Crossing forest thresholds: inertia and collapse in a Holocene sequence from south-central Spain

Abstract

A Holocene palaeoecological sequence from Villaverde, south-central Spain, is presented. The pollen stratigraphy is used to infer past vegetation changes within a catchment area that represents the boundary between semi-arid, plateau and mountain vegetation. From c. 9700-7530 cal. yr BP, Pinus is dominant, probably as a result of a combination of a relatively dry climate and natural fire disturbance. From c. 7530-5900 cal. yr BP, moderate invasion by Quercus appears to be a migrational response following increased moisture and temperature, but in part shaped by competitive adjustments. From c. 5900-5000 cal. yr BP, the pine forests are replaced by deciduous-Quercus forests with an important contribution from Corylus, Betula, Fraxinus and Alnus. Mediterranean-type forests spread from c. 5000 to 1920 cal. yr BP coincident with expansions of Artemisia, Juniperus and other xerophytes. From c. 1920-1160 cal. yr BP, Pinus becomes dominant after a disturbance- mediated invasion of the oak forests. Human impact upon the regional landscape was negligible during the Neolithic, and limited in the Bronze and Iron Ages. Local deforestation and the expansion of agro-pastoral activities occur after c. 1600 cal. yr BP.

Centennial-scale vegetation and North Atlantic Oscillation changes during the Late Holocene in the southern Iberia

“…We suggest that this could explain the different fire recurrences during this period in one of the Sierra de Cazorla records (Siles lake; Carrión et al, 2002) with an annual precipitation average of 800-1000 mm. However in the other record from the Sierra de Cazorla (Villaverde lake; Carrión et al, 2001b) a lesser annual precipitation average of around 225 mm is recorded and it is not possible to apply this hypothesis but another of the many factors controlling fire in the area. Gil-Romera et al (2010) summarized pollen and charcoal records from southeastern Spain and showed that differences in fire regimes could be explained by variations in climate, vegetation, altitude and human activity.…”

“…This suggests that higher fire activity at this time could have been related to the presence of abundant fuel load (Daniau et al, 2007;Linstädter and Zielhofer, 2010;Jiménez-Moreno et al, 2013b). Nevertheless, two different records in Sierra de Cazorla show a reverse trend in fire activity during this period (Carrión et al, 2001b;Carrión et al, 2002), which may be due to different characteristics in fire regimes related with precipitation (Linstädter and Zielhofer, 2010;Jiménez-Moreno et al, 2013b). For example, in typically arid and semiarid environments in the Mediterranean area fuel load limits fire regimes.…”

“…Martín-Puertas 2008; Morellón et al, 2011;Currás et al, 2012;Corella et al, 2013). Most of the Holocene paleoclimate reconstructions in the southern Iberian Peninsula come from lake and peat deposits at low and montane altitudes, as well as from marine cores (Carrión, 2002;Carrión et al, 2001aCarrión et al, , 2001bCarrión et al, , 2003Carrión et al, , 2007Carrión et al, , 2010Martín-Puertas et al, 2008, 2010Nieto-Moreno et al 2011;Jiménez-Moreno et al, 2015). Studies at higher elevations are scarcer and mostly come from lake and peat bog sedimentary deposits from the Sierra Nevada range (Anderson et al, 2011;Jiménez-Moreno and Anderson, 2012;García-Alix et al, 2012Jiménez-Moreno et al, 2013b).…”

Aportaciones hidrogeológicas al estudio arqueológico de los orígenes de la Edad del Bronce de La Mancha: la cueva monumentalizada de Castillejo del Bonete (Terrinches, Ciudad Real, España)

“…Es uno de los eventos climáticos holocenos de aridez más extrema, registrado a escala mundial . Se relaciona con una oscilación de la órbita terrestre que modificó la radiación solar recibida por la Tierra (Gibbons 1993;Weiss et al 1993;Wilkinson 1997;Menotti 1999;Carrión et al . 2001;Julià et al .…”

Vulnerabilidad y resiliencia de los pinares de alta montaña de la Sierra de Gredos (Ávila, Sistema Central): dos mil años de dinámica socioecológica

“…El uso del territorio y la antropización de estos espacios han provocado profundas modificaciones en la estructura y composición de las comunidades vegetales, condicionadas, además, por la variabilidad climática (Carrión et al, 2001a(Carrión et al, , 2001b(Carrión et al, , 2007López-Sáez et al, 2014, 2017a. Evidencias de estos hechos se manifiestan, en la zona central de la Península Ibérica, tanto en el registro arqueológico como en el paleoambiental, cuyo estudio integrado supone la mejor forma de entender dichos cambios en los ecosistemas a escala regional (BlancoGonzález et al, 2009(BlancoGonzález et al, , 2015López-Sáez et al, 2014;Rubiales y Génova, 2015).…”