quantified in 51 sampling units of 2500 m-long river sections for each period to describe the river morphology. Shannon-Wiener Index (H’) was applied as a descriptor of the morphological diversity. Data analysis revealed a narrowing of the main channel, an overall reduction of the sinuosity, a smaller number of instream geomorphic units and abandoned lateral channels on the most recent period. Morphological alterations were driven primarily by the reduction of floods and sediment inputs, caused by streamflow regulation, while the agricultural intensification, the augment of forest plantations and the reduction of the Mediterranean scrublands induced changes in sediment dynamics and altered the riparian connectivity. The Upland zone showed the highest morphological alterations switching from a historical high-energy section to a low-dynamic zone. We also observed a high morphological variability in the Middle course exhibiting multifaceted gradients of change, while the Lowland zone reflected continuous but less pronounced modifications. River management planning should express the insights of how past and present human alterations affect morphological processes in river-floodplain systems, particularly taking into account river zones’ specificities and how they may react or constrain potential restoration processes.

Giant reed is an aggressive invasive plant of riparian ecosystems in many sub-tropical and warm-temperate regions, including Mediterranean Europe. In this study we tested a set of geometric, spectral and textural attributes in an object based image analysis (OBIA) approach to map giant reed invasions in riparian habitats. Bagging Classification and Regression Tree were used to select the optimal attributes and to build the classification rules sets. Mapping accuracy was performed using landscape metrics and the Kappa coefficient to compare the topographical and geometric similarity between the giant reed patches obtained with the OBIA map and with a validation map derived from on-screen digitizing. The methodology was applied in two high spatial resolution images: an airborne multispectral imagery and the newly WorldView-2 imagery. A temporal coverage of the airborne multispectral images was radiometrically calibrated with the IR-Mad transformation and used to assess the influence of the phenological variability of the invader. We found that optimal attributes for giant reed OBIA detection are a combination of spectral, geometric and textural information, with different scoring selection depending on the spectral and spatial characteristics of the imagery. WorldView-2 showed higher mapping accuracy (Kappa coefficient of 77%) and spectral attributes, including the newly yellow band, were preferentially selected, although a tendency to overestimate the total invaded area, due to the low spatial resolution (2 m of pixel size vs. 50 cm) was observed. When airborne images were used, geometric attributes were primarily selected and a higher spatial detail of the invasive patches was obtained, due to the higher spatial resolution. However, in highly heterogeneous landscapes, the low spectral resolution of the airborne images (4 bands instead of the 8 of WorldView-2) reduces the capability to detect giant reed patches. Giant reed displays peculiar spectral and geometric traits, at leaf, canopy and stand level, which makes the OBIA approach a very suitable technique for management purposes.

The giant reed ( Arundo donax L.) is amongst the one hundred worst invasive alien species of the world, and it is responsible for biodiversity loss and failure of ecosystem functions in riparian habitats. In this work, field spectroradiometry was used to assess the spectral separability of the giant reed from the adjacent vegetation and from the common reed, a native similar species. The study was conducted at different phenological periods and also for the giant reed stands regenerated after mechanical cutting (giant reed_RAC). A hierarchical procedure using Kruskal–Wallis test followed by Classification and Regression Trees (CART) was used to select the minimum number of optimal bands that discriminate the giant reed from the adjacent vegetation. A new approach was used to identify sets of wavelengths – wavezones – that maximize the spectral separability beyond the minimum number of optimal bands. Jeffries Matusita and Bhattacharya distance were used to evaluate the spectral separability using the minimum optimal bands and in three simulated satellite images, namely Landsat, IKONOS and SPOT. Giant reed was spectrally separable from the adjacent vegetation, both at the vegetative and the senescent period, exception made to the common reed at the vegetative period. The red edge region was repeatedly selected, although the visible region was also important to separate the giant reed from the herbaceous vegetation and the mid infrared region to the discrimination from the woody vegetation. The highest separability was obtained for the giant reed_RAC stands, due to its highly homogeneous, dense and dark-green stands. Results are discussed by relating the phenological, morphological and structural features of the giant reed stands and the adjacent vegetation with their optical traits. Weaknesses and strengths of the giant reed spectral discrimination are highlighted and implications of imagery selection for mapping purposes are argued based on present results.

