Structure and species diversity of Bromus erectus grasslands of biancana badlands

Citation
S. Maccherini et al., Structure and species diversity of Bromus erectus grasslands of biancana badlands, BELG J BOT, 133(1-2), 2000, pp. 3-14
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Plant Sciences
Journal title
BELGIAN JOURNAL OF BOTANY
ISSN journal
0778-4031 → ACNP
Volume
133
Issue
1-2
Year of publication
2000
Pages
3 - 14
Database
ISI
SICI code
0778-4031(2000)133:1-2<3:SASDOB>2.0.ZU;2-J
Abstract
Species richness, diversity and structure were studied in Bromus erectus gr asslands on the top of biancana landforms of the Orcia Valley, Tuscany (cen tral Italy). Three community types were recognized : uneven B. erectus gras slands on less stable morphologies, and compact B. erectus grasslands and B . erectus grasslands colonized by Spartium junceum scrub, both on more stab le morphologies. The main difference between them was a dramatic decline in species richness and diversity from the former to the latter. The number a nd cover of annual herbs, many of which are low-growing species (e.g. legum es and graminoids), also decreased significantly in the same order. The fre quency of B. erectus was constant (100%) in all three types of community, w hereas percentage cover increased sharply (54.2 vs. 85.5%) between uneven a nd compact grasslands, remaining high in the scrub communities (83.8%). Cov er of phanerophytes showed low values in the uneven and compact grasslands, but reached 80% in the scrub communities. The increase in cover of B. erec tus caused the disappearance of species typical of the pioneer vegetation o f Pliocene clay soils with Artemisia cretacea. Colonization of the compact grasslands by S. junceum induced a reduction in grassland species of the cl ass Festuco-Brometea. The implications of these findings for the conservati on of B. erectus grasslands and biancana badlands are discussed.