The distribution and regeneration of Boswellia papyrifera (Del.) Hochst. in Eritrea

Boswellia papyrifera (Del.) Hochst. is a deciduous gum-producing multipurpose perennial tree species growing in Sudanian and Sahelian regions. The tree is tapped on the stem for oleo-gum called olibanum (true frankincense). Land clearing for agriculture and un-regulated grazing are threatening the future of the natural Boswellia woodlands in Eritrea. Against this background, a study was carried out to investigate the distribution of the species and the factors determining its distribution in Eritrea, to study the structure and dynamics of Boswellia populations, including the natural regeneration, and to identify the factors causing the decline of Boswellia woodlands and measures which can reverse this situation. At macro-level, the distribution of the species was found to be limited to the southwestern and southern parts of the country between 800-1850 m altitude receiving a mean annual rainfall of 375-700 mm with a dependable length of growing period of 45-100 days. At micro-level, the abundance and distribution of the species was found to be affected in order of importance by altitude, land use intensity, soil organic matter, and to a lesser extent by silt and pH. Tree development studies showed that trees in the lowlands were twice as high as those in the highlands. The most important outcome of the population structure study is the lack of regeneration. Out of five areas investigated regeneration was only found at two sites where trees were not tapped and which were not accessible to livestock. Further research showed that the present system of intensive annual tapping throughout the dry season leads to low production of non-viable seeds and that where viable seeds are produced, seedlings and saplings are usually destroyed by livestock. Establishment of enclosures in which tapping and grazing is not allowed were found to be an effective measure to promote natural regeneration. Further research is needed to refine this system and to investigate the feasibility of replanting former Boswellia areas.</p

Realising the European network of biodosimetry: RENEB-status quo

Creating a sustainable network in biological and retrospective dosimetry that involves a large number of experienced laboratories throughout the European Union (EU) will significantly improve the accident and emergency response capabilities in case of a large-scale radiological emergency. A well-organised cooperative action involving EU laboratories will offer the best chance for fast and trustworthy dose assessments that are urgently needed in an emergency situation. To this end, the EC supports the establishment of a European network in biological dosimetry (RENEB). The RENEB project started in January 2012 involving cooperation of 23 organisations from 16 European countries. The purpose of RENEB is to increase the biodosimetry capacities in case of large-scale radiological emergency scenarios. The progress of the project since its inception is presented, comprising the consolidation process of the network with its operational platform, intercomparison exercises, training activities, proceedings in quality assurance and horizon scanning for new methods and partners. Additionally, the benefit of the network for the radiation research community as a whole is addressed

Population structure and morphology of the frankincense tree Boswellia papyrifera along an altitude gradient in Eritrea

In Eritrea, the frankincense tree Boswellia papyrifera is a multipurpose plant. Human induced factors such as land clearing for agriculture, overgrazing by livestock and overtapping of resin are threatening its distribution. Against this background, a study was carried out to investigate the species current population structure and tree morphology in five Boswellia areas along an altitude gradient (range 800 - 2000 m a.s.l.). In each area sample plots of 20 by 20 m were inventoried; a total of 144 plots were studied. The population structure analysis showed that there was an overall absence of juvenile trees between 1 and 8 cm DBH. Natural regeneration was found only in two areas in which trees were not tapped for resin and inaccessible to livestock. Tree height, DBH, crown depth and crown diameter decreased with increasing altitude. In the lowland areas trees were about two times taller (10 to 12 m) with deeper crowns than those growing in the highland areas. This indicates that the species grows better in the warm moist lowlands than in the moist and dry highlands. To promote natural regeneration and seedling establishment in existing Boswellia woodlands control measures are needed including proper tapping procedures and controlled grazing

The distribution of the frankincense tree Boswellia papyrifera in Eritrea: the role of environment and land use

Aim We determined the present and past distribution, and the abundance, of Boswellia papyrifera in Eritrea, and the environmental and land-use factors determining its distribution limits. Location Eritrea, in the Horn of Africa. Methods In 1997 a Boswellia field survey was conducted in 113 village areas covering four administrative regions. Species occurrence was related to rainfall, air temperature and length of growing period. Additionally, the relationship between the abundance of Boswellia trees and selected physical and chemical soil factors, topography and land-use types was determined for five study areas (with a total of 144 plots) situated along an altitude gradient of 800¿2000 m a.s.l. Results The geographical distribution of B. papyrifera was limited to the southwestern and southern parts of the country between 800 and 1850 m altitude receiving a mean annual rainfall of 375¿700 mm, with a growing period of 45¿100 days. Species abundance was affected by, in order of importance: altitude, land-use intensity and soil organic matter. Most trees were found in hilly areas; tree density increased from the foot slope to the hill summit; no trees occurred in valleys. Land-use intensity, especially agriculture, fallow and grazed areas, had a profound negative effect on tree abundance. Natural regeneration of the species was promoted in areas where grazing by livestock was not allowed or regulated. Main conclusions The distribution of B. papyrifera in Eritrea has decreased during past decades, mainly due to an increasing human population, resulting in the conversion of woodlands into agricultural fields and increasing livestock pressure hindering natural regeneration. Consequently, Boswellia trees are found mainly in hilly areas on steep slopes with shallow soils of low fertility. The species appears to be able to adapt to these harsh growing conditions: in adjacent countries it was also found in comparable growth habitats

East African agriculture and climate change: Eritrea

Located in the Horn of Africa, Eritrea has a long coastline on the Red Sea. The country has varied topography, rainfall, and climate, with altitude ranging from 60 to more than 3,000 meters above sea level. Eritrea’s total population is about 5.27 million people, of whom 50–60 percent live in highlands that comprise only about 10 percent of the country’s total area. Agriculture is still an important sector for Eritrea, employing about half of the population and producing about 20 percent of GDP. Eritrea has several agricultural systems: rainfed cereal and pulses; semi-commercial and periurban agriculture; small-scale irrigated horticulture; commercial farming; agropastoral rainfed farming; and agropastoral spate irrigation systems. The major food crops grown in Eritrea are sorghum, millet and barley