Spatial dynamics of sweet chestnut orchards in a disease-affected region
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abstract
Along with agriculture abandonment, sweet chestnut (Castanea sativa) diseases are important drivers of
landscape dynamics in the northern regions of Portugal. Ink disease (Phytophthora cinnamomi Rands) has
affected orchards historically but chestnut blight (Cryphonectria parasitica (Murrill) Barr) became a major cause
of tree mortality after its establishment in 1989. We analysed the spatial structure of sweet chestnut
plantations in the Curopos parish (Vinhais, Portugal) over the 1985 2006 period in order to understand the role
of diseases in landscape dynamics. We mapped chestnut plantations in 1985, 1995 and 2005 from aerial
photography and determined total chestnut orchard area, number of orchards, average orchard area, area of
disease caused mortality, and area and number of new plantations. Mortality was very high in both 1985 1995
and 1995 2005 decades, above 40% in area. New plantations represented more than 100% of the chestnut
area in the first decade and near 50% in the second. New plantations were established in diseased affected
orchards (53%) and in marginal agriculture land recently abandoned (47%). The balance between mortality and
new plantations resulted in a 75% net increment in area over the period of study. Number of plantations and
average area also increased. We concluded that in spite of high incidence and tree mortality in Curopos over
the last 20 years, there was relevant investment in new chestnut plantations which was responsible for
relevant landscape dynamics.
