Showing papers by "International Union for Conservation of Nature and Natural Resources published in 1999"

Sustaining Natural and Human Capital: Villagers and Scientists

Abstract: Community-based natural resource management (CBNRM) is a rural development paradigm that combines biological conservation and sustainable use of natural resources. In southern Africa, CBNRM has contributed to the wellbeing of human communities and to the conservation of elephants and other threatened species. Success in this arena requires the establishment of a respectful partnership between villagers and scientists that draws upon their complementary knowledge and skills.

Measurement and modelling of the effects of initial soil conditions and slope gradient on soil translocation by tillage

Abstract: Tillage erosion studies have mainly focused on the effect of topography and cultivation practices on soil translocation during tillage However, the possible effect of initial soil conditions on soil displacement and soil erosion during tillage have not been considered This study aims at investigating the effect of the initial soil conditions on net soil displacement and the associated erosion rates by a given tillage operation of a stony loam soil Tillage erosion experiments were carried out with a mouldboard plough on a freshly ploughed (pre-tilled) soil and a soil under grass fallow in the Alentejo region (Southern Portugal) The experimental results show that both the downslope displacement of soil material and the rate of increase of the downslope displacement with slope gradient are greater when the soil is initially in a loose condition This was attributed to: (i) a greater tillage depth on the pre-tilled soil and (ii) a reduced internal cohesion of the pre-tilled soil, allowing clods to roll and/or slide down the plough furrow after being overturned by the mouldboard plough An analysis of additional available data on soil translocation by mouldboard tillage showed that downslope displacement distances were only significantly related to the slope gradient when tillage is carried out in the downslope direction When tillage is carried out in the upslope direction, the effect of slope gradient on upslope displacement distances was not significant This has important implications for the estimation of the tillage transport coefficient, which is a measure for the intensity of tillage erosion, from experimental data For our experiments, estimated values of the tillage transport coefficient were 70 and 254 kg m -1 per tillage operation for grass fallow and pre-tilled conditions, respectively, corresponding to local maximum erosion rates of ca 8 and 35 Mg ha -1 per tillage operation and local maximum deposition rates of ca 33 and 109 Mg ha -1 per tillage operation

Magnitude-frequency analysis of water redistribution along a climate gradient in Spain

Abstract: Banded patterns in soils and vegetation form part of important discontinuities on semi-arid slopes in Spain. At fine scales (

Estimate of shallow groundwater recharge in the Hadejia–Nguru Wetlands, semi-arid northeastern Nigeria

Abstract: The Hadejia–Nguru Wetlands are annually inundated flood plains in semi-arid northeastern Nigeria. The area has a unique ecosystem that forms a natural barrier against the encroachment of the Sahara desert. Both the rich wetland vegetation and local farmers using shallow tube wells depend on a groundwater mound (with a water table less than 6 m below the surface) that is present in the unconfined aquifer under the flood-plain area. Using well records (1991–97) and a hydrogeologic profile based on piezometers that were monitored for two years, it is shown that recharge through the annually inundated flood plains is the source of the groundwater mound. Maintenance of the groundwater-recharge function of the flood plains depends on wet-season releases from two large upstream dams. On the basis of a water-budget method, the mean (1991–97) wet-season unconfined groundwater recharge in the flood-plain area between Hadejia and Nguru and in the immediate vicinity (1250 km2) is estimated to be 132 mm (range, 73–197 mm). Outflow from the unconfined flood-plain aquifer to the unconfined upland aquifer is approximately 10% of the wet-season flood-plain recharge. The unconfined groundwater outflow from the flood-plain area can provide a significant contribution to the present-day rural water supply in the surrounding uplands, but it does not offer much potential for additional groundwater abstraction. In addition to outflow to the upland aquifer (∼14 mm), the distribution of the annually recharged water volume of the shallow flood-plain aquifer is (1) domestic uses (3 mm), (2) small-scale irrigation (∼15 mm), and (3) evapotranspiration ( 1 100 mm). Along the hydrogeologic profile, the recharge in the upland (i.e., outflow from the unconfined flood-plain aquifer and possibly diffuse rain-fed recharge) is in balance with the water uses (i.e., domestic uses, groundwater outflow, and evapotranspiration). The absence of a seasonal water-level trend in the two piezometers in the upland indicates that no rain-fed recharge occurs through preferential path-way (macropore) flow.

Reintroductions, introductions, and the importance of post-release monitoring: lessons from Zanzibar

Abstract: Between 1991 and 1996 Struhsaker & Siex (1998) made a valiant and worthwhile series of surveys to assess the outcome of earlier attempts to establish viable popu­ lations of the Zanzibar red colobus monkey Procoio/Jos kirk!i, one of Africa's most endangered primates. Between 1977 and 1981 red colobus were released at three sites in Zanzibar, two of which, Masingini and Kichwele, were believed to have probably held red colobus before the 1800s, whereas red colobus never naturally occurred at the third site, on the island of Pemba (Struhsaker & Siex, 1998). The results of the surveys indicated that one of these releases was successful, with red colobus still present and apparently breeding only at Masingini. In reading this paper I was struck by how it high­ lighted the importance of the three 'P's of wildlife restoration projects: Preparation, Post-release moni­ toring and Publication. The paper also revealed a need for improved standardization of terminology. The expansion of the use of reintrod uctions as a means to restore threatened species, and the growing need to ensure that any such projects have the greatest possible chance of success, prompted the IUCN/SSC's Re­ introduction Specialist Group to produce a series of guidelines for reintroductions (IUCN, 1998). These guidelines set out the stages and requirements for any serious reintroduction attempt. The guidelines also define a number of terms in order to standardize their usage and avoid confusion in the published literature. Struhsaker & Siex (1998) considered the release of red colobus into their former range to constitute a transloca­ tion, that is 'the capture of free-ranging wild animals in their native habitat and their release into natural or near-natural habitat within their geographical range', distinguishing this from a reintroduction, that is 'the transfer of captive animals (usually captive-bred) into the wild' (Struhsaker & Siex, 1998: 278). These definitions are at odds with the ones used in the IUCN Guidelines, where a translocation is 'a deliberate and mediated movement of wild individuals to an existing population of conspecifics', and a reintroduction is 'an attempt to establish a in an area which was once part its historical range, but from which it has been extirpated or become extinct (TUCN, 1(98). The principal difference with the IUCN definition of reintroduction is that the animal to be released can corne from any source, the key point being their release into habitat in which the is no longer found. The

Costa Rica's biodiversity law: Sharing the process 1

Abstract: This article assesses the prospects for Costa Rica's new Biodiversity Law. We believe that this analysis could also provide a valuable case study of national implementation of the Convention on Biological Diversity (CBD). The article is not intended to be a primer on the CBD, nor will it defend its precepts. The authors believe that each nation must formulate a legal framework to regulate biodiversity that reflects their unique national circumstances.

The Convention on Biological Diversity: a solid foundation for effective action

Abstract: Having been deeply involved with the Convention on Biological Diversity (CBD) since it was first conceived at the World Parks Congress in Bali in 1982 (de Klemm 1984), I wish to respond to Guruswamy's (1999) critique of it.