title: Vegetation Diversity and Distribution Along the Bale Mountains Afroalpine Hotpot of Biodiversity in the Face of a Fast-Changing World
Creators: name: Kidane, Yohannes
Publisher: name: University of Bayreuth
Year: 2022
Subjects: subject: Biogeography
subject: Afroalpine
subject: Tropical Mountains
subject: Biodiversity loss
subject: Vegetation dynamics
subject: Endemism
subject: Elevational gradient
subject: Landuse change
subject: Remote sensing
subject: Tropical mountains
subject: Species Distribution Modeling
subject: Socioeconomic change
subject: Climate change
subject: LULC chnage
subject: 550

description: Mountain ecosystems, particularly tropical alpine ecosystems, host important biodiversity hotspots in small, primarily remote mountain tops. One of those ecosystems, Afroalpine ecosystems, the habitats above the treeline of tropical African mountains, have experienced long-term spatial isolation and extreme climatic conditions, leading to the formation of "Sky Island" like ecosystems endowed with unique flora and fauna rich in endemics. One of these ecosystems is Ethiopia's Bale Mountains, which is home to Africa's most extensive Afroalpine plateau, Altiplano, with no spacious high summits that provide space for an upward shift. Over the last fifty years, this pristine Afroalpine ecosystem has experienced and suffered from excessive human presence, hence significant LULC change besides climate change. Consequently, the once pristine natural Afroalpine mountain ecosystems have changed entirely cultural landscapes. Lately, the long-existing environmental relationships that shape Afroalpine mountain ecosystems' stability and instability are changing rapidly in response to the recent rapid global change, especially to the synergistic impacts of drivers of ecosystem change such as Land Use Land Cover (LULC) and climate change. Here, we investigated the effects of fifty years long Spatio-temporal LULC change and climate change on Afromontage and Afroalpine vascular plants richness patterners, particularly that of Afroalpine endemics; effects of current and projected variability of temperature and moisture- related predictor on the diversity and distribution of the phenotypically highly adapted dominant cover types; and possible impacts of the synergy between the main drivers of biodiversity change particularly that of LULC and climate change on the Afroalpine vegetation. The research used in-situ plot data, ex-situ open data sources, and state-of-the-art research approaches and methodologies. The fifty-year Spatio-temporal LULC change study identified cover types such as Agricultural Fields, Upper Montane Forest, Afroalpine Grasslands, Afromontane Dwarf Shrubs, and Herbaceous Formations increased overtime. Conversely, Afromontane Grasslands, Closed Erica Forest, Isolated Erica Shrubs, Aroalpine Dwarf Shrubs, and Herbaceous Formations reduced considerably. However, despite some simplification at the lower margins, the Afromontane Rainforest (Harenna Rainforest), located south of the Bale Mountains, has remained relatively stable. Contemporarily, the ecotone between the Upper Montane and the afroalapine ecosystems are "biodiversity loss hotspots." Population growth, infrastructural expansion, frequent fire, over-grazing, deforestation, inadequate conservation and management measures, and lack of protection during the political transition and uncertain political atmosphere are some of the leading local causes of biodiversity loss. Besides, the massive mid to low-altitude areas, formerly sparsely populated agriculturally fertile regions, face large-scale agricultural land acquisition, and land grabbing. LULC change is expected to become even more intensive and is likely to continue imposing unprecedented pressures on the largely endemic biota of the area. Our finding further indicated hump-shaped species richness patterns across the massif. In addition, the proportion of endemic species increases monotonically towards the summit on all slopes. However, climate change will profoundly impact vascular plants' diversity and richness patterns, i.e., it impacts species' and ecosystems' structure, composition, functioning, and distribution patterns. Furthermore, it will results in a shift in ecosystem boundaries, potentially affecting vulnerable Afroalpine ecosystems and their uniquely adapted species. Our study indicated that future climate change would significantly alter species distribution patterns with a pronounced effect on the Afroalpine ecosystems and endemic species restricted to the Afroalpine plateau, e.g., at 2oC, up to 8.6% of total endemics will become extinct. However, all vascular plants and ecosystems will not respond to the change uniformly. The ericaceous woody vegetation, located between the low-elevation Broadleaf Forests and high- elevation Afroalpine vegetation, is anticipated to be affected differently. Our model ensemble projections indicated increased dominance and upward range shift of ericaceous vegetation by the first half of the 21st century. It will increase in the western, northwestern, northern, and eastern parts of the massif and the Sanetti plateau. Towards the turn of the 21st century, ericaceous vegetation will continue to increase across its current range and shift towards the Afroalpine meadow while receding from the lower range across the massif. Moreover, the current ericaceous vegetation range correlates to the current temperature and precipitation trends, reaffirming the critical role of temperature and precipitation in determining species distributions along elevation. The competition between Afroalpine specialists and plants with a broader range of distribution will further facilitate the extinction rate of Afroalpine specialists and endemics. Overall, the dissertation developed innovative research approaches and applied cost-effective and efficient biodiversity monitoring approaches that utilize the vast geospatial data acquired from Remote Sensing and advanced geospatial analysis tools and techniques. In developing countries, environmental management, climate change mitigation, and adaptation decisions are often made without proper consultation with the local stakeholders in a top-down approach that is usually variable with changing government and political transitions. Hence, policy failure and lack of appropriate local conservation and management strategies are the root causes of the Afroalpine biodiversity loss. Therefore, continuous biodiversity monitoring and assessment utilizing state-of- the-art geospatial information and tools and technologies such as Remote Sensing, qGIS, R2, and others are essential. Recently, information acquired from Remote Sensing provides frequent and consistent data that can be traced a few decades back and cover a large swath of land. Our results indicate the high likelihood of considerable changes in this biodiversity hotspot in Eastern Africa.