Quercus Pyrenaica Forests Research Articles

Climatic classification and ordination of the Spanish Sistema Central: relationships with potential vegetation

Monthly precipitation and monthly mean temperature records from 255 meteorological stations in Central Spain (Spanish Sistema Central) were analyzed by cluster and principal component analyses. Classification separated 14 groups according to altitude, geographical distribution, as well as the combination of rainfall and temperature. The first cluster emerged as significantly higher and colder than the second. Then, two ordinations were carried out: one for the 14 groups extracted from the classification and a second for the total station pool. The second ordination was compared with potential natural vegetation data taken around each station. The first ordination summarized the principal climatic characteristics of the Spanish Sistema Central: its behaviour is that of a typical Mediterranean mountainous territory combining summer aridity and variation of temperature with altitude and the influence of winter winds. The ordination of all stations reflected a thermal, rainfall and summer aridity gradient. Meteorological stations situated at the highest altitude or with highest precipitation records characterized by scrub communities or pine woods and Quercus pyrenaica forests, appeared well-separated along the first two axes. Only the most thermophilous Q. rotundifolia associations could be clearly separated. The fourth axis was useful in clarifying some vegetation overlap of deciduous and sclerophyllous forests, along an east-west summer aridity gradient. Nomenclature: Tutin et al. (1964-1980) for plants; Rivas-Martinez (1987) and Rivas-Martinez et al. (1987) for syntaxa.

Succession of epiphytic bryophytes in a Quercus pyrenaica forest from the Spanish Central Range (Iberian Peninsula)

Succession of epiphytic bryophytes in a Quercus pyrenaica forest from the Spanish Central Range (Iberian Peninsula)

Long-term decomposition process of leaf litter from Quercus pyrenaica forests across a rainfall gradient (Spanish central system)

On a etudie le processus de decomposition a long terme (3 annees) des feuilles de quatre chenaies a Quercus pyrenaica qui suivent un transect pluviometrique. Les contenus de matiere organique des sols forestiers sont lies au facteur pluviometrique, mais la pluviometrie n'affecte pas de maniere significative le processus de decomposition des feuilles du chene, car ce processus est plutot affecte par l'humidite du sol. Cette distribution des pluies est similaire dans tous les sols forestiers, mais la difference de la quantite de pluie se manifeste en hiver, c'est-a-dire quand les sols sont humides. La decomposition est liee a l'humidite du sol, et elle est arretee quand le sol est sec. Ainsi l'effet du climat est plus important que la composition chimique a court terme; a long terme, l'importance du climat diminue. La constante de decomposition des feuilles obtenue par la methode de « litter-bag » est plus basse que celle calculee a partir des donnes de production des litieres et de la teneur en litiere permanente, ce qui est du a la limitation de l'activite de la mesofaune dans les « litter-bags ». Les constantes de decomposition varient de 0,33, dans la station la plus pluvieuse, a 0,47, dans la station la plus seche. Les temps de residence varient de 2,0 a 1,1 annees, respectivement. Il faut tenir compte du fait que chaque bioelement a son propre temps de residence.

Water and bioelement fluxes in four Quercus pyrenaica forests along a pluviometric gradient

Les bilans d'eau et de plusieurs nutriments ont ete etablis pour quatre ecosystemes de Quercus pyrenaica le long d'un gradient pluviometrique important situe dans la Sierra de Gata (centre de l'Espagne) afin d'obtenir des informations sur l'effet de la quantite de pluie sur l'evapotranspiration annuelle et estivale, le lessivage des nutriments, et l'evolution de la fertilite des sols. Une correlation positive entre l'evapotranspiration annuelle et la pluviometrie de la periode de mai-aout a ete observee. Elle ne se retrouve pas avec la precipitation annuelle. Parmi les flux d'eau dans les ecosystemes, le drainage profond presente les variations les plus marquees entre parcelles. Il existe un exces d'eau dans le sol qui provoque un lessivage de nutriments et une diminution importante de la fertilite qui s'accentue avec le gradient pluviometrique. Ceci est confirme par le bilan net de plusieurs bioelements, le taux de perte de cations, la relation Ca/Al, le pH de la solution du sol et les valeurs de lessivage de la canopee.

Comparison between the soil seed banks of a burnt and an unburnt Quercus pyrenaica Willd. forest

Soil samples from burnt and unburnt sites dominated by Quercus pyrenaica Willd. forest in Leon province (NW Spain) were collected, separated into an upper layer (0–2 cm depth) from a lower layer (2–5 cm), put in a greenhouse, and seeds allowed to germinate. A total of 670 identified seedlings comprising 56 species and belonging to 24 families were recorded. Most seedling were herbaceous perennials (hemicryptophytes: 59%), followed by annuals (therophytes: 23%). Many species that germinated from buried seeds were not observed as plants at any site, and came from exogenous communities. The principal means of seed dissemination were anemochory (45%) and autochory (23%). The number of species as well as seedlings was not significantly different between soils from the burnt and unburnt sites, but seedlings were more numerous in samples from the unburnt sites, as the number of seedlings was always highest in the upper soil layer. Germination behaviour of four particular species was characterized. Seedlings from the seed bank temporarily were found in the early stages of recovery of the burnt Quercus pyrenaica forests.

Interaction between litter and soil epipedons in forest ecosystems of the Sierra de Gata Mountains, province of Salamanca, Spain

Potential and actual minimum returns of bioelements were estimated in four oak (Quercus pyrenaica) forest of the Sierra de Gata Mountains, Province of Salamanca, Spain, during two annual cycles. Leaves were the principal pool of potential bioele‐ment return, accounting for approximately 80% of return in Navasfrias and Villasru‐bias forests, and 70% in El Payo and Fuenteguinaldo forests. The greatest potential return of bioelements occurred in Fuenteguinaldo, especially N and Ca (53 and 32 kg ha−1 yf−1, respectively). The acidity of parent material seemed to affect the turnover of N, P, and K. The greater actual returns of N were found in Fuenteguinaldo (11.7 kg ha−1 yr−1), favored by a lower acidity of soil (pH = 5.4), and the losses of K were higher in the granite‐based soils (3.50 in the El Payo and 3.45 kg ha−1 yr−1 in the Fuenteguinaldo plots) due to an apparently greater plant assimilation of K. Granitic soils, above all at Fuenteguinaldo, were better nutrient balanced than the soils on schists, but ...

La lagartija de Bocage, Podarcis bocagei (SEOANE, 1884): Primeros datos sobre su distribución, colorido y ecología

AbstractP. bocagei is considered a valid species, and several criteria are used for distinguish it in sympatry of P. hispanica, a closely related species. A detailed distribution map is provided for this lizard, which occurs in Galicia, León, Orense, Zamora, western slopes of the Sistema Central, and probably, the north of Portugal. P. hispanica males and females in the Sistema Central are significant larger than males and females of P. bocagei. Significant differences in size, scalation and ecology are apparent between the Sistema Central and northern populations of P. bocagei, but no taxonomic decisions are made, pending a more detailed study. The examination of the masseteric shield revealed its large size in P. bocagei and its absence in most of the P. hispanica studied. P. bocagei has a relatively robust, deep skull, probably related to his terrestriral habits, unlike P. hispanica, which has a flattened skull and, at least in the Sistema Central, is a saxicolous species. P. bocagei is very common in Galicia and is found there at altitudes between 0 and 1500 meters, but in the Sistema Central is restricted to Quercus pyrenaica forests, between 800 and 1200 meters.