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Black Pine (black + pine)
Selected AbstractsCoevolution between crossbills and black pine: the importance of competitors, forest area and resource stabilityJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2009C. W. BENKMAN Abstract Studies of predator-prey interactions have found that geographically structured coevolution has played an important role in the adaptive diversification of crossbills (Loxia spp.). We extend those studies by considering common crossbills (L. curvirostra) in the Mediterranean where they rely on seeds in the cones of black pine (Pinus nigra). On the continent, where tree squirrels (Sciurus vulgaris) are present, enhanced defenses against crossbills were most evident in larger areas of pine forest. On islands in the absence of tree squirrels, crossbills and black pine have coevolved in a predator-prey arms race on Cyprus but not Corsica. In contrast to other conifers that island endemic crossbills rely upon, black pine does not hold seeds in its cones year round. Consequently, key to the strong crossbill,pine interaction on Cyprus is likely the presence of an alternative conifer that provides seeds during early summer when black pine seeds are scarce. [source] Use of Shrubs as Nurse Plants: A New Technique for Reforestation in Mediterranean MountainsRESTORATION ECOLOGY, Issue 2 2002Jorge Castro Abstract Common techniques currently used for afforestation in the Mediterranean basin consider the pre-existing vegetation (mainly shrubs) as a source of competition for trees, and consequently it is generally eliminated before planting. Nevertheless, it has been demonstrated that woody plants can facilitate the establishment of understory seedlings in environments that, like the Mediterranean area, are characterized by a pronounced dry season. In this study, we experimentally analyze the usefulness of shrubs as nurse plants for afforestation of two native conifers, Pinus sylvestris L. (Scots pine) and Pinus nigra Arnold (black pine). Two-year-old seedlings were planted in four microhabitats: (1) open interspaces without vegetation (which is the usual method used in afforestation programs), (2) under individuals of Salvia lavandulifolia, (3) under the north side of spiny shrubs, and (4) under the south side of spiny shrubs. Pine survival was remarkably higher when planted under individuals of the shrub S. lavandulifolia (54.8% for Scots pine, 81.9% for black pine) compared with open areas (21.5% for Scots pine, 56.8% for black pine; chi square, p < 0.05). The survival of both pines was also higher when planted on the north side of spiny shrubs, although the survival on the south side was similar to that found in open areas. In addition, pine growth was not inhibited when planted in association with shrubs. This pattern appears to result from the combination of abiotic conditions imposed by the presence of a nurse shrub, which leads to improvement in seedling water status and therefore reduced summer mortality by drought. The results show that the use of shrubs as nurse plants is a technique that offers both economic and ecological advantages, in terms of savings in labor and plant material and reduced and even negligible impact on the pre-existing vegetation. [source] An Analysis of Forest Restoration 120 Years after Reforestation on Badlands in the Southwestern AlpsRESTORATION ECOLOGY, Issue 1 2002Daniel R. Vallauri Abstract We report the results of descriptive and functional analyses of a representative forest and watershed in the southwestern Alps, where the Forest Service has attempted reforestation of badlands for erosion control since 1860, relying on the non-native Pinus nigra ssp. nigra (Austrian black pine). One hundred twenty years after the first tree plantings, the plant communities are still early seral assemblages for the most part, with Austrian black pine occurring alone in the canopy. In contrast, most of the marly soils have physically recovered part of their total depth, with layers of fragmented and altered material equal to 50 cm, but their structure and chemical fertility is still poor. Autogenic soil restoration is proceeding however, largely engineered by earthworms (up to 49 individuals and 27 g/m2). Two dominant species are presumed keystone: Lumbricus terrestris and Octolasion cyaneum (Lumbricidae). The reestablishment of indigenous tree species is apparently not inhibited by site fertility or lack of nearby seed pools. We hypothesize that excessive stand density is responsible for the poor regeneration because it discourages the birds and rodents that control seed dissemination. Mortality of pines due to infestation by Viscum album subsp. austriacum (mistletoe) is creating large openings and should be specially managed. One hundred twenty years after the first plantings, the nineteenth-century vision that restoration of badlands was ecologically feasible is validated, as is the strategy to establish pioneer tree species. Here Austrian black pine acts as a nurse stand and enables the return of indigenous broad-leaved trees and a wide array of herbaceous species as well. However, our results clearly indicate that appropriate silvicultural tactics should now consist of tree thinning to promote the true restoration of native biodiversity and ecosystem functions. [source] | ||||||||||