Browsing by Author "Wickham, James"

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Collective Action in the Management of Water Sources in the Highlands of Eastern Africa
(2008) Mowo, J.G.; German, Laura; Wickham, James; Zenebe, A.; Mazengia, Waga
"Participatory constraints and opportunities analysis conducted in three watersheds in Tanzania and Ethiopia established that water quantity and quality were the major constraints to adopting integrated natural resource management (INRM) practices. The African Highlands Initiative (AHI) working with communities in the three watersheds considered management of water sources as an important entry point for enhanced INRM. Focus group discussion, key informants interviews and historical trend analysis were used to obtain information on the status of water sources in the target watersheds, reasons why most of them have deteriorated, the impact of this on NRM and available opportunities for reversing this trend. The study established that rehabilitation of water sources was possible through collective action, which in this paper refers to direct actions carried out by groups of people working toward common goals. Further, appropriate policies and realistic by-laws, planting of water friendly tree species and putting in place an effective management structure were necessary for the long term survival of the water sources. Through AHI interventions, 32 water sources have been rehabilitated in Baga Watershed in Tanzania where target communities indicated a reduction on the time spent in collecting water from 5 hours to 5 minutes. A health centre in one village in this watershed reported a 55 % reduction in the incidences of waterborne diseases. In Ginchi (Ethiopia) three springs have been rehabilitated and are being used to protect the catchments around through enacting of local rules and regulations for their management. In Areka (Ethiopia) a total of 300 households have benefitted from rehabilitated water sources while reduction in the time for collecting water has increased the time available to attending to other developmental activities. It is concluded that collective action in managing water sources is an effective way of addressing issues that are beyond the capability of individual households, and through this, save time that can be directed to other activities including NRM, apart from having a healthier community."
Distribution and Causes of Global Forest Fragmentation
(2003) Wade, Timothy G.; Riitters, Kurt; Wickham, James; Jones, K. Bruce
"Because human land uses tend to expand over time, forests that share a high proportion of their borders with anthropogenic uses are at higher risk of further degradation than forests that share a high proportion of their borders with non-forest, natural land cover (e.g., wetland). Using 1-km advanced very high resolution radiometer (AVHRR) satellite-based land cover, we present a method to separate forest fragmentation into natural and anthropogenic components, and report results for all inhabited continents summarized by World Wildlife Fund biomes. Globally, over half of the temperate broadleaf and mixed forest biome and nearly one quarter of the tropical rainforest biome have been fragmented or removed by humans, as opposed to only 4% of the boreal forest. Overall, Europe had the most human-caused fragmentation and South America the least. This method may allow for improved risk assessments and better targeting for protection and remediation by identifying areas with high amounts of human-caused fragmentation."
Global-Scale Patterns of Forest Fragmentation
(2000) Riitters, Kurt; Wickham, James; O'Neill, Robert; Jones, Bruce; Smith, Elizabeth
"We report an analysis of forest fragmentation based on 1-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km 2 (9 x 9 pixels, 'small' scale) to 59,049 km 2 (243 x 243 pixels, 'large' scale) were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe-Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types) and Europe-Asia (four types), in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 forest types, of which only a few would be considered as 'naturally patchy' (e.g., dry woodland). The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf."
Use of Road Maps in National Assessments of Forest Fragmentation in the United States
(2004) Riitters, Kurt; Wickham, James; Coulston, John
"The question of incorporating road maps into U.S. national assessments of forest fragmentation has been a contentious issue, but there has not been a comparative national analysis to inform the debate. Using data and indices from previous national assessments, we compared fragmentation as calculated from high-resolution land-cover maps alone (Method 1) and after superimposing detailed road maps (Method 2). There was more overall fragmentation with Method 2. However, because roads were often adjacent to other nonforest land cover, Method 1 typically detected > 80% of the forest edge and > 88% of the fragmentation of core, i.e., intact, forest that was detected by Method 2. Indices based on individual patch size changed much more for Method 2; for example, area-weighted average patch size was typically 50-90% smaller. The relative geographic distribution of core forest was the same for both methods. Our results emphasize that the question of incorporating road maps must consider the purpose of the assessment, the characteristics of the data, and the relative sensitivities of indices to different patterns of fragmentation. As a practical matter, unless road-caused fragmentation is of special interest, land-cover maps alone may provide an adequate representation of the geography of forest fragmentation."