Plant communities, wetlands and landscapes of the Parque Nacional de Banhine, Moçambique

M. STALMANS and M. WISHART

Stalmans, M. and M. Wishart. 2005. Plant communities, wetlands and landscapes of the Parque Nacional de Banhine, Moçambique. Koedoe 48(2): 43–58. Pretoria. ISSN 0075- 6458. The Parque Nacional de Banhine (Banhine National Park) was proclaimed during 1972. It covers 600 000 ha in Moçambique to the east of the Limpopo River. Until recently, this park, originally and popularly known as the ‘Serengeti of Moçambique’, was char- acterised by neglect and illegal hunting that caused the demise of most of its large wildlife. New initiatives aimed at rehabilitating the park have been launched within the scope of the Greater Limpopo Transfrontier Park. A vegetation map was required as input to its management plan. The major objectives of the study were firstly to under- stand the environmental determinants of the vegetation, secondly to identify and describe individual plant communities in terms of species composition and structure and thirdly to delineate landscapes in terms of their plant community and wetland make-up, environmental determinants and distribution. A combination of fieldwork and analysis of LANDSAT satellite imagery was used. A total of 115 sample plots were surveyed. Another 222 sample points were briefly assessed from the air to establish the extent of the different landscapes. The ordination results clearly indicate the overriding impor- tance of moisture availability in determining vegetation composition in the Parque Nacional de Banhine. Eleven distinct plant communities were recognised. They are described in terms of their structure, composition and distribution. These plant commu- nities have strong affinities to a number of communities found in the Limpopo Nation- al Park to the west. The sandveld community is relatively the most species-rich of all communities. Different combinations of these plant communities can be grouped in five major landscapes, namely the Wetland, Grassland, Mopane, Sandveld and Androstachys landscape. These different landscapes hold six different wetland types as defined by the RAMSAR classification. The landscapes with their individual plant communities and wetland types represent a unique combination of habitats that have great intrinsic con- servation value. These habitats are key to the long-term maintenance and survival of a diverse avifauna, including the original ostrich population, as well as wattled cranes. Key words: Parque Nacional de Banhine, Greater Limpopo Transfrontier Park, TFCA, landscape, wetland.

M. Stalmans, International Conservation Services, P.O. Box 19139, Nelspruit, 1200 Republic of South Africa ([email protected]); M. Wishart, Freshwater Research Unit, Department of Zoology University of Cape Town, Rhodes Gift, 7701 Republic of South Africa. Introduction drafting of its management plan (Anony- mous 2002). The Parque Nacional de Banhine (PNB) was proclaimed during 1972. It covers 600 000 ha Little or no botanical surveys were carried out in Moçambique between 1980 and 1994 in Moçambique to the east of the Limpopo during the long period of internal conflict River and forms one of the major compo- that affected much of the country (Anony- nents of the Greater Limpopo Transfrontier mous 1997). The extent of the area, its rela- Park (Fig. 1). A vegetation map was required tive inaccessibility due to poor road infra- as one of the essential building blocks for the structure, and the limited time available pre-

ISSN 0075-6458 43 Koedoe 48/2 (2005) Fig. 1. Locality map of the Parque Nacional de Banhine.

cluded a traditional fine-scale vegetation followed whereby landscapes were mapped description and map of the PNB. Such a fine- explicitly whereas the embedded plant com- scale input is in any case likely to be too munities are implicit. A landscape is defined detailed for the scale of management envis- as ‘an area with a specific geomorphology, aged, certainly in the short to medium term. climate, soil vegetation pattern and associat- ed fauna’ (Gertenbach 1983). Vegetation is often used as a surrogate or building block for the definition of habitats The objectives of this study were firstly to (Timberlake et al. 1993). The use of broad understand the environmental determinants habitat units defined by a combination of of the vegetation, secondly to identify and environmental factors and vegetation would describe individual plant communities in probably represent the most useful input for terms of species composition and structure, the drafting of the management plan. This is and thirdly to identify and delineate land- because such units have relevance to differ- scapes in terms of their plant community and ent species of wildlife, they may differ in wetland make-up, environmental determi- their ecological capacity and availability of nants and occurrence. water, they might require different fire This is the second in a series of three articles regimes, and they will differ in their sensi- on the vegetation of the Limpopo, Banhine tivity to utilisation and development. and Zinave National Parks that are located in As both the Limpopo National Park and the the Moçambican component of the Greater PNB form major components of the Greater Limpopo Transfrontier Park. Difficult Limpopo Transfrontier Park, it was decided access, limited resources and a lack of previ- to build on the work recently completed in ously published information have severely the Limpopo National Park (Stalmans et al. limited the sampling intensity, the extent of 2004). A similar conceptual approach was the descriptions and the detail of the map-

