. Protéger et améliorer les forêts et les pâturages de l'Amérique : 1986 Réalisations de recherche. Les forêts et la foresterie United States ; Parcours United States. Site où des vergers à graines et comment déployer suffisamment de semences de graines sont essentielles pour le reboisement. La recherche dans le sud de la station a montré que la production de semences peut être considérablement augmentée par la localisation des vergers à graines de pin dans les climats chauds. Problèmes avec la phénologie de reproduction, toutefois, peut limiter le transfert dans les climats subtropicaux. La recherche se poursuit sur la question de savoir si "after effects" de la production de semences- changements persistent après

• Contributeur: The Book Worm / Alamy Banque D'Images
• ID de l’image: RF3T7E
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• Dimensions: 1625 x 1538 px | 27,5 x 26 cm | 10,8 x 10,3 inches | 150dpi

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. Protecting and enhancing America's forests and rangelands : 1986 research accomplishments. Forests and forestry United States; Rangelands United States. Where To Site Seed Orchards and How To Deploy Seed Sufficient seed supplies are critical to reforestation. Research in the Southern Station has shown that seed production can be greatly increased by locating pine seed orchards in warmer climates. Problems with reproductive phenology, however, may limit transfer into subtropical climates. Research is continuing on whether "after effects" of the seed- production climate persist after seedlings are planted in cooler locations. The photograph shows an abundant cone crop harvested from a grafted Virginia pine tree planted in south Mississippi (450 miles southwest of its origin). This seed will be planted at more northern sites, and seedling progress will be closely monitored. As increasing quantities of genetically improved seed are available from seed orchards, forest managers need to make informed decisions about deploying this material. The challenge is to maintain genetic diversity in commercial forests while at the same time seizing opportunities for greater yields through the use of genetically improved stock. If seeds harvested from seed orchards are collected by family and sown separately in the nursery, forest managers can plant stands with mixtures of desirable genotypes, on the basis of fiber- yield capacity or other traits of interest to the manager. By varying the timing and spatial patterns of genetic groups, almost any pattern of genetic diversity could be achieved with either pure or mixed stands. Also, different management regimes can be tailored to match the requirements of the planted genetic material.. This Virginia pine produced a substantial cone crop despite being planted in southern Mississippi, 450 miles southwest of its origin. 75. Please note that these images are extracted from scanned page images that may have been digitally enhan

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