Flood plain

This study performs a meta-analysis of existing studies of European riparian forests to investigate which exotic species have successfully established in intact riparian forests and which characteristics of these forests correspond with successful establishment. We used analysis of covariance models to investigate the relationship between community species richness, percent exotic species, and several environmental variables. We found a total richness of 1380 species, of which 45 (3.3%) were exotic. Species-rich communities generally had the higher percentage of exotics, but were not significantly related to latitude or environmental variables. Exotics, in contrast, were at generally higher levels at lower latitudes and were more abundant in large river plains and communities with intermediate levels of disturbance. These results suggest that future climate change and human actions that mimic intermediate levels of disturbance may further enhance the spread of exotic species.

Workshop transdisciplinaire "Regards croisés sur l’Anthropocène" - 17-18/11/2016 Université d'Angers
http://letg.cnrs.fr/article827.html

Les rivières  sont l’objet d’enjeux grandissants, qui gravitent autour de plusieurs thématiques : la qualité et la quantité d’eau, la production d’énergie, les continuités écologiques et la biodiversité, les activités récréatives, le cadre de vie… Ces enjeux ont évolué au fil des siècles et années, engendrant des modes de gestion et d’aménagements différents voire contradictoires qui questionnent les politiques publiques.
Les hydrosystèmes secondaires restent peu étudiés, quand bien même ils se positionnent comme « paysages ordinaires », couvrant de vastes espaces. L’objectif de cette étude est de caractériser les trajectoires d’aménagements en fonction de leur contexte pour contribuer aux réflexions de gestion de ces espaces.
Cette contribution s’attachera à présenter l’évolution de deux hydrosystèmes secondaires ligériens, en utilisant comme entrée le paysage des fonds de vallée. Elle présentera des exemples de changements morphologiques sur certains tronçons des rivières étudiées en mobilisant différentes ressources cartographiques. Plus largement, les dynamiques paysagères des fonds de vallées, telles que l’enfrichement et le boisement de certains secteurs, questionnent quant au devenir de ces espaces. Quels sont les facteurs qui interviennent dans ces phénomènes ? Ces derniers sont-ils localisés ? Comment agir sur la gestion de ces espaces ?
La thèse dans laquelle cette présentation s’inscrit aborde les dynamiques paysagères par le biais d’une analyse comparative. Deux bassins versants ont été sélectionnés, évoluant dans des contextes géographiques distincts. L’approche comparative permettra d’évoquer l’importance des différents facteurs impliqués dans ces modifications paysagères.  Ces contextes ont généré différents types d’aménagements et de gestion qu’il est intéressant d’interroger. Quels espaces ont subi les modifications paysagères les plus fortes ? A quelles périodes ont-elles eu lieu ? Quels sont les différents facteurs concernés par ces dynamiques ? Comment les mobiliser pour gérer ces espaces ?

In the past, the excavation of gravel placed Jar{ki prod among areas of great opportunity, but this was followed by a major ecological blow: the filling of gravel pits with waste. The area started to regain significance with the construction of a drinking water pumping station and in accordance with the Spatial Plan of the City Municipality of Ljubljana is today seen as a forested area with a pronounced ecological or recreational importance. In spite of suitable legal foundations, as a protected water catchment area Jar{ki prod is in practice still unprotected. Considering the most important natural (shallow groundwater, easily permeable layer of gravel) and social characteristics (location near a densely populated area, irresponsible attitudes), the groundwater is an extremely endangered natural resource.

Interspecific differences in diet of the two sympatric fish species of the subfamily Aphyocharacinae were investigated. Both were sampled monthly (March 2000 to February 2001) during the rainy and dry season in North region of the Pantanal. Aphyocharax anisitsi was an invertivorous/insectivorous species, feeding mainly on aquatic insects during the rainy season and terrestrial insects in the dry season. Aphyocharax dentatus remained

This research assesses the impact of rainfall variability on the flooding regime of the Zambezi floodplain as part of the scientific endeavour to understand the dynamics of hydrologic variability in natural systems such as riverine and floodplain ecosystems. In the context of global environmental change, hydro-climatic fluctuations are observed to be intensifying in magnitude and frequency with notable impacts on both human and natural systems. Understanding variability is important for the effective management of ecosystems which sustain human livelihoods. The study was conducted on a temporal scale of 50 years from 1965 to 2014 based on observed discharges and rainfall at the Chavuma National Gauge Station in the Zambezi district of Zambia. The research was guided by the hypothesis that there were no significant variations in the discharge on account of rainfall variability. Statistical methods of data analysis employed included exploratory, frequency and sensitivity analysis techniques. The results of the analysis revealed significant inter-annual variation of 21% in the discharge time series with a dominant periodicity of 10 years in its sinusoidal discharge signal. The sensitivity of the discharge to rainfall was found to be insignificant with a very low precipitation elasticity of streamflow of 0.03. In view of these findings, the conclusion of the study is that the flooding regime of the Zambezi floodplain is seemingly robust against the variability of rainfall. However, further research needs to be undertaken to provide deeper insight into the changes in the flooding regime of the Zambezi floodplain taking into account a broader spectrum of natural and anthropogenic forcing, and to quantify the flooding regime for integrated wetland management linking the dynamics of flooding to the biological diversity in the ecosystem.

Résumé/Abstract Après un rappel sur les conditions écologiques dans les zones inondables alpines au début du 19ème siècle, on décrit succinctement les aménagements sardes puis français qui constituent des enchaînements de perturbations dans les vallées de La ...

Studies of macrophyte productivity in the Amazon region are limited by accessibility and costs; hence, they may suffer from reduced sample size and representation. The present study compares a phenometric (indirect) method and a subsampling (direct) method in terms of accuracy and applicability to estimation of aquatic macrophyte biomass in the Amazon. The results show that phenometric models were not as effective as selective subsampling for the estimation of macrophyte biomass under the studied conditions. Phenometric models performed more acceptably for predicting emergent biomass, and less for submerged and total biomass (r2 = 0.77, p < 0.05, RMSE = 200–600 g/m2 dry mass). Improvements in r2 by using species-specific phenometric models were mostly not significant. Phenotypic variation across the studied region was large enough to preclude the generalization of phenometric relationships into accurate numeric models, while the direct subsampling method was able to account for t...

One of the main issues in community ecology is the detection of structure and the identification of its related causes. In this study, co-occurrence null models were used to identify possible spatio-temporal patterns in the assemblage of aquatic macrophytes in the Upper Paraná River floodplain. The samples were obtained through the Long Term Ecological Research (LTER) Program at two different grains:(1) a coarser spatial grain in January and August 2001 (entire floodplain lagoons);(2) and a finer spatial grain in ...

Hydrobiologia 435: 99–107, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands. ... Characteristics of cladoceran and copepod communities in floodplain habitats of the Atchafalaya River Basin ... Norman L. Davidson, Jr., William E. Kelso