Koedoe 48/2 (2005) 44 ISSN 0075-6458 ping. Nevertheless, it is hoped that these first An overflow is present on the eastern bound- published accounts of the vegetation and ary, draining into the Changane River landscapes of these parks will provide a (Fig. 2). The PNB falls within the Mopane basis on which further research projects can vegetation of the Sudano-Zambezian Region expand, much as the level of knowledge of as described by Werger & Coetzee (1978). the Kruger National Park has been improved Mopaneveld has been described for the hot, upon over the years. dry valley bottom of the Limpopo River in Moçambique (Wild & Barbosa 1967). The area was formerly often popularly referred Study area to as the ‘Serengeti of Moçambique’ because of the large numbers of zebra, wildebeest The physical environment largely deter- and eland that occupied its wide-open grass- mines the vegetation composition and struc- lands. Most of this diverse and numerous ture. The Parque Nacional de Banhine is sit- large herbivore component has been lost uated between latitudes 22º30'–23º20'S and over the last decades, mostly through indis- longitudes 32º15'–33º25'E in the Gaza criminate and illegal hunting. There are Province of Moçambique (Fig. 1). Total area approximately 2000–3000 people living in is ca. 600 000 ha. The PNB forms part of the and adjacent to the PNB in 11 villages. Greater Limpopo Transfrontier Park with the These people are highly dependent on the Limpopo National Park to the west and the direct consumption of park resources for Zinave National Park to the north-east. day-to-day survival, including basic house- According to the Köppen classification the hold needs of shelter, water, food and medi- area has a warm arid climate with a dry win- cines, crop and livestock production. ter and a mean annual temperature exceed- ing 18 ºC (van Rooyen et al. 1981). A mean annual rainfall value of 399 mm applies to Methods the western half of the PNB and 427 mm to the eastern half using the grid at 0.5 degree longitude/latitude resolution of the Leemans Sampling & Cramer (1991) database. Considerable A total of 115 plots of 40 x 40 m were sub- variations can be expected within and jectively located in representative stands of between seasons (Kelly & Walker 1976). The highest elevation is on the north-western boundary at 181 m above sea level. The area dips generally in a south-easterly direction with the lowest point being at 69 m asl on the eastern boundary. The area is underlain by arenaceous and argillaceous sediments with colluvium in the east (Anonymous 1995). The PNB is covered with a pale grey sandy soil mantle that overlies a layer of calcrete about seven metres below the surface. Very occasionally, there are broken lines of cal- crete that reach the surface and extend for distances of up to a hundred metres. The PNB represents a converging endorheic delta-type system with limited overflow (Tinley pers. comm. 2002). A number of ephemeral streams converge from the north- west into a delta-type system forming an Fig. 2. Schematic representation of the endorheic endorheic basin with thin alluvial deposits. wetland system of the Parque Nacional de Banhine.

ISSN 0075-6458 45 Koedoe 48/2 (2005) Fig. 3. Position of vegetation sample plots and control points in the Parque Nacional de Banhine.

vegetation to cover the variation in eleva- tive visual assessment relative to the formal- tion, soils and terrain position. The limited ly surveyed sites. A total of 222 such pseudo- road network was used during the ground plots were assessed during several fixed- survey (Fig. 3). Edwards’ (1983) structural wing and microlight flights (Fig. 3). classes were used to describe the overall structural properties of the sampled plots. Overall cover was estimated for the woody, Analysis grass, forb and geophyte components, Data were analysed through a combination respectively, using the semi-quantitative of classification and ordination techniques. measures of the Braun Blanquet approach Classification is used to identify groups and (Mueller-Dombois & Ellenberg 1974). to impose structure to raw data. Ordination Cover and height classes were recorded for aims at arranging species and samples in a individual woody and grass species. Records low-dimensional space such that similar of environmental data included GPS posi- entities are close by and dissimilar entities tion, geology, landscape position (Land Type far apart. Survey Staff 1989), slope steepness, soil tex- ture (using the sausage method (National ATWINSPAN classification (Hill 1979) was Working Group for Vegetation Ecology performed on the sample data. Two-way 1986)) and rockiness. Fieldwork was under- indicator species analysis (TWINSPAN) is a taken from May to June 2002. Access to the polythetic divisive technique based on recip- study area can be very difficult due to flood- rocal averaging ordination (Gauch 1982). It ing during summer. Vegetation sampling is one of the preferred hierarchical tech- subsequently had to be postponed till the end niques because of its effectiveness and of the summer season into winter although robustness. It results in the definition of this is not ideal in terms of plant species communities, each characterised by its own identification. distinctive species combination. Although In order to further increase sampling intensi- more contemporary and sophisticated soft- ty, so-called ‘pseudo-plots’ were also used. ware packages are available for vegetation These consisted of a GPS point and subjec- classification, TWINSPAN’s simplicity and

Koedoe 48/2 (2005) 46 ISSN 0075-6458 robustness were appealing within the con- map and the LANDSAT image. The land straints of this particular study. cover map (“Carta de Uso e Cobertura da Terra”) has been derived for Moçambique The CANOCO package (Ter Braak 1992) was from LANDSAT satellite imagery at a scale selected to analyse relationships between the of 1:250,000 (Anonymous 1999). A ‘best fit’ data set of 115 plots by 168 species and the map of the landscapes was subjectively underlying environmental factors. CANOCO allows for canonical ordination. This is an drawn by matching the individual land cover intermediate technique that combines polygons to the field sampling data and the aspects of regular ordination with aspects of 222 pseudoplots. Furthermore, polygon regression (Jongman et al. 1987). CCA boundaries were manually edited following (Canonical Correspondence Analysis) was visual inspection of the satellite image. The used. The resulting ordination diagram coverage of the polygons by the available expresses not only the pattern of variation in data set was assessed in order to derive a species composition but also the main fea- measure of certainty or uncertainty regarding tures of species distributions along the gradi- the quality of the final landscape map. ent of environmental variables (Ter Braak 1986). Results and discussion Delineation of landscapes Causal factors of vegetation pattern in the The relevant landscapes for the PNB were PNB identified using the knowledge gained through the ordination and classification of The first ordination run with the full set of the PNB field data. A combined approach 115 vegetation plots resulted in two distinct was used to map these landscapes using the ‘clouds’ of sample plots in ordination space available soils map, the existing land cover (Fig. 4). The environmental variables

Fig. 4. CANOCO ordination of 115 vegetation sample plots in the Parque Nacional de Ban- hine. Note dense cloud of sample plots on left side of diagram with outlying plots to the right that represent vegetation in areas with high moisture availability.

