Grazing and abandonment determine different tree dynamics in wood-pastures

Abstract

Wood-pastures are threatened biotopes in which trees and livestock grazing maintain high conservation values. However, browsing may threaten tree regeneration, whereas abandonment leads to tree encroachment. We studied the regeneration of trees in a grazed and abandoned boreal wood-pastures. In grazed sites, the density of young spruces (Picea abies) was high, while the density of young birches (Betula spp.) was very low. Sprucification can be prevented only by removing spruces. The number of young birches and pines (Pinus sylvestris) was correlated with the number of junipers (Juniperus communis), probably because thorny junipers protect palatable seedlings from browsing. In abandoned sites, deciduous trees and spruces regenerated abundantly. In the long term, both grazing and abandonment lead to changes in tree species compositions and low diversity wood-pastures. Landscape scale planning and disturbance dynamics are needed for the creation of new wood-pastures and the maintenance of all pasture types within the landscape.

Experimental rewilding may restore abandoned wood-pastures if policy allows

“…Abandoned wood-pastures develop secondary woodlands (normally Norway spruce in Sweden) which reduces biodiversity (Paltto et al 2011 ). In boreal Finland, Oldén et al ( 2017 ) showed that spruce regeneration was abundant in all kinds of abandoned wood-pastures (birch-, pine-, spruce- and broadleaved-mixed dominated wood-pastures) and regeneration was only reduced by removal or by increasing canopy openness. In our experimental study spruce was avoided.…”

“…In our experimental study spruce was avoided. In this regard, Oldén et al ( 2017 ) concluded that sprucification is a major problem in wood-pastures due to resulting landscape homogenization and vegetation compositional changes towards spruce-dominated wood-pastures and suggested spruce regeneration removal to benefit rare plant and insect species characteristic of semi-open woodlands (Oldén et al 2017 ). A recent study reported that 66% of the most valuable oak wood-pasture habitats in Östergötland (Sweden) were abandoned (with subsequent secondary woodland development) and grazing could not be resumed due to lack of farmers and livestock (Garrido et al 2017 ).…”

“…These large herbivore grazers are fundamental in wood-pasture formation and dynamics (Vera et al 2006). Oldén et al (2017)…”

“…These large herbivore grazers are fundamental in wood-pasture formation and dynamics (Vera et al 2006 ). Oldén et al ( 2017 ) have recently investigated how grazing and abandonment determined different tree dynamics in boreal wood-pastures in Finland, highlighting the importance of resume livestock grazing for wood-pasture formation and development. Bocherens ( 2018 ) recently postulate that some of the megaherbivore functions in ecosystems were replaced by human agriculturalists through animal and plant domestication, and agriculture and husbandry practices.…”

Recovery of boreal forest soil and tree stand characteristics a century after intensive slash-and-burn cultivation

“…>100 years) on natural ecosystem recovery. In boreal forests, there is unexpected recent evidence that natural recovery following cessation of active land-use can in the long term lead to less diverse ecosystems (Oldén et al 2017), but the authors suggest that on the landscape scale biodiversity nonetheless increases with passive recovery (Oldén et al 2017). Other studies show that recovery in disturbance-driven habitats may lead toward the targeted undisturbed ecosystem (Nikodemus et al 2012;Johnson et al 2014;Tikkanen et al 2014).…”