C1. Escarpment and plateau miombo woodland

At elevations over 1000m, this is the most important and extensive vegetation type of the Muchinga escarpment. Brachystegia-Julbernardia-Isoberlinia miombo woodland can be separated into three distinct vegetation subtypes dictated by substrate. Subtype 1 occurs over most of the upper escarpment, on deep laterite soils. Subtype 2 is rare in the NLNP and is found in isolated patches on shallower plateau soils. Subtype 3 is associated with the granite outcrops dotted throughout the escarpment terrain.

Vegetation type C1 (subtype 1) corresponds to Trapnell's E and E1 types (Trapnell et al., 1950), which occur on the deep soils of the escarpment, as evidenced by the dominance of Brachystegia utilis and B. spiciformis, species which cannot tolerate shallow soils (Fanshawe, 1971). The tall trees and comparatively sparse grass layer seen in this vegetation type are probably due to the improved drainage and better soils associated with the dissected terrain (Cole, 1963). In this vegetation type, laterite was more commonly found as nodules in the B horizon rather than the impermeable layer characteristic of the pediplain plateau soils (C1 subtype 2). Subtype 2 corresponds to Trapnell’s P4 type (Trapnell et al., 1950), and Subtype 3 is described by White (1983) as “Zambezian rupicolous bushland and thicket”.

Subtype 1 - Upper Escarpment miombo woodland

Upper escarpment miombo woodland is the dominant vegetation type of the upper Muchinga escarpment to the west of the NLNP and SLNP, and is found at elevations ranging from 1000m to >1300m a.s.l. over deeply dissected terrain where relief is measured in hundreds of metres.

Subtype 1 is associated with deep, red, stoneless sandy loams or sandy clays . These soils are slightly acid (pH 6.6-7.0) and usually contain laterite nodules and mica aggregates in the B horizon.

Upper escarpment miombo woodland takes the form of a clearly two-storeyed woodland with an open to lightly closed canopy of semi-evergreen trees 15-20m high. Characteristic canopy trees include Julbernardia paniculata, Brachystegia spiciformis, Brachystegia utilis, Isoberlinia angolensis, Marquesia macroura, Parinari curatellifolia, Brachystegia manga and Pericopsis angolensis. Common lower storey trees are Brachystegia stipulata, Uapaca kirkiana and spp., Craterosiphon quarrei, Phyllocosmos lemaireanus, Memecylon flavovirens, Dalbergia nitidula, Combretum zeyheri, Brachystegia longifolia, Anisophyllea pomifera, Diplorhynchus condylocarpon and Pseudolachnostylis maprouneifolia. Frequent shrubs are Keetia gueinzii, Keetia venosa, Rothmannia engleriana, Landolphia parvifolia and Protea spp. Climbers are infrequent in this vegetation type, Strophanthus welwitschii being a notable exception. In upper escarpment miombo woodland, the grass layer is sparse and generally restricted to scattered clumps of predominantly tall grasses. Common species are Andropogon chinensis, A. schirensis, Anthephora elongata, Heteropholis sulcata, Loudetia simplex, Sporobolus sanguineus and Trichopteryx fruticulosa. The herb layer is sparse but varied. Pteridium aquilinum subsp. centrali-africanum is locally common, and sedges such as Ascolepis elata, Carex echinochloe subsp. nyasensis, Bulbostylis spp., Cyperus spp. and Scleria spp. are found in poorly drained areas. Frequent subshrubs are Psychotria spithamea, Psychotria eminiana, Indigofera emarginelloides, Tapiphyllum cinerascens, Desmodium barbatum and Kotschya spp. Typical herbs include Costus spectabilis and Siphonochilus rhodesicus at the beginning of the rains, followed by Thunbergia kirkiana, Endostemon dissitifolius, Hybanthus enneaspermus, Otiophora scabra, Nidorella spartioides, Rhynchotropis poggei, Aspilia spp., Becium spp., Spermacoce spp., Tephrosia spp. and Triumfetta spp.

Subtype 2 - Plateau miombo woodland

Plateau miombo woodland occurs in isolated patches in the far west of the NLNP, and is associated with flat terrain. Plateau soils tend to be shallow, poor in nutrients and humus, slightly acid, and are typically leached, with a laterite or gley horizon near the surface. In contrast to upper escarpment miombo woodland, plateau miombo woodland is of single storey structure and is characterised by stunted Brachystegia-Julbernardia, interspersed with Uapaca, Protea, Faurea and Monotes species. In addition, the shrub and grass layers are comparatively well-developed, with Hyparrhenia and Andropogon spp. predominant. This subtype occurs on the comparatively shallow, infertile soils of the plateau peneplain and over large areas of Zambia appears to be secondary miombo woodland which has been subjected to repeated fires and cultivation (Fanshawe, 1971).

Subtype 3 - Rupicolous miombo woodland

The rocky outcrops and granite kopjes of the Muchinga Escarpment support a distinctive vegetation type and although many of the taxa listed above may occur, additional species such as Brachystegia microphylla, Pterocarpus rotundifolius, Schrebera trichoclada, Kirkia acuminata, Landolphia parvifolia and Tarenna neurophylla are typical. Carphalea pubescens is a characteristic subshrub.