Stefaan Dondeyne

Gully erosion in South Eastern Tanzania: spatial distribution and topographic thresholds

Summary. Though gully erosion is often mentioned as a major process of land degradationin South Eastern Tanzania, little information is available on its distribution. The Makondeplateau and adjacent inland plains are of particular concern as they are densely populated andare major areas of cashew nuts production. The occurrence of gully erosion was assessed in 66villages selected by stratified random sampling in an area of 13,000 km 2 . Difference in suscep-tibility to gully erosion between landscape units was assess by determining topographicthreshold parameters of 22 gullies on the Makonde plateau and 14 in the inland plains. Over-all, gullies are common and spread equally over the different landscape units. Their occurrenceis positively associated with terrain roughness (Cramer’s V = 0.30; P = 0.05) and negatively withpopulation density ( V = 0.44; P 0.01). On the Makonde plateau occurrence of gully erosionis associated with the presence of roads, while on the inland plains it is predominantly foundin fields (

A call to action: strong long-term limnological changes in the two largest Ethiopian Rift Valley lakes, Abaya and Chamo

Abstract The 2 largest Ethiopian Rift Valley lakes, Abaya and Chamo, are dominant socioecological systems with important potential for ecotourism because of their attractive setting with Nechisar National Park. We report on changes in water quality in these lakes during recent decades. We integrated data on key limnological variables during the last 55 years by supplementing historical literature data with our own field measurements. Our analyses provide strong evidence for a steady increase in nutrient concentrations and decrease in water transparency. Total phosphorus and total nitrogen concentrations in both lakes over the study period increased 5- and 7-fold, respectively. Similarly, water transparency decreased, especially in Lake Chamo, which used to have clear water but is now becoming a sediment-loaded lake similar to Lake Abaya. We reconstructed fertilizer use and land use changes in the region during the past decades. The combined data suggest that the dramatic eutrophication we observed in the lakes is likely associated with increased fertilizer use or other activities related to intensified agricultural practices, and the decline in water transparency is probably associated with low tree cover due to deforestation. The profound changes in the ecology of both lakes may jeopardize the delivery of ecosystem services in the region, including water supply, fisheries, and ecotourism. Our results stress the urgent need for measures that prevent further environmental deterioration of the unique heritage provided by the Ethiopian Rift Valley lakes.

Formalising land rights based on customary tenure: community delimitation and women's access to land in central Mozambique *

The Mozambican Land Law of 1997 intends to provide flexible rules of access to land, while securing local people’s customary rights, as well as equal rights for women and men. Drawing on participant observation during a ‘land delimitation’ process in central Mozambique, this article analyses the complex negotiation ensuing from the implementation of the land law in a local community. It shows how the delimitation process provided spaces for asserting – male – roles of power and authority, while local women were increasingly marginalised in the process. By presenting oral testimonies from women in the community, the authors seek to balance the account, providing women’s perspectives on the highly gendered character of interests in, access to, and exclusion from land. The analysis ends with the question: What would be required to provide a space for local women to articulate their interests in a secure access to land during the delimitation process itself? * A research grant from the Research Council of Norway (NFR) through the programme ‘Poverty and Peace’ provided funding for part of the fieldwork carried out in Mozambique. The authors would like to thank two anonymous reviewers for valuable comments on an earlier version of this article. Furthermore, we must express our gratitude to Milagre Nuvunga, James Bannerman, Sr Malunguisse, Sr Selcio, Sr Lidio and Sr Washington for their support and cooperation, and acknowledge the value of experiences shared by local staff at the ORAM, iTC, MICAIA, Pambere, and Kwaedza Simukai offices in Manica province. In particular, Benilde Nhabomba, Tina Krüger and Zacarias Jemusa Gumbo are thanked for their assistance in interviewing 21 women in the community. Special thanks to James Bannerman for commenting and revising

Where are we with whole regolith pedology? A comparative study from Brazil

An integrated knowledge of the soil and its deeper substratum is required when dealing with environmental issues and Critical Zone research. Though the lower boundary for classifying soils is set at 200 cm in both Soil Taxonomy (ST) and the World Reference Base (WRB), these systems are ill equipped for categorising layers below diagnostic horizons. The authors reflect on the need for classifying the solum–subsolum continuum based on data of four soil profiles from Brazil. The solum was classified with ST, WRB and the Brazilian Classification, and the subsolum with the Saprolite-Regolith Taxonomy (SRT) and the Subsolum Reference Groups (SRG). Soil classification systems provide limited information on shallow soils but this can conveniently be complemented with subsolum classification. SRT differs from SRG as it focuses on deeper material and on geotechnical applications, whereas SRG focuses on layers directly under diagnostic horizons and on environmental applications. Both systems still need more field testing. SRT seems to require more specialist knowledge on lithology than SRG and being a hierarchical classification system is less flexible than the open, low hierarchical organised SRG classification. It is concluded that future soil classification systems need more integration of the concept of ‘whole regolith pedology.’

