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Nematode distribution in cultivated and undisturbed soils of Guinea Savannah and semi-deciduous Forest zones of Ghana

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Geoscience Frontiers 2019年第2期10卷 381-387页

作者： Obed Asiedu Charles Kodia Kwoseh Haddish Melakeberhan Thomas Adjei-Gyapong Kwame Nkrumah University of Science and Technology Michigan State University

Climate change affects air temperature, sea levels as well as the soil and its ecosystem. The Guinea Savannah and semi-deciduous Forest zones of Ghana are characterized by different climatic conditions and vegetative cover. Annual average temperature has been steadily increasing whilst annual total rainfall has been decreasing in both zones, and this has been causing a southward shift of the Savannah into the Forest zone. Soil organisms provide crucial ecosystem services which are required for sustainable agriculture and food production yet crop cultivation disturbs the soil ecosystem. The harsh conditions associated with the Savannah further expose the soil ecosystem to disturbance and loss of biodiversity which threatens food production and security. Soil nematodes are the most abundant animals in the soil and play a central and critical role in the soil food web complex. Studying the nematode community structure gives a reflection of the status of the entire soil ecosystem. Soil samples were taken from cultivated and natural landscapes in the Guinea Savannah and semi-deciduous Forest agroecological zones to analyse the nematode community. Results from the study showed the Guinea Savannah zone recording warmer soil temperatures, lower organic matter percentage and lower nematode diversity(Genus Richness) as compared to the semi-deciduous Forest zone. If the Savannah continues to shift southward, the Forest zone soil ecosystem risks disturbance and loss of biodiversity due to the harsh Savannah conditions. Our findings indicate that prevailing crop cultivation practices also disturb soil ecosystem in the two ecological zones which span across West Africa. A disturbed soil ecosystem endangers the future of food production and food security.

关键词： Climate change Guinea Savannah semi-deciduous Forest Soil temperature Soil nematode diversity

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Natural Regeneration Dynamics of Tree Seedlings on Skid Trails and Tree Gaps Following Selective Logging in a Tropical Moist semi-deciduous Forest in Ghana

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Open Journal of Forestry 2014年第1期4卷 49-57页

作者： Akwasi Duah-Gyamfi Boateng Kyereh Kwame A. Adam Victor K. Agyeman Michael D. Swaine Faculty of Renewable Natural Resources Kwame Nkrumah University of Science and Technology Kumasi Ghana Forestry Research Institute of Ghana Council for Scientific and Industrial Research Kumasi Ghana Ghana Timber Millers Organization Kumasi Ghana Institute of Biological and Environmental Sciences University of Aberdeen Aberdeen UK

One of the main threats to the sustainability of timber production in naturally managed forests in Ghana is insufficient regeneration of timber tree species. This study assessed regeneration success of a logged forest by comparing the species composition, diversity, density, recruitment, mortality, and growth of naturally established seedlings in 160 seedling plot samples of 50 m2 located randomly on main skid trails, secondary skid trails, felled tree gaps and unlogged parts of the same forest. The study was done within a 134-ha compartment in a selectively logged moist semi-deciduous forest in Ghana over a period of 33 months involving four enumerations. Seedlings population was initially dominated by pioneers, but after 33 months, population in all sites was dominated by non-pioneers. Seedling densities showed an increase initially in all the sites after logging, but declined after 10 months. The high seedling densities were driven by four (Albizia zygia, Ceiba pentandra, Celtis mildbraedii and Turreanthus africanus) out of the 37 species that regenerated. All four species exhibited a period of exceptionally high new seedling recruitment in the first 10 months. Diversity differed significantly among disturbance types initially, but after 33 months diversity was lower in the unlogged areas though not significant. Seedling mortality was initially greater in unlogged areas of the forest and growth rates higher in the logged areas. These results show that disturbed areas appear to be suitable sites for the regeneration of timber species following logging, although the long-term fate of trees growing on these areas remains uncertain as growth rates declined with time.

关键词： Disturbance Forest Succession Ghana Logging Regeneration Tropical Moist semi-deciduous Forest

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Wood density and carbon concentration of coarse woody debris in native forests,Brazil

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Forest Ecosystems 2019年第2期6卷 149-158页

作者： Andrea B.Moreira Timothy G.Gregoire Hilton Thadeu Z.do Couto Department of Forestry Sciences-Luiz de Queiroz College of Agriculture(ESALQ)-University of Sao Paulo(USP) Rua Pádua Dias11-13418-900PiracicabaSPBrazil School of Forestry&Environmental Studies Yale University06511 New HavenCTUSA

Background: With the objective of increasing knowledge on biomass and carbon stocks, and thus improving the accuracy of published estimates, the present study explored wood density and carbon concentration of coarse woody debris (diameter≥10) by decay class in a Seasonal semi-deciduous Forest (SSF) area in the Atlantic Rain Forest and in a Cerrado sensu-stricto (CSS) area (Brazilian savanna), in Brazil. Two strata were identified in each area and ten sampling units were systematic located in each stratum. Data were collected according to the line intersect sampling method. Each tallied element, the diameter, length, and perpendicular width were recorded at the transect intersection point. Each element was classified into a decay class, and the species was identified when possible. Sample discs were cut from each element, from which cylindrical samples were extracted and oven-dried to determine density. These cylinders were milled and analyzed using a LECO-C632 to determine carbon concentration as percentage of mass. Results: In both areas, wood density decreased as the decay class increased. For SSF the mean carbon concentration of all analyzed samples was 49.8% with a standard deviation of 3.3, with a range of 27.9–57.0% across 506 observations. For CSS the general mean was 49.6% with a standard deviation of 2.6, with a range of 31.2–54.5% over 182 observations. Carbon concentration barely change between decay classes. Carbon stock was estimated at 3.3 and 0.7 MgC/ha for the SSF and the CSS, respectively. Similar results were obtained when using a 50% conversion constant. Conclusions: The present study concludes that wood density decreases as the woody debris becomes more decomposed, a pattern found in many previous studies. The carbon concentration, however, barely changes between decay classes, and that result is consistent with most of the literature reviewed. Our carbon concentrations are very close to the 50% used most commonly as a conversion factor. We stron

关键词： Carbon concentration Wood density Coarse woody debris Seasonal semi-deciduous forest Brazilian savanna

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