Riparian Ecology

The management and restoration of riparian zones has received considerable attention throughout the United States. Numerous studies have shown that riparian buffer strips of sufficient width protect and improve water quality by intercepting non-point source pollutants. Buffer strips also clearly provide a diversity of other functions, including movement corridors and habitat for a large variety of organisms. However, criteria for determining proper dimensions of buffer strips for most ecological functions are not well established. Although riparian zones are being restored along thousands of streambank miles throughout the country, the ecological benefits of variable buffer strip designs (e.g., width, length, vegetation type, placement within the watershed) have not been adequately recognized. There have been few systematic attempts to establish criteria that mesh water quality width requirements with other riparian functions. Subsequently, management prescriptions (e.g., width recommendations) are frequently based upon anecdotal information with little regard for the full range of effects these decisions may have on other riparian functions. Our objectives are to address the suitability of riparian zones to protect water quality while enhancing biodiversity, and to discuss recent strides in providing improved guidance for corridor and buffer designs based primarily on ecological criteria.

Riparian vegetation performs important
ecosystem functions, since it maintains regional
biodiversity and provides a range of environmental
services. However, anthropogenic activity, land use
type, and edge effects are factors that modify the
riparian species assemblage and properties. The
present study analyzes the influence of adjacent land
use on the structure and diversity of riparian vegetation
in four hydrographic regions that form the
watershed of the river Duero, in the state of Michoaca
´n, Mexico. Using a survey of woody plants of dbh
C 2.5 cm in ten different 0.1 ha sites, we found that
the average number of stems and individuals was
lower under agricultural (AGR) and urban (URB) land
use, compared to forested areas (FOR). The proportion
of multistemmed plants differs among land uses: this
value was greater in AGR than in the FOR and URB
categories. This proportion also differed among the
four hydrographic regions. The land use type FOR
presented the highest alpha and beta diversity, with a
high number of native species occurring only in areas defined by this land use. The results indicate that the
category FOR plays an important role in the conservation
of regional flora and is a possible source of
germplasm for restoration programs in sites degraded
by human disturbance. This study shows how anthropogenic
activities affect riparian vegetation and highlights
the importance of further study of this
ecosystem to apply sustainable management strategies
that are compatible with its conservation.

The Clarion River is a major tributary of the Allegheny River in northwestern Pennsylvania. Abundant water and close access to forest resources fueled the rise of a heavy industry base along the upper Clarion River in the late 1800s, which at its height in the early 1900s included eight tanneries, eleven wood chemical plants, and a large paper mill. The Clarion River was the sink for the effluents from these industries which were discharged directly into river with no or minimal treatment. Cumulative effluent loading from the Clarion River’s main industries was estimated to exceed 25 million gallons daily in the early 1900s. In this presentation I gauge the relative impacts of these different industries on the environment of the Clarion River and show how the ebb and flow of industries set the stage for the eventual recovery of the river.

The Segura River Basin is one of the most arid and regulated zones in the Mediterranean as well as Europe that includes four hydrologic river types, according to their natural flow regime: main stem rivers, stable streams, seasonal streams and temporary streams. The relationships between flow regime and fluvial and riparian habitats were studied at reference and hydrologically altered sites for each of the four types. Flow regime alteration was assessed using two procedures: (1) an indirect index, derived from variables associated with the main hydrologic pressures in the basin, and (2) reference and altered flow series analyses using the Indicators of Hydrologic Alteration (IHA) and the Indicators of Hydrologic Alteration in Rivers (IAHRIS). Habitats were characterized using the River Habitat Survey (RHS) and its derived Habitat Quality Assessment (HQA) score, whereas riparian condition was assessed using the Riparian Quality Index (RQI) and an inventory of riparian native/exotic species. Flow stability and magnitude were identified as the main hydrologic drivers of the stream habitats in the Segura Basin. Hydrologic alterations were similar to those described in other Mediterranean arid and semiarid areas where dams have reduced flow magnitude and variability and produced the inversion of seasonal patterns. Additionally, the Segura Basin presented two general trends: an increase in flow torrentiality in main stems and an increase in temporality in seasonal and temporary streams. With the indirect alteration index, main stems presented the highest degree of hydrologic alteration, which resulted in larger channel dimensions and less macrophytes and mesohabitats. However, according to the hydrologic analyses, the seasonal streams presented the greatest alteration, which was supported by the numerous changes in habitat features. These changes were associated with a larger proportion of uniform banktop vegetation as well as reduced riparian native plant richness and mesohabitat density. Both stream types presented consequent reductions in habitat and riparian quality as the degree of alteration increased. However, stable streams, those least impacted in the basin, and temporary streams, which are subject to great hydrologic stress in reference conditions, showed fewer changes in physical habitat due to hydrologic alteration. This study clarifies the relationships between hydrologic regime and physical habitat in Mediterranean basins. The hydrologic and habitat indicators that respond to human pressures and the thresholds that imply relevant changes in habitat and riparian quality presented here will play a fundamental role in the use of holistic frameworks when developing environmental flows on a regional scale.

