Social and environmental trade-offs in tree species selection: a methodology for identifying niche incompatibilities in agroforestry

Natural resource degradation in highland regions is of increasing concern to the global community due to its role in aggravating poverty and the loss of environmental services to local and downstream users. The integration of trees into smallholder farming systems has been promoted as a means to enhance rural livelihoods while reversing the degradation of soil, water, biodiversity and related environmental services. Yet in addition to these benefits, negative impacts of trees on certain stakeholders or system components have also accompanied such efforts—suggesting that important trade-offs accompany afforestation. This paper presents a methodology for diagnosing problems stemming from cultivation of certain tree species in specific landscape niches. Data derived from the application of this methodology in two sites in the eastern African highlands are presented. Participatory diagnoses of landscape-level problems suggest that the negative impact of trees on water resource availability and crop yield are of critical concern to smallholder farmers. Ethnoecological data highlight the properties of different tree species that determine their suitability to specific farm and landscape niches. These data point to important opportunities for more socially- and environmentally-optimal integration of indigenous and exotic tree species into agricultural landscapes, and highlight the critical importance of local knowledge in forging solutions appropriate to contemporary realities.     

Vegetation dynamics, and land use and land cover change in the Bale Mountains, Ethiopia

Shifts in biological communities are occurring at rapid rates as human activities induced global climate change increases. Understanding the effects of the change on biodiversity is important to reduce loss of biodiversity and mass extinction, and to insure the long-term persistence of natural resources and natures’ services. Especially in remote landscapes of developing countries, precise knowledge about on-going processes is scarce. Here we apply satellite imagery to assess spatio-temporal land use and land cover change (LULCC) in the Bale Mountains for a period of four decades. This study aims to identify the main drivers of change in vegetation patterns and to discuss the implications of LULCC on spatial arrangements and trajectories of floral communities. Remote sensing data acquired from Landsat MSS, Landsat ETM + and SPOT for four time steps (1973, 1987, 2000, and 2008) were analyzed using 11 LULC units defined based on the dominant plant taxa and cover types of the habitat. Change detection matrices revealed that over the last 40?years, the area has changed from a quite natural to a more cultural landscape. Within a representative subset of the study area (7,957.5?km^?2), agricultural fields have increased from 1.71% to 9.34% of the total study area since 1973. Natural habitats such as upper montane forest, afroalpine grasslands, afromontane dwarf shrubs and herbaceous formations, and water bodies also increased. Conversely, afromontane grasslands have decreased in size by more than half (going from 19.3% to 8.77%). Closed Erica forest also shrank from 15.0% to 12.37%, and isolated Erica shrubs have decreased from 6.86% to 5.55%, and afroalpine dwarf shrubs and herbaceous formations reduced from 5.2% to 1.56%. Despite fluctuations the afromontane rainforest (Harenna forest), located south of the Bale Mountains, has remained relatively stable. In conclusion this study documents a rapid and ecosystem-specific change of this biodiversity hotspot due to intensified human activities (e.g., deforestation, agriculture, infrastructure expansion). Specifically, the ecotone between the afromontane and the afroalpine area represent a “hotspot of biodiversity loss” today. Taking into consideration the projections of regional climate warming and modified precipitation regimes, LULCC can be expected to become even more intensive in the near future. This is likely to impose unprecedented pressures on the largely endemic biota of the area.     

Should we Leave Nature Unattended or Assist through Enrichment to Foster Climate Change Mitigation? Exclosure Management in the Highlands of Ethiopia

Environmental Management - In order to foster the potential of exclosures to sequester carbon, it is understood that they are increasingly assisted through enrichment planting. To study the impact...