Journal Article

Changes in biodiversity and vegetation composition in the central Swiss Alps during the transition from pristine forest to first farming

Colombaroli, Daniele, Curdy, Philippe, Beckmann, Madlena, van der Knaap, Willem O., Tinner, Willy

2013

Overview

Aim: We investigate the response of vegetation composition and plant diversity to increasing land clearance, burning and agriculture at the Mesolithic—Neolithic transition (c. 6400—5000 BC) when first farming was introduced. Location: The Valais, a dry alpine valley in Switzerland. Methods: We combine high-resolution pollen, microscopic charcoal and sedimentological data to reconstruct past vegetation, fire and land use. Pollen evenness, rarefaction-based and accumulation-based palynological richness analyses were used to reconstruct past trends in plant diversity. Results: Our results show that from c. 5500 cal. yr BC, slash-and-burn activities created a more open landscape for agriculture, at the expense of Pinus and Betula forests. Land clearance by slash-and-burn promoted diverse grassland ecosystems, while on the long term it reduced woodland and forest diversity, affecting important tree species such as Ulmus and Tilia. Main conclusions: Understanding the resilience of Alpine ecosystems to past disturbance variability is relevant for future nature conservation plans. Our study suggests that forecasted land abandonment in the Alps will lead to pre-Neolithic conditions, with significant biodiversity losses in abandoned grassland ecosystems. Thus, management measures for biodiversity, such as ecological compensation areas, are needed in agricultural landscapes with a millennial history of human impact, such as the non-boreal European lowlands. Our study supports the hypothesis that species coexistence is maximized at an intermediate level of disturbances. For instance, species richness decreased when fire exceeded the quasi-natural variability observed during the Mesolithic times. Under a more natural disturbance regime, rather closed Pinus sylvestris and mixed oak forests would prevail.

• Publisher: Blackwell Publishing Ltd,Blackwell Publishing,Blackwell,John Wiley & Sons, Inc
• Subject: Abandoned land / Agricultural land / Agriculture / Agroecosystems / Alps / Alps, beta‐diversity / Animal, plant and microbial ecology / Applied ecology / beta-diversity / Betula / Biodiversity / Biodiversity loss / BIODIVERSITY RESEARCH / Biological and medical sciences / Charcoal / Climate change / conservation biogeography / Ecosystems / Farming / Forest ecosystems / Forest fires / Forestry / Forests / Fundamental and applied biological sciences. Psychology / General aspects / General forest ecology / Generalities. Production, biomass. Quality of wood and forest products. General forest ecology / Grasslands / human impact / intermediate disturbance hypothesis / Land use / Mixed forests / Nature conservation / Neolithic / palynological richness / Palynology / Pine trees / Pinus / Pinus sylvestris / Plant diversity / Plant species / Plants / Pollen / Slash and burn / Species diversity / Species richness / Taxa / Tilia / Ulmus / Vegetation / Woodlands