ISSN 0075-6458 47 Koedoe 48/2 (2005) Fig. 5. CANOCO ordination of 73 vegetation sample plots in the Parque Nacional de Banhine (excluding sample plots along major drainage lines, on floodplains and on termite mounds).

‘floodplain’ had a high canonical coefficient are dominated by Xanthocercis zambesiaca of 0.74 with the first axis and ‘drainage line’ in association with Salvadora persica, Allo- had a canonical coefficient of 0.56. phylus africanus, Ficus capreifolia, Maclura africana and Rhus guenzii. These bush The 37 plots on the right of the diagram rep- resent all the pans, riverbanks and reed beds clumps on termite mounds have a high clay that were sampled (Fig. 4). The amount of content. The parameter ‘soil texture’ has a available moisture as determined through canonical coefficient of 0.89 and t-value of landscape position therefore represents a 10.3 for the first axis. This clearly indicates major environmental determinant of vegeta- the increasing clay content of the soils. tion composition along the first ordination Once again, the five outlying plots were axis. The different sample scores of a specif- removed and the remaining data set was ic environmental variable are represented ordinated. The split between ‘sandveld’ and within the ordination diagram by a single non-sandveld sample plots is very clear point, called the ‘centroid’. The grasses along the gradient of decreasing clay content Cynodon dactylon and Eragrostis cf. het- of the soil along the first ordination axis eromera are typical of these floodplain con- (Fig. 5). The parameter ‘soil texture’ has a ditions. The woody species Mimusops canonical coefficient of 0.76 and t-value of obtusifolia, Grewia sulcata, Spirostachys 9.6 for the first axis. There is a weaker gra- africana and Acacia robusta are typical for dient in terms of landscape position with the fringes of the major drainage lines feed- crest and upper slope positions negatively ing the Banhine system from the north. correlated to the second axis (canonical The 37 plots associated with the floodplain coefficients of 0.66 and 0.46 respectively). and drainage line were removed from the The non-sandveld sample plots are charac- data set and a second ordination was run. terised by mopane Colophospermum The resulting diagram identifies an outlier in mopane. Sandveld has typically no mopane the mopane veld on the northern boundary (or only a low cover percentage for this with the grass layer being dominated by species) with typical sandveld species such Cymbopogon. The other outliers represent as Xerroderris stuhlmannii, Strychnos mada- the bush clumps found in the floodplain that gascariensis and Guibourtia conjugata.

Koedoe 48/2 (2005) 48 ISSN 0075-6458 savanna can assume (Scholes & Walker 1993). Fire and herbivory then determine the actual form and function within that range. Similarly, Timberlake et al. (1993) consider soil moisture in this environment as a major determinant in the distribution of vegetation types. Soil moisture availability results from the inter- action between rainfall, topogra- phy, soil texture, soil depth, drainage and rooting habit. Siebert et al. (2003) identified a gradient of decreasing soil mois- ture availability along the first axis of ordination of more than 2000 sample plots in mopane veld straddling South Africa, Namibia and Botswana. Stalmans (1994) and Stalmans et al. (2004) identified water availability (as controlled by the position of the sample in the landscape and by its soil texture) as the major determi- nant of vegetation composition in an area adjacent to the Gonarezhou National Park in Zimbabwe and in the Limpopo Fig. 6. TWINSPAN dendrogram for 115 vegetation sample plots National Park respectively. in the Parque Nacional de Banhine.

TWINSPAN Dendrogram The results from the TWINSPAN The successive ordination runs clearly indicate the over- classification are presented by riding importance of moisture availability (in conjunc- means of a hierarchical dendro- tion with soil texture) in determining vegetation compo- gram (Fig. 6). Starting from the sition in the PNB. Firstly, the obvious differences in top of the dendrogram, the set of moisture availability by virtue of sample positions along 115 sample plots is divided into drainage lines and in the floodplain came out of the first two groups. The left group repre- ordination. Thereafter, the gradient in soil clay content sents the bulk of the sample plots (as a result of underlying geological substrate and land- (n=83). The right group with scape position) and landscape position per se (in deter- indicator species Cynodon dacty- mining water flow) largely determine soil moisture and lon, Eragrostis heteromera, Pani- nutrient availability. cum coloratum and Paspalidium The interplay of soil moisture and soil nutrient avail- obtusifolium represent vegetation ability conforms to the current understanding of the associated with seasonally or per- determinants of savanna. The four-determinant model manently flooded conditions. gives water availability and nutrient availability equal These two main divisions are status in establishing the range of possible forms a now described separately.