According to the Water Framework Directive phytobenthos (diatoms) and macrophytes are part of the same biological element, the aquatic flora, which should be used in monitoring programs for rivers ecological assessment. However, they have been treated separately over time, and different indices are used to reach an Ecological Quality Status. Here we build a predictive model (the AQUAFLORA) based on communities composed of diatoms and macrophytes, with the aim of determining if these two elements of the aquatic flora could be combined in a single model to evaluate the streams ecological quality. For that we used biological and environmental information from 200 reference and 171 disturbed sites distributed through the entire Portuguese mainland territory. After clustering analysis, 5 biological reference groups significantly different (ANOSIM Global R = 0.685; p

The bioassessment and monitoring of the ecological status of rivers using macrophytes has gained new momentum since macrophytes were recognised as biological quality elements for the implementation of the European Water Framework Directive (WFD; EU/2000/60). Our objectives were to test the suitability of two predictive modelling approaches to macrophyte communities as a tool for water quality assessment, and to compare their performance with other more common approaches—the use of macrophytes as indicators of the trophic status of rivers and multimetric indices. We used floristic and environmental data that were collected in the spring of 2004 and 2005 from around 400 sites on rivers across mainland Portugal, western Iberia. We build two predictive models: MACPACS (MACrophyte Prediction And Classification System) and MAC (Macrophyte Assessment and Classification) based on RIVPACS and the BEAST methods, respectively. Whereas MACPACS is derived from taxa occurrence data, MAC uses a quantitative measure of taxa abundance. Both models showed good performance in predicting reference sites to the correct group and low rate of misclassification errors. However, they performed differently. MAC depicts a reliable response to the overall human-mediated degradation of fluvial systems, as does the multimetric index (RVI, Riparian Vegetation Index), but MACPACS presented only a poor correlation with the Global Human Disturbance Index and with the nutrients input. The incorporation of abundance data in vegetation predictive models appears to be particularly important to the detection of high levels of degradation. The values for correlations with physical–chemical pressure variables were lower than expected for MTR (Mean Trophic Rank) due to an insufficient number of scoring species found in Portuguese fluvial systems. Our results suggest that the most effective methods for bioassessment in Mediterranean-type rivers are either the RVI or the MAC predictive model.

Chronological studies (1951–1995) of the changing land use in three river basins belonging to the Tagus fluvial system (Portugal) were conducted using remote sensing data. The spatial characteristics of riparian woody vegetation and the temporal changes therein were quantified using landscape metrics such as average riparian canopy width, length of stand canopy closure types on river segments and patchiness indicators (e.g., the number of changes between types per survey unit). We also studied the predictive potential of geomorphology and climate features for explaining biological variability. We identify significant spatio-temporal land use changes on the adjacent floodplains, accompanied by remarkable differences in riparian integrity. Neither fragmentation patterns nor the loss or increase of riparian cover were consistent with similar land use changes throughout the rest of the studied basins, particularly in urbanizing landscape patches. The longitudinal patterns of streamside forests along Mediterranean-type rivers – particularly in Iberia – appear to be complex and dependent upon the previous life-history features of land use. Results also suggest that the proximity, type and extension of land use patch interplay influence the degree of changes in riparian integrity, which in overall terms displayed appreciable resistance to alterations and indirect disturbance. The results are broadly discussed with regard to spatial fine-grained scale changes in both land use and riparian integrity.

Aquatic and riparian plant species were examined in order to propose a multimetric plant index to assess the biotic integrity in Iberian rivers. An additional analysis with two other plant indices was performed to evaluate the present approach. A floristic survey was undertaken during May and early June 2000 in southern Iberian rivers. After the identification of two vegetation types, a partial canonical correspondence analysis of the floristic data with anthropogenic variables permited the recognition of the least perturbed sites, using the environmental characteristics as co-variables to account for natural site variability. From the 22 candidate-metrics, 8 were selected for inclusion on the final multimetric index: 3 representing composition measures (number of riparian and aquatic species, and number of annual species), 3 reflecting direct human-disturbances (abundance of Arundo donax, number of exotic, ruderal species), 1 trophic measure (number of nitrophyllous species) and 1 related with the riparian integrity (relative riparian width). Quality outputs were correlated with a global disturbance measure in order to evaluate the index performance and compared with the results of other plant indices. The Iberian multimetric plant index (IMPI) displayed a promising ability to relate riparian vegetation features to the current range of global disturbance. The IMPI will need to be further validated, with an enlarged set of metrics and a wider geographical area with clearly unimpaired reference sites in each vegetation type.