Phragmites

Phragmites australis on the coast of Dänholms

The reed (Phragmites australis; Syn. Phragmites communis Trin ) is a cosmopolitan species of grasses ( Poaceae ) and is also commonly referred to as reeds. There are three subspecies, all of which occur in Europe.

Features

The reed is a rhizome - Geophyt and a marsh plant. The normal form, Phragmites australis, is more than four meters high. In the main growth period of the reed, the rhizomes at the top extend daily by up to three inches. The oldest rhizome die off ( Wurzelkriech and siltation pioneer ), respectively. The leaves of the reeds have taken the ligule ( ligule ) a hair wreath. The flattening of the first, as the leaf sheath -tube Spreite carried out by a joint. The reed is a bluegrass. The flower spike can grow up to 50 centimeters long. The plant is wind-pollinated from " langstaubfädigen type". The Blütenährchen have at the bottom male, about hermaphrodite flowers. The flowering period extends from July to September.

The Ährchenachse the fruit has long, projecting hairs. The tiny Fruchtährchen spread as Schirmchenflieger. Also a floating spread and a water detention propagation is possible. The fruits are ripe earlier in December. The fruit set varies from year to year; it is also dependent upon the site. The fruits are light to germinate, the germination rate is about 80 percent. The germination capacity is retained 1-4 years.

The wettability of the sheet surface is small. Water trickles into droplets on how it can be also observed in lotus flowers, and does, on the surface of particles of dirt with (lotus effect).

The vegetative propagation is strongly influenced by the up to 20-meter runners and by low- lying, at the node bewurzelnde culms ( stalks laying ). Whole " reed beds " often represent only a single plant dar. In the Danube Delta was found plants whose age was estimated to be about 8000 years. Large reed beds offer numerous birds protection. In excess of nutrients, however, the reed displaces the remaining riparian vegetation. When too strong nutrient inputs, the population breaks but also back together and will be replaced for example by Eutrophierungszeigern as the Great swaths water ( Glyceria maxima). If you want to actively contribute to the growth of reeds, one must in the summer Halmstücke with 1-3 knots off and bury it deep in a few centimeters gutters near the shore. After a few weeks, the stems rooting nodes, and form daughter rung out.

Reed is natural monoculture stocks in lakes and ditches. Are water supply and nutrient supply cheap, it displaces its dominance by other wild herbs and grasses. In the often huge areas covering " natural monocultures " of the reed regulate animal pests themselves: The caterpillars of the Schilfeule ( Nonagria Typhae ) climbing eating in the internodes up and destroy the growing point at the top. Because of the resulting thinning of the stock numerous thin stalks are formed in the following years, so that the reed owl population perishes at these locations.

Subspecies

• Phragmites australis ssp. australis (up to four meters high)
• Phragmites australis ssp. altissimus (up to 10 meters high)
• Phragmites australis ssp. humilis (up to 1.2 meters high)

Locations

The reed frequently and consistently occurs in the reed zone of standing and slowly flowing waters up to one meter of water, besides also in source moors, on moorland meadows or in alder and willow woods Nauen. It loves not too cold silt and mud floors, which should be nitrogen- and base- rich and may be relatively low in oxygen. Torrential floods can not stand. According to the ecologists Heinz Ellenberg is the way a heat pointer, a pointer and a change of water Klassencharakterart the reed beds and sedge marshes ( Phragmitetea australis). On non- flooded sites, it displays moving groundwater. As a deep-rooting, it is difficult to expel from waterlogged fields. However, injured Schilfrhizome die off during long periods of flooding when water penetrates into the aerenchyma. Similarly, a high levels of ground water prevents a low growth of the rhizomes.

The type plays a major role in the siltation of water bodies. Between the dense stalks accumulates over time a lot of mud and slowly leads to silting.

Economic use

The young shoots are used in some areas as a vegetable, the typical reed taste this Süßgrasart is however getting used to, and flour for baking bread can be made from the dried roots.

In addition to these Terms of reeds mainly plays a role as a natural building material. Reed used in the form of thatch as a roofing material and in the form of multilayer reed plates (20 and 50 mm, bound with galvanized wire) or single reed as a plaster base ( Rabitzgeflecht ) as a structural material in earth building. The reed does not absorb moisture and rot therefore only slowly, it is stable and due to its non-slip surface structure an excellent plaster base. Due to its content of silica reed is also fire resistant. Other components are insulation products for exterior and interior insulation, reed tissue or partitions for organic drywall.

Thin mats made ​​of reeds are used for shading greenhouses, thicker as thermal insulation and wind protection. The species is also used for the decorative design of riverside areas as an ornamental plant and for land reclamation (eg in the IJsselmeer ).

Theory is also an energetic use of reed bsp. possible for the production of biogas or as lignocellulosereicher raw material for the production of cellulosic ethanol.

Reeds in wastewater treatment

Wetlands

Reed is very suitable for planting in a wetland. It acts by large leaf surface and through the release of oxygen hollow, air-conducting parts of the stalk ( aerenchyma ) under water purifying waters (oxygen entry: 5 -12 grams of oxygen per square meter / day). The oxygen transfer promotes the microbial degradation of organic matter by aerophilic bacteria which settle in a large amount to the root hairs of the reeds.

Soil filter

Also, retention soil filters are often planted with reeds to achieve improved performance. The reed beds to loosen its permanent rhizome growth, the substrate, thus reducing the Kolmationsrisiko. An intensive rooting increases the cleaning capacity of the filter, since oxygen transfer and root exudates cause a stimulation of microbial degradation of contaminants in the rhizosphere, are the same nutrients ( and sometimes harmful ) of the soil solution withdrawn.

An established reed area perspires 800 - 1000 liters of water per m² and growing season, resulting in the leachate generation reduced accordingly in the soil filter. This favors the sorption and - due to the longer contact time - even root uptake and biodegradation.

The closed vegetation cover improved by shading and insulation the near-ground microclimate. Under dead reeds find bacteria in winter to temperatures by 5 ° C before. Reeds as well as continuous supply wide-meshed scattered vegetation residues form on soil filters an above-ground " spatial filter ". His Sedimentationsoberflächen complement the actual substrate filtration and protect the filter additionally from external clogging.

A major disadvantage of the use of reeds in soil filters is that soil filters do not belong to the ideal settlement areas of reed canary grass due to the periodic supply and short residence times of the water. High losses during growth on the intermittently dry soil filters are the result. This ensures optimal cleaning and filtering effect in relation to the waste water supplied by the weakened reed vegetation is not guaranteed. In addition, Reed is sensitive to mechanical stress, especially against buckling stress ( laying down of inventory in the main flow region ).

Reed 8a Federal Nature Conservation Act of nature conservation bodies assessed positively the engagement compensation pursuant to §. In contrast to conventional solutions schilfbepflanzte filters were even allowed in nature and landscape protection areas. In addition, can help avoid additional compensatory measures for new development areas, which is increasingly important in economic considerations schilfbepflanzte soil filters in combination with green spaces and green patches.