ISSN 0075-6458 49 Koedoe 48/2 (2005) The Androstachys woodlands and thickets necessarily a trained botanist. Community already become a separate entity at Level 2 names were chosen subjectively so as to of the diagram (Community 1). The Xantho- have practical value in the field through the cercis zambesiaca bushclumps on termitaria use of two species which are visually and/or are split off from the remaining plots at diagnostically important. The communities Level 3 (Community 2). At Level 4, the divi- broadly conform to the lower divisions of the sion is according to the clay content in the dendrogram and they are therefore discussed soil profile. The vegetation on more clayey from left to right following Fig. 6. A total of soils is divided into two communities, name- 11 communities were identified. ly closed woodlands along seasonal drainage lines (Community 3) and typical mopane woodlands (Community 4). The split at Description of plant communities Level 5 for the more sandy substrates pro- duces a group of plots located on well- 1 Androstachys johnsonii-Croton pseudopulchellus drained soils and Community 7 that is found Closed Woodlands on sandy soils with a high water table. Final- ly at Level 6, the remaining plots on sandy This is a species-poor community found on soils are split into the sandy variant of the red, deep sandy soils. It consists of an mopane community (Community 5) and the extremely dense, short (5–10 m) woodland true sandveld of Community 6. dominated by Androstachys johnsonii. Other species have a very low percentage cover Within the wetland and floodplain vegeta- value and biomass. The woody species Cro- tion, the split at Level 2 is into units that are ton pseudopulchellus, Guibourtia conjugata, wooded or not wooded. At Level 3, in the Xeroderris stuhlmannii and Manilkara wooded units, the Acacia borleae shrubland mochisia are also found in this community. that is found encroaching from the mopane The grass cover is very low with the peren- into the grasslands becomes distinct (Com- nial Panicum maximum and the annual munity 8). Community 9 represents wooded Brachiaria deflexa being the most important grasslands. Within the non-wooded unit, the species. This community is mostly found on grasslands of the seasonally flooded flats the north-western boundary as well as in the (Community 10) are separated from the pans southern corner of the park. It is generally and true wetland. The latter two communi- sharply demarcated from other communities ties are differentiated by Cynodon dactylon and occurs in patches ranging from a few on seasonally flooded grasslands and Paspa- dozen metres in diameter to large areas cov- lidium obtusifolium as a typical (but not ering many hectares. This community corre- exclusive) exponent of the pans. sponds to the Androstachys johnsonii-Croton pseudopulchellus Dry Forest described by Definition of plant communities Van Rooyen et al. (1981) in the northern part of the Kruger National Park and to the The community concept is applied in its Androstachys johnsonii-Guibourtia conjuga- broad sense and reflects a recurring assem- ta Short Forest described by Stalmans et al. blage of grass and woody species of charac- (2004) for the Limpopo National Park. teristic composition and structure, growing in an area of essentially similar environmen- tal conditions and land use history (adapted 2 Xanthocercis zambesiaca - Salvadora persica Thickets from Gabriel & Talbot (1984)). The classification outcome was evaluated This community occurs as distinct bush subjectively against photographs of each clumps with a diameter of 20–30 m on ter- sample plot. The main criterion applied was mitaria, mostly on the transition from the the need for each community to be identifi- grasslands to the wetlands. Each clump is able in the field by an observer who is not characterized by an emergent Xanthocercis

Koedoe 48/2 (2005) 50 ISSN 0075-6458 zambesiaca (Nyala tree) that is surrounded Xeroderris stuhlmannii, Strychnos madagas- by a variety of other species forming a fringe cariensis, Guibourtia conjugata, Boscia around the core of the clump. These other albitrunca and Sclerocarya birrea are impor- species comprise Allophylus africanus, tant components. The grass component also Grewia sulcata, Rhus guenzii, Ficus reflects the more sandy nature of the soils capreifolia, Maclura africana and Salvadora with Panicum maximum, Digitaria eriantha, persica. The grass layer is poorly developed Perotis patens, Eragrostis pallens and Aristi- and consists mostly of Panicum maximum. da stipitata. Heteropogon contortus is almost totally absent. 3 Mimusops obtusifolia-Spirostachys africana Closed Woodlands 6 Guibourtia conjugata - Eragrostis pallens Woodlands This community is found along seasonal rivers, mostly on the northern boundary of This community is found on deep sandy the park. This riverine community occupies a soils. Characteristic woody species of the narrow strip of 10–20 m wide along these ‘sandveld’ are Hugonia orientalis, Pteleop- drainage lines. The most important species sis myrtifolia, Cleistanthus schlechteri, apart from the dominant Mimusops obtusifo- Hymenocardia ulmoides and Xylotheca lia and Spirostachys africana are Grewia kraussiana. Other important species are the sulcata, Acacia robusta, Combretum more wide-spread Combretum apiculatum, imberbe, Garcinia livingstonei and Ziziphus Terminalia sericea, Strychnos madagas- mucronata. The most important grass cariensis and S. spinosa. The grass layer is species is Panicum maximum. represented by Eragrostis pallens, Panicum maximum, Tricholaena monachme, Perotis 4 Colophospermum mopane - Urochloa mosambi- patens and Aristida spp. This particular com- censis Woodlands munity very closely resembles the Termina- lia sericea-Pogonarthria squarrosa Tree This represents the most extensive ‘mopane’ Savanna identified by Van Rooyen et al. vegetation found in the PNB . It occurs on slightly more clayey soils (sandy loam) than (1981) in the Punda Milia area of the Kruger the mopane of community 5. Prominent National Park. It also encompasses the woody species are Combretum apiculatum, Xeroderris stuhlmannii - Combretum apicu- Sclerocarya birrea, Dichrostachys cinerea, latum Tree Savanna of Van Rooyen et al. Dalbergia melanoxylon and Drypetes (1981). These communities in turn are simi- mossambicensis. A major difference with the lar to the Terminalia sericea - Eragrostis community 5 is the marked absence of Ter- pallens Low Woodland described for the minalia sericea and Xeroderris stuhlmannii, Limpopo National Park by Stalmans et al. as well as the lower frequency of occurrence (2004). and lower cover of Combretum apiculatum. The most important grasses are Panicum 7 Hyphaene petersiana - Eragrostis gummiflua maximum, Digitaria eriantha, Schmidtia Bushlands pappaphoroides, Aristida adscencionis and Heteropogon contortus. This community consists of a generally fair- ly open, but sometimes closed vegetation 5 Colophospermum mopane - Eragrostis pallens with a mix of trees and shrubs on the transi- Woodlands tion from the sandveld to the wetland. In addition to the Hyphaene palms, the trees This is still a mopane-dominated community Terminalia sericea and Garcinia livingstonei but represents a more ‘sandy’ variant. In are prominent. The grass layer is dominated addition to mopane, the woody species Com- by Eragrostis gummiflua, E. pallens, Perotis bretum apiculatum, Terminalia sericea, patens and Digitaria eriantha. The palms

