Tag: erosion control
Rapid soil redistribution within alleys: why simple extension models for contour hedgerows may not be appropriate
Use of calliandra–Napier grass contour hedges to control erosion in central Kenya
Contour hedgerow systems consisting of various combinations of tree and grass species can be used on sloping lands to minimize erosion, restore fertility, and improve crop productivity, but there is need to evaluate the effectiveness of each system for its suitability at any locality as effective erosion control. The objectives of this study were to determine the amount of soil conserved by contour calliandra (Calliandra calothyrsus)–Napier grass (Pennisetum purpureum) hedgerows, and then develop a support practice P-subfactor for conservation planning in central Kenya. As a benefit beyond soil conservation, biomass yield and N and P retention by the hedgerows were determined. Cumulative data for five cropping seasons from 1997 to 1999 indicated that the contour hedges on 20% slope conserved more soil (168 Mg ha1) than on the 40% slope (146 Mg ha1) compared to the control plots. For both slopes, this was equivalent to a 0.7 P-subfactor for use by the Revised Universal Soil Loss Equation (RUSLE) model in predicting soil erosion. The N and P losses between the hedges and control were statistically significant only on the 20% slope (P=0.05). Combined biomass yield from the calliandra–Napier grass hedges were 12 and 9 Mg ha1 per year and 40% slopes, respectively. This soil conservation technology may be used by small-scale farmers that use mixed farming systems in the highlands of central Kenya and similar ecoregions as a step towards sustainable farming.
Between scattered extraction and specialized production : which alternatives for the development of non-timber forest resources?
Management systems for NTFPs are far from being homogenous. They globally range from scattered collection in natural forests foe occasional consumption to intensive specialized production for international markets, going through various types of “integrated management” and “occasional cultivation” or ” per-domestication”. These various systems have obviously different features in terms of either ecological, economic or social sustainability, of short term or long term productivity, or of cultural validity. Among others, they may have totally diverging impacts on either forest ecosystems and biodiversity conservation, on forest populations development and welfare, or even on the respect of indigenous people rights. This paper will first attempt to give a dynamic overview of this diversity of current management practices for NTFPs, highlighting past and present evolutionary trends and insisting on those currently less investigated models that are intermediary between “extraction from natural stocks” and “true domestication for cultivation”, with a special focus on the Southeast region. Starting from these current situations, it will elaborate on the available “existing models” for NTFPs management, giving attention to matters such as scale and scope of management, levels of inputs and knowledge, economic and social logics, institutional and social bases. It will launch important bases for a comparative assessment of the global sustainability of these models, examining ecological, economic, cultural and social efficiency and gaps. It will finaly try to derive “alternative models” for future scenarios of forest management, giving a special attention to unexplored ways for demestication of forest resources.