Innovative Alley coppice Systems-mixing timber and bioenergy woody crops: 7 years growth and ecophysiological results in exper plots, northern Italy, Po Valley

Land use competition between food/feed and energy crops could exclude the establishment of Short Rotation Coppice (SRC) plantations, as bioenergy woody crop, on productive agricultural land. A solution could be the cultivation of multipurpose plantations producing biomass and logs for industry, as an innovative alley coppice system. This is a mixture between high value timber trees and SRC of poplars and willows. The advantages of this cultural model could be that: i) the farmers can receive payments for biomass every 2-5 years during juvenile phase of the high value timber trees, ii) the timber trees can be planted at final spacing, avoiding plantation thinning, iii) the SRC, with a rapid canopy closure, has a positive environmental impact, reducing soil erosion and increasing biodiversity, iv) the SRC can protect the timber trees from wind and storm, v) a modulated light competition of SRC towards the timber trees causes the correct growth of their stem, reducing pruning intensity. This paper refers preliminary results obtained during the first 7 years in experimental plots, in northern Italy, comparing alley coppice of poplar SRC with Sorbus and Pyrus trees and sole timber trees without any mixture. Data reported concern on tree growth and stem form, along with some preliminary observation on light competition. The timber trees in the alley coppice treatment reached satisfactory stem dimensions, associated with improved wood quality in comparison to the sole timber trees. Although the timber trees in the alley coppice plots were dominated by the poplar SRC shoots, the light competition was not so intensive for inhibiting the growth of the Sorbus and Pyrus trees. Research funded by Moprolegno Project (2006-'09) and "AgroCop" Project"-WoodWisdom-Net - ERA-NET Bioenergy (2012-'15).