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The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs, which are particularly sensitive to projected climate change. In this context, the rate of carbon (C) accumulation in Chao de Veiga Mol, an intact raised bog, was analysed. Changes in the accumulation rate over the past 10 millennia were determined in a peat core of 847 cm in depth, with a high mean rate of peat growth (11 yr cm−1, 0.09 cm yr−1). An age-depth model was generated from 22 14C dates and fallout radionuclides. Chronological, stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago. The total mean C content was 50.2%, and over 10 millennia 583 kg C m−2 accumulated at a mean rate of 35.3 g C m−2 yr−1, with a long-term (apparent) rate of carbon accumulation in the catotelm of 59.9 g C m−2 yr−1. These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere. The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene. They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes. The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies, especially in relation to regional and local modulations in southern Europe.

Las turberas son ecosistemas con una distribución muy restringida en la Península Ibérica. Entre ellas las turberas ombrotróficas de cobertor constituyen un hábitat aún más escaso y en peligro grave de desaparición, a pesar de estar bajo la protección de diferentes normativas vigentes, tanto nacionales como internacionales. Además de su importancia ecológica, uno de sus mayores valores radica en su funcionamiento como archivos paleoambientales del pasado, principalmente del período Holoceno. La tesis está organizada en nueve capítulos; los tres primeros de carácter general, en el primero de los cuales se presenta una recopilación de información bibliográfica sobre turberas, haciendo hincapié en turberas de cobertor, sobre macrofósiles vegetales y sobre propiedades de la turba, particularmente el grado de humificación de la misma. El segundo capítulo contempla los objetivos de la tesis y el tercero la metodología utilizada. En el cuarto se presenta un estudio detallado de los distintos macrofósiles vegetales estudiados en tres turberas de cobertor y una elevada del norte de la Península Ibérica. De todos los taxones de macrofósiles identificados se realiza una descripción y se establecen las bases para su identificación, mediante claves dicotómicas con ilustraciones detalladas de los caracteres de mayor valor taxonómico. En los capítulos quinto y sexto se realizan las reconstrucciones paleoambientales durante el Holoceno, en la turbera vasca de Zalama en primer lugar y posteriormente en el caso de la turbera gallega de Borralleiras de Cal Grande; realizadas a partir de los macrofósiles vegetales extraídos de la turba y de los resultados de los análisis de la turba, especialmente los del grado de humificación, el contenido en elementos litogénicos, carbones y la tasa de crecimiento vertical. La comparación de diferentes registros bióticos y abióticos ha permitido reconstruir la dinámica de las condiciones hidrológicas, es decir, de la humedad superficial de la turbera

In the present study we reviewed the genesis, development and classification of peatlands in the Iberian Peninsula by conducting chronostratigraphic analysis of 108 of these ecosystems. The findings are summarised as follows: 1. The region has a wide variety of peatlands which are classified according to their biogeochemical, geomorphological and ecological characteristics into different types of bogs and fens. 2. Most of the peatlands occur in the Atlantic region followed by the Mediterranean and Alpine regions. Fens are more widely distributed than bogs, and blanket and raised bogs are mainly found in the Eurosiberian biogeographical region. 3. In many of the fens, the last active peat-forming cycle occurred during the Late Holocene (43 %). In most of the bogs, the peat-forming cycle occurred in the Middle Holocene (70 %), although in a substantial proportion of blanket bogs these processes occurred in the Early Holocene (30 %). 4. The peat formed in the last active cycle is, on average, thicker in raised bogs (322 cm) than in blanket bogs (257 cm) and fens (156 cm). 5. Vertical peat accumulation rates varied between 16 and 30 yr cm-1 in more than 40 % of the peatlands. The accumulation rates differed significantly between the different types of peatlands and were highest in the raised bogs. The accumulation rates were very variable in the fens. 6. The genesis, evolution and types of Iberian peatlands are similar to those observed in peatlands in northern latitudes in Europe and North America