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Enhancement of diversity,stand structure and regeneration of woody species through area exclosure:the case of a mopane woodland in northern Botswana

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Ecological Processes 2018年第1期7卷 41-55页

作者： Demel Teketay Keotshephile Kashe Joseph Madome Monica Kabelo John Neelo Mmusi Mmusi Wellington Masamba Department of Crop Science and Production Botswana University of Agriculture and Natural ResourcesPrivate Bag 0027GaboroneBotswana University of Botswana Okavango Research InstitutePrivate Bag 285MaunBotswana

Introduction:An area exclosure is the practice of land management that involves the exclusion of livestock and humans from openly accessing an area that is characterized by severe *** exclosures have been employed as cheap and convenient means of rehabilitating degraded forests/woodlands.A study was carried out to(i)assess the species richness,diversity and evenness;(ii)determine the densities,frequencies,dominance and importance value index;and(iii)assess the population structure and regeneration status of woody species inside and outside the fence(area exclosure)of Okavango Research Institute(ORI)located in Maun,northern ***:Thirty-five woody species were recorded inside(32 spp.)and outside(24 spp.)the ORI compound,and the population structure and regeneration status of the woody species were better inside than outside the ORI *** exclosure had seven times higher mean density of woody species than outside ORI,and an exceptional regeneration of seedlings was observed inside than outside the ORI compound,suggesting the process of recovery of the degraded *** frequencies of more than half of the woody species also showed increment inside than outside the *** results suggest that the exclosed area is still in an initial recovery stage since it had been an open grazing area prior to the establishment of the *** of the woody species encountered outside ORI showed hampered recruitment and regeneration,owing to different anthropogenic impacts and overgrazing by ***:Despite the relatively short period(10 years)of exclosure establishment,results from the present study have further provided empirical evidences on the actual crucial roles played by area exclosures to increase woody species richness,diversity,evenness,density,frequency,dominance and important value index as well as enhance the population structure and regeneration of the woody species in northern *** research is recomm

关键词： Frequency Density important value index Maun Population structure Species richness

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Effect of exclosure ages on woody plant structure,diversity and regeneration potential in the western Tigray region of Ethiopia

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Journal of Forestry Research 2018年第3期29卷 693-703页

作者： Tsegay Gebregerges Zewdu K.Tessema Emiru Birhane Shire-Maytsebri Agricultural Research Center PO Box 81ShireEthiopia Rangeland Ecology and Biodiversity Program School of Animal and Range SciencesCollege of Agriculture and Environmental SciencesHaramaya UniversityPO Box 138Dire DawaEthiopia Department of Land Resources Management and Environmental Protection College of Dryland Agriculture and Natural ResourcesMekelle UniversityPO Box 390MekelleEthiopia Department of Ecology and Natural Resource Management Norwegian University of Life SciencesPO Box 50031432 AsNorway

Exclosure is a method of rehabilitating degraded lands by protecting them from the interference of animals and from human encroachment, and is used to regenerate native vegetation as a way to reduce soil erosion, increase rain water infiltration and provide fodder and woody biomass in degraded grazing lands. Therefore, we studied woody plant structure, diversity and regeneration potentials in 5-and 10-year grazing exclosures in comparison with open grazed sites in a semi-arid environment. Data on species diversity, abundance, structure, basal area, frequency, density, and regeneration status were collected from 270 sample plots. Forty-one woody species representing 20 families were identified, with 18, 28 and 38 species found in open grazed areas, and in 5-and 10-year grazing exclosures, respectively. The 10-year grazing exclosures had a higher(P <0.05) species richness and plant densities compared to the 5-year grazing exclosures and the open grazed areas. The population structure and regeneration status of woody species in both grazing exclosures showed an inverted J-shape, indicating a healthy regeneration status, whereas hampered regeneration was observed in open grazed areas. The establishment of grazing exclosures had positive effects in restoring woody plant diversity and improving vegetation structure and regeneration potentials of degraded grazing lands.

关键词： Basal area Diversity important value index Population structure Regeneration status Species composition Exclosures

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Potential of exclosure on aboveground biomass carbon stock and ecological fitness of woody species in Jabi Tehnane district, northwestern Ethiopia

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Ecosystem Health and Sustainability 2019年第1期5卷 79-85,I0017页

作者： Melkamu Terefe Asmare Abdella Gure Jimma Center Ethiopian Environment and Forest Research InstituteJimmaSouth West Ethiopia Wondo Genet College of Forestry and Natural Resources Hawassa UniversityShashemenEthiopia

Assessment of ecological fitness of woody species across land use is critical issues in degraded land ***,little is known about AGBC stored capacity,important value and distribution index of woody species grows in exclosure and adjacent open ***,this research is aimed to(i)analyse impact of exclosure on AGBC(ii)ecological fit species.A random sampling method was *** sample plots(50m*50m)were *** stocks(mean±SE)of woody species in adjacent open grazing and exclosure land use of GW site was 0.11±0.07 and 1.24±0.27Mg ha^(-1) *** in adjacent open grazing and exclosure land use of WG site,the value was 0.27±0.03 and 2.79±0.27Mgha^(-1) *** both site exclosure land uses,the proportion of rare,occasional and common woody species were better than their adjacent open grazing *** lustanica from open grazing and Vernonia auriculifera from exclosure land use of WG as well as Croton macrostachyus from open grazing and Leucaena leucocephala fromexclosure land use of GWsite were recorded as top ecologically fit *** is recommended to protect degraded lands via integrating ecologically adapted native species and fully used their diversity to achieve the potential benefits of land restoration.

关键词： Aboveground biomass carbon distribution index exclosure important value index

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Changes in tree species diversity and dominance across a disturbance gradient in Nepalese Sal (Shorea robusta Gaertn. f.) forests

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Journal of Forestry Research 2010年第1期21卷 25-32,I0001,I0002页

作者： Indra Prasad Sapkota Mulualem Tigabu Per Christer Odén Swedish University of Agricultural Sciences Southern Swedish Forest Research Centre Tropical Silviculture and Seed Science Group

Disturbance is often touted as a management tool, as moderate disturbance is believed to enhance diversity; thus an understanding of frequent and fluctuating disturbance regimes in forests and their effects on stand structure, dominance and diversity is very crucial. Here, the effects of different disturbance regimes, along a gradient, on diversity and dominance of five Shorea robusta Gaertn. f.-dominated forests were investigated in 25 one-ha plots in Nepal. A total of 67 tree species were recorded; of which 41 species were encountered in least disturbed and 10 species in beavily disturbed forest. Significant variations among forests were observed for all measures of alpha diversity. Alpha diversity measures declined linearly along a disturbance gradient while dominance increased linearly. Relative basal area of S. robusta increased as the level of disturbance increased, which in turn produced more than two-fold higher important value index in heavily disturbed forest than the least disturbed forest. All alpha diversity measures declined in an order of three with increasing relative basal area of S. robusta. The similarity in species composition between each pair of disturbed forests was generally low （Jaccard＇s similarity index 〈 57%）, suggesting a higher Beta diversity, It can be concluded that diversity of Sal forests declines with increasing magnitude of disturbance, which in turn favors a higher domi- nance of S. robusta. Controlling the population of the dominant species, mainly S. robusta, is recommended to enhance diversity and to achieve multiple-use forest management objectives.

关键词： Human pressure disturbance ecology species richness alpha diversity important value index

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