Open access publications in the SLU publication database

Abstract

In commercial practice, willows are propagated from dormant cuttings. Use of non-dormant propagules could reduce the establishment costs. The overall objective of this study was to assess the effects of propagule phenology (non-dormant versus dormant), planting system (cuttings versus billets) and planting time on establishment and biomass production of willows grown in controlled and field experiments. Willows are susceptible to weed competition and weeds are a major constraint in willow establishment and biomass production. The potential risk of long-lasting weed infestations in crops cultivated after willow termination is also of concern. Thus the effects of weeds on growth performance, and long-term development and floristic diversity of the weed flora in crops established after termination of a willow cultivation were investigated in controlled and field experiments.

Willow growth was significantly affected by propagule phenology, planting system, planting time, clone, and weed treatment. Non-dormant cuttings planted early in the season sprouted earlier and had similar aboveground biomass production as dormant cuttings. Willow grown from non-dormant cuttings planted later in the season had lower competitive ability than dormant cuttings. Survival was not affected by propagule phenology, but was higher for willows grown from cuttings (91%) than from billets (39%), and in weeded (69%) than in unweeded (54%) plots. More aboveground biomass was produced from dormant than non-dormant cuttings planted later in the growing season (59%), from cuttings than from billets (52%), from willows in weeded than unweeded plots (64% and 83% for the bucket and field experiment, respectively). For a given diameter, total and stem mass were larger for willows grown without than grown with weeds. Specific leaf area was higher for leaves formed on stems from non-dormant than dormant cuttings, and lower for willows grown without than with weeds. Impact of planting time and willow clone on willow performance parameters was also observed. Higher weed flora species richness, cover, diversity and composition was observed in willow than in cereal stands in the long-term field experiment.

Willow establishment costs can be reduced by using non-dormant propagules planted early in the growing season but not by using billets instead of cuttings. Higher weed flora species richness, cover, diversity and composition in willow compared with cereal stands does not impose risk of weed infestation to succeeding crop. Therefore, willow cultivations may contribute to floristic diversity within the agricultural landscape by hosting diverse weed flora, without compromising subsequent crop yields.