Eulophia angolensis is an endangered plant species found in the Okavango Delta. Generally, there is lack of botanical information on this species in Botswana, which is necessary for its in-situ and ex-situ conservatio...Eulophia angolensis is an endangered plant species found in the Okavango Delta. Generally, there is lack of botanical information on this species in Botswana, which is necessary for its in-situ and ex-situ conservation. The objectives of this research are to map areas where E. angolensis occurs, determine the species that co-exist with it, and establish soil factors that influence its abundance and distribution in the Okavango Delta. A survey of the area where the plant was sighted in 2004 was carried out using recorded GPS points. Soil samples were collected at 0 - 20 cm depth from the floodplain where the species occurred to determine the macronutrients: total nitrogen, phosphorus, potassium (N, P, and K) and soil organic carbon (SOC) contents. The researchers could not find the plant at all GPS locations where the plant was sighted in 2004, but discovered a new unrecorded site for the species. The species was very close to the water channel;approximately 40 cm away, with only one plant about 60 cm away. The mean macronutrients concentrations in the site that contained E. angolensis were total N = 2.61 ± 0.61 mg/L, P = 7.02 ± 0.8 mg/L and K = 14.41 ± 4.28 mg/L. SOC concentration was 40.1 ± 10.28 mg/L. Furthermore, there was K biogeochemical gradient within the E. angolensis habitat, with more concentrations directly around the plant. Therefore, E. angolensis needs critical amounts of N, P, K and SOC, with K, SOC and water requirement being the crucial factors. Frequent monitoring of the endangered species found in the Okavango Delta is required, and ex-situ conservation of the species in the country in the form of a botanical garden should be established for future generations.展开更多
Production of energy crops is perceived as a potential source of alternative energy for petroleum oil. However, it is cru-cial to ensure that there is adequate land and water available for production of energy crops b...Production of energy crops is perceived as a potential source of alternative energy for petroleum oil. However, it is cru-cial to ensure that there is adequate land and water available for production of energy crops before indulging into the business of producing such crops. This paper assesses the availability of land and water resources for production of energy crops in the SADC region using landuse/landcover data, hydrological and meteorological data, as well as socioeconomic data. It is found that Botswana and Mozambique have large amounts of bushland that can be used for expansion of agricultural land including production of energy crops. Zimbabwe has the highest amount of land under cultivation, which makes it difficult for the country to expand its agricultural land. However, land reform processes taking place in Zimbabwe provides a good opportunity to diversify agricultural production including reallocation of farms for production of energy crops. Mozambique has favorable rainfall for production of maize and sugarcane, whereas Zimbabwe can explore growing Jatropha on degraded land and use irrigation for cultivation of sugarcane. High frequency of crop failure in Botswana makes it difficult to grow maize or sugarcane as energy crop. The country can promote production of sweet sorghum, which is traditionally grown by small scale farmers, and explore production of Jatropha in degraded and desert land. A regional approach to address land and water requirements for production of energy crops is considered important as compared to planning for production in each country as the constraints and potential of each country can be fully recognized. More detailed country specific research is needed on the production of the specified energy crops to ensure sustainability of the production systems.展开更多
文摘Eulophia angolensis is an endangered plant species found in the Okavango Delta. Generally, there is lack of botanical information on this species in Botswana, which is necessary for its in-situ and ex-situ conservation. The objectives of this research are to map areas where E. angolensis occurs, determine the species that co-exist with it, and establish soil factors that influence its abundance and distribution in the Okavango Delta. A survey of the area where the plant was sighted in 2004 was carried out using recorded GPS points. Soil samples were collected at 0 - 20 cm depth from the floodplain where the species occurred to determine the macronutrients: total nitrogen, phosphorus, potassium (N, P, and K) and soil organic carbon (SOC) contents. The researchers could not find the plant at all GPS locations where the plant was sighted in 2004, but discovered a new unrecorded site for the species. The species was very close to the water channel;approximately 40 cm away, with only one plant about 60 cm away. The mean macronutrients concentrations in the site that contained E. angolensis were total N = 2.61 ± 0.61 mg/L, P = 7.02 ± 0.8 mg/L and K = 14.41 ± 4.28 mg/L. SOC concentration was 40.1 ± 10.28 mg/L. Furthermore, there was K biogeochemical gradient within the E. angolensis habitat, with more concentrations directly around the plant. Therefore, E. angolensis needs critical amounts of N, P, K and SOC, with K, SOC and water requirement being the crucial factors. Frequent monitoring of the endangered species found in the Okavango Delta is required, and ex-situ conservation of the species in the country in the form of a botanical garden should be established for future generations.
文摘Production of energy crops is perceived as a potential source of alternative energy for petroleum oil. However, it is cru-cial to ensure that there is adequate land and water available for production of energy crops before indulging into the business of producing such crops. This paper assesses the availability of land and water resources for production of energy crops in the SADC region using landuse/landcover data, hydrological and meteorological data, as well as socioeconomic data. It is found that Botswana and Mozambique have large amounts of bushland that can be used for expansion of agricultural land including production of energy crops. Zimbabwe has the highest amount of land under cultivation, which makes it difficult for the country to expand its agricultural land. However, land reform processes taking place in Zimbabwe provides a good opportunity to diversify agricultural production including reallocation of farms for production of energy crops. Mozambique has favorable rainfall for production of maize and sugarcane, whereas Zimbabwe can explore growing Jatropha on degraded land and use irrigation for cultivation of sugarcane. High frequency of crop failure in Botswana makes it difficult to grow maize or sugarcane as energy crop. The country can promote production of sweet sorghum, which is traditionally grown by small scale farmers, and explore production of Jatropha in degraded and desert land. A regional approach to address land and water requirements for production of energy crops is considered important as compared to planning for production in each country as the constraints and potential of each country can be fully recognized. More detailed country specific research is needed on the production of the specified energy crops to ensure sustainability of the production systems.