ISSN 0075-6458 51 Koedoe 48/2 (2005) and Eragrostis gummiflua are usually an Other species are cf. Acroceras macrum, indication of a high water table. Sporobolus consimilis, Digitaria eriantha and Eragrostis gummiflua. As in communi- 8 Acacia borleae Shrublands ty 9, the sedge component is highly visible. A crust of detritus and algae which is a This community also occurs on ecotones, but residue from the flooding occurs. This most this time between the mopane woodlands likely plays a very important role in nutrient and the grasslands. Besides Acacia borleae supplementation in a community on sandy and Rhigozum zambesiacum, few other soils with limited nutrient content. Below the woody species occur in association with alluvial plug (Fig. 2), along the banks of the Colophospermum mopane. Acacia borleae is Changane on the eastern boundary, the vege- generally known to occur on clayey soils. tation indicates almost saline characteristics The grass layer is characterised by the dom- with the presence of succulent halophytes inance of Eragrostis cf. heteromera in asso- and Sporobolus spp. (probably S. kentrophyl- ciation with Sporobolus spp., Paspalum sp. lus). Similar-looking grasslands were and Eragrostis viscosa. observed from the air, 15 km north-north- west of Pio Cabral. The Cynodon dactylon 9 Cynodon dactylon - Panicum coloratum open grasslands are considered to be ‘natur- Wooded Grasslands al’ (given the edaphic control in combination with fires). They do, therefore, not represent This is an open community with a low cover a secondary degradation product of savannas and diversity of woody species. The most that would be expected to occur under the prominent woody species are Hyphaene prevailing climatic conditions. This view- petersiana, Colophospermum mopane, Aca- point is in support of the analysis by cia nilotica and A. xanthophloea. The grass Matthews et al. (1999) for the coastal grass- layer is dominated by Cynodon dactylon, lands of Maputaland. Panicum coloratum, Digitaria eriantha and Eragrostis cf. heteromera with occasionally 11 Paspalidium obtusifolium Open Grasslands Setaria incrassata and Ischaemum afrum on more clayey and poorly drained soils. The These open grasslands are found in small sedge component (family Cyperaceae) is depressions and in the larger wetland in very prominent. A crust of detritus and algae areas that are flooded for long periods. The was found on most sample plots. This meta- most obvious difference with community 10 phyton originates as floating algae popula- is the absence of Cynodon dactylon. The tions that aggregate along the shore line pans are sometimes fringed by the tree Com- through wave action and the recession of bretum imberbe. Other important grass flood waters (Wetzel 2001). Die-back of species are Sporobolus consimilis, Era- trees (including Acacia xanthoploea) as a grostis cf. heteromera, cf. Acroceras result of long periods of flooding was macrum and Echinochloa colona. In deeper observed. water, dense stands of Phragmites australis or P. mauritianus reeds and bulrushes Typha 10 Cynodon dactylon Open Grasslands capensis are found. These could not be sam- pled because of problems in terms of acces- These are open grasslands with hardly any sibility. The blue water lily Nymphaea woody species present. They are found in nouchali, as well as the small yellow water seasonally flooded areas where the high lily Nymphoides thunbergiana and the water table prevents (probably in combina- white-flowered Nymphoides indica ssp. tion with recurrent fires) any permanent occidentalis are very conspicuous. presence of trees. The grass layer is domi- nated by Cynodon dactylon, Eragrostis cf. The communities described above are very heteromera and Paspalidium obtusifolium. dynamic in nature. As waters recede, com-

Koedoe 48/2 (2005) 52 ISSN 0075-6458 munity 11 gives way to community 10. catchment runoff reaches the wetland. The Community 10 can become more wooded if right conditions mainly tend to occur when flooding does not occur for a number of tropical cyclones move in over the PNB years, it also being encroached upon by catchment from the Mozambique Channel, expanding Acacia borleae of community 8. mainly during the period December to Stands of 5 m tall dead Acacia xanthophloea March. and mopane have been observed. This indi- Such a hydrological regime means that water cates that trees could establish themselves flows in to the wetland system only as a and thrive for a number of years before being result of intense and sporadic storm events. killed during a long period of inundation. These driving pulses result in a high degree of diversity and productivity within the Wetland types of the PNB PNB’s wetland systems. The continuous transition between the terrestrial and aquatic The wetlands of the PNB are characterised condition as a result of the cyclic flooding by episodic flooding from sporadic storm and drying of the PNB system creates a events that produce ephemeral flows fol- dynamic ecotone supporting an array of lowed by a gradual drying out. This process diverse temporal habitats and rich fauna and is determined not only by the amount of rain- flora. The pulsed nature of inflows from fall, but also by the intensity and duration of within the catchment brings with it a rich the event. These factors, along with levels of sediment load high in nutrient content. As a soil saturation, determine how much of the result of this pattern, and the concentration

Fig. 7. Landscape map of the Parque Nacional de Banhine.

