Willow Carr Research Articles

Soligenous wetlands of North-western Poland as an environment for endangered mire species

Environmental conditions and the occurrence of protected and rare species have been studied in 18 groundwater-fed wetland complexes in north-western Poland. The plant cover of studied objects consisted of 81 syntaxa of water-, spring-, rush and sedge-, mire-, meadow-, tall-forb-, willow carr- and alderwood communities, as well as of 4 syntaxa of the mesophytic forests. Their microhabitat differentiation has been discussed. The expression of environmental conditions in the groundwater-fed communities has been analysed on the basis of Ellenberg's indicator values and the occurrence of protected and rare species. A signifficant negative correlation has been found between the occurrence of rare species and the trophy index. The special position of the mesotrophic rich fen communities, concerning their role in preservation of a large number of endangered species, as well as of rare plant communities is emphasized.

Beaver assisted river valley formation

AbstractWe examined how beaver dams affect key ecosystem processes, including pattern and process of sediment deposition, the composition and spatial pattern of vegetation, and nutrient loading and processing. We provide new evidence for the formation of heterogeneous beaver meadows on riverine system floodplains and terraces where dynamic flows are capable of breaching in‐channel beaver dams. Our data show a 1.7‐m high beaver dam triggered overbank flooding that drowned vegetation in areas deeply flooded, deposited nutrient‐rich sediment in a spatially heterogeneous pattern on the floodplain and terrace, and scoured soils in other areas. The site quickly de‐watered following the dam breach by high stream flows, protecting the deposited sediment from future re‐mobilization by overbank floods. Bare sediment either exposed by scouring or deposited by the beaver flood was quickly colonized by a spatially heterogeneous plant community, forming a beaver meadow. Many willow and some aspen seedlings established in the more heavily disturbed areas, suggesting the site may succeed to a willow carr plant community suitable for future beaver re‐occupation. We expand existing theory beyond the beaver pond to include terraces within valleys. This more fully explains how beavers can help drive the formation of alluvial valleys and their complex vegetation patterns as was first postulated by Ruedemann and Schoonmaker in 1938. Copyright © 2010 John Wiley & Sons, Ltd.

Two subassociations of the Salici cinereae-Sphagnetum recurvi (Zólyomi 1931) Soó 1954

The physiognomy and the species composition of the Salici cinereae-Sphagnetum recurvi (Zólyomi 1931) Soó 1954 are variable in Hungary. This association has been divided into two new subassociations by the authors, due to the slight differences in their moss layer. As a representation they compared 27 phytocoenological relevés, made by 4 different botanists in 10 different mires, by multivariate analysis. Those peat moss dominated willow carrs, in which the dominant moss species are Sphagnum squarrosum and/or Sphagnum fimbriatum subsp. fimbriatum, are called Salici cinereae-Sphagnetum recurvi sphagnetosum squarrosi subass. nov., on the contrary those, in which any species of the Sphagnum recurvum agg. (S. fallax, S. angustifolium, S. flexuosum) and/or Sphagnum palustre are dominant, are called Salici cinereae-Sphagnetum recurvi sphagnetosum recurvi subass. nov. The two submitted subassociations of peat moss dominated grey willow carr are very similar. They could be found together or independently, on a terrestrial or on a floating mire. All of them are a part of the successional series of mire development, which can result a continental raised bog under recent climate, too.

Floristic variation and willow carr development within a southwest England wetland

Abstract. Woodland colonization on wetlands is considered to have a detrimental effect on their ecological value, even though detailed analysis of this process is lacking. This paper provides an evaluation of the ecological changes resulting from succession of poor fen (base‐poor mire) to willow wet woodland on Goss Moor NNR in Cornwall, UK. Different ages of willow carr were associated with eight understorey communities. During willow colonization, in the ground flora, there was a progressive decrease in poor fen species and an associated increase in woodland species, which appeared to be related to an increase in canopy cover and therefore shade. The most diverse community was found to be the most recent willow and was dominated by poor fen species. The oldest willow was the second most diverse and was associated with a reduction in poor fen species and an increase in woodland species. Architectural features were used successfully to assess the general condition and structure of willow. Tree height and DBH were identified as useful parameters to accurately assess willow age in the field. The implications of active intervention to remove willow in order to conserve the full range of communities within the hydrosere are discussed.

