排序方式: 共有7条查询结果,搜索用时 0 毫秒
1
1.
Sam Provoost Carole Ampe Dries Bonte Eric Cosyns Maurice Hoffmann 《Journal of Coastal Conservation》2004,10(1):33-42
Grey dunes are a priority habitat type of the European Union Habitats Directive and demand special attention for conservation
and management. Knowledge of the ecology of coastal grey dunes can contribute to this policy. Dune grassland succession is
initiated by fixation and driven by the complex of soil formation (humus accumulation) and vegetation development. Leaching
and mobilization of CaCO3. which are important in nutrient dynamics, complicate the picture. At present, grass- and scrub encroachment greatly overrules
these fine scaled soil processes and causes substantial loss of regional biodiversity. Belgium has an international responsibility
in grey dune conservation because of the limited range of its characteristic vegetation, flora and fauna. As biomass removal
seems essential in grassland preservation, grazing is an important management tool. Evaluation of management measures focuses
on biodiversity measurements on the levels of landscape, community and species. 相似文献
2.
In order to comply with dioxin and furan (PCDD/F) emission regulations in Belgium, the IVRO municipal waste incinerator adopted catalytic filters for use in the plant's two existing fabric filters. This system replaced the injection of powdered activated carbon (PAC) because of concerns that PAC, used at temperatures above 200 degrees C, would ignite and lead to fires and plant down-time. The performance of the catalytic filter system, since its installation in 1997, is described. PCDD/F emissions are controlled to well below the regulatory limit of 0.1 ng I-TEQ/Nm3. The amount of PCDD/F entering and exiting the fabric filter is quantified. The resulting mass balance shows that greater than 99.5% of the gaseous PCDD/F entering the fabric filter is destroyed by the catalyst within the filter media. 相似文献
3.
The coexistence of four cryptic species of Rhabditis (Pellioditis) marina (Nematoda: Rhabditidae) at small geographical scale challenges ecological competition theory and was therefore studied in
the laboratory at two different salinities, where their performance in combined cultures was compared with that in monospecies
cultures. We found that three of the four cryptic species were able to coexist, but that interspecific interactions (competition
and facilitation) were common. Salinity had an effect on these interactions, with a shift from contest to scramble competition.
This shift may result from an increased population development of two of the four species at the lower salinity in the monospecific
cultures. This experiment demonstrates that abiotic conditions may play an important role in achieving coexistence between
cryptic species and can alter the interspecific interactions between them. 相似文献
4.
The impact of grazing on spider communities in a mesophytic calcareous dune grassland 总被引:1,自引:0,他引:1
During 1994–1995 and 1997–1998 spiders were sampled with pitfall traps in a botanically rich, mesophytic, calcareous dune
grassland in Belgium. As a consequence of intensive cattle grazing, vegetation variation in a large part of the area had diminished.
The study area was also patchily grazed by rabbits. Community analysis with TWINSPAN revealed five distinct spider communities.
Ecological differentiation was best explained by combination of the habitat variables: distance from grazed or non-grazed
vegetation,Rosa pimpinellifolia cover and grass cover in both summer and winter. Species diversity was highest in the border zone between the cattle-grazed
and non cattle-grazed sites.
Correlation of the most abundant spider species with the vegetation determinants explains the ecological differentiation between
the spider communities. Species were classified into seven major groups that reflect the species’ habitat preferences. The
group showing clear association with non cattle-grazed, tall vegetation consists of common species. Characteristic species
for the intensively cattle-grazed sites are common aeronauts and rare species such asWalckenaeria stylifrons, Mastigusa arietina, Ceratinopsis romana andPardosa monticola. The latter are shown to be dependent on ungrazed vegetation for juvenile development and overwintering. Intensive grazing
results in homogeneous short vegetation, which can only be colonized by ‘open ground’ species with a well-developed dispersal
capacity, or by species which are not dependent on litter-rich situations for juvenile development. An extensive cattle grazing
regime results in a patchy mosaic grassland where, in addition to the above mentioned groups of species, other species survive
by migrating between the buffered litter rich ungrazed vegetation and the short vegetation. Additionally, some typical and
rare species prefer the transition zone between the grazed and the ungrazed vegetation because they are associated with specific
habitat structures or inhabiting ant-species. 相似文献
5.