ISSN 0075-6458 53 Koedoe 48/2 (2005) affected through high evaporation rates, results of the satellite imagery analysis. They nutrient levels within some of the smaller often occur in a fine-scaled mosaic that wetland systems would appear to be reflects small variations in topography and extremely high. accompanying moisture regime. These fac- tors cannot always be mapped in sufficient The following six wetland types (based on detail to allow for extrapolation and correla- the Ramsar Convention classification) occur tion with the vegetation. Broader units have in the park: thus been mapped out of necessity. L Permanent inland deltas; Landscapes have been defined that have M Permanent rivers/streams/creeks; N Seasonal/intermittent/irregular rivers/streams/ bearing on management requirements and creeks; development potential as they represent a P Seasonal / intermittent freshwater lakes (>8ha) composite of topographical factors, underly- including floodplain lakes; ing soil, hydrology and current vegetation Tp Permanent freshwater marshes/pools; ponds pattern. Different combinations of the plant (below 8ha), marshes and swamps on inorganic soils; with emergent vegetation water-logged communities can be grouped in five major for at least most of the growing season; landscapes. Extensive use was made of the Ts Seasonal/intermittent freshwater marshes/ existing “Carta de Uso e Cobertura da Terra” pools on inorganic soils; includes sloughs, (Anonymous 1999) for the mapping of the potholes, seasonally flooded meadows, sedge marshes. following individual landscapes (Fig. 7): Wetland landscape – comprises the seasonal- ly to permanently flooded areas in the north- Landscapes of the PNB eastern part of the park, particularly towards Not all of these 11 plant communities can be Pio Cabral. This landscape is characterised mapped individually, not even using the by community 11, although communities 9

Fig. 8. Sampling intensity across original land cover polygons in the Parque Nacional de Banhine. Polygons with no or only one sample indicate greater uncertainty as to their correct landscape classification.

Koedoe 48/2 (2005) 54 ISSN 0075-6458 & 10 occur on levees and patches of higher tion of ostriches Struthio camelus that is ground within the landscape. Large areas of found in the park. Oribi Ourebia ourebi open water with dense stands of Phragmites occur in this landscape, particularly towards australis/mauritianus reeds, Typha capensis the ecotone with the Wetland landscape. and sedges occur. This landscape holds Mopane landscape – this landscape is found examples of wetland types L and Tp as on more loamy to clayey soils, specifically described earlier. It covers 6 588 ha or 1.1 % where the sand mantle has been eroded of the PNB. Wattled cranes Grus caruncula- away, to the north-west of the wetland and tus have been observed in the wetland land- grassland landscapes. Its dominant feature is scape during 2002, 2003 and 2004 (M. Stal- the closed woodlands of communities 4 & 5. mans pers. obs.). Embedded within the mopane are the sea- Grassland landscape – this landscape repre- sonal streams representing wetland type N sents the seasonally flooded areas surround- (with vegetation community 3). These ing the wetland landscape. Its characteristic streams channel water from the areas north feature is its open grasslands (community of the park towards the wetland above the 10), sometimes with scattered trees (commu- alluvial plug. Further downstream these nity 9), bush clumps on termitaria (commu- streams become ill-defined, with an almost nity 2) and Acacia borleae shrublands (com- ‘braided’ character. They are wide and munity 8) and Hyphaene petersiana - Termi- grassy, covered by communities 9 & 10, with nalia sericea trees (community 7) on its mar- community 11 in small pans within those ill- gins. ‘Islands’ of sandveld, Colophosper- defined drainage lines. This landscape there- mum mopane and baobabs Adansonia digita- fore holds elements of wetland types N and ta with Commiphora spp. occur on slightly Ts. It covers 212 226 ha or 33.9 % of the higher ground within the extensive grass- Parque Nacional de Banhine. lands. This landscape represents the flooded Sandveld landscape – this landscape covers meadows of wetland type Ts with seasonal the larger part of the park, particularly to the pans as well as larger seasonal floodplain west and south. It typically consists of com- lakes of wetland type P. It covers 85 170 ha munity 6 with patches of community 5. Pans or 13.6 % of the PNB. The Grassland land- in this landscape are covered by community scape is very important to the large popula- 11. Wetland type Ts is therefore represented.

Table 1 Relative species richness of plant communities in the PNB Community No. of Total Expected no. Actual no. Relative sample species of species as % of diversity plots expected 1 5 9 18 50 Medium 2 5 22 18 123 Medium 3 3 29 11 259 High 4 28 81 96 85 Medium 5 22 102 75 135 High 6 13 83 45 185 High 7 7 24 25 97 Medium 8 2 9 8 115 Medium 9 13 26 45 58 Low 10 12 9 42 22 Low 11 5 6 18 33 Low