Initially introduced to western United States to provide ecosystem services such as erosion control, Tamarix by the mid-1900s had became vilified as a profligate waster of water. This large shrub continues, today, to be indicted for various presumed environmental and economic costs, and millions of dollars are expended on its eradication. In this review, we examine the role of scientists in driving changes in perceptions of Tamarix from valuable import to vilified invader and (in some instances) back to a productive member of riparian plant communities. Scientists over the years have sustained a negative perception of Tamarix by, among other things, (1) citing outmoded sources; (2) inferring causation from correlative studies; (3) applying conclusions beyond the scope (domain) of the studies; and (4) emphasizing findings that present the species as an extreme or unnatural agent of change. Recent research is challenging the prevailing dogma regarding Tamarix’s role in ecosystem function and habitat degradation and many scientists now recommend management shifts from “pest plant” eradication to systemic, process-based restoration. However, prejudice against this and other non-native species persists. To further close the gap between science and management, it is important for scientists to strive to (1) cite sources appropriately; (2) avoid reflexive antiexotic bias; (3) avoid war-based and pestilence-based terminology; (4) heed the levels of certainty and the environmental domain of studies; (5) maintain up-to-date information on educational Web sites; and (6) prior to undertaking restoration or management actions, conduct a thorough and critical review of the literature.

"A catastrophic draught event was reported across much of the north of South America during August - December 2005. This resulted in extensive and irreversible damage in parts of the
Amazon river network. The 2005 Amazon draught followed very unusual changes in the Atlantic Ocean’s circulatory system that altered typical wind and rain patterns. Many climatic models predict the future desiccation of the Amazon region. This paper discusses dangers of sudden swings in the Amazon’s climate and how these risks can be reduced and securing the future of the river system.

The Amazon river systems’ inability to adapt to the new seasonal climate patterns in 2005, which led to a complete destruction of some river ecosystems, suggested us to look at water engineering solutions to prevent the risks of more tributaries of such dying. We made a case study to oxygenate the Amazon river to raise its draught-stress threshold during the likely future draughts that may be even worse than today if the Atlantic weather system generates more storms as the world’s temperature rises.

We studied a 100 kilometre wide section near the Amazon’s mouth. We assumed temperature +30C (when 100% oxygenated water contains 7,6 mg O2 / litre). The addition of 2,5 mg O2 / l represents 1/3 of the total, i.e. raising from 70% to 100%. This large water body oxygenation project requires 4 million kg O2 / day. 2,000 MIXOX units consume 80 MW / 100 km of river. 1,000 km demand is at 800 MW (1 power station), costing ~500 million euros p.a." http://www.vesieko.fi/yhteystiedot

Dispersal of biota by humans is a hallmark of civilization, but the results are often unforeseen and sometimes costly. Like kudzu vine in the American South, some examples become the stuff of regional folklore. In recent decades, “invasion biology,” conservation-motivated scientists and their allies have focused largely on the most negative outcomes and often promoted the perception that introduced species are monsters. However, cases of monstering by scientists preceded the rise of popular environmentalism. The story of tamarisk (Tamarix spp.), flowering trees and shrubs imported to New England sometime before 1818, provides an example of scientific “monstering” and shows how slaying the monster, rather than allaying its impacts, became a goal in itself. Tamarisks’ drought and salt tolerance suggested usefulness for both coastal and inland erosion control, and politicians as well as academic and agency scientists promoted planting them in the southern Great Plains and Southwest. But when erosion control efforts in Arizona, New Mexico and Texas became entangled with water shortages, economic development during the Depression and copper mining for national defense during World War Two, federal hydrologists moved quickly to recast tamarisks as water-wasting foreign monsters. Demonstrating significant water salvage was difficult and became subsidiary to focusing on ways to eradicate the plants, and a federal interagency effort devoted specifically to the latter purpose was organized and continued until it, in turn, conflicted with regional environmental concerns in the late 1960s.

