Selection of inter-row herbaceous covers in a sloping, organic, non-irrigated vineyard.

Inter-row vegetation in vineyards is classified as a service crop as it provides many ecosystem services. The vegetation is often removed but maintaining them can mitigate the negative effects on the environment. However, the type of species or mixture choice can affect their success. A field trial was conducted in an organically-managed vineyard of Cabernet sauvignon Vitis vinifera L. cultivars in north-eastern Italy, in which three blends of grass species (Shedonorus arundinaceus, Lolium perenne and Festuca rubra) and two grass-legume mixtures were grown in the inter-rows and compared with resident vegetation and regularly tilled bare soil. Each vegetation type, including resident vegetation, was subjected to mulching and non-mulching treatments. The aim of this study was to evaluate the use of seeded species or mixtures in the inter-row spaces of the vineyard in north-Italy as an alternative management to resident vegetation and tilled soil. The experiment was conducted over two years to monitor the persistence of the sown vegetation and the influence of vegetation types on vine performance and grape composition, and on soil compaction and erosion. The relative abundances of each species, vegetation height, percentage green cover and normalised difference vegetation index (NDVI), vine shoot length, number of leaves per vine shoot, leaf area, bunch weight, vine NDVI, soil compaction and erosion, and depth and width of tractor tyre prints were measured. Over time, weed invasion altered the botanical composition of all vegetation types except for the S. arundinaceus blend, which remained stable throughout the study period. Our results showed that vine parameters were not affected by the type of vegetation in the inter-rows, nor were there differences between the grassed and bare soil inter-rows. Soil compaction and erosion, and tractor tyre prints were not directly affected by the type of vegetation cover, but they were affected by tillage in the plots with bare soil in the inter-rows or where it was used to prepare the soil for sowing. Soil compaction and erosion were related to the percentage vegetation cover. Mulching did not affect any of the parameters measured. Therefore, species selection plays a crucial role in inter-row vegetation management and in minimising environmental impacts. S. arundinaceus gave high protection against soil erosion due to its high persistence throughout the year and had the lowest growth rate thus requiring fewer cuttings.

Event-tree analysis with imprecise probabilities.

Novel methods are proposed for dealing with event-tree analysis under imprecise probabilities, where one could measure chance or uncertainty without sharp numerical probabilities and express available evidence as upper and lower previsions (or expectations) of gambles (or bounded real functions). Sets of upper and lower previsions generate a convex set of probability distributions (or measures). Any probability distribution in this convex set should be considered in the event-tree analysis. This article focuses on the calculation of upper and lower bounds of the prevision (or the probability) of some outcome at the bottom of the event-tree. Three cases of given information/judgments on probabilities of outcomes are considered: (1) probabilities conditional to the occurrence of the event at the upper level; (2) total probabilities of occurrences, that is, not conditional to other events; (3) the combination of the previous two cases. Corresponding algorithms with imprecise probabilities under the three cases are explained and illustrated by simple examples.