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Presentation Oral presentation
Title Deforestation and biodiversity-loss due to cultivation? An interdisciplinary analysis in North-East Namibia

Short title Landuse patterns of Kavango

Author(s) Falk, T.; Gröngröft, A.; Hecht, J.; Hinz, M.; Kangombe, F.; Keil, M.; Petersen, A.; Pröpper, M.; Strohbach, B.; Wisch, U.

Presenting author ---

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Keywords Kavango, deforestation, cultivation, communal land management, patterns of diversity, soil nutrients, cultural perceptions of biodiversity

Abstract As in many regions of the world land-clearing for agricultural purposes is the main threat for Namibian forests such as Kavango woodlands and a main reason for the loss of local biodiversity. Over the past decades the Kavango region in North-East Namibia has experienced a strong population growth. Three quarters of the rural population depend on subsistence natural resource use such as dryland rain-fed cultivation. Livelihoods of subsistence farmers are vulnerable due to unpredictable precipitation and low nutrition values of the soil. This study aims to analyse the local system of subsistence farming and use of natural resources in order to enable an evaluation of biodiversity loss of the region and to predict the trends for future action.

The study area falls within the extensive Kalahari sand basin. These aeolian sands build a pattern of Kalahari typical longitudinal, east-west orientated dunes. Through erosion, the topography at the study area was flattened to less than 10 m relative difference in relief, although the remnants of the dune fields are still clearly visible in satellite images. The Kavango is dominated by open woodlands with numerous hardwood species, including Baikiaea plurijuga, Pterocarpus angolensis and Guibourtia coleosperma. Wood harvesting for construction purposes and/or commercial timber trade poses a threat to the vegetation, particularly the large hardwood species. A more serious threat to biodiversity in the area, however, is the continuous clearing for crop fields due to the low productivity soils. Typically, the soils are deep, very pure sands with little nutrients. Slightly heavier textured soils have formed only in the omiramba (singular - omuramba - a wide, flat watercourse with no visible gradient) and interdunal corridors. A number of these omiramba cross the study area in an east-west direction, contributing to the Mpuku Omuramba. These omiramba and interdunal corridors, because of their more nutrient-rich soils, are sought-after for fields by the local population. As a reaction on the low productivity of the soils ever new fields are cleared. Between 1990 and 1995, the annual rate of deforestation in the Kavango region was estimated to be 0.3 percent and land cleared for crops increased between 1943 and 1996 (by more than seven times) from 0.5 percent to 4.0 percent of the total Kavango area.
These trends found in official statistical data can be fortified by the analysis of remote sensing data acquired since the 1970ies, giving also evidence on the spatial patterns and temporal development of clearing. The investigation of multi-temporal satellite data additionally delivers information on land use, fallow lands, and affected vegetation types. The Namibian government is very much aware of the problem and tries to increase incentives for sustainable cultivation with policy reforms. From a legal and economic perspective it is analyzed to which degree these reforms are able to increase tenure security and to solve conflicts between customary and statutory law.

In this presentation the interdisciplinary BIOTA Kavango working cluster presents joint findings on drivers and causes of human-biodiversity impact as well as motives and perceptions for behavior. We will link soil science results on agricultural impact on soil compositions to botanical observations on species occurrence, remote sensing data on change detection, anthropological findings on local biodiversity knowledge, and institutional analysis regarding statutory and customary use regulations.

Congress Topic Land use, impact and value

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Ref. No. 86