Floristic variation and willow carr development within a southwest England wetland

Floristic variation and willow carr development within a southwest England wetland

Phenology and growth of Dermocybe uliginosa in a willow carr. II. Fruiting duration and performance

Total number of fruit bodies of Dermocybe uliginosa produced during the fruiting period, the rate of production and the length of the fruiting period were correlated with various micrometeorological factors. The number of fruit bodies produced per season (fruiting performance) depended mainly on the length of the fruiting period. This, in turn, depended on the fall of daily minimum air temperature immediately above soil surface (Tmin) below the critical level of 5·5 °C during the fruiting period. Short falls of Tmin ( < 3 d) increased while longer falls ( > 3 d) diminished or stopped the fruiting. The rate of production of new fruit bodies was most closely correlated with the daily mean and minimum air temperature, soil temperature and water-vapour pressure integrated for the immediately preceding 5 d. The rate of desiccation of the fruit bodies was most closely correlated with soil surface temperature and soil temperature at 0·05 m depth, again integrated for the immediately preceding 5 d. The possibility of using the total number of fruit bodies produced per fruiting period for estimating fruit body biomass production is discussed.

Phenology and growth of Dermocybe uliginosa in a willow carr. I. Phenology of fruiting

The onset of fruiting by Dermocybe uliginosa was studied in a willow carr surrounded by a sedge-grass marsh. The seasonal courses of various micrometeorological factors, monitored for 10 yr, were analysed as to their importance in relation to the initiation and intensity of fruiting. The regime of soil temperature at 0·05 m depth (Ts), daily minimum temperature above the soil surface (Tmin) and water-vapour pressure (e) were found to control the initiation of fruiting. Ts must attain, at least, 12·5 °C. A fall of Tmin betw I and about 5·5° for one or two days during this time was an additional stimulus to the initiation of fruiting. A decrease or increase of e for 10–20 d immediately afterwards determined whether fruit bodies were abundant or scarce.

Phenology and growth of Dermocybe uliginosa in a willow carr. III. Fruit-body growth and biomass production

Seasonal growth and production of individual fruit bodies were examined indirectly in permanent quadrats over 3 yr. Biomass was calculated from the ratio between average cap diameter and total fruit-body fresh or dry wt. The estimated total dry wt production in 1986 was 4·22 kg ha−1 season−1. Seasonal changes in standing live biomass, total production and total dead biomass were established using growth curves of individual fruit bodies. The relative growth and death rates were derived for total production and total dead biomass for 3 yr. The daily average biomass increments were correlated most significantly with soil, soil surface and air temperature and water-vapour pressure.

Time of passage, habitat use and mass change ofAcrocephaluswarblers in a South Wales reedswamp

Studies on the mass change of Reed Acrocephalus scirpaceus and Sedge Warblers A. schoenobaenus were undertaken in a coastal area of Phragmites swamp and Willow carr at Llangennech, south west Wales...

Influence of microclimate on growth of the mycorrhizal fungus dermocybe uliginosa

The occurrence of the mycorrhizal fungus Dermocybe uliginosa was studied in association with Salix cinerea and S. pentandra in a willow carr that was periodically flooded. In this habitat where the substrate was always moist, the initiation of fruitbody production seemed to be dependent upon a period of substrate temperature at 12.6°C or higher followed by a short episode at 5°C or less. After the appearance of fruitbodies their production seems to be directly related to relative humudity.

Patterns of temperature and humidity in wetland biotopes

Less predictable hydrological changes in the catchment area, superimposed on the general climatic seasonality, affect the distribution and stratification of temperature in central European wetlands. Long-term observations in sedge-grass marsh, willow carr and shallow water bodies in Czechoslovakia suggest an efficient role of life forms, geometry of vegetation and dead litter in the seasonal and diurnal course of temperature.

