Post-grazing Scots pine colonization of mid-elevation heathlands: population structure, impact on vegetation composition and diversity

Abstract

-Scots pine (Pinus sylvestris L.) pioneer woodlands have established spontaneously on former grasslands and heathlands on MontLozère (Cévennes National Park, France) since their abandonment in the 1950's. Subsequently, late-successional beech (Fagus sylvatica L.) has progressively invaded the ageing pine stands. We studied 44 plots according to a gradient of forest colonization and maturation, from heathlands to mature beech stands. The objective was to assess the impact of forest colonization on the vegetation composition and richness of legally-protected grasslands and heathlands. Dendrometric characteristics and demography were assessed on each 20 × 20 m plot. An extensive ground vegetation analysis was carried out, focusing on plant functional traits that may be sensitive to canopy closure. Results indicated the persistence of most heathland species under pure and young Scots pine stands, but quite high species turnover. Xerothermic and strictly shadeintolerant species rapidly disappeared, whereas thermophilic forest species were apparent. In submature and mature pine stands, the establishment of a beech understorey entailed considerable species turnover, and prevent pine regeneration. In pure beech stands, ruderal and stress-tolerators were replaced by shade-tolerant and competitive species. Ellenberg's scores for light, nutrients and water confirmed the changes in vegetation composition and plant life traits, whereas the Shannon diversity index remained quite constant among pure and mixed pine stands.

Impacts of Land Abandonment on Vegetation: Successional Pathways in European Habitats

“…Finally, the increase in species richness in mid-elevation grasslands may be explained by the high light availability in woody stages composed of birch or Scots pine facilitating the coexistence of semi-shade-tolerant species as well as heathland species (Prévosto 1999;Curt et al 2003). Similarly, in arable field (1), the peak of species richness at mid-stages of succession before tree canopy closure was also due to the coexistence of different life forms and dispersal strategies (Harmer et al 2001;Bonet and Pausas 2004;Dölle et al 2008).…”

Long-Term Forest Dynamics and Land-Use Abandonment in the Mediterranean Mountains, Corsica, France

“…In the absence of management, chestnut forests tended to be invaded by other tree species, giving way to an evolutionary dynamic toward climax forests, as observed in many European regions in recent decades (Arnaud et al 1997, Conedera et al 2000. However, the strong progressions of broadleaf forests also concern coniferous forests that might have been dependent on rapid colonization, notably through the abandonment of open-land habitats (Quézel and Médail 2003), because the recruitment rate for pines is also associated with declines in local human http://www.ecologyandsociety.org/vol18/iss2/art38/ population and regional livestock (Curt et al 2003, Chauchard et al 2007). The dynamics of a system at a particular scaleof-interest cannot be understood without taking into account the dynamics and cross-scale influences of the processes from scales above and below it.…”

Competition for water between beech seedlings and surrounding vegetation in different light and vegetation composition conditions

“…Grazing abandonment in the "Chaîne des Puys", a volcanic massif located in the French Massif Central, has led to a natural afforestation of former agricultural land by pioneer trees such as Scots pine (Pinus sylvestris L.) [11,24] and Silver birch (Betula pendula Roth.). Natural establishment of shade-tolerant broadleaved species such as beech (Fagus sylvatica L.) is observed beneath these pioneer stands [10].…”