The Swaziland National Biodiversity Strategy and Action Plan, 1999

[ Contents | Executive Summary | 1.0 Introduction | 2.0 The Status of Biological Diversity in Swaziland | 3.0 Assessment of Current Conservation and Management of Biodiversity in Swaziland | 4.0 Strategy and Action Plan | 5.0 Implementation of BSAP | 6.0 Monitoring and Evaluation | 7.0 References ] 

2.0 The Status of Biological Diversity in Swaziland

2.1 The Classification System Adopted

Swaziland recognises the importance of taking an ecosystem approach for the successful conservation of its biodiversity. The following four ecosystems are recognised in Swaziland (see Figure 2.1):

1. Montane grasslands
2. Savanna-woodland mosaic
3. Forests
4. Aquatic systems (including rivers, streams, wetlands, marshes)

The justification for these four ecosystems is as follows. An ecosystem comprises a distinct biological community together with (and often shaped by) its associated physical environment. An ecosystem is, therefore, a functional unit which is distinct from other ecosystems in both its species composition and the ecological processes driving that ecosystem. 

Seven biomes, defined by similar criteria to that stated above, have been recognised in southern Africa (Rutherford & Westfall, 1994) and are: grassland, savanna, forest, nama karoo, succulent karoo, fynbos and desert. The first three biomes occur in Swaziland and are recognised as functional ecosystems. The grassland, savanna and forest ecosystems are, however, all terrestrial systems. Aquatic systems are driven by very different forces and, therefore, a separate aquatic ecosystem is also recognised.

The montane grasslands (more or less restricted to the highveld and the highest parts of the middleveld) occur in western parts of Swaziland and for the most part comprise a distinct flora and fauna. The savannas and woodlands, although separated into several middleveld and lowveld physiographic zones, are faunistically uniform and are driven by the same forces of fire and herbivory. It has been shown that the variation in species composition of mammals, frogs and birds is insignificant within the savanna zone, but is distinct from that of the montane grasslands. 

This strengthens the argument for separating the savanna-woodland ecosystem from the grassland ecosystem. It also argues for recognising only a single savanna-woodland ecosystem, rather than attempting to subdivide it into further vegetation units which do not represent distinct functional ecological units. Forests are restricted to a few (dwindling) patches located mostly in the west and the Lubombo Mountains in the east. Although species composition varies somewhat between forests in these two zones they are recognised as being part of the same ecosystem because the basic ecological functioning of these two forests is similar. The aquatic ecosystem consists of rivers, streams, marshes and other wetlands which are inundated for a significant part of the year.

There are two distinct advantages to using the proposed classification system:

1. It follows the classification system in place for southern Africa and therefore allows a comparison of the ecosystems found in Swaziland with ecosystems in neighbouring states.
2. There is now considerable evidence (obtained from recent studies of vertebrates) that these ecosystems are reflected by changes in their faunal assemblages. 

This adds to the plausibility of these ecosystems being functioning ecological units rather than simple descriptions of the vegetation.

The four ecosystems as defined here also correspond with the physiographic zones of Sweet and Khumalo (1994) which are mostly been based on geography, grazing resources for cattle and vegetation types (none of which necessarily define functional ecological units); as well as the veld types of I’Ons (1967), Acocks (1988) and Low & Rebelo (1998). 

The montane grasslands correspond to the highveld, while the savanna-woodland mosaic corresponds to the middleveld, lowveld and Lubombos. The forest and aquatic ecosystems are interspersed throughout the four physiographic zones. Low & Rebelo recognise seven biomes, of which their forest, grassland and savanna biomes correspond with the forest, savanna-woodland mosaic and montane grassland ecosystems as presented here.

2.2 Biodiversity Description of Ecosystems

Swaziland lies between latitudes 25 and 28 degrees south and 31 and 32 degrees east in the south-eastern part of Africa. The country is landlocked and covers an area of 17 364 km². It is bounded by South Africa in the north, west and south, and by Mozambique in the east. Although Swaziland is small in size, it has great variation in landscape, geology and climate.

