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Alterations of steppe-like grasslands in Eastern Europe: a threat to regional biodiversity hotspots.

Domenii publicaţii > Biologie + Tipuri publicaţii > Articol în revistã ştiinţificã

Autori: Cremene, C; Groza, G; Rakosy, L; Schileyko, AA; Baur, A; Erhardt, A; Baur, B

Editorial: CONSERVATION BIOLOGY, 19 (5), p.1606-1618, 2005.

Rezumat:

Recent changes in agriculture (intensification or abandonment) have resulted in a critical reduction
of steppe-like grasslands in Eastern Europe. These grasslands harbor an extraordinarily high diversity of
plants and invertebrates, including endemics, and are considered refugia for numerous threatened open-land
species. We examined species richness, and abundance, proportion of open-land, endemic and threatened vascular
plants, gastropods, and diurnal and nocturnal Lepidoptera in six different vegetation types all originating
from steppe-like grasslands in Transylvania, Romania. Vegetation types included extensively grazed pastures
(initial stage), three seral stages of succession (early stage of abandoned grassland, abandoned grassland with
shrubs, and mature forest), and two human-made grassland alterations, namely abandoned vineyards and
Pinus plantations. A total of 852 species (291 vascular plants, 24 gastropods, 129 diurnal and 408 nocturnal Lepidoptera) were found in the 22 study sites. The four taxonomic groups differed in their response to the
abandonment of steppe-like grassland, except that species richness of plants and diurnal Lepidoptera were positively
correlated. The complementarity of species composition increased with successional age in all taxonomic
groups examined. The number of characteristic open-land species decreased with successional age in plants and gastropods. All investigated vegetation types harbored threatened (red-listed) species. Endemic species were found in all vegetation types except mature forests and Pinus plantations. All Transylvanian endemics and the majority of threatened species found were open-land species. Extensively cultivated vineyards, which have been abandoned for two to three decades, also maintained high plant and invertebrate diversities, comparable to
those of the corresponding stages of grassland succession. In contrast, Pinus plantations (a recent grassland
alteration) have changed habitat quality and will have a devastating effect on the unique, indigenous diversity of these steppe-like grasslands as soon as the canopy closes. To prevent losses of characteristic species, we suggest
a rotational grassland management program that maintains different seral stages. Succession to mature forest
and additional Pinus plantations should be prevented.

Cuvinte cheie: lepidoptere diurne, lepidoptere nocturne, specii endemice, extinctie, garstopode, modificari de habitat, specii din Lista Rosie, succesiune ecologica, plante vasculare // diurnal Lepidoptera, nocturnal Lepidoptera, endemic species, extinction, gastropods, habitat alteration, red-data species, succession, vascular plants