Depuis la fin du XIXè siècle et l'arrivée des premières grandes vagues de colons dans le quart Nord-Ouest américain, une part importante de l'environnement aquatique et riparien du territoire autochtone des Indiens Nez Percé a été dégradée. La restauration écologique, entamée il y a plusieurs décennies, porte entre autres sur l'habitat du saumon, la qualité de l'eau et les zones humides. La Tribu des Nez Percé, le gouvernement fédéral, les États fédérés, des groupes de citoyens et des individus envisagent la gestion de l'environnement de manière contrastée. Si certains compromis ont débouché sur une restauration écologique, des conflits et certaines dégradations environnementales majeures persistent.

El castor es un animal salvaje que destaca por su historia asociada a la de ser humano, siendo considerado un animal totémico en muchas culturas por su presencia en leyendas, historias, mitos y cuentos infantiles. No obstante, estas creencias no impidieron que la codicia humana ocasionara una de las persecuciones más masivas de un animal salvaje en todo el planeta, lo cual estuvo a punto de acarrear su extinción total. En los últimos tiempos, asistimos a una recuperación parcial demográfica y de la distribución de la especie, gracias a la protección legal otorgada y al cumplimiento efectivo de la misma, pero en el reto de la conservación del castor y en la defensa de los intereses públicos, intervienen múltiples estamentos y actores (públicos y/o privados), con diferentes roles y responsabilidades. En un escenario de cambio global mundial, en el que los fenómenos climáticos se agudizarán, los responsables de la gestión y los profesionales de la información tienen un papel fundamental en la emisión de mensajes a la ciudadanía.
Una apuesta decidida por parte de los medios de comunicación debería integrar mensajes que demanden a nuestros gestores la restauración y el espacio a los ríos mediante la devolución de superficie inundable, y el respeto, o incluso el aumento, del Dominio Público Hidráulico.
Una sociedad comprometida con la conservación de la naturaleza, en términos generales, debiera buscar e implementar fórmulas realistas y eficaces para conjugar razonablemente tres objetivos plenamente complementarios: primero, el mantenimiento y restauración de la salud ambiental de nuestros ríos; segundo, el derecho a la información veraz; y por último, la ecuanimidad social, de tal manera, que sea la sociedad en su conjunto la que se haga cargo de esta tarea. Estamos convencidos de que esto no sólo es posible, sino que es una tarea a la altura de un país que presume de modernidad y respeto ambiental.
Por todo ello, hemos elaborado este modesto manual que pretende ofrecer información objetiva sobre el castor, informar con argumentos rigurosos contrastados para dar apoyo a los periodistas y a los comunicadores en general.

Se estudiaron los bosques ribereños del río Kakada en su desembocadura en el río Erebato, estado Bolívar, Venezuela, para conocer su composición florística y estructura. Se establecieron seis parcelas de 0,1 ha y se midieron e identificaron todos los individuos con DAP > 10 cm. Los resultados mostraron, para un área acumulativa de 0,6 ha, 36 familias y 61 especies. Las parcelas muestreadas se agruparon en tres tipos de bosque con altura media (16-24 m). La densidad promedio alcanzó a 738 individuos/ha. y área basal promedio de 29,4 m 2 /ha. De acuerdo a los valores del Índice de Valor Familiar (IVF) las familias más importantes son Fabaceae seguida de Caesalpiniaceae, Chrysobalanaceae, Euphorbiaceae, Sapotaceae, Melastomataceae, Myristicaceae, Clusiaceae, Arecaceae y Mimosaceae. Las especies con mayor importancia en bosques en cubetas o depresiones son Macrolobium acaciifolium y Licania pallida; en bosques en bancos y diques se tienen a Eperua jenmanii y Licania pallida y en bosques en terrazas y diques a Henriettea succosa y Cupania cinerea. Se realizó un inventario general donde se reconocieron 48 familias y 97 géneros entre helechos y árboles, arbustos, lianas, epifitas y hierbas de angiospermas representadas por 110 especies. Se presenta una lista de las especies registradas.

Como parte del trabajo enmarcado en un proyecto para el estudio de los sitios de forrajeo de la especie Piaractus brachypomus (Chordata), conocida como morocoto, se estudiaron los bosques ribereños del caño Kani, en la cuenca del Bajo Caura, Venezuela, para conocer su composición florística y estructura. Se analizaron dos parcelas de 0,1 ha en los sitios donde se alimenta el morocoto y se midieron e identificaron todos los individuos con DAP > 10 cm. Para un área acumulativa de 0,2 ha, los resultados arrojaron 22 familias y 29 especies, donde Fabaceae está compuesta por tres especies; le siguen Melastomataceae, Caesalpiniaceae, Mimosaceae y Chrysobalanaceae con dos cada una. Las parcelas muestreadas se ubicaron en un bosque con altura media (16-25 m). La densidad promedio alcanzó a 590 individuos/ha y área basal promedio de 33 m 2 /ha. De acuerdo con el Valor de Importancia Familiar (FIV) las familias más relevantes son Caesalpiniaceae, Myrtaceae, Melastomataceae, Mimosaceae, Lauraceae, Fabaceae, Lecythidaceae, Chrysobalanaceae, Flacourtiaceae y Moraceae. Las especies con mayor importancia son Macrolobium acaciifolium, Calyptranthes minutiflora, Eschweilera subglandulosa, Parkia pendula, Mouriri acutiflora, Macrolobium angustifolium y Homalium guianense. Se presenta una lista de las especies colectadas y observadas.

