Decline of traditional landscape in a protected area of the southwestern Alps: The fate of enclosed pasture patches in the land mosaic shift

Abstract

Traditional landscape elements such as pasture patches enclosed in a forest matrix are progressively disappearing throughout the European Alps. We assessed the land mosaic shift of a protected area located in the western Italian Alps. In particular, the dynamics of pasture patches were studied at both landscape and stand level. Land-cover mapping through object-oriented analysis of historical aerial photographs was used to assess land-cover changes between 1954 and 2000. Spatial statistics were used to quantify landscape patterns, and field samplings within pasture patches were used to explore tree regeneration structure and composition. Our results showed a significant increase in the number of pasture patches caused by their fragmentation following forest expansion. The total surface area of pasture patches decreased by 43% and their core area decreased by 94%. The encroachment of trees on less accessible areas of the pasture patches caused a reduction of patch shape at landscape scale. The gap filling process started 40-50 years ago and began with an early invasion of light demanding species like sycamore maple (Acer pseudoplatanus L.) and common ash (Fraxinus excelsior L.), followed by European beech (Fagus sylvatica L.) and secondarily silver fir (Abies alba Mill.). Traditional land-use and population decline in the Pesio Valley led to a reduction in ecotone areas. A transition to a more homogeneous landscape is expected in the next decades. Given the cultural and productive nature of these mountain meadow-pasture communities, extensive livestock grazing systems could be used to manage their future conservation.

Environmental and land use determinants of grassland patch diversity in the western and eastern Alps under agro-pastoral abandonment

“…During the second post-war period, these two valleys were affected by widespread socio-economic changes which led to the abandonment of mountain agriculture and landscape transformation over large surfaces (Patella 1969;Pedrotti 1988;Garbarino et al 2014). Agro-pastoral changes have included the reduction in the number of farms, available manpower and domestic herbivores reared and the intensification of the remaining agriculture within smaller areas.…”

Browsing ratio, species intake, and milk fatty acid composition of goats foraging on alpine open grassland and grazable forestland

“…In north Italy, in the mountain belt, small semi-natural grasslands are interspersed within forests (Sitzia and Trentanovi, 2011;Garbarino et al, 2014). These areas had been traditionally grazed for millennia.…”

Relevance of secondary forest successions and their possible management

“…Another important factor is definitely landscape texture: small patches of agricultural land inside the forest are in fact rapidly colonized as compared with large agricultural fields, far from forests and characterized by few rows or isolated trees ( Fig. 3) (Gambarino et al, 2014). Moreover, other basic factors are the periodical disturbances, such as fires (Romero-Calcerrada and Perry, 2004), cuttings, mowing etc., which can slow down the colonization process and produce a selection of tree species.…”

“…In the Alpine region, the progressive raising of the tree line due to the abandonment of pasture and global warming is produced by direct colonization of trees. A few pine species, larch, spruce, birch, alder, and other broadleaved tree species colonize directly abandoned land and pasture (Motta et al, 2006;Gambarino et al, 2001Gambarino et al, , 2014. Sometimes, the first stages of colonization are characterized by a shrub layer (hazel, green alder, dwarf mountain Pine, Rhododendron, Juniper, etc.).…”