Bruno Verbist

Negotiation Support Models for Integrated Natural Resource Management in Tropical Forest Margins

Natural resource management research has to evolve from a focus on plans, maps, and regulations to an acknowledgment of the complex, sometimes chaotic, reality in the field, with a large number of actors making their own decisions. As outside actors, we can only try to facilitate and support a process of negotiation among the stakeholders. Such negotiation involves understanding the perspectives of all stakeholders, analyzing complementarities in views, identifying where differences may be settled by “science,” where science and social action can bring innovative alternatives for reconciliation, and where compromises will be necessary to move ahead. We distinguish between natural resource management problems at village level, within country, or transboundary, and those that relate local stakeholder decisions to global issues such as biodiversity conservation. Tree-based systems at plot or landscape level can minimize conflicts between private and public interests in local environmental services, but spatial segregation of functions is an imperative for the core of global biodiversity values. The complex agroforests developed by farmers as alternatives to food-crop-based agriculture integrate local and global environmental functions, but intensification and specialization may diminish these non-local values. For local biodiversity functions, a medium-intensity “integrate” option such as agroforests may be superior in terms of resilience and risk management. Major options exist for increasing carbon stocks by expanding tree-based production systems on grasslands and in degraded watersheds through a coherent approach to the market, policy, and institutional bottlenecks to application of existing rehabilitation technologies. Agroforestry mosaics may be an acceptable replacement of forests in upper watersheds, provided they evolve into multistrata systems with a protective litter layer. Challenges to INRM research remain: how should the opportunities for adaptive response among diverse interest groups, at a number of hierarchical levels, be included in the assessment of impacts on the livelihoods of rural people?

Vegetation response to precipitation variability in East Africa controlled by biogeographical factors

Ecosystem sensitivity to climate variability varies across East Africa, and identifying the determinant factors of this sensitivity is crucial to assessing region-wide vulnerability to climate change and variability. Such assessment critically relies on spatiotemporal datasets with inherent uncertainty, on new processing techniques to extract interannual variability at a priori unknown time scales and on adequate statistical models to test for biogeographical effects on vegetation-precipitation relationships. In this study, interannual variability in long term records of Normalized Difference Vegetation Index (NDVI) and satellite-based precipitation estimates was detected using Ensemble Empirical Mode Decomposition (EEMD) and Standardized Precipitation Index (SPI) with varying accumulation periods. Environmental effect modeling using additive models with spatially correlated effects showed that ecosystem sensitivity is primarily predicted by biogeographical factors such as annual precipitation distribution (reaching maximum sensitivity at 500 mm yr-1), vegetation type and structure, ocean-climate coupling and elevation. The threat of increasing climate variability and extremes impacting productivity and stability of ecosystems is most imminent in semi-arid grassland and mixed cropland ecosystems. The influence of oceanic phenomena such as El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) is foremost reflected in precipitation variability, but prolonged episodes also pose risks for long-term degradation of tree-rich ecosystems in the East African Great Lakes region.

Quantifying successional land cover after clearing of tropical rainforest along forest frontiers in the Congo Basin

State-of-the-art impact-modeling studies in environmental and climatological sciences require detailed future deforestation scenarios that allow forest to be replaced by a mosaic of multiple successional land-cover types, rather than the simple conversion of forest to a single land-cover type, such as bare soil or cropland. Therefore, not only the amount and location of forest removal has to be known (as is typically provided by scenarios), but also knowledge about the successional land-cover types and their relative areal proportions is needed. The main objective of this study was to identify these successional land-cover types and quantify their areal proportions in regions deforested during the past 37 years around the city of Kisangani, D.R. Congo. The fallow vegetation continuum was categorized in different stages, adapted from existing classifications. Ground-truth points describing the present-day vegetation were obtained during a field campaign and used for supervised and validated land-cover classification of these categories, using the Landsat image of 2012. Areal proportions of successional land-cover types were then derived from the resulting land-cover map. The second objective of this study was to relate these areal proportions to time since deforestation, which is expected to influence fallow landscapes. Landsat images of 1975, 1990, and 2001 were analyzed. Present-day mature tree fallow is less abundant on areas deforested during 1975–1990. The relative areal proportions were used to refine a deforestation scenario and apply it to existing data-sets of LAI and canopy height (CH). Assuming a simple conversion of forest to cropland, the deforestation scenario projected a reduction of grid-cell-averaged CH from 25.5 to 7.5 m (within deforested cells), whereas the refined scenarios that we propose show more subtle changes, with a reduced CH of 13 m. This illustrates the importance of taking successional land cover correctly into account in environmental and climatological modeling studies.