En este documento se presenta la propuesta de un nuevo método de evaluación
ecológica para ecosistemas riparios, el cual se origina a partir de una innovación
metodológica y se complementa con algunos elementos de métodos ya existentes.
Esta nueva herramienta se ha denominado; “Método de Evaluación Integral de
Ecosistemas Riparios” (Método EIER), y se fundamenta principalmente en
conceptualizar a los ecosistemas como unidades complejas e integradas, donde las
estrechas relaciones entre sus componentes bióticos y abióticos, mantienen el
funcionamiento saludable del sistema. Otros elementos importantes que
complementan el método son: la integración de dos enfoques de evaluación, aquel
que valora las condiciones ecológicas temporales de los elementos del ecosistema y
cuantifica el grado de alteración de los mismos (Medina, Baker, & Neary, 1996); y el
enfoque que considera el cambio constante en las condiciones ecológicas como
parte del funcionamiento dinámico de los ecosistemas naturales (Medina et al.,
1996). Asi mismo, el método integra el diseño y uso de procedimientos y elementos
de evaluación que consideran variables ambientales y propias del ecosistema ripario
que pueden influir en la evaluación, reduciendo así errores en el cálculo de la calidad
ecológica, entre otros elementos importantes.

I discuss results from AERA work at the Heit el-Ghurab (HeG) site and at the Khentkawes Town (KKT) and relate those results to discussion, observations, and conclusions about the floodplain and Nile flood levels at Dahshur, in the Memphis/Saqqara area, near Giza, and points northwest in the region of Ausim and Abu Roash, with an emphasis on the Old Kingdom.

La vegetación ribereña comprende la zona ecotonal en la transición entre un cuerpo de agua y el ambiente terrestre
contiguo, desempeñando un rol elemental en el funcionamiento de los ecosistemas acuáticos. La cobertura, estructura, y
composición de la vegetación influyen de manera fundamental en el control de la entrada de energía al ecosistema acuático.
Las múltiples funciones ambientales que cumplen los ecosistemas ribereños, y el flujo de servicios ecosistémicos que
directa o indirectamente influyen en el bienestar de la sociedad, hacen que el conocimiento de la calidad ecológica de estas
áreas sea considerado como un buen indicador ambiental, útil en la planificación y gestión del territorio, especialmente en
ecosistemas costeros. Mediante la aplicación del índice QBR se determinó la calidad de la vegetación ribereña en los ríos
Lingue y Chaihuín, ambas cuencas costeras del sur de Chile. Los resultados obtenidos indican que el río Chaihuín presenta
una vegetación de mejor calidad en sus riberas, en comparación con el río Lingue, donde los bajos valores de QBR son
producto de la sustitución de la vegetación ribereña natural para el establecimiento de terrenos agrícolas y plantaciones
forestales. La aplicación de este índice y la experiencia global de su utilización indican que resulta ser un instrumento
económico y de rápida aplicación, que entrega resultados confiables y útiles para la toma de decisiones en el diagnóstico
territorial, considerando las múltiples funciones y valores que hacen de los ecosistemas ribereños buenos indicadores
ambientales, diagnosticando los principales impactos y problemas para proponer medidas de restauración y/o mitigación.

Initially introduced to western United States to provide ecosystem services such as erosion control, Tamarix by the mid-1900s had became vilified as a profligate waster of water. This large shrub continues, today, to be indicted for various presumed environmental and economic costs, and millions of dollars are expended on its eradication. In this review, we examine the role of scientists in driving changes in perceptions of Tamarix from valuable import to vilified invader and (in some instances) back to a productive member of riparian plant communities. Scientists over the years have sustained a negative perception of Tamarix by, among other things, (1) citing outmoded sources; (2) inferring causation from correlative studies; (3) applying conclusions beyond the scope (domain) of the studies; and (4) emphasizing findings that present the species as an extreme or unnatural agent of change. Recent research is challenging the prevailing dogma regarding Tamarix's role in ecosystem function and habitat degradation and many scientists now recommend management shifts from “pest plant” eradication to systemic, process-based restoration. However, prejudice against this and other non-native species persists. To further close the gap between science and management, it is important for scientists to strive to (1) cite sources appropriately; (2) avoid reflexive antiexotic bias; (3) avoid war-based and pestilence-based terminology; (4) heed the levels of certainty and the environmental domain of studies; (5) maintain up-to-date information on educational Web sites; and (6) prior to undertaking restoration or management actions, conduct a thorough and critical review of the literature.

