Early anthropogenic change in western Mediterranean mountains (Sierra Nevada, SE Spain)

Abstract

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Biological Interaction as a Possible Ultimate Driver in the Local Extinction of Cedrus atlantica in the Iberian Peninsula

“…The starting hypothesis arises from the fact that the distribution of each species is restricted to separate continents and that the Cedrus and Pinus spp. show some negative temporal association in the pollen profiles of the fossil records from both sides of the Mediterranean [1,16,17,[21][22][23][24][25][26]. However, both species show a similar ecological behavior (they form forests in the high Mediterranean mountains), which raises the question of whether and to what extent they share a niche.…”

“…The absence of macro-remains (charred wood) of Cedrus on the European continent led to the statement that the presence of cedar pollen in the Iberian fossil record responded to its airborne uptake by winds from Africa [2,5,7,8]. However, the constancy of the pollen type in numerous deposits [1,3,7,[9][10][11][12], its proportion and the low dispersal power of grains [1,13,14]; the Cedrus-Abies assemblage in the records [10]; and the low correlation between the presence of pollen and the origin of the winds from Africa [15,16] question this possibility and support the hypothesis that Cedrus lived in southern Europe during the Holocene as a component of mixed conifers woods or as small copses [3].…”

“…In the Iberian Peninsula, its last populations had to take refuge in the southern mountains of the Baetics as small, isolated nuclei [3,15]. In this context, it has been proposed that the definitive extinction of Cedrus in Europe during the Holocene could be motivated by human action [16,19,20], or even by competition with other species [3,16]. In this sense, an examination of the pollen diagrams of the available deposits on both sides of the Strait of Gibraltar (Baetic Mountain Range and Rif) revealed inverse patterns in the relative abundance of the Pinus and Cedrus pollen types; while, in the Baetics, Pinus dominates and Cedrus is scarce, in the Rif, Pinus appears meager where Cedrus is the dominant type [1,16,17,[21][22][23][24][25][26].…”

“…In this context, it has been proposed that the definitive extinction of Cedrus in Europe during the Holocene could be motivated by human action [16,19,20], or even by competition with other species [3,16]. In this sense, an examination of the pollen diagrams of the available deposits on both sides of the Strait of Gibraltar (Baetic Mountain Range and Rif) revealed inverse patterns in the relative abundance of the Pinus and Cedrus pollen types; while, in the Baetics, Pinus dominates and Cedrus is scarce, in the Rif, Pinus appears meager where Cedrus is the dominant type [1,16,17,[21][22][23][24][25][26]. If the ecological affinities of the species are not mutually exclusive and in the absence of barriers to dispersal, this negative association between species suggests the possibility that species of both genera have interacted in the past, mutually excluding each other in areas where they shared a niche and where the one that was more competitive would have ultimately remained [27,28].…”

Colonization Pattern of Abandoned Croplands by Quercus pyrenaica in a Mediterranean Mountain Region

“…Quercus pyrenaica Willd. woodlands, like other forest formations in the Mediterranean region, have been subjected to intense anthropogenic pressures over time [24,25], which have led to the reduction in their distribution area, as well as in modifications of their floristic and structural patterns [26][27][28]. Historically, the woodlands of Q. pyrenaica have been exploited mainly for firewood, charcoal, and tannins [29,30].…”