Holocene fire and vegetation dynamics in the Central Pyrenees (Spain)

Abstract

Fire-vegetation relationships are critical to understand transient mountain ecosystems and their long-term landscape dynamics, which is essential for alpine forest conservation. In this paper we aim to 1) reconstruct the Holocene fire history at high altitudes of the southern Central Pyrenees, 2) add evidence to the debate on fire origin, naturally or anthropogenically produced, 3) determine the importance of fire as a disturbance agent for sub-alpine and alpine vegetation, in comparison with the plant community internal dynamics applying conditional

Palaeoenvironmental data indicate late quaternary anthropogenic impacts on vegetation and landscapes in Mzimba, northern Malawi

“…First, Cyperaceae pollen, reflecting wetland sedges, persisted throughout all periods of study and are evidence of continuation of seasonal wetland conditions in the studied locations from the Late Pleistocene to present (or nearly present) day. Second, increases in Podocarpus and Pinus (tree) taxa in the last 200 years occurred in the auger samples despite evidence for increased concentrations of microcharcoal, which is in general contrast to expected results based on simulated (Keane et al, 2004;D'Odorico et al, 2006;Phelps et al, 2020) and observed (Bakker et al, 2013;Marchant et al, 2018;Leunda et al, 2020) occurrences in ecological research. However, spatially and taxonomically complex ecological simulations challenge simplistic fire-driven forest-to-savannah formation models, demonstrating that fires consume saplings and seedlings that contribute negligibly to biomass (Hanan, 2008).…”

Transhumance and long-term deforestation in the subalpine belt of the central Spanish Pyrenees: An interdisciplinary approach

“…Nevertheless, fire activity increased at ca. 3700 cal BP, indicating a reinforcement of human activities and forest clearing (Leunda et al, 2020).…”

“…This author attributed the rapid deforestation to the need for more summer grasslands as the conquest of the lowlands of the Ebro Depression advanced. Charcoal data from the Basa de la Mora and Marboré sequences from 1250 years BP, and especially during the last 300 years, indicated increasing fire activity during recent centuries (Leunda et al, 2020). In fact, it is impossible to explain the rapid expansion and consolidation of transhumance without a widespread deforestation of the subalpine and upper montane belts, and their transformation into large open landscapes dominated by grasslands.…”

What the past can say about the present and future of fire

“…In the Bereket surroundings, fires appear to have catalyzed a simplification of the vegetation structure and associated increases in soil erosion, pasture expansion, and intensive cultivation (Kaniewski et al, 2008). Leunda et al (2020) use paleofire data from the Central Pyrenees in Spain to show the transition from climate-driven fire regimes in the early-to-mid-Holocene to human-driven landscape change over the last 3700 years. Many similar examples exist throughout Europe.…”