ISSN 0075-6458 55 Koedoe 48/2 (2005) This is the most extensive landscape and sandveld in the Limpopo National Park covers 292 350 ha or 46.7 % of the PNB. (Stalmans et al. 2004). This is similar to the situation in the Limpopo National Park where the Nwambia Land use patterns and their influence on the sandveld landscape covers 41 % of the park. Sandveld is not well represented in the vegetation of the PNB Kruger National Park on the South African A number of people reside within the bound- side of the Greater Limpopo Transfrontier aries of the PNB. They practise mainly sub- Park. sistence farming and rely on the fish resources of the wetland. Subsistence farm- Androstachys (Nsimbitsi) landscape – this ing takes mostly place on bushclumps, in landscape is very uniform and mostly con- mopane woodlands and in the wetland. sists of community 1. It is interleaved with Bushclumps of community 2 are cleared and the sandveld landscape in the extreme north- maize is planted in the fertile soil of the ter- western corner of the park and with the mitarium. The number of bushclumps that mopane and sandveld landscapes in the have been destroyed in this manner seems extreme south. It covers 29 688 ha or 4.7 % fairly limited. However, it can be anticipated of the PNB. that recovery will take many years. The The map boundaries are drawn subjectively whole functioning (and therefore recovery) because of the fact that there is seldom a def- may be affected by the loss of the emergent inite and visible border between landscapes, Xanthocercis zambesiaca trees. Manual but rather a gradient in terms of vegetation clearing of mopane woodlands (communi- and topography. The sampling did not cover ties 4 & 5): with stacking of the material all land cover polygons (Fig. 8), with 12 % around the bigger trees is followed by burn- of the PNB not being assessed at all. The ing that kills those trees. Crops are planted in greatest uncertainties with regard to the the ashbed that increases fertility. Crops can landscape map are along the western bound- only be produced for a very few years before ary and in the south-eastern corner of the these lands must be left fallow to restore soil fertility. The total area that has been cleared PNB. and is in some stage of recovery is therefore much larger than the extent of land that is Plant community and landscape diversity actively cultivated in any given year. As waters recede, crops are planted in the wet- The available time frame and limited ground land (community 11). The extent of cultivat- coverage did not allow for a detailed inven- ed land is relatively limited and the impact is tory of plant diversity. However, a relative probably fairly small as the next flood cycle measure of plant community diversity can be probably ‘resets’ the cultivated patch and derived by comparing the total species count surrounding areas to a similar state. to the sampling intensity for each respective community. The number of species per com- Use is made of trees for firewood, building munity in relation to the expected species of dwellings, livestock pens, and carving of number (based on the average accumulated various items. The impact of these activities number of species per sample plot) is depict- is selective. Whereas this use does not seem ed in Table 1. to impact significantly on the overall woody resource, no data are available on the impact Communities 3 (riverine), 5 (partly sand- on specific species. Grass is cut and used for veld) and 6 (pure sandveld) are relatively thatching (mostly Heteropogon contortus). more species-rich than expected from the Much use is made of medicinal plants and number of samples assessed. In particular, wild fruits (eg. Strychnos spp.). No data are the sandveld of community 6 much exceeds available regarding the impact thereof on the expected value. The same applied for specific species. The Hyphaene palms are

Koedoe 48/2 (2005) 56 ISSN 0075-6458 heavily tapped for their sap. This involves Acknowledgements the cutting of the stems. As a result very few Dr Ken Tinley provided unpublished data which he tall palms have been observed in the field. collected during the 1970s. These data proved The Devil’s claw Harpagophytum procum- invaluable in describing the functioning of this wet- land system. Warden Armando Nguenya provided bens (family Pedaliaceae) occurs in the PNB logistical support and accompanied the survey team (Dr A.B. (Tony) Cunningham pers. comm. in the field. Dr Jeremy Anderson assisted with access 2003). The root tubers of this plant are trad- to the area, provided assistance with the vegetation ed internationally and concern has been sampling and organised over flights of the PNB. expressed at the CITES level regarding its Members of the Bateleur group of pilots (in particu- situation (Anonymous 2003). lar Joe Holmes and Avroy Shlain) graciously provid- ed fixed-wing and micro-light flying time. Craig Levels of herbivory (both grazing and Beech of the Peace Parks Foundation assisted with browsing) seem presently very limited in the GIS data. Mervyn Lötter, Ernst Schmidt, Warren PNB. Current numbers of game are certainly McLeland and John Burrows of the Plant Specialist very low. Livestock numbers are also rela- Group assisted with species identification. The veg- tively limited including cattle and goats. etation and hydrological research was undertaken as part of the planning work by Development Alterna- During the subjective scoring of the sample tives Inc that was funded by USAID in support to the plots only 7 out of 115 plots had a medium Direcção Nacional de Áreas de Conservação of the level of grazing pressure and one had a Ministério do Turismo, Moçambique. More specifi- medium browsing impact (old elephant utili- cally, the management plan for the PNB was com- sation). No heavy grazing was observed. The piled by the ecologists Dr D Grossman and Ms P grass and tree layer are generally in a good Holden. condition. It offers suitable habitat for the herbivores that could be expected in this environment (both those occurring histori- References cally and those still present). ANONYMOUS. 1995. Legenda da carta nacional de The only alien plant species observed was solos (Escala 1:1.000.000). Maputo, Moçam- the prickly pear (Opuntia sp.). It occurs in a bique: Compilada pelo Departemento Terra e Agua. few dense stands near the village of Tchove. ANONYMOUS, 1997. First national report on the con- Fires are very prominent within the PNB servation of biological diversity in Moçambique. Ministry for the Coordination of Environmental with signs of old and recent fire events visi- Affairs. Maputo. ble throughout the landscape. Although a ANONYMOUS. 1999. Carta de Uso e Cobertura da number of fires likely originate from light- Terra. Moçambique: Joint venture IGNFI - ning, the most probable cause of fire is CENACARTA - DINAGECA. through the activities of the inhabitants of ANONYMOUS. 2002. Banhine National Park, Manage- ment and Development Plan. Unpublished the PNB, e.g., clearing of lands, producing a report to the National Directorate for Conserva- green flush for livestock grazing, smoking tion Areas, Ministry of Tourism, Republic of out of beehives. Within the constraints of the Moçambique. present study it was not possible to assess the ANONYMOUS. 2003. Devils’ claw (Harpagophytum fire return period and its appropriateness. Of procumbens). Fauna & Flora 4 (April 2003): 28. interest is the relatively small-scale pattern BROCKETT, B.H., H.C. BIGGS & B.W. VAN WILGEN. that can be observed in the field. This pattern 2001. A patch mosaic burning system for con- of spatially and temporally varying fire para- servation areas in southern African savannas. meters (frequency, seasonality, intensity and International Journal of Wildland Fire 10:169- type of fire) across the landscape is likely to 183. COETZEE, B.J. 1983. Phytosociology, vegetation be required for the maintenance of diversity structure and landscapes of the Central District, (Brockett et al. 2001; Gill & McCarthy Kruger National Park. Dissertationes Botanicae 1998). 69: 1-456.

