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41.
Plant species diversity of homegardens of Cuba and its significance for household food supply 总被引:3,自引:0,他引:3
The cultivation of different plants in homegardens for self-sufficiency has a long tradition in Cuba, but knowledge about homegardens in Cuba is small. To analyse this more deeply, cultivated plants of 31 homegardens were surveyed in three villages in eastern Cuba in 2001. Two of the study villages were located in a humid area with an annual precipitation of about 2200 mm. The third village was situated in a semiarid area with about 450 mm precipitation. The plants studied in the homegardens included those for human consumption such as fruits, vegetables, tubers and cereals as well as spices and medicinal plants. In total, 101 different plant species were found with an average number of 18 to 24 species per homegarden for the three villages. A broad range of species was found in all villages, because irrigation is used under semiarid conditions, which lead to a relative high similarity in species composition between the villages. But, also differences due to the climatic situation became evident, particularly with the medicinal plants. In general, homegarden production provided a broad and diverse basis for self-sufficiency of the households. Although homegarden production showed to be only a small source of income, it is particularly important because of low-paid outside work and minimal food provision of the state.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
42.
We examined patterns of variation in richness, diversity, and composition of understory vascular plant communities in mixedwood boreal forests of varying composition (broadleaf, mixedwood, conifer) in Alberta, Canada, before and for 2 years following variable-retention harvesting (clearcut, 20 and 75% dispersed green tree retention, control). Broadleaf-dominated forests differed from mixedwood or conifer-dominated forests in that they had greater canopy cover, litter depth, soil nitrogen, warmer soils, as well as greater shrub cover, herb and shrub richness and diversity (plot scale). In contrast, conifer, and to a lesser extent mixedwood, forest had greater β diversity than broadleaf forest. Overall, mixedwood and conifer forests were similar to one another, both differed from broadleaf forest. Several species were found to be significant indicators of broadleaf forest but most of these also occurred in the other forest types. Understory composition was related to canopy composition and edaphic conditions. Variable-retention harvesting had little effect on understory cover, richness, or diversity but resulted in reduced richness and β diversity at a larger scale. The clearcut and 20% treatments affected composition in all forest types. Early successional species and those common in disturbed sites were indicators of harvesting while evergreen, shade-tolerant understory herbs were indicators of the control forest and 75% retention harvest. We conclude that it is important to maintain a range of variation in canopy composition of mixedwood forests in order to conserve the associated understory communities. The presence of conifers in these forests has a particularly important influence on understory communities. The threshold for a lifeboat effect of variable-retention harvesting is between 20 and 75% retention. Examination of richness and β diversity at a variety of scales can provide interesting information on effects of harvesting on spatial reorganization and homogenization of understory plant communities. 相似文献
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After investigating and studying the vegetation, we have established that Makehe Forest, in Sanjiangyuan Nature Reserve, Qinghai
Province, is host to a total of 364 different species, representing 173 “genera” in 55 different vegetative families. We propose
five quantifiable indices for evaluating the level of threat to these plants: 1) the distribution frequency of the “line transect”;
2) the distribution frequency of sample plots; 3) the distribution density inside sample plots; 4) the existing abundance
in the forest region; and 5) plant fidelity. The results show that there are two endangered species, six vulnerable species,
12 nearly threatened species and 344 safe species. The study tried to evaluate the urgency for conserving these plants, according
to coefficients of closeness to disappearance, of genetic loss and of usefulness. Results also showed that the number of species
of primary concern is two; of secondary concern, nine; of the third level, 23; and of least concern, 330 species.
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Translated from Journal of Beijing Forestry University, 2006, 28(3): 20–25 [译自: 北京林业大学学报] 相似文献
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Green stem cuttings, obtained from 2-year old managed stockplants, with 30, 50 or 100% leaf area were rooted in a non-mist propagator following treatment with 0, 0.2, 0.4 or 0.8% IBA solution. The rooted cuttings were transferred to polythene pots and grown in a nursery for 12 weeks. Rooting percentages of IBA treated cuttings did not significantly differ from those of control cuttings. Likewise leaf area did not significantly influence the percentage of cuttings that rooted. The effects of leaf area and/or IBA treatment in the propagation unit were manifested on the growth of rooted cuttings in polythene pots. Number of roots increased with the increase in IBA concentration and this response was enhanced by increasing leaf area. Root biomass increased with the increase in leaf area even in the control cuttings. Root development was highly influenced by the leaf area and IBA, and hence the growth of rooted cuttings. Cuttings treated with 0.2 or 0.4% IBA at 100% leaf area yielded the best performing rooted cuttings. 相似文献
48.
回顾了从外省和国外引入云南的经济植物,说明由于云南特殊的地理、气候及生物多样性对不同引种植物造成不同的试种结果、发展状况及出现的问题。从而指出在云南高生物多样性森林生态系统条件下,引入外地经济植物种植的有效利用是树种或品种(品系)与当地多样性的适合性配置;可持续发展的种植方式是植物种或品种(品系)的单位种植面积不宜过大,以多种块状混交为宜;减小风险的方式是经10~12年以上的多点种植考验和控制单一种种植比例;发展当地树种风险小,但要保护好当地的生物多样性。 相似文献
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腾冲北海湿地动植物资源及其环境状况评价 总被引:2,自引:0,他引:2
云南腾冲北海湿地为中国西南唯一的高原火山堰塞湖,是云南省典型的高原自然永久性浅水湖和沼泽,景观独特,属"漂浮状苔草沼泽湿地"。在北海湿地16 29km2的狭小区域内,湿地植被类型丰富,物种多样性程度高,有重要的国家级水生保护植物5种、国家级保护树种达9种;28种鸟类被分别列入国家和全球的重要鸟类保护名录。由于过去不合理的"围湖造田"和过度的森林砍伐,加之外来有害物种的不断侵入,导致北海湿地生态系统功能降低,生物多样性流失严重,本文通过对北海湿地的资源与环境状况进行分析评价,提出了相应的保护措施与发展策略。 相似文献