Swaziland is located between the South African plateau (reaching over 1500 metres) and the coastal plains of Mozambique. Thus the western part of the country lies in escarpment area, and the eastern part in the zone of the coastal plains. Separating the Swaziland coastal plains from the Mozambique coastal plains, is the Lubombo Mountain Range.

Despites her small size, Swaziland supports a rich and varied biodiversity. 

Over 820 species of vertebrates have been recorded here (Clay, 1976; Hyslop, 1994; Boycott, 1992a; Parker, 1994; Monadjem, 1997b, 1998a). Although the country’s higher plants have been collected and studied since the 1950s (Compton, 1966, 1976; Kemp, 1983), the distributions of most species are poorly known and new records are constantly being added. 

To date, at least 2418 species of plants have been recorded within Swaziland (L. Dobson, in lit.), but this figure may well rise to over 3000 species with additional field work. In addition to harbouring a high species richness, Swaziland also supports 18 endemic species of plants and one endemic vertebrate (at present, invertebrates of Swaziland are too poorly known to be included in the analysis). 

Considering the country’s small size, these figures suggest that Swaziland’s biodiversity is of global significant.

The savanna and grassland ecosystems cover 48% and 46% of Swaziland, respectively, while the forest and aquatic ecosystems cover the remaining 6% (refer to Table 2.1, and see Figure 2.1 for distributions of these ecosystems). What follows is an assessment of the biodiversity of each ecosystem (as defined in section 2.1 above). It is important to bear in mind that the distributions of most species are poorly known in Swaziland. The findings presented here must, therefore, be accepted as preliminary, to be revisited at such time when sufficient data are available. Included in the assessment are the biological resources available in each ecosystem as well as the threats to each ecosystem. In order to make a meaningful assessment, only the predominant resources and threats are listed. An exhaustive list of the resources available and the threats to them would be very extensive but would contribute little to this exercise.

Montane grasslands

The grassland ecosystem occurs in the west of Swaziland, generally at elevations above 1000m. A dominant feature of this ecosystem is its treeless nature which is determined by climate and fire. Numerous woody species, however, do occur in fire-excluded areas such as rock outcrops. A large number of plant and animal species are restricted to this ecosystem (on a southern African scale). Although the grassland ecosystem is extensive, and floristically very diverse, only 1.1% of its area is currently conserved in southern Africa. This underscores the conservation importance of this ecosystem at a regional scale.

Within Swaziland the grassland ecosystem covers an area of 7990 km² or 46% of the nation (refer to Table 2.1 below). Currently, only 2% of this ecosystem is conserved in Swaziland, while a significant portion (25%) has been converted to other forms of land use (predominantly plantation forestry and to a lesser extent urban development). Most of this conversion took place before 1985 (refer to Table 2.1). An additional 526 km² (7% of the grassland ecosystem) has been proposed as protection worthy, but at present does not enjoy any form of protection.

The grassland ecosystem supports a large diversity of fauna and flora (refer to Table 2.2 below). In fact, this is the richest ecosystem in terms of plant species, and the second richest in terms of vertebrate species. Many of these species are restricted to the grassland ecosystem, but do not qualify as national endemics as they also occur in neighbouring South Africa. However, 13 species of endemic plants and the only endemic vertebrate (the lizard Afroedura major) occur in the grassland ecosystem (This lizard does not actually live in grassland habitats; it occurs in rocky outcrops along rivers and hence survives in granite islands within the grassland ecosystem). 

Hence, over 70% of Swaziland’s known endemics are restricted to the grassland ecosystem. The grassland ecosystem also supports a significant portion of the threatened flora and fauna of Swaziland (refer to Table 2.2 below). Numerous species of animals are restricted to this ecosystem (but also occur in neighbouring South Africa, and therefore are not national endemics, but could be viewed as regional endemics) including the birds: Oenanthe bifasciata, Geocolaptes olivaceus and Macronyx capensis; the mammals: Pelea capreolus, Otomys irroratus and Amblysomus hottentotus; the reptiles: Chamaesaura aenea, Lygodactylus ocellatus and Lamprophis swazicus.

