LOWER ZAMBEZI RIVER BASIN BASELINE DATA ON LANDUSE ...

classifications within the region are of little value for management and are only broadly indicativeof biodiversity pattern for survey design purposes.50. Given the current paucity of data, the present survey has added significantly new baselineinformation to the GOM knowledge base. In ten days a highly mobile team of five specialistswith one week of prior intensive training in assessment methods was able to document keyfeatures of environmental gradients and patterns of biodiversity richness and composition acrossthree Provinces (Tete, Sofala, Zambezia) and eight districts (Cahora Bassa, Moatize, Mutarara,Morrumbala, Marromeu, Mopeia, Chinde and Nicoadala). The 32 transects deployed along thelower Zambezi gradsect provide an important environmental context for the future selection ofsample sites within the five districts. The baseline survey included all ecoregions in Fig. 2.1, inaddition to recording biodiversity in both relatively natural and intensively managed land usetypes including monocropping sequences in flooded riparian systems in Mutarara, slash and burnsubsistence gardens near Chinde and a commercial, irrigated plantation in Marromeu.51. In global terms the lower Zambezi valley subregion is low in biodiversity. Despite theeffects of the dry season and fired landscapes, this conclusion is generally consistent withfindings from other researchers in the Mopane- Brachystegia forests and woodlands. Datarecorded from the same transects in July and September revealed little change other thanincreased deciduousness. Reasons for low biodiversity are not clear but appear to be associatedwith generally low levels of labile soil nutrients that are likely to be continually removed fromthese ecosytems by annual firing. In Southern Africa low biodiversity is not necessarilyassociated with low biodiversity – the southern Cape Fynbos heaths on sandstones provide anexample of high biodiversity associated with low soil nutrients. In Mutarara skeletal soils onRhyolite rock outcrops (Transect 11 Chinsomba) also supported relatively high species and PFTdiversity.52. Criteria for biodiversity conservation should not be driven by high diversity alone but shouldinclude other criteria such as endemicity, plant functional diversity, uniqueness of habitat andvulnerablility. When these are considered, the lower Zambezi valley contains outstandingexamples of unique biodiversity features, especially among succulent (Euphorbiaceae,Agavaceae, Apocynaceae) and primitive (Zamiacaeae) genera. All are of significant interest tothe global horticultural and floricultural community and may be of economic potential if suitablemarkets could be established. While present findings are indicative of the basic status quo ofbiodiversity for this subregion, a more intensive survey will better quantify the biodiversityvalues of the project area.3.7. PROSPECTS FOR COUPLING BIODIVERSITY DATA WITH REMOTELYSENSED AND HYDROLOGICAL DATA FOR MODELLING PURPOSES53. Preliminary analyses indicate that biodiversity data acquired from this survey can beeffectively coupled with remotely sensed data. Land cover expressed as different classes ofvegetation (savanna, deciduous broadleaf forest, woodlands…) compiled for the Zambezi basinfrom global data 33 were overlaid by the 32 transects as a check for vegetation representativenesswithin the region. A potential mapping program DOMAIN 34 was used for this purpose and theresults (Fig. 3.5) show that the gradsect reflects the majority of vegetation types below 500melevation .33 N.Voisin and L McGeoch, Hydrology Group, Civil and Environmental Engineering, Univ. Washington,Seattle USA.34 Carpenter et al. (1993)25