Azorean open dry, acid to neutral grassland

Non-grazed perennial grasslands of rocky outcrops and slopes dominated by strictly Azorean endemic grasses, hemicryptophytes and dwarf chamaephytic forbs. The majority of the non-woody vascular Azorean endemics are found in this habitat. The habitat can be divided in subtypes that are different in substrate, geomorphology and bioclimate, and thus in species composition, vegetation structure and dominance. It spans from the thermomediterranean (Santa Maria and SW of São Miguel Islands only) and thermotemperate to the supratemperate belts of the Azorean biogeographical Province. Two main subtypes can be distinguished:

Subtype #1. Open grasslands with scattered megaphorbs dominated or co-dominated by combinations of Deschampsia foliosa, Festuca francoi (=F. jubata), Holcus rigidus, Agrostis azorica, Leontodon rigens and Leontodon filii. They grow in meso-supratemperate climate (i.e. in altitudes above 300 m.), in nutrient-poor, acid soils, either in steep earthy or rocky slopes subject to gravitational disturbance, slope deposits with peat formation or under the permanent influence of gusting winds. Pioneer versions can be found colonizing former biotopes, like blanket bogs that were removed by catastrophic mass movements. The subtype contacts with vegetation of Azorean Juniperus woodland (G3.9c) and Azorean heath (F4.3).

Subtype #2. Low-altitude (thermomediterranean and thermotemperate) open grasslands of cliffs and landslide scarps, either in rock outcrops or earthy platforms between rocks, dominated by combinations of Agrostis congestiflora subsp. congestiflora, Festuca petraea, Holcus rigidus and Brachypodium gaditanum. The main contacts are woody vegetation of Picconia azorica and/or Pittosporum undulatum (alliance Myrico fayae-Pittosporion, habitat G2.3) and Azorean heath (F4.3).

The enormous extent of zooanthropic swards of introduced grasses in the Azores, used for dairy production, is a severe threat to the endemic grasslands. Soil tilling followed by cattle grazing causes immediate destruction of the endemic habitat type and its permanent substitution by alien-dominated swards. Also, even if endemic grasslands are preserved well in sites far from artificial swards, alien flora tends to invade them by seed dispersal, leading to invasion of endemic grassland by alien grasses with similar ecological requirements and genetic contamination of Azorean endemics by taxonomically close relatives (i.e. aliens of the same genus). The main alien grasses of artificial swards are Anthoxantum odoratum, Holcus lanatus, Dactylis glomerata and Agrostis castellana. Some other frequent aliens are Lotus pedunculatus, Rumex conglomeratuss, Crepis lampsanoides and Hypochaeris glabra. Ecological integrity of Azorean endemic grasslands is beste maintained by exclusion of man-induced disturbances and keeping distance to zooanthropogenic swards.

Indicators of good quality:

• absence of alien plant species
• no human disturbances

Synthesis of Red List assessment

Confidence in the assessment

Pressures and threats