Water for All and All for Water? Governmental Interventions Affecting Property of Natural Resources in Northern Ethiopia

In spite of growing international attention for natural resource management, relations of property regarding natural resources have hardly been studied in Ethiopia, a country known for its oxen-plow-based agriculture and revolutionary land reforms. This article goes beyond the agricultural focus and provides an actor-oriented analysis of water management in an Ethiopian microlevel context within a theoretical framework that builds on development discourses, social interfaces, and relations of property. The disconnectedness between government policies and local reality and the repercussions thereof for policy implementation are unraveled and so bring to light hybrids of development discourses. Relations of property still appear to be based on former private landholding systems in spite of socialist land reform, and hybrids of development discourses are deployed at three levels of institutionalization, policymaking, and implementation that are disconnected from each other, which leads to discrepancies between policy discourse and practice.

Extracting drainage networks and their connectivity using LiDAR data

Policies, measures, and models geared towards flood prevention and managing surface waters benefit from high quality data on the presence and characteristics of drainage ditches. As a cost and labour effective alternative for acquiring such data through field surveys, we propose a method (a) to extract vector data representing ditch drainage networks based on local morphologic features derived from high resolution digital elevation models (DEM) and (b) to identify possible connections in the ditch network by calculating a probability of the connectivity using a logistic regression where the predictor variables are characteristics of the ditch centre lines or derived from the DEM. Using Light Detection and Ranging (LiDAR) derived DEMs with a 1m resolution, the method was developed and tested for a mixed agricultural residential area in north-eastern Belgium. The derived ditch segments had an error of omission of 8% and an error of commission of 5%. The original positional accuracy of the centre lines of the extracted ditches was 0.6m and could be improved to 0.4m by shifting each vertex to the position of the lowest LiDAR point located within a radius equal to the spatial resolution of the used DEM. About 69% of the false disconnections in the network were identified and corrected leading to a reduction of the unconnected parts of the ditch network by 71%. The extracted and connected network approximated the reference ditch network fairly well.

Agro-ecological implications of forest and agroforestry systems conversion to cereal-based farming systems in the White Nile Basin, Ethiopia

ABSTRACT The Afromontane forests of southwest Ethiopia are high in endemism and biodiversity. However, the increasing human population and expansion of agricultural land have led to deforestation. We evaluated the effects of land use change on species composition, species diversity and soil fertility. Woody and herbaceous plant species were recorded in natural forest, agroforestry and cropland at different altitudes, using 15 plots with three replicates. A total of 90 soil samples were taken. In total, 77 woody and herbaceous species have been recorded. The selective felling of trees and shrubs in the agroforestry system to favor coffee growth through enhanced light penetration also favors grass and herb diversity. A Factor Analysis based on the soil characteristics shows a gradient in soil fertility from both forests and agroforestry to croplands. The bulk density, pH, organic C, total N, available P, cation exchange capacity and base cations saturation of the forest soil are equivalent with that of agroforestry. However, forests and agroforestry are significantly different from croplands regarding those soil characteristics. Therefore, this study suggests that the agroforestry practices are important for keeping biodiversity and soil fertility at levels which are similar to the natural forest.

‘Facing conservation’ or ‘conservation with a human face’? People–park interactions in southern Ethiopia

ABSTRACT Whereas some conservationists argue that ‘people-oriented approaches’ failed to achieve conservation goals, Nechisar National Park presents a case where ‘strict conservation approaches’ have at best been only partly successful. Nechisar National Park, heralded as a success in the 1990s, today shows a collapsed population of the endemic Swayne’s hartebeest and severe degradation of the emblematic grasslands of the plains. The park is also heavily under pressure from firewood collectors and fish stocks have plummeted. Drawing on the concepts of ‘indirect’ and ‘direct’ costs/benefits of conservation areas – as proposed by Richard Bell – we wanted to get beyond the ‘strict’ versus ‘people-oriented’ conservation debate. Based on semi-structured interviews (12 women, 4 men) and oral testimonies (19 women, 17 men) we analyse how access to natural resources evolved under different political regimes and conservation strategies. The strict conservation approach resulted in strong opposition against the park. By considering both the ‘indirect’ costs (such as loss of land) and the ‘direct’ costs’ (such as historical and cultural ties with the land) important insights for a conservation strategy with a ‘human face’ could be gained. Conservation with a human face will require: first formally involving the local people in the management of the park; second, that the historical rights of the pastoralists and the farmers over the area, as well as the legitimacy of their grievances with regard to the past management, are recognised. Such a new conservation strategy will however require political commitment and strong institutions at all levels.