Biological Characteristics

Types of Habitats

Given the habitats of the Directive DC92/43/EEC, it is necessary to highlight the importance of the Biosphere Reserve Terras do Miño in continental wetlands conservation since in it we can find 22 types of habitat represented, included in the annexes of that Directive, and that are representative some type of wetland (lakes, ponds, meadows and peat).

Within the group of freshwater habitats, in the Biosphere Reserve Terras do Miño up to 8 different types are present, being able to observe within their territory all types of freshwater habitats mentioned in the autonomous community of Galicia. Within the freshwater habitats can establish two subgroups depending on the mobility of water, thus differentiating among 6 types of habitat characteristic of stagnated freshwater and other two characteristic of sections of river with running water.

Although a significant part of the permanent ponds and pools of the Upper Miño were isolated naturally or by increased agricultural activity, others constitute a complex mosaic in which permanent lagoon environments with an oligotrophic, mesotrophic and eutrophic character cohabit, caused by the uneven composition of sediments and the and hydro, along with grass and hygrophitic bushes and hygrophitic peatland-related phenomena. These areas that hold a greater wealth of aquatic resources (flood plain of Begonte, Lagoon of Cospeito, Bardancos, Toiral and Fabás) in which the greatest diversity of species is included, among which one would emphasize the populations of Eryngium viviparum and Luronium natans (Annex II), as well as various taxa included in the catalogues of endangered species (Isoetes fluitans, Pilularia globulifera).

Most distrophic lagoon environments (3160) correspond to small temporary ponds within existing peat or hygrophitic peatland-related bushes, distributed along peripheral mountain ranges. As permanent lagoon environments only the Pozo do Ollo (the Well of the Eye) is included in the category of dystrophic lakes, lake originated in a deep tectonic fracture, which is included within an extensive floodplain covered by humid forests. The contributions of organized matter which gets from flooded area determine the dystrophic character of the waters and sediments existing in its neritic area.

The rest of the permanent lagoon environments existing in the Upper Miño, match environments of mesotrophic and oligotrophic waters, characterised characterised by the predominance of communities of Litorella uniflora (3110) or Isoeto-Nanojuncetea (3130). These lagoon environments are distributed among the peripheral unit and the central unit. In the central unit the existence of ancient karst systems fossilized by Tertiary sediments, or, in turn, the presence in these sediments of carbonate materials determines the existence of permanent lagoon environments of mesotrophic waters and communities (3140), in which Characeae communities predominate, together with eutrophic environments (3150) with aquatic communities belonging to Magnopotamion.

The various fluvial sections existing in the Upper Miño represent a length of over 2,400 km, forming an intricate biological corridor which acts as a barrier and a link between the different wetlands of the territory. The greatest diversity and biological richness of the river system of the Upper Miño is established around the central unit, where the channels show a high degree of heterogeneity, with large wandering meanders, dead arms, earth islands, areas of rapids or otherwise lentic environments, etc. Complexity that should be to tied to the fact that many of these sections are integrated with other wetlands, flood plains generally, permanent lagoon environments, etc.

Other wetland habitats, and of particular importance within the Biosphere Reserve Terras do Miño, are the wet Atlantic Queirogais of Erica ciliaris and Erica tetralix (4020 *). Such habitats concentrate most of its area in the northern mountains and are the main and most extensive habitat of the Biosphere Reserve. Along with this type of “queirogal” (territory where queiroas abound, one-metre-bushes with purple, pink and white flowers), the geological and climatic features of the territory favour the existence of various types of peatland and peatland-related environments that mostly correspond to the group of Active Hig Peat Bogs (7110 *) and Active Blanket Peat Bogs (7130 *). With a much smaller distribution, focused on the area of Begonte, we can find good representations of formations of Cladium mariscus (* 7210), whose presence in this territory was already indicated by the Reverend Father Jesuit Baltasar Merino at the beginning of the twentieth century (Merino, 1901).

The grassy formations with a natural or semi-natural character present an important geographical distribution in Terras do Miño, being shaped by two types of Priority Habitat (6220 * and 6230 *) and 3 types of Habitats of Community Interest. This includes various types of hygrophitic environments, developed on inorganic substrates, with emerging vegetation during most of the year (6410 and 6420). These environments at water level undergoes significant variations throughout the year in the soil, remaining however in the sub-surface horizons in the summer months so that it can be taken advantage of by most of the hygrophitic vegetation, and specifically by annual elements. Among these communities, we can find others of less superficial entity dominated by Nardus Strict (* 6230) or megaphorbia (6430).

The set of rocky and cave habitats has, as its mapping unit, a low representation within the Upper Miño, concentrating the largest number and area of such habitats in peripheral mountainous relieves. Therefore, the presence of a grassy habitat linked to rocky outcrops of priority should be noted: sub-steppe areas of grass and annual species of Thera-Brachypodietea (6220 *).

The forest area of the Biosphere Reserve appears dominated by dry queirogais (4030) and various types of mesophilic planedeciduous forests (Galician-Portuguese oak woods, 9230) and particularly the various humid forests (alluvial forests * 91E0, wooded peatlands 91D0 *, and large forests on the banks of large rivers 91F0).

In total, 32 Habitats of Community Interest were identified (Annex I DC 92/43/EEC) into the territory of the Biosphere Reserve Terras do Miño, 9 of which are considered a priority:

Hábitats de interés comunitario
Hábitats de agua dulce
Augas oligotróficas (Littorelletalia uniflorae)
3120 Augas oligotróficas (Isoetes spp.)
3130 Augas oligotróficas ou mesotróficas
Augas oligomesotróficas calcáreas (Chara spp.)
3150 Logos eutróficos naturales (Magnopotamion o Hydrocharition)
Lagos e estanques distróficos naturais
Ríos de pisos de chaira a montano
Ríos de beiras lamacentas (Chenopodion rubi p.p., Bidention p.p)
Hábitats de Brezos y matorrales de zona templada
Queirogais húmidos atlánticos de Erica ciliaris e E. tetralix
4030 Queirogais secos europeos
Hábitats de Formaciones herbosas naturales y seminaturales
6220* Zonas subestépicas de gramíneas e anuais do Thero-Brachypodietea
6230* Formacións herbosas con Nardus
6410 Prados con Molinias
6430 Megaforbios eutrofos higrófilos das orlas de chaira
6510 Prados pobres de sega de baixa altitude
Hábitats de Turberas altas, bajas y áreas pantanosas
7110* Tubeiras altas activas
7120 Tubeiras altas degradadas
7130* Tubeiras de Cobertor
7140 'Mires' de transición
7150 Depresións sobre substratos turbosos de Rhynchosporion
7210* Turbeiras calcáreas de Cladium mariscus e do Caricion davallianae
7230 Turbeiras baixas alcalinas
Hábitats rocosos de cuevas
8130 Desprendementos mediterráneos occidentais e termófilos
8220 Encostas rochosas silíceas con vexetación casmofitica
8230 Rochedos silíceos con vexetación pioneira
8310 Covas non explotadas polo turismo
Hábitats de Bosque
9180* Bosques de ladeiras, desprendementos o barrancos do Tilio-Aceiron
91D0* Tubeiras boscosas
91E0* Bosques aluviais de Alnus glutinosa y Fraxinus excelsior
91F0 Bosques mistos nas ribeiras dos grandes ríos
9230 Carballeiras galaico-portugueses con Quercus sobur e Quercus pyrenaca
9380 Bosques de llex aquifolium

Fuente: IBADER

Instituto de Biodiversidade Agraria e Desenvolvemento Rural

GI-TB Territorio - Biodiversidade