Project Database

Abstract:

A large variety of remote sensing-based land use/land cover (LULC) products are currently available on national and global scales. This literature review and in situ validation study evaluate the suitability of these products for local scale applications in the complex terrain of the Ethiopian mountains. For the review, 146 research papers are analyzed. Most studies (73%) have been published since 2013 and are based on individually computed maps. Not a single study relied on readily available LULC products. Nine readily available LULC products with 20-, 30-, 300-, 500-, and 1000-m spatial resolution have been identified at national and global scales. To complement and extend this body of research, the recent (since 2013) LULC products are validated using 185 ground truth points collected in the Bale Mountains National Park between 1500 and 4385 m a.s.l. The results indicate a rather poor overall accuracy (<50%).

Abstract:

Aim: One objective was to quantify the impact of the Giant Mole Rat (Tachyoryctes macrocephalus) on vegetation communities and their composition. A second objective was to assess plant biomass (plant volume) via photography at the Sanetti Plateau. Third objective was to assess spatial distribution of the Giant Mole Rat across the Bale Mountains. In order to do that a predictive model has been applied. Location: Bale Mountains in south-eastern Ethiopia. Taxon: Tachyoryctes macrocephalus (Spalacideae). The species is related to other rats in eastern Africa and endemic to the Bale Mountains. Methods: The vegetation was sampled using a paired plot design along a transect from the southern to the northern rim of Sanetti Plateau and at sites where Giant Mole Rats were most abundant. Therefore, a total of 94 plots were established, 47 on Giant Mole Rat mounds and 47 in the zonal vegetation as control plots. Species identification and vegetation cover was investigated and photographs taken for further analysis of plant biomass. GPS data of around 1200 Giant Mole Rat mounds were recorded in order to upscale points on a larger area and detect the distribution of the Giant Mole Rat across the Bale Mountains. For that purpose Sentinel-2 satellite data was used with spatial resolution of 10 m, using a Forward Feature Selection. Results: We found out that the Giant Mole Rat is distributed across the whole Afroalpine zone of the Bale Mountains. It concentrates on the northern part of the Sanetti Plateau, in Sodota and Morebawa in wet and swampy habitat structures. Giant Mole Rats cover an area of 8301,16 ha and an estimated population density of 22 individuals/ha via upscaling could be proved. The Giant Mole Rat provides advantages to plants that require mixed and heterogen soil characteristics. The genera of Alchemilla and Salvia are examples for that and could be found on a major part of the Giant Mole Rat mounds. The genus of Helichrysum is abundant in the normal vegetation pattern and is almost completely absent on the Mole mounds. The presence of Helichrysum causes higher plant volume in the normal vegetation, which is 1,7 times higher than on the Mole mounds. Main conclusions: Giant Mole Rats change habitat and plant community structures. Shrub or woody plants do not occur on Giant Mole Rat mounds. The Giant Mole Rat is distributed across the whole Sanetti but most abundant in the northern part of Sanetti, Sodota and Morebawa. It prefers wet and swampy habitat.

Abstract:

The Bale Mountains of Ethiopia are a biodiversity hot spot in the south-eastern African highlands. Human pressure on the ecosystem strongly increases steadily because of a vast growing population of that region and the people's dependence on natural resources. The main impact of human land use is initial burning which shapes a whole vegetation zone: The Ericaceous belt. A plethora of research was and is conducted to analyze where fire has been and is set, to identify fire hot spots - areas which are very likely to be burnt - and ultimately to develop a fire management plan which might be applied in the future. Yet, the effect fire has on the vegetation of the Ericaceous belt of the Bale Mountains is unknown. In my study, I investigate the present post-fire floristic composition of the Ericaceous belt and identify the drivers of its dynamics. Especially altitude, climatic conditions and regeneration time as well as browsing by livestock were examined pertaining to their effect on vegetation's recovery. Data was first generated through vegetation assessment then subsequently through plant identification and analyzed by linear ordination methods. The vegetation's age was revealed applying different age methods of remote sensing, interviews and dendrochronology. In the whole Ericaceous belt not a single unburnt area was detected. The oldest recorded vegetation was determined to be 25 years old. Within these 25 years of regeneration no significant changes in floristic composition occurred. Little variation in floristic composition within the vegetation zone could be observed and was mainly associated with the slope of the mountains while elevation was of the second largest impact. Age, inclination, distance to settlements and browsing of the youngest vegetation additionally affected the species composition. Up to 70 % of variation of the floristic composition in the recently burnt areas and 50 % in older vegetation were associated with these variables. The name-giving Erica regenerated by resprouting from fire-surviving biomass. It's growth of height showed large variability in the researched areas and was directly and indirectly related to livestock browsing. With the baseline of information on post-fire vegetation recovery which I provide, I aim to contribute to prove that the current Ericaceous belt - contrary to previous considerations - does not consist of natural vegetation but was rather shaped by humans for a long time.