Browsing by Author "Balmford, Andrew"

Now showing 1 - 3 of 3
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    Assessing Fern Diversity: relative species richness and its environmental correlates in Uganda
    (Biodiversity & Conservation, 1998) Lwanga, Jeremiah S.; Balmford, Andrew; Badaza, Rose
    Techniques for the rapid quantification of tropical biodiversity are of critical importance in deciding where to invest scarce conservation resources. Here we describe a simple survey method for assessing species-level richness of a poorly known plant group, the pteridophytes. We then illustrate the use of a powerful, rarefaction- based technique of controlling for inevitable differences in sampling effort to calculate the relative species richness of our study sites. Lastly, we explore how closely observed patterns of relative species richness of Ugandan forests are correlated with a suite of simple environmental variables. We find that fully 75% of the variance in our estimate of fern diversity can be predicted from just two measures: soil fertility (scored as C/N ratio, itself related to rainfall); and distance from the nearest putative Pleistocene refugium.
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    Complementarity and the Use of Indicator Groups for Reserve Selection in Uganda
    (Nature, 1998) Howard, Peter C.; Kigenyi, Fred W.; Baltzer, Michael; Lwanga, Jeremiah S.; Matthews, Roger A.; Balmford, Andrew
    A major obstacle to conserving tropical biodiversity is the lack of information as to where efforts should be concentrated. One potential solution is to focus on readily assessed indicator groups, whose distribution predicts the overall importance of the biodiversity of candidate areas. Here we test this idea, using the most extensive data set on patterns of diversity assembled so far for any part of the tropics. As in studies of temperate regions we found little spatial congruence in the species richness of woody plants, large moths, butterflies, birds and small mammals across 50 Ugandan forests. Despite this lack of congruence, sets of priority forests selected using data on single taxa only often captured species richness in other groups with the same efficiency as using information on all taxa at once. This is because efficient conservation networks incorporate not only species-rich sites, but also those whose biotas best complement those of other areas. In Uganda, different taxa exhibit similar biogeography, so priority forests for one taxon collectively represent the important forest types for other taxa as well. Our results highlight the need, when evaluating potential indicators for reserve selection, to consider cross-taxon congruence in complementarity as well as species richness.
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    A Nationwide Assessment of the Biodiversity Value of Uganda’s Important Bird Areas Network
    (Conservation Biology, 2006) Tushabe, Herbert; Kalema, James; Byaruhanga, Achilles; Asasira, Josephine; Ssegawa, Paul; Balmford, Andrew; Davenport, Tim; Fjeldsa, Jon; Friis, Ib; Pain, Deborah; Pomeroy, Derek; Williams, Paul; Williams, Charles
    BirdLife International’s Important Bird Areas (IBA) program is the most developed global system for identifying sites of conservation priority. There have been few assessments, however, of the conservation value of IBAs for nonavian taxa.We combined past data with extensive new survey results for Uganda’s IBAs in the most comprehensive assessment to date of the wider biodiversity value of a tropical country’s IBA network. The combined data set included more than 35,000 site × species records for birds, butterflies, and woody plants at 86 Ugandan sites (23,400 km2), including 29 of the country’s 30 IBAs, with data on additional taxa for many sites. Uganda’s IBAs contained at least 70% of the country’s butterfly and woody plant species, 86% of its dragonflies and 97% of its birds. They also included 21 of Uganda’s 22 major vegetation types. For butterflies, dragonflies, and some families of plants assessed, species of high conservation concern were well represented (less so for the latter). The IBAs successfully represented wider biodiversity largely because many have distinctive avifaunas and, as shown by high cross-taxon congruence in complementarity, such sites tended to be distinctive for other groups too. Cross-taxon congruence in overall species richness was weaker and mainly associated with differences in site size. When compared with alternative sets of sites selected using complementarity-based, area-based, or random site-selection algorithms, the IBA network was efficient in terms of the number of sites required to represent species but inefficient in terms of total area. This was mainly because IBA selection considers factors other than area, however, which probably improves both the cost-effectiveness of the network and the persistence of represented species.