Abstract
The potential of Scots pine (Pinus sylvestris) for regeneration and encroachment onto dry grasslands in the forest-steppe ecotone was experimentally studied at the south-eastern distribution limit of the species in Mongolia. The experiment consisted of a sowing and planting (2-year old seedlings) assay at two different distances from the forest line and manipulation of the water supply by irrigation in one half of the replicate plots. Seedling emergence was strongly inhibited by post-dispersal seed predation (between 50 and >90 % of the seeds were apparently consumed) and by drought. Seedling survival was limited by drought and phytopathogenic fungi that infected the needles. Herbivory by insects or rodents, a key factor for seedling mortality in Larix sibirica, the most frequent tree species in Mongolia’s forest-steppe ecotone, was of little importance in Scots pine, probably due to the production of efficient allelochemicals. The potential of Scots pine to regenerate in Mongolia’s forest-steppe ecotone and to encroach onto the steppe is very limited and mostly restricted to the immediate vicinity of the forest; it might even decrease in future in the face of climate warming. The observed dependence of seedling emergence and survival on soil moisture suggests that regeneration outside the forest may only be successful in exceptionally moist years. Livestock grazing is certainly an additional limiting factor for Scots pine regeneration in Mongolia, but was not relevant in the present study area.
Highlights
Scots pine (Pinus sylvestris L.) is the most widely distributed tree species in the northern hemisphere
Plant Ecol (2013) 214:139–152 present study, we examined the potential of Scots pine to establish at the forest margin in the drought-affected forest-steppe ecotone and to encroach onto grasslands in front of the forest line in northern Mongolia
Drought, and fungal infections, but not that much herbivorous insects or rodents clearly limit the regeneration of Scots pine in the forest-steppe ecotone of northern Mongolia
Summary
Scots pine (Pinus sylvestris L.) is the most widely distributed tree species in the northern hemisphere. While Scots pine may cover large areas in boreal forests, especially at disturbed sites and in more continental climates, it is restricted to marginal habitats in terms of water and nutrient availability at the southern fringe of its range. The species is characteristic of very dry forest communities, which often grow on mountain ridges, where they form the treeline and a transitional zone to the steppe (Dulamsuren et al 2005). This ecological preference matches the occurrence of Scots pine in summer-dry mountain forests of the Mediterranean region, including Italy and southern Spain, in the south-western extensions of its range (Alia et al 2001; Scalfi et al 2009). In the recent past, such dry forests have received increased attention in conjunction with global warming
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
