Abstract: Increasing temperatures and wildfire incidence and decreasing precipitation and river runoff in southern Africa are predicted to have a variety of impacts on the ecology, structure, and function of semi-arid savannas, which provide innumerable livelihood resources for millions of people. This paper builds on previous research that documents change in inundation and fire regimes in the Chobe River Basin (CRB) in Namibia and Botswana and proposes to demonstrate a methodology that can be applied to disentangle the effect of environmental variability from land management decisions on changing and ecologically sensitive savanna ecosystems in transboundary contexts. We characterized the temporal dynamics (1985–2010) of vegetation productivity for the CRB using proxies of vegetation productivity and examine the relative importance of shifts in flooding and fire patterns to vegetation dynamics and effects of the association of phases of the El Niño—Southern Oscillation (ENSO) on vegetation greenness. Our results indicate that vegetation in these semi-arid environments is highly responsive to climatic fluctuations and the long-term trend is one of increased but heterogeneous vegetation cover. The increased cover and heterogeneity during the growing season is especially noted in communally-managed areas of Botswana where long-term fire suppression has been instituted, in contrast to communal areas in Namibia where heterogeneity in vegetation cover is mostly increasing primarily outside of the growing season and may correspond to mosaic early dry season burns. Observed patterns of increased vegetation productivity and heterogeneity may relate to more frequent and intense burning and higher spatial variability in surface water availability from both precipitation and regional inundation patterns, with implications for global environmental change and adaptation in subsistence-based communities.
Abstract: Soil loss is not limited to change from forest or woodland to other land uses/covers. It may occur when there is agricultural land-use/cover modification or conversion. Soil loss may influence loss of carbon from the soil, hence implication on greenhouse gas emission. Changing land use could be considered actually or potentially successful in adapting to climate change, or may be considered maladaptation if it creates environmental degradation. In semi-arid northern Ghana, changing agricultural practices have been identified amongst other climate variability and climate change adaptation measures. Similarly, some of the policies aimed at improving farm household resilience toward climate change impact might necessitate land use change. The heterogeneity of farm household (agents) cannot be ignored when addressing land use/cover change issues, especially when livelihood is dependent on land. This paper therefore presents an approach for simulating soil loss from an agro-ecosystem using multi-agent simulation (MAS). We adapted a universal soil loss equation as a soil loss sub-model in the Vea-LUDAS model (a MAS model). Furthermore, for a 20-year simulation period, we presented the impact of agricultural land-use adaptation strategy (maize cultivation credit i.e., maize credit scenario) on soil loss and compared it with the baseline scenario i.e., business-as-usual. Adoption of maize as influenced by maize cultivation credit significantly influenced agricultural land-use change in the study area. Although there was no significant difference in the soil loss under the tested scenarios, the incorporation of human decision-making in a temporal manner allowed us to view patterns that cannot be seen in single step modeling. The study shows that opening up cropland on soil with a high erosion risk has implications for soil loss. Hence, effective measures should be put in place to prevent the opening up of lands that have high erosion risk.
Abstract: We use the hybrid modeling laboratory of the Mediterranean Landscape Dynamics (MedLanD) Project to simulate barranco incision in eastern Spain under different scenarios of natural and human environmental change. We carry out a series of modeling experiments set in the Rio Penaguila valley of northern Alicante Province. The MedLanD Modeling Laboratory (MML) is able to realistically simulate gullying and incision in a multi-dimensional, spatially explicit virtual landscape. We first compare erosion modeled in wooded and denuded landscapes in the absence of human land-use. We then introduce simulated small-holder (e.g., prehistoric Neolithic) farmer/herders in six experiments, by varying community size (small, medium, large) and land management strategy (satisficing and maximizing). We compare the amount and location of erosion under natural and anthropogenic conditions. Natural (e.g., climatically induced) land-cover change produces a distinctly different signature of landscape evolution than does land-cover change produced by agropastoral land-use. Human land-use induces increased coupling between hillslopes and channels, resulting in increased downstream incision.
Abstract: The present study aimed to detect the main shifts in land-use architecture and assess the factors behind the changes in typical tropical semi-arid land in Burkina Faso. Three sets of time-series LANDSAT data over a 23-year period were used to detect land use changes and their underpinning drivers in multifunctional but vulnerable ecologies. Group discussions in selected villages were organized for mapping output interpretation and collection of essential drivers of change as perceived by local populations. Results revealed profound changes and transitions during the study period. During the last decade, shrub and wood savannahs exhibited high net changes (39% and −37% respectively) with a weak net positive change for cropland (only 2%,) while cropland and shrub savannah exhibited high swap (8% and 16%). This suggests that the area of cropland remained almost unchanged but was subject to relocation, wood savannah decreased drastically, and shrub savannah increased exponentially. Cropland exhibited a null net persistence while shrub and wood savannahs exhibited positive and negative net persistence (1.91 and −10.24), respectively, indicating that there is movement toward agricultural intensification and wood savannah tended to disappear to the benefit of shrub savannah. Local people are aware of the changes that have occurred and support the idea that illegal wood cutting and farming are inappropriate farming practices associated with immigration; absence of alternative cash generation sources, overgrazing and increasing demand for wood energy are driving the changes in their ecosystems. Policies that integrate restoration and conservation of natural ecosystems and promote sustainable agroforestry practices in the study zone are highly recommended.
Abstract: The socio-ecological system dominated by pastureland in the Asteroussia Mountains (Crete, Greece) was analyzed over a long time interval (1945–2010) to identify the most relevant system’s characteristics and changes. Vegetation cover and land-uses have been quantified by analyzing aerial photographs exploring the whole study period. Soil characteristics have been assessed by carrying out an extensive field survey for the last reference year (2010) and by estimating the average soil loss for the past period using the PESERA soil erosion model validated by field measurements. Based on environmental, social and economic attributes, three major periods characterizing the socio-ecological system of Asteroussia Mountains have been distinguished. During the first and second period, the land was satisfactorily managed with moderate–low soil erosion rates despite the adverse (prevailing) soil, topographic and climate conditions for vegetation growth. The third time interval featured a rapid growth in the livestock density causing increased soil erosion rates, loss in plant productivity, and a generalized over-exploitation of natural resources. As a consequence, the desertification process has significantly increased in the last period. The analysis of the long-term evolution of socio-ecological system provided evidence to understand the main drivers of land degradation and to recommend mitigation policies specifically addressing Mediterranean pastureland.
Abstract: Human appropriation of net primary production (HANPP) quantifies alteration of the biosphere caused by land use change and biomass harvest. In global and regional scale assessments, the majority of HANPP is associated with agricultural biomass harvest. We adapted these methods to the watershed scale and calculated land cover change and HANPP in an agricultural watershed in 1968 and 2011. Between 1968 and 2011, forest cover remained near 50% of the watershed, but row crop decreased from 26% to 0.4%, pasture increased from 19% to 32%, and residential area increased from 2% to 10%. Total HANPP decreased from 35% of potential Net Primary Productivity (NPP) in 1968 to 28% in 2011. Aboveground HANPP remained constant at 42%. Land use change accounted for 86%–89% of HANPP. Aboveground HANPP did not change despite the major shift in agricultural land use from row crop and pasture. The HANPP and land use change in Doddies Creek watershed reflects changing land use patterns in the southeastern US, driven by a complex interaction of local to global scale processes including change in farm viability, industrialization of agriculture, and demographic shifts. In the future, urbanization and biofuel production are likely to become important drivers of HANPP in the region. At the watershed scale, HANPP can be useful for improving land use decisions and landscape management to decrease human impact on the ecosystem and ensure the flow of ecosystem services.