ISSN 0075-6458 57 Koedoe 48/2 (2005) EDWARDS, D. 1983. A broad scale structural classifi- binomial classification system. Technical Com- cation of vegetation for practical purposes. Both- munication 3. alia 14: 705-712. SCHOLES, R.J. & B.H. WALKER. 1993. An African GABRIEL, H.W. & S.S. TALBOT. 1984. Glossary of savanna. Cambridge Cambridge: University landscape and vegetation ecology for Alaska. Press. BLM-Alaska Technical Report 10. U.S. Depart- SIEBERT, F., G.J. BREDENKAMP & S.J. SIEBERT. 2003. ment of the Interior. A comparison of Mopaneveld vegetation in GAUCH, H.G. 1982. Multivariate analysis in commu- South Africa, Namibia and Zimbabwe. Bothalia nity ecology. Cambridge: University Press. 33(1):121-134. GERTENBACH, W.P.D. 1983. Landscapes of the STALMANS, M. 1994. Vegetation survey of Malilang- Kruger National Park. Koedoe 26:9-121. we. Unpublished report to the Malilangwe Con- GILL, A.M. & M.A. MCCARTHY. 1998. Intervals servation Trust. between prescribed fires in Australia: what STALMANS, M., W.P.D GERTENBACH & F. CARVALHO- intrinsic variation should apply? Biological SERFONTEIN. 2004. Plant communities and land- Conservation 85:161-169. scapes of the Parque Nacional do Limpopo, HILL, M.O. 1979. TWINSPAN - A FORTRAN program for Moçambique. Koedoe 47(2): 61-81. arranging multivariate data in an ordered two- TER BRAAK, C.J.F. 1986. Canonical correspondence way table by classification of the individuals and analysis: a new eigenvector technique for multi- attributes. Ithaca, New York: Cornell University. variate direct gradient analysis. Ecology 67(5): 1167-1179. JONGMAN, R.H.G., C.F.J. TER BRAAK & O.F.R. VAN TER BRAAK, C.J.F. 1992. CANOCO - A FORTRAN pro- TONGEREN. 1987. Data analysis in community gram for canonical community ordination. Itha- and landscape ecology. Wageningen: Pudoc. ca, New York, USA: Microcomputor Power. Kelly, R.D. & B.H. Walker. 1976. The effect of dif- TIMBERLAKE, J.R., N. NOBANDA & I. MAPAURE. ferent forms of land use on the ecology of a 1993. Vegetation survey of the communal lands- semi-arid region in South-eastern Rhodesia. north and west Zimbabwe. Kirkia 14(2): 171- Journal of Ecology 64:553-576. 270. LAND TYPE SURVEY STAFF. 1989. Land types of the VAN ROOYEN, N., G.K. THERON & N. GROBBELAAR. map 2530 Barberton. Memoirs of the Agricultur- 1981. A floristic description and structural al Natural Resources of South Africa 13. analysis of the plant communities of the Punda LEEMANS, R. & W. CRAMER. 1991. The IIASA data- Milia-Pafuri-Wambiya area in the Kruger base for mean monthly values of temperature, National Park, Republic of South Africa: 2. The precipitation and cloudiness of a global terrestri- sandveld communities. Journal of South African al grid. International Institute for Applied Sys- Botany 47(3):405-449. tems Analysis (IIASA). RR-91-18. WERGER, M.J.A. & B.J. COETZEE. 1978. The MATTHEWS, W.S., A.E. VAN WYK & N. VAN ROOYEN. Sudano-Zambezian Region. In: WERGER, M.J.A. 1999. Vegetation of the Sileza Nature Reserve (ed.). Biogeography and ecology of southern and neighbouring areas, South Africa, and its Africa. The Hague: W. Junk. importance in conserving the woody grasslands WETZEL, R.G. 2001. Limnology: lake and river of the Maputaland Centre of Endemism. Both- ecosystems. 3rd Edition. San Diego: Academic alia 29(1):151-167. Press. MUELLER DOMBOIS, D. & H. ELLENBERG. 1974. Aims WILD, H. & L.A.G. BARBOSA. 1967. Supplement of and methods of vegetation ecology. New York: the vegetation map of the Flora zambesiaca John Wiley. area. Pp. 1-71. In: WILD, H. & A. FERNANDES. NATIONAL WORKING GROUP FOR VEGETATION ECOLO- Vegetation map of the Flora zambesiaca region. GY. 1986. Soil classification according to the Harare, Zimbabwe.

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