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Birds play vital roles as seed dispersers helping to maintain and restore plant communities. With restoration increasingly key to global conservation, it is important to understand the landscape attributes and bird community characteristics that most influence avian seed dispersal in human-altered landscapes. We examined bird community structure and seed-dispersal patterns in agricultural countryside in Costa Rica that is typical of much of the Neotropics. Contrary to expectations, bird abundance, not richness, best predicted the richness of bird-dispersed seeds. Neither forest patch size or proximity, nor total tree cover, influenced seed dispersal. The richness and abundance of dispersed seeds, however, was strongly correlated with “wetness,” a remotely-sensed metric of vegetation, at several scales. These results suggest that in this human-dominated tropical region: (1) bird abundance, not species richness or size, may drive seed dispersal, and (2) remote-sensing combined with field verification can detect landscape elements that are helpful for maintaining the option of bird-mediated reforestation. 相似文献
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Jon D. Unruh 《Agroforestry Systems》1990,11(2):175-197
Fallow utilization schemes are becoming increasingly popular in agroforestry designs. However little attention has been given to the fate of valuable fallow plants after the end of the initial fallow cycle, and over successive fallow cycles on a regional or inter-fallow level. Evidence is presented here for the spontaneous long-term community enrichment of an area with valuable plants in a cyclic or iterative fashion, in the context of an existing fallow utilization scheme in the Amazon. Review of the ecological processes which operate at microsite, field and community levels indicate that:
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a. | Due to valuable plants left uncut in the swidden, seeds from valuable species are better able to survive the burn, and may experience a favored germination and establishment because of reduced competition, enhanced fertility of the young swidden, nutrient input from litterfall, and reduced soil temperatures and soil moisture evaporation. |
b. | The much greater frequency of suitable germination and establishment sites in and around canopy gaps created by management practices during the fallow cycle interacts with a spatial and temporal distribution of fruit trees which may encourage a specific optimal foraging strategy among large numbers of frugivores. The net effect of this interaction would be to decrease competition for, and increase efficiency of, seed dispersal into the large number of available establishment sites. |
c. | A greater opportunity for frugivore generated seed shadows exist in managed fallows due to the larger number of trails in and around these sites, which are used as flyways. |
d. | A presence of the more efficient specialist fruit tree seed dispersal strategy in managed fallows — as opposed to the opportunist strategy — which produces patterns of seed dispersal more beneficial to the plant, and may have a longer more evenly spread fruiting season; which, along with relatively large numbers of trees would encourage frugivores to camp out on the resource, depositing seeds nearby. |
e. | The existence of relict plant species that reflect pre-historic forest management which has led to long term and persistent effects on forest tree species composition. |
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During a mast‐fruiting event we investigated spatial variability in fruit availability, consumption, and seed removal at two sympatric tree species, Manilkara bidentata and M. huberi (Sapotaceae) at Nouragues Natural Reserve, French Guiana. We addressed the question of how Manilkara density and fruits at the community level might be major causes of variability in feeding assemblages between tree species. We thus explored how the frugivore assemblages differed between forest patches with contrasting relative Manilkara density and fruiting context. During the daytime, Alouatta seniculus was more often observed in M. huberi crowns at Petit Plateau (PP) with the greatest density of Manilkara spp. and the lowest fruit diversity and availability, whereas Cebus apella and Saguinus midas were more often observed in M. bidentata crowns at both Grand Plateau (GP), with a lowest density of M. bidentata and overall greater fruit supply, and PP. Overall, nearly 53% and 15% of the M. bidentata seed crop at GP and PP, respectively, and about 47% of the M. huberi seed crop were removed, otherwise either spit out or defecated beneath trees, or dropped in fruits. Small‐bodied primates concentrated fallen seeds beneath parent trees while large‐bodied primate species removed and dispersed more seeds away from parents. However, among the latter, satiated A. seniculus wasted seeds under conspecific trees at PP. Variations in feeding assemblages, seed removal rates and fates possibly reflected interactions with extra‐generic fruit species at the community level, according to feeding choice, habitat preferences and ranging patterns of primate species. 相似文献
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动物取食和扩散森林植物种实研究进展 总被引:1,自引:0,他引:1
动物取食扩散森林植物种实作为森林生态系统中植物和动物联系的一个重要方面,不仅是联系母株与其子代幼苗的重要桥梁,也是植物生活史中的一个重要阶段。文中综述了近年来关于动物取食森林植物种实及其与这些植物种子散布、萌发、幼苗生长和种群扩展等方面关系的研究成果。动物在取食和破坏森林植物种实的同时也将这些植物的种子扩散到一个新的生境斑块,其消化道机械的或化学的作用提高了这些森林植物的种子萌发率和萌发进程,促进了其早期定居和种群扩大。动物对森林植物的这种作用具有长期性,形成特定动植物间或多物种间的协同进化。近年来,森林生态系统受到了严重的干扰和破坏,可能会因为干扰了森林植物种实的动物散布者而影响森林植物种群的扩展。 相似文献
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