This paper describes comparative study of various controllers on Rotary Inverted Pendulum (RIP). PID, LQR, FUZZY LOGIC and H∞ controllers are tried on RIP in MatLab Simulink. The same four controllers have been tested on test bed of RIP system the controllers are compared from various aspects. The controllers in simulink are compared with the controllers in real time.

Die überarbeitete 2. Version der Planungshilfe Engineered Log Jams (der bisher einzigen Fachpublikation zu diesem Thema im deutschsprachigen Raum), dient als Standard- und Nachschlagewerk für ELJs und wurde umfassen überarbeitet und aktualisiert.
Das Handbuch widmet sich den aus den USA stammenden «Engineered Log Jams» (ELJ), welche den ingenieurbiologischen Nachbau von natürlichen Stammverklausungen («log jams») im Flussbau beschreibt. Untersuchungen an natürlichen log jams haben ergeben, dass die in sich verkeilten Strukturen erstaunlich dauerhaft sind, sich in natürlicher Umgebung mit einem entsprechenden Nachschub an Totholz durch den Prozess der Akkumulation und die Sukzession von Gehölzen laufend selbst erneuern können und sich deutlich positiv auf die Fischfauna auswirken.
Das Vorkommen grosser Mengen Totholz wie auch das Entstehen langlebiger log jams dürfte für alle Fliessgewässergrössen und -typen unterhalb der Baumgrenze natürlich und standorttypisch sein. In Bächen können diese bereits durch kleinere, simplere Totholzbautypen initialisiert werden. Der Fokus dieses Handbuchs liegt aber auf den grossen Stammverklausungen, die typischerweise in grösseren Gerinnen entstehen (Sohlenbreiten > 10 m).
Einerseits soll mit dem vorliegenden Werk ein Verständnis für den enormen ökologischen und morphodynamischen Wert von grösseren log jams in Fliessgewässern geschaffen werden. Dankenswerterweise kann hierzu auf den bereits vorhandenen Reichtum an wissenschaftlichen Arbeiten aus dem englischsprachigen Raum zurückgegriffen werden. Andererseits sollen konkrete Beispiele, Planskizzen und detaillierte Angaben zu Projektierung und Bau anregen, ELJs in weiteren Flussbauprojekten einzusetzen, wobei die Chancen und Grenzen dieser neuen Bauweisen transparent dargelegt werden.
Der unverzichtbare, technisch geprägte Teil der Planungshilfe richtet sich in erster Linie an Wasserbausachverständige (Bauherren, Ämter und Fachstellen sowie Ingenieure und Planer). Mit den bildhaften Ausführungen und detaillierten Schemaskizzen möchten wir aber explizit auch weitere Fachleute aus dem Naturschutz-, Umwelt- und Forstbereich sowie Fischerinnen und Fischer und interessierte Laien für das Thema begeistern.
Die für Nordamerikanische Verhältnisse erarbeiteten Grundlagen, Publikationen und Arbeitshilfen fliessen in die vorliegende Planungshilfe ein, sie ist jedoch auf Mitteleuropäische Verhältnisse ausgelegt.
Seit der Erstausgabe 2019 hat das Thema spürbar an Fahrt aufgenommen, so wurden weitere ELJs in Schweizer Gewässern realisiert und auch kosten- und materialoptimierte Bautypen erarbeitet. Die vorliegende zweite Version der Planungshilfe ELJ wurde daher umfassend überarbeitet und aktualisiert. Den Autoren ist bewusst, dass der Erfahrungszeitraum mit ELJ hierzulande relativ kurz ist und es in einigen Jahren eine neue Überarbeitung der vorliegenden Publikation bedarf.

