The Effect of Natural and Artificial Shade on the Macrophytes of Lowland Streams and the Use of Shade as a Management Technique

Dawson, F.H.; Kern-Hansen, Ulrich

doi:10.1002/iroh.19790640402

Cited by 83 publications

(42 citation statements)

References 12 publications

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“…In others rivers, the reduction in natural shade has increased the productivity and coverage of aquatic plants (cf Dawson and Kern-Hansen, 1979). Consequently extensive and frequent weed cutting has been undertaken for many years in many rivers to maintain their key functions, which include flood water conveyance, riparian water level control and viable fisheries (e.g.…”

Section: Southern and Eastern England Hosts The Largest Chalk River Rmentioning

confidence: 99%

Instream and riparian implications of weed cutting in a chalk river

Old

Naden

Rameshwaran

et al. 2014

Ecological Engineering

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were monitored at a site on the River Lambourn (The CEH River Lambourn Observatory) and major instream and riparian impacts were observed. Measurements clearly demonstrated how weed cutting enhanced flood flow conveyance, reduced water levels (river and wetland), increased river velocities, and mobilised suspended sediment (with associated chemicals) and reduced the capacity for its retention within the river channel. Potential implications in relation to flood risk, water resources, downstream water quality, instream and riparian ecology, amenity value of the river, and wetland greenhouse gas emissions were considered. Provided the major influence of macrophytes on instream and riparian environments is fully understood then the manipulation of macrophytes represents an effective management tool that demonstrates the great potential of working with nature.

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Section: Southern and Eastern England Hosts The Largest Chalk River Rmentioning

confidence: 99%

Instream and riparian implications of weed cutting in a chalk river

Old

Naden

Rameshwaran

et al. 2014

Ecological Engineering

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“…These authors identified light as a primary factor limiting growth. Moreover, the reduction of light has been considered as a technique for the limitation of excess growth of aquatic macrophytes (DAWSON and KERN-HANSEN 1979, DAWSON 1978, DAWSON and HASLAM 1983, DAWSON 1981, BUNN et al 1998. A vinyl-coated fiberglass screen with a mesh size of 64 apertures cm -2 (Aquascreen Menadri-Southern Corp.commercial product) provided effective control of weeds when applied on the bottom (MAYER 1978, PERKINS et al 1980, NICHOLS and SHAW 1993.…”

Section: Introductionmentioning

confidence: 99%

Impact of riparian trees shade on aquatic plant abundance in conservation islands

Ali¹,

Hassan²,

Shaheen³

2011

Acta Botanica Croatica

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Temperature, acidity, light conditions, total dissolved salts, conductivity, dissolved oxygen, submerged macrophytes and shade and sun path directions were measured at 23 sites along the River Nile banks with Acacia nilotica growing at water's edge around the First Cataract Conservation Islands. Ceratophyllum demersum and Potamogeton crispus were common in the shaded and unshaded zones, Myriophyllum spicatum and Vallisneria spiralis were found only in the unshaded zone and Azolla filiculoides only in the shaded zone. Banks of the sites surveyed were oriented to five directions (NW, SE, NE, SW, N). There is a significant difference in both the type and density of submerged plants growing under the shade of riparian trees (Acacia nilotica) as compared to unshaded areas. Water column irradiance is the most influential variable dictating the distribution of submerged plants. The area of the shade provided by riparian trees was affected by environmental and/or plant variables. Environmental variables comprised the daily course of the exposition to sun; and plant variables included the area of the tree crown, the height of the tree and geographical position of the tree in relation to sun exposition. Trees on the west bank of the islands at the SW-NE direction have the highest shading effect. The management of tree vegetation might control incoming solar radiation affecting submerged macrophytes.

