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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