Die Neuerungen der aktuellen Ausgabe auf einen Blick:
– Konstruktionspläne und Begleitdokumente zu den neuen, kosten- und materialoptimierten Bautypen, die im Rahmen eines vom Tiefbauamt des Kantons Bern geleiteten Workshops erarbeitet wurden:
– «ELJ-BMU-Buhne»
– «ELJ-BMU-Deflektor»
– Bautypen und Fallbeispiele der jüngst in Schweizer Gewässern realisierte ELJs:
– «ELJ-Buhne» in der Aare (Abschnitt Schützenfahr)
– «Inselkopf-ELJ» in der Sense (Abschnitt Ruchmühle)
– «Inselkopf-ELJ» in der Emme (Abschnitt Bätterkinden/Utzenstorf)
– Einbezug neuer Fachliteratur, u.a. Bedeutung für Auen-, Hochwasser- und Klimaschutz
– Neue Verbindungstypen aus Holz anstelle von Stahlverbindungen
– Forstwirtschaftliche Vorgaben zur Materialgewinnung
– Neue Grundlagen zur Gehölzbepflanzung
– Neue Abbildungen/Illustrationen

The current study was carried out on the riparian vegetation of Lund Khuwar, Kaloshah, District Mardan. During research 77 plant species belonging to 61 genera and 36 families were observed and described ecologically. Asteraceae having 8 genera (13.11%) and 10 species (12.98%), followed by Poaceae which was represented by 8 genera (13.11%) and 8 species (10.8%). Lamiaceae having 4 genera (6.55%) and 4 species (5.19%) and Moraceae had 3 genera (3.91%) and 4 species (5.19%). The leading genera were Acacia and Chenopodium with 3 (4.91%) species each. Genera like Amaranthus, Euphorbia, Juncus, Marsilea, Morus, Populus, Polygonum, Tegetes, Zinnia and Zizipus were consisting of two 2 (3.27%) species each. There were 2 (5.55%) families of Pterediophytes which were consisting of 4 (5.19%) species and 3 (4.91%) of the total genera. There were 4 (11.1%) families of Monocotyledoneae with 12 (15.85%) species and 30 (83.83%) families of Dicotyledoneae. The dicot families comprised of 61 (79.22%) species of the total number of species. Life form, leaf size, phenology and abundance classes were also determined during present study. The plants were identified with the help of available literature (Flora of Pak). The plants were submitted to the Herbarium of Centre of Plant Biodiversity, University of Peshawar, Pakistan.

Aquatic plants fulfil a wide range of ecological roles, and make a substantial contribution to the structure, function and service provision of aquatic ecosystems. Given their well-documented importance in aquatic ecosystems, research into aquatic plants continues to blossom. The 14th International Symposium on Aquatic Plants, held in Edinburgh in September 2015, brought together 120 delegates from 28 countries and six continents. This special issue of Hydrobiologia includes a select number of papers on aspects of aquatic plants, covering a wide range of species, systems and issues. In this paper, we present an overview of current trends and future directions in aquatic plant research in the early twenty first century. Our understanding of aquatic plant biology, the range of scientific issues being addressed and the range of techniques available to researchers have all arguably never been greater; however, substantial challenges exist to the conservation and management of both aquatic plants and the ecosystems in which they are found. The range of countries and continents represented by conference delegates and authors of papers in the special issue illustrates the global relevance of aquatic plant research in the early twenty first century but also the many challenges that this burgeoning scientific discipline must address.

Significant ecological, hydrologic, and geomorphic changes have occurred during the 20th century along many large floodplain rivers in the American Southwest. Native Populus forests have declined, while the exotic Eurasian shrub, Tamarix, has proliferated and now dominates most floodplain ecosystems. Photographs from late 19th and early 20th centuries illustrate wide river channels with largely bare in-channel landforms and shrubby higher channel margin floodplains. However, by the mid-20th century, floodplains supporting dense Tamarix stands had expanded, and river channels had narrowed. Along the lower Green River in eastern Utah, the causal mechanism of channel and floodplain changes remains ambiguous due to the confounding effects of climatically driven reductions in flood magnitude, river regulation by Flaming Gorge Dam, and Tamarix invasion. This study addressed whether Tamarix establishment and spread followed climate- or dam-induced reductions in annual peak flows or whether Tamarix was potentially a driver of floodplain changes. We aged 235 Tamarix and 57 Populus individuals, determined the hydrologic and geomorphic processes that controlled recruitment, identified the spatial relationships of germination sites within floodplain stratigraphic transects, and mapped woody riparian vegetation cohorts along three segments of the lower Green River.
The oldest Tamarix established along several sampling reaches in 1938, and 1.50–2.25 m of alluvium has accreted above their germination surfaces. Nearly 90% of the Tamarix and Populus samples established during flood years that exceeded the 2.5-year recurrence interval. Recruitment was most common when large floods were followed by years with smaller peak flows. The majority of Tamarix establishment and Green River channel narrowing occurred long before river regulation by Flaming Gorge Dam. Tamarix initially colonized bare instream sand deposits (e.g., islands and bars), and most channel and floodplain changes followed the establishment of Tamarix. Our results suggest that Tamarix recruitment was triggered by large annual floods that were followed by years with lower peak flows, not by periods of low flow alone. Tamarix appears to have actively invaded floodplains, while Populus colonization has been limited. Thus, Tamarix invasion may have greatly influenced floodplain development and riparian vegetation composition along the lower Green River since the early 20th century.