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“…Bien qu'ayant un rôle positif dans la lutte contre l'érosion et dans la fixation des sédiments meubles, la végétation aquatique peut engendrer simultanément par la présence de gros herbiers, un effet négatif sur l'écoulement en le ralentissant, et en réhaussant le niveau de l'eau (DAWSON et KERN-HANSEN, 1979). Un développement important d'hélophytes en bordure des cours d'eau peut aussi en réduire considérablement le lit.…”

Section: -Les éCoulementsunclassified

“…C'est pour cette raison que DAWSON et HASLAM (1983) préconisent, pour limiter les peuplements macrophytiques, l'ombrage par plantation d'arbres sur les berges des cours d'eau. DAWSON et KERN-HANSEN (1979) ont montré son efficacité sur la réduction de la croissance des végétaux. Ils suggèrent un ombrage partiel qui réduirait de manière significative la biomasse, et augmenterait la diversité floristique.…”

Section: L'éclairementunclassified

“…Les teneurs en azote et phosphore présentes dans les eaux superficielles et les eaux interstitielles des sédiments sont très rarement limitantes de la production des macrophytes. Selon DAWSON et KERN-HANSEN (1979), il faudrait diminuer jusqu'à des valeurs extrêmement faibles les quantités de nutriments présents dans l'eau et le sédiment pour contrôler la production de biomasse, et l'action sur le carbone inorganique dissous dans l'eau serait peu envisageable. BARROIN (1999) suggère en plan d'eau des teneurs limitantes de 50µg/l pour le phosphore et 360 µg.L -1 pour l'azote avec un rapport de N/P proche de 7.…”

Section: La Qualité Des Eauxunclassified

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Les Proliférations Végétales Aquatiques en France :Caractères Biologiques Et Écologiques Des Principalesespèces Et Milieux PROPICES.II. Impact Sur Les Écosystèmes Et Intérêt Pour Lecontrôle Des Proliférations.

Peltre¹,

Dutartre

Barbe³

et al. 2002

Bull. Fr. Pêche Piscic.

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RÉSUMÉDe nombreux milieux aquatiques de nature et d'usages divers sont plus ou moins régulièrement le siège de proliférations végétales. Le contrôle de celles-ci pose des difficultés, principalement liées à l'appréciation des déséquilibres induits dans le milieu et à celle des nuisances anthropiques qui en découlent. En effet, dans le cas d'un constat de prolifération, source et témoin d'un dysfonctionnement, le manque d'analyse objective des situations, les limites de compatibilité des différents usages du milieu, la mauvaise connaissance des végétaux en cause et du fonctionnement écologique des milieux sont autant de freins à une gestion cohérente de ces sites.La présentation de quelques exemples, à travers différents modes connus de gestion des milieux et de régulation des peuplements végétaux (notamment les méthodes mécaniques, chimiques ou biologiques), illustre la mise à profit des connaissances sur les caractéristiques biologiques et écologiques des macrophytes proliférants. Bull. Fr. Pêche Piscic. (2002) AQUATIC PLANT PROLIFERATIONS IN FRANCE: BIOLOGICAL AND ECOLOGICAL FEATURES OF THE MAIN SPECIES AND FAVOURABLE ENVIRONMENTS. II. IMPACT ON ECOSYSTEMS AND INTEREST FOR PLANTS MANAGEMENT. ABSTRACTWater-bodies of diverse nature and uses can be affected by prolific growths of plants. Their management leads to several problems which are related to assessment of created imbalances, as well as the impact of negative effects on practical uses of the water-bodies by man. In case of proliferation events, source and evidence of dysfunction, a lack of objective analysis of the phenomena, compatibility limits for different uses of this water-body, a bad knowledge of plants and of environmental functioning, are frequent limits to a coherent management of sites.Some examples of its possible improvement are developed here, through different ways of environmental management and control of these plants (as mechanical, chemical and biological methods). They illustrate the benefit of knowledge of biological and ecological features of prolific species, applied to this reflection.This knowledge should improve understanding of these events and evaluation of the perturbation created by proliferations. It should also provide more information for management and control practices, by allowing to intervene, if necessary, in better conditions and to envisage a restoration of the concerned ecosystems allowing a best satisfaction of the different uses.

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The Effect of Natural and Artificial Shade on the Macrophytes of Lowland Streams and the Use of Shade as a Management Technique

Cited by 83 publications

References 12 publications

Instream and riparian implications of weed cutting in a chalk river

Instream and riparian implications of weed cutting in a chalk river

Impact of riparian trees shade on aquatic plant abundance in conservation islands

Les Proliférations Végétales Aquatiques en France :Caractères Biologiques Et Écologiques Des Principalesespèces Et Milieux PROPICES.II. Impact Sur Les Écosystèmes Et Intérêt Pour Lecontrôle Des Proliférations.

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