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Most umbrella pine (Pinus pinea L.) stands are managed as agroforestry systems, whose main production is fruit, due to the edible and highly nutritious kernels, and are frequently associated to natural or seeded pastures and grazing. The stands have low density, in order to enhance crown growth and fruit production. Nevertheless, cone production, both with regard to number and weight, varies greatly between stands, trees and years. In this study were selected three agroforestry systems, representative of umbrella pine stands whose main production is fruit, and one stand representative of the timber production system, where fruit is the secondary production. It was evaluated the variability in cone production as a function of the tree's diameter at breast height and crown diameter and the individual tree's competition status. The results indicate that stands managed in agroforestry systems with lower competition and individuals with larger diameter at breast height and crown diameter tend to produce more and heavier cones per tree. The first two principal components of the principal component analysis explain 84 % of the variance in cone production, trees' dimensions and competition index. Tree competition status has a negative impact on production per tree.

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It is a fact that farmers face increasing costs on labor-intensive manual pruning of olive trees. Pruning intervals tend to be lengthened and trees are left severely pruned when fi nally the operation is performed. It is expected that such substantial reduction in the volume of the canopy may lead to a decrease in production, at least in following years until the tree has recovered. Although no precise data was found available to quantify the overall problem, it is believed that a cheaper, more mechanized, less labor-intensive technique is needed. Th ese facts justify this study.A mechanized alternative involves pruning cuts made in the tree canopy by a tractor-mounted cutting device progressing at a constant speed between the tree rows (Pastor and Humanes, 1998). Th e potential of mechanized vs. manual pruning was previously shown in long-term research by these authors. Th ey conducted rain-fed fi eld trials in a 12 by 12 m olive grove array using the Picual cultivar. Observations from 1981 to 1997 revealed similar olive yield per tree in mechanized and manual pruned trees. Th ese authors also stated the importance of occasional manual selective pruning to clear excessive wood from trees that were subjected to mechanized pruning.Pastor and Humanes (1998) also conducted rain-fed fi eld trials in a much denser olive grove of 8 by 4 m using the same cultivar.Th e objective was to compare diff erent intervals for mechanized pruning with traditional manual pruning. Observations from 1981 to 1989 revealed that in all the mechanized pruning tests, irrespective of pruning interval, olive yield per tree was similar to the yield of manual pruned trees. Th ese tests indicate that mechanized pruning does not need to occur at frequent intervals, thus it can be part of a management program that reduces costs.Pastor and Humanes (1998) also conducted fi eld trials of different pruning methods executed every 2 yr, methods included selective manual pruning, mechanical pruning, and mechanical pruning complemented by a manual clearing of excessive wood. Observations from 1989 to 1997 revealed that all the mechanized pruning treatments with or without manual complement, resulted in similar olive yield per tree which, in turn, was signifi cantly higher than the yield of manual pruned trees. Th is research emphasized the potential of mechanized pruning as well as suggesting that a selective manual complement to the mechanized pruning does not provide any further advantages. Fontanazza and Baldoni (1991) and Fontanazza (1996) put forward sequences of pruning action combining mechanized pruning and manual pruning to be performed in diff erent years.Th e potential of the sequence suggested by Fontanazza (1996) was evaluated by Camerini et al. (1999). Field trials were conducted in a rectangular array of 6 by 3 m, 8 yr-old olive grove of the Frantoio and Leccino cultivars, trained as "monocone". Th e sequence started by hedging both sides of the tree in the fi rst year, no cut in the second year, followed by manual pruning in the third y...

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