Spatial subsidies of energy and nutrients can influence the distribution of consumers in riparian habitats. This study compared the abundance and composition of bird assemblages and the availability of volant insect prey within the riparian zone (≤ 30 m from the stream) and further inland (100-250 m away) within a secondary forest in monsoonal Hong Kong. Replicated point-counts of birds and insect light trapping were conducted in each zone during the wet and dry season of 2006-2007. The biomass of adult aquatic insects in the riparian zone was nine to 12 times higher than inland during both seasons, however, total insect biomass (aquatic plus terrestrial insects) in the riparian zone was only 49 percent (wet season) and 18 percent (dry season) greater. More birds (both numbers of individuals and species) were recorded in the riparian zone, and this difference was particularly conspicuous during the wet season. Most of the wet-season difference was due to the greater number of insectivorous birds in the riparian zone (123% greater than inland), and may have reflected the relative availability of adult aquatic insects. These findings confirm the importance of riparian zones as feeding habitats for forest birds, and have implications for conservation planning and setting the boundaries of protected areas.

The empress tree, Paulownia tomentosa (Thunb.) Steud., is native to eastern Asia
and naturalized in portions of the eastern United States. In a central Virginia streamside forest, P. tomentosa trees ranged from 6 to 30 years in age (mean age = 17.1 years). The age distribution of P. tomentosa was unimodal with a strong peak in the 18 and 20 year age classes, demonstrating a major recruitment pulse in the early 1970s correlated with the passage of Hurricane Camille (August 1969). Paulownia tomentosa had the lowest importance value (=15.1) among the four dominant forest trees of the study area (Liriodendron tulipifera = 30.1, Betula lenta = 28.5, Platanus occidentalis = 16.0). Diameter distributions for all major tree species, except P. tomentosa, followed a concave pattern, which is representative of increasing or self-maintaining populations. The diameter and age distributions for P. tomentosa were convex, which indicates episodic establishment. Unlike many exotic woody plants naturalized in forests of the eastern United States, P. tomentosa is noninvasive and functions much as it does in the mesophytic forests of eastern Asia, producing small, scattered populations that arise chiefly as a result of large-scale
disturbance.

El libro aborda el tema de los sistemas ribereños y se centra en el estudio de los existentes en el Parque Nacional Popo-Izta (México).
This book addresses the issue of riparian systems and focuses on the study of those existing in the Popo-Izta National Park (Mexico).

Riparian areas are significant ecosystems due to the numerous and substantial services they provide. These ecosystem services can range from wildlife habitat, water quality improvement, flood mitigation and recreational opportunities. Human developments, including cities and towns are frequently established in the riparian areas and degrade their functionality. Maintaining healthy riparian areas in urban settings that sustain their connectivity with the natural riparian areas should be of a great priority. Fragmented riparian areas lose many of the aforementioned ecosystem services. At the same time healthy riparian areas are aesthetically pleasing, creating a feeling of escape for the inhabitants, while also increasing the real estate value of the adjacent structures. In this study examples of healthy and degraded urban riparian areas from two Greek cities are presented. Overall, the proper restoration and sustainable management of these areas can improve the quality of life in urban settings and maintain the services they provide.

Few studies addressed the distribution of riparian trees and shrubs, and the factors affecting their distribution and structure in Lebanon. The objective of this investigation is to identify the riparian tree and shrub species around Nahr Ibrahim River. We selected 21 sites covering all altitudinal range from sea level up to 1766 m as well as a cross section gradient from river bed. Results showed that biodiversity indices are affected by bioclimatic conditions (vegetation stages) and river flow regime. A moderate dry period of less than 3 months seems to have a positive effect on species richness and composition (trees vs shrubs). A regulated flow would increase the number of tree individuals and reduce biodiversity. Salix acmophylla Boiss., Salix alba L. and Platanus orientalis L. are obligate riparian (phreatophytes) and Salix libani Bornm., Ostrya carpinifolia Scop., Juglans regia L., Crataegus monogyna Jacq. are classified as facultative riparian (facultative phreatophytes). Further we were able to classify riparian species according to gradients related to altitude, slope, distance from river bed and number of dry months.