Evapotranspiration of a willow carr in summer

The daily course of evapotranspiration ( E) in a willow carr (stand of Salix cinerea L. and Salix pentandra L.) was calculated from meteorological data for 3 months (July–September 1983) by the Bowen-ratio method, and compared with evapotranspiration of the surrounding sedge-grass marsh ( Carex gracilis Curt., Calamagrostis canescens (Weber) Roth and Glyceria maxima (Hartm.) Holmberg evaluated in the previous years by the same method. A considerable difference was found only for July, which was extremely hot in 1983. The daily average E was 4.8, 3.2 and 2.4 mm day −1, in July, August and September, respectively. The enhancement or reduction of E under non-neutral air stability conditions were less than 10% of E under air stability conditions. Calculation of E for non-neutral air stratification is discussed in the paper.

Changes of several characteristics of native litter during its exposure in periodically flooded biotopes

The litter-bag method was used to expose the native litter in five stands of three wetland communities (four of them were in a sedge-and-grass marsh and one was a willow carr) with increasing soil water content (a hydrosere) for 15 months in 1978 and 1979. The litter-mass changes, rates of litter decomposition, ash, N, P, K, Na and Ca contents were determined and expressed in terms of concentration and % remaining of initial amount of the respective element. Two main factors were distinguished that controlled the above characteristics: the overlying biomass effect that was most obvious at the end of August 1978, and the strong flood effect of spring 1979. The data on the living and dead plant biomass from all marsh sites and some data on climatic and hydrological conditions are also included.

Bankhead Moss, Fife: The survival of a raised bog flora in the midst of intensive agriculture

Summary Bankhead Moss, a small raised bog in east Fife, was studied with special emphasis being put on vegetation, water content of the peat, pH and nutrient status; contrasts with the adjacent willow carr are brought out. Despite its small size the bog supports a typical raised bog flora; this is illustrated by a comparison with the type described by Ratcliffe (1964).

The Effects of Mowing on the Meadow Cranes-Bill Geranium pratense L., and on the Weevil Zacladus geranii (Payk.)

Many plants which formerly were characteristic of meadows and rough pastures are now largely confined to road verges. Way (1969) studied the effects of cutting and spraying practices on the plant communities of road verges to determine how floristic diversity is affected and how to maintain a rich flora while fulfilling the requirements of highway authorities. However, little is known about the response of the majority of individual plant species to roadside management and still less about the reactions of the fauna. The management of road verges has altered markedly during the past 20 years and is still in a state of change; adjustments in the flora and associated fauna are still, therefore, taking place. This study was designed to assess the short-term effects of a range of cutting treatments on the performance of a moderately common and attractive roadside plant and on an insect which depends on its ripening seeds. Meadow cranesbill is a widespread, if local, plant over most of Britain though absent as a native from the south-west, much of Wales, west Scotland and Norfolk. In Warwickshire it occurs most commonly on roadsides, railway banks and waste places (41%0 of records), by watersides (24%)0 in grassland (210%) -and in hedgerows (13%) (Cadbury, Hawkes & Readett 1971). Elsewhere it is most often reported from moist meadows, roadsides, waste places, by streams and in damp shady places such as willow carr. It occurs throughout Cambridgeshire, except on the sands, and is locally frequent on boulder clay in the south-west of the county (Evans 1939; Perring, Sell & Walters

Ecological and Morphological Observations on a Population of Cyclotella Pseudostelligera Hustedt

During the spring and summer of 1963, regular samples collected from Priest Pot, near Esthwaite North Fen, Lancashire (Grid Ref. 35/357978), revealed appreciable populations of a small centric diatom at first thought to be Cyclotella woltereckii Hustedt (1942) and later found to be identical with C. pseudostelligera Hustedt (1939), previously recorded from here by Lund (1960). Because the cells were seen to show considerable variation in valve pattern a more detailed study was undertaken. Priest Pot has an area of approximately 1-3 ha and a maximum depth of 5 m. Except for two small areas at the northern and southern ends the banks drop vertically to a depth of about 1 m, whence the bottom slopes smoothly down to the centre. A zone of intermittent alder and willow carr, approximately 4 m in height, surrounds the pool, beyond which to the south is Esthwaite North Fen, while in the other directions are open meadows. The water is readily circulated and mixed by the wind and can often be seen in motion. The only apparent inflows are two or three slow-flowing ditches, a few field drains and ground water. Into one of the ditches a neighbouring farm discharges effluent with a high nitrogen and phosphorus content.