During 1994–1995 and 1997–1998 spiders were sampled with pitfall traps in a botanically rich, mesophytic, calcareous dune
grassland in Belgium. As a consequence of intensive cattle grazing, vegetation variation in a large part of the area had diminished.
The study area was also patchily grazed by rabbits. Community analysis with TWINSPAN revealed five distinct spider communities.
Ecological differentiation was best explained by combination of the habitat variables: distance from grazed or non-grazed
vegetation,Rosa pimpinellifolia cover and grass cover in both summer and winter. Species diversity was highest in the border zone between the cattle-grazed
and non cattle-grazed sites.
Correlation of the most abundant spider species with the vegetation determinants explains the ecological differentiation between
the spider communities. Species were classified into seven major groups that reflect the species’ habitat preferences. The
group showing clear association with non cattle-grazed, tall vegetation consists of common species. Characteristic species
for the intensively cattle-grazed sites are common aeronauts and rare species such asWalckenaeria stylifrons, Mastigusa arietina, Ceratinopsis romana andPardosa monticola. The latter are shown to be dependent on ungrazed vegetation for juvenile development and overwintering. Intensive grazing
results in homogeneous short vegetation, which can only be colonized by ‘open ground’ species with a well-developed dispersal
capacity, or by species which are not dependent on litter-rich situations for juvenile development. An extensive cattle grazing
regime results in a patchy mosaic grassland where, in addition to the above mentioned groups of species, other species survive
by migrating between the buffered litter rich ungrazed vegetation and the short vegetation. Additionally, some typical and
rare species prefer the transition zone between the grazed and the ungrazed vegetation because they are associated with specific
habitat structures or inhabiting ant-species.
Nomenclature: Roberts (1987, 1995) forAraneae; van der Meijden et al. (1990) for vascular plants; Corly et al. (1981) for bryophytes; Schaminée et al. (1996) for vegetation
associations. 相似文献
6.
7.
A. J. de Bonte A. Boosten H. G. J. M. van der Hagen K. V. Sýkora 《Journal of Coastal Conservation》1999,5(1):59-68
In 1990, grazing was introduced in a section of Meijendel, a coastal sand dune system near The Hague, The Netherlands. After
five years an evaluation was made of the effects of grazing on vegetation development. Three transects were established, two
in grazed areas and one in an ungrazed area. Field survey data were classified by means of TWIN-SPAN, ordinated with Detrended
Correspondence Analysis and the resulting vegetation types interpreted according to Westhoff & den Held (1969). All associations
were found in both the grazed and the ungrazed areas, but at the subassociation and variant level some communities appeared
to be restricted to the grazed area. These variants were five grassland variants characterized by disturbance indicators such
asSenecio sylvaticus andCynoglossum officinale.
The total number of plant species in the 19 permanent plots, which had been observed to have been decreasing since 1960, showed
a considerable increase after the introduction of horses and cows in 1990. A marked decrease in the cover ofCalamagrostis epigejos andCarex arenaria since 1990 was evident, while in some plots species such asRibes rubrum andViburnum opulus increased considerably.
A series of false-colour aerial photographs were used to compare vegetation structure in the three transects between 1990
and 1995. In the grazed area the tall grass vegetation had almost totally disappeared, whereas the areas of open sand. sand
with moss and lichens, and low grass vegetation had increased and the pattern had become more fine-grained. In the ungrazed
area the area covered by low grass vegetation had increased at the expense of the area of sand with moss and lichens and the
pattern had become more coarse-grained. 相似文献
1