The structure and composition of the lower Orinoco River flooded forests upstream the Orinoco´s superior delta up to the village of El Almacén, Venezuela, was inventoried and described. In thirty 0,1 ha plots, distributed in both the right and left bank of the Orinoco River, following a corridor's classification in five functional riparian landscapes, all individuals with DBH > 10 cm were measured and identified, resulting, for a 3 ha cumulative area, in 32 families, 51 genera and 60 species, where Leguminosae is composed of 5 species of Papilionoidea, 5 of Caesalpinoidea and 5 of Mimosoidea; followed by Rubiaceae with 4 species and Euphorbiaceae, Polygonaceae, Moraceae and Meliaceae with 3 species each one. The sampled plots were grouped into three type of forests, with medium to low height (20-15 m). The mean density was 356 individuals/ha and the basal area 38,9 m 2 /ha. The IVI´s most important species in seasonally flooded forests in backswamps or depressions are Piranhea trifoliata and Tachigali davidsei; in seasonally flooded forests in banks and levees they are Nectandra pichurim, Cordia tetrandra and Cecropia latiloba and in infrequently flooded forests in terraces and levees Pseudanamomis umbellulifera and Machaerium dubium. Abstract Kuawäi Revista Arbitrada del Departamento Hombre y Ambiente Volumen 1• Nº 1 • Enero-Junio, 2008 • Depósito Legal: Pp200802BO2806 • ISSN: 18568726 • Pg: 13-39 Kuawäi Revista Arbitrada del Departamento Hombre y Ambiente Volumen 1• Nº 1 • Enero-Junio, 2008 • Depósito Legal: Pp200802BO2806 • ISSN: 18568726 • Pg: 13-39

Riparian vegetation performs important ecosystem functions, since it maintains regional biodiversity and provides a range of environmental services. However, anthropogenic activity, land use type, and edge effects are factors that modify the riparian species assemblage and properties. The present study analyzes the influence of adjacent land use on the structure and diversity of riparian vegetation in four hydrographic regions that form the watershed of the river Duero, in the state of Michoacán, Mexico. Using a survey of woody plants of dbh C 2.5 cm in ten different 0.1 ha sites, we found that the average number of stems and individuals was lower under agricultural (AGR) and urban (URB) land use, compared to forested areas (FOR). The proportion of multistemmed plants differs among land uses: this value was greater in AGR than in the FOR and URB categories. This proportion also differed among the four hydrographic regions. The land use type FOR presented the highest alpha and beta diversity, with a high number of native species occurring only in areas defined by this land use. The results indicate that the category FOR plays an important role in the conservation of regional flora and is a possible source of germplasm for restoration programs in sites degraded by human disturbance. This study shows how anthropogenic activities affect riparian vegetation and highlights the importance of further study of this ecosystem to apply sustainable management strategies that are compatible with its conservation. Keywords Agriculture Á Land use change Á Management Á Riparian trees Á Urbanization Communicated by Glenn Stewar.

Park managers are increasingly faced with responding to the recent rise of those experiencing unsheltered homelessness residing in urban green spaces. In response, researchers have explored and attempted to mitigate a variety of negative social and ecological impacts associated with unsheltered homelessness in urban parks. However, these impacts are often mitigated through the enforcement of policies criminalizing homeless park use or through environmentally harmful changes to landscapes. To help generate more equitable and beneficial solutions to unsheltered homelessness in urban green spaces, this study based in the United States interrogated a variety of stakeholders' perspectives, including park managers, local community members, and relevant social service organizations. Overall, data expressed how unsheltered homelessness and related cyclical mitigations negatively affected the social and environmental benefits of urban park systems, as well as illuminating the need for a more informed citizenry about the challenges facing individuals experiencing homelessness through public education. Implications for urban park managers and stakeholders are discussed.

The Allegheny River Islands Wilderness (ARIW) consists of seven islands located along 90 km of the Allegheny National Wild and Scenic River in northwestern Pennsylvania. I surveyed riparian plant communities in the ARIW to provide an inventory of the species composition and distribution of the alien flora and to identify species of potential management concern. Forty-one alien plant species were tallied from 42 survey sites across the seven islands of the ARIW. The largely herbaceous floodplain scour community supported the greatest number of alien plant species (36 species; 18.9% of the community flora), followed by the Acer saccharinum L. – Platanus occidentalis L. floodplain forest community (23 species; 16.8% of the community flora) and the P. occidentalis  - Carya cordiformis (Wang.) K. Koch – Ulmus rubra Muhl. floodplain forest community (14 species; 12.4% of the community flora). Ten alien plant species (24.4% of the alien flora) occurred across all three community types. The alien flora of the ARIW included a range of species with varied ecological impact potential, distribution across plant communities, and difficulty of control. Potential control strategies for alien plant species in the ARIW must address the influence of an altered hydrologic regimen as well as control protocols for specific species on the islands and surrounding river corridor.