B1. Mixed alluvial thicket

Mixed alluvial thicket is found on the alluvial soils associated with the Luangwa river in the east of the NLNP and SLNP, and is the characteristic thicket vegetation type north of the Mwaleshi river. Elevation in this area is between 600m and 625m and the terrain undulates slightly with a relief of only a few metres. This vegetation type is frequently found in mosaic with Chloris-Dactyloctenium-Echinochloa secondary grassland (F1) but occupies higher ground and better drained, sandy soils so that while the surrounding grassland becomes waterlogged during the wet season, the areas of thicket remain comparatively dry.

Soils associated with this vegetation type are freely draining and are typically pale brown to orange, stoneless, sandy clay loams (60-75% sand) of slightly acid to neutral pH (pH 6.5- 7.0).

Vegetation type B1 comprises closed and open stands of bushes 2-7m high with occasional tall trees. Colophospermum mopane is present to a greater or lesser extent. It is found in clumps on patches of calcareous or sodic clay soil but also as individual, usually tall, trees dotted throughout the habitat. Other occasional tall trees include Xeroderris stuhlmannii, Pseudolachnostylis maprouneifolia, Stereospermum kunthianum and Adansonia digitata. Common smaller trees are Boscia angustifolia, Excoecaria bussei (also a shrub), Schrebera trichoclada and Diospyros quiloensis (occasionally a large tree). Vegetation type B1 is dominated by the shrubs Croton gratissimus, Friesodielsia obovata, Mundulea sericea, Combretum obovatum, Vangueria infausta, Markhamia obtusifolia and Markhamia zanzibarica. Baphia massaiensis is locally common. The grass and herb layer is not well-developed in Mixed alluvial thicket but contains elements of vegetation types D1, E1 and F1. Grasses include Digitaria acuminatissima, Sporobolus cordofanus, Urochloa mossambicensis, Dactyloctenium spp. and Chloris spp. In the wetter sump areas, Brachiaria deflexa, Sporobolus pyramidalis and Setaria spp. are characteristic. Common herbs are Hibiscus cannabinus, Hibiscus calyphyllus, Cleome monophylla, Cleome hirta, Senna absus, Blepharis tenniramea, Clerodendrum spp. and Duosperma spp.