Hybrid poplars have been intensively managed in Italy for timber production mostly as monoculture plantations. Intercropping poplar trees with arable crops and in linear plantations along field edges is also common in agroforestry systems. However, agroforestry systems sharply declined in the last decades with the rapid deployment of mono-cropping agriculture, following the support of the Common Agricultural Politic of EU (Facciotto et al., 2015). The need of adaptation and mitigation actions connected to global changes (carbon sequestration, bioenergy, soil erosion control) should open new prospective for agroforestry, combining bioenergy and timber production with food security and environmental safeguard. The Rural Development Plans (2014-20) are currently supporting agroforestry with direct grants and including agroforestry in the Ecological Focus Area. Following the context of previous activities (www.agforward.eu), the present work aims at: i) assessing competition and/or synergies between crops and trees; ii) to compare productivity in agroforestry and conventional agricultural systems; iii) evaluating the effects of wide tree spacing on timber quality. The research took place at Casaria Farm, Veneto Region, Italy. During the year 2015, we analysed the interrelationships in water and nitrogen uptake in young poplar and oaks plantations intercropped with sugar beet. In doing that, stable isotope techniques were used. Oxygen stable isotopes can be used as natural tracers for studying the sources of water and processes of water use by plants. Soil water is usually characterized by complex patterns of isotopic composition (?18O) along the soil profile. Both climate and hydrology influence the ?18O values of different water pools so the water table and the waters in the shallow, medium and deep soil layers usually differ in their isotopic compositions. No isotopic effects occur during water uptake by roots or during xylem transport, so that xylem water ?18O reflects a weighted average of the different water sources used by the plant. In contrast, leaf water ?18O is enriched by evaporative effects that occur during transpiration. Oxygen stable isotopes were used for elucidating the strategies of plant water use in pure and mixed systems, based on variations in oxygen isotope composition of soil profiles and plant tissue waters (Lauteri et al., 2006). We tested the hypothesis that poplar and oak trees may exploit different water pools from those used by the intercrops. Other relevant agro-ecological features of the studied systems are those related to the crop water-use efficiency (WUE) and to N fertilization and cycling. In this respect, C and N stable isotopes analyses can provide important insights in modelling agroforestry systems' efficiency and sustainability.
Inter-specific interactions on the light, water and nitrogen availaibility in a young poplar silvoarable system
Pierluigi Paris;Luca Tosi;Luca Leonardi;Marco Ciolfi;Marco Lauteri
2016
Abstract
Hybrid poplars have been intensively managed in Italy for timber production mostly as monoculture plantations. Intercropping poplar trees with arable crops and in linear plantations along field edges is also common in agroforestry systems. However, agroforestry systems sharply declined in the last decades with the rapid deployment of mono-cropping agriculture, following the support of the Common Agricultural Politic of EU (Facciotto et al., 2015). The need of adaptation and mitigation actions connected to global changes (carbon sequestration, bioenergy, soil erosion control) should open new prospective for agroforestry, combining bioenergy and timber production with food security and environmental safeguard. The Rural Development Plans (2014-20) are currently supporting agroforestry with direct grants and including agroforestry in the Ecological Focus Area. Following the context of previous activities (www.agforward.eu), the present work aims at: i) assessing competition and/or synergies between crops and trees; ii) to compare productivity in agroforestry and conventional agricultural systems; iii) evaluating the effects of wide tree spacing on timber quality. The research took place at Casaria Farm, Veneto Region, Italy. During the year 2015, we analysed the interrelationships in water and nitrogen uptake in young poplar and oaks plantations intercropped with sugar beet. In doing that, stable isotope techniques were used. Oxygen stable isotopes can be used as natural tracers for studying the sources of water and processes of water use by plants. Soil water is usually characterized by complex patterns of isotopic composition (?18O) along the soil profile. Both climate and hydrology influence the ?18O values of different water pools so the water table and the waters in the shallow, medium and deep soil layers usually differ in their isotopic compositions. No isotopic effects occur during water uptake by roots or during xylem transport, so that xylem water ?18O reflects a weighted average of the different water sources used by the plant. In contrast, leaf water ?18O is enriched by evaporative effects that occur during transpiration. Oxygen stable isotopes were used for elucidating the strategies of plant water use in pure and mixed systems, based on variations in oxygen isotope composition of soil profiles and plant tissue waters (Lauteri et al., 2006). We tested the hypothesis that poplar and oak trees may exploit different water pools from those used by the intercrops. Other relevant agro-ecological features of the studied systems are those related to the crop water-use efficiency (WUE) and to N fertilization and cycling. In this respect, C and N stable isotopes analyses can provide important insights in modelling agroforestry systems' efficiency and sustainability.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
