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Investigation of the invasion of Prosopis juliflora and its effects on indigenous plant species are important for the control of the species. The study aimed to assess: (1) the effects of Prosopis juliflora invasion on the diversity of plant species in Awash Fentale and Amibara Woredas; (2) the effects of Prosopis juliflora invasion on the regeneration potential of native woody species. Sample collection was performed in habitats of Prosopis juliflora thicket, Prosopis juliflora mixed with native species stands, non-invaded woodlands, and open grazing lands. The vegetation was stratified into invasion levels of Prosopis juliflora and then a random sampling technique for data collection. Among species of plants, the highest proportion of species, 75 (47.8%), was recorded under non-invaded woodlands, but the lowest proportion of species, 22 (14%), was recorded under open grazing lands. The invasion of Prosopis juliflora reduced the Shannon diversity index. The mean values of the Shannon diversity index and species richness under Prosopis juliflora mixed with native species (H′=2.22, R=14) and non-invaded woodlands (H′=2.23, R=13) were significantly higher than Prosopis juliflora thicket (H′=1.96, R=12) and open grazing lands (H′=1.84, R=10). The highest total density (358 stems ha?1) of seedlings was recorded under Prosopis juliflora mixed with native species. But, the lowest total density (153 stems ha?1) of seedlings was recorded under Prosopis juliflora thickets. Moreover, 102 trees ha?1 native woody species were recorded under Prosopis juliflora thicket, but 1252 trees ha?1 native species were recorded under non-invaded woodlands. If the invasion of Prosopis juliflora and its effects on native species diversity continue coupled with a drier climate, plant diversity of the Afar flora region will be highly affected and its ecosystem services will be under question. Thus, the participation of all stakeholders and multidisciplinary research approaches should be designed for the management of the species and rehabilitation of the rangelands in the region. 相似文献
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Javier Caraveo‐Patiño Yiqun Wang Luis A. Soto Kebreab Ghebremeskel Catherine Lehane Michael A. Crawford 《Marine Ecology》2009,30(4):437-447
The radiation of the mammalian land species that became the baleen whales happened about 27–34 Mya. Mammals require omega 6 fatty acids for reproduction. With this long exposure to the omega 3‐rich marine food chain, the Gray whale (Eschrichtius robustus) might be expected to have lost its requirement for omega 6 fatty acids. We report an unexpectedly high content of omega 6 arachidonic acid (ArA) in the Gray whale liver and muscle lipids. This whale migrates 10,000 km from the cold polar, omega 3 oil‐rich food chain to that of the breeding lagoons of the tropical waters. The food web of tropical waters is a source of omega 6 fatty acids, which are hardly present in the cold polar food web. We suggest the reason for this longest of migrations from cold to warm waters is to meet the requirement for omega 6 fatty acids for mammalian reproduction and brain growth. This extreme conservation of omega 6 fatty acids in Gray whale biology has critical implications for mammalian biology and especially for whale conservation. 相似文献
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Berhe Goitom Clive Oppenheimer James O. S. Hammond Raphaël Grandin Talfan Barnie Amy Donovan Ghebrebrhan Ogubazghi Ermias Yohannes Goitom Kibrom J- Michael Kendall Simon A. Carn David Fee Christine Sealing Derek Keir Atalay Ayele Jon Blundy Joanna Hamlyn Tim Wright Seife Berhe 《Bulletin of Volcanology》2015,77(10):1-21
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