Typical grass species include Themeda triandra, Hyparrhenia hirta, Diheteropogon amplectans and Loudetia simplex. A large variety of forbs and herbs also occurs. Fire plays an important role in this ecosystem and changes in the fire regime can dramatically alter the vegetation, in turn affecting the fauna. Studies (mostly conducted in South Africa) have shown that the highest species diversity is observable in grasslands which are burnt on a 2-4 year cycle (Rowe-Rowe & Lowry, 1981). Grasslands burnt more or less frequently rapidly decline in species richness. This is compounded by the effect of overgrazing which also serves to reduce species richness (Bowland & Perrin, 1989). 

Much of the variation in habitat quality in the grassland ecosystem is explicable in terms of these two factors. However, geology and soil type also influence habitat structure in this ecosystem. For example, grassland in rocky outcrops (which are common in parts of the grassland ecosystem) provides suitable conditions for many plants and animals not found elsewhere (e.g. Oenanthe bifasciata, Leucospermum gerrardii and Protea parvula). Furthermore, the grasslands in the north are recognised as distinct from those in the south (Acocks, 1988) and they support a slightly different avian community (Parker, 1994).

The predominant biological resources currently utilised or potentially available from this ecosystem are livestock fodder, natural medicine and food, and wildlife (see Table 2.3 below). The magnitude to which each of these biological resources has been, or currently is being, utilised varies extensively depending on land use. In protected areas exploitation of biological resources is either part of the management strategy (e.g. culling) or is due poaching. On SNL, however, biological resources are used extensively and it is not unusual for families or communities to depend on them for their livelihood. Hence, wildlife resources (especially antelopes and their mammalian predators) have been decimated in this ecosystem. With the exception of protected areas (covering a mere 2%) and afforested areas almost the entire grassland ecosystem is utilised for livestock grazing. 

On SNL, grazing pressure can be enormous and there are no mechanisms in place to prevent over-grazing. Fauna and flora are utilised both for the preparation of natural medicine and for food. This has lead to the destruction of wildlife (as outlined above), and is now contributing to the demise of medicinal plants. There is currently no mechanism in place to ensure the regeneration of what is being harvested. There appears to be an increase in the harvesting of medicinal plants, but this trade has not been quantified. Two other major threats to the grassland ecosystem are the continued clearing of grassland for cultivation of rain-fed crops, and afforestation with exotic plantations. 

The rate of afforestation has declined in the past two decades (see Table 2.1 below), while the rate of clearing for cultivation of crops has increased. The detrimental effects of the injudicious use of fire must not be overlooked. On SNL, Grasslands typically are burnt annually in the dry season. This results in a flush of green grass at a time when the food supply of livestock is low. However, as mentioned above, annual burning has been shown to reduce biodiversity of grasslands. Lastly, the impact of alien invasive plants can be observed over much of this ecosystem, though it tends to be patchy in distribution. Amongst the worse invaders is the black wattle which is spreading at an alarming rate.

Savanna-woodland mosaic

The savanna ecosystem is the most extensive in southern Africa (comprising 34% of the area of South Africa). The characteristic feature of the savanna ecosystem is the co-existence of grasses and trees. The amount of tree cover can vary widely from a few scattered trees (open savanna) to 75% canopy cover (closed woodland). On a regional scale, the savanna ecosystem has the best conservation status (with over 8% of the area conserved in South Africa).

This ecosystem occurs in the central, eastern and northern parts of Swaziland, covering 8327 km² or 48% of the country (refer to Table 2.1). Nationally, 5% of this ecosystem falls within formally protected areas, and a further 2% is currently managed for wildlife conservation. A quarter of this ecosystem has been converted to some other form of land use (predominantly for cultivation of sugar cane).

The savanna ecosystem is very rich in species, supporting a similar number of plant species to the grassland ecosystem, but almost double the number of vertebrate species (refer to Table 2.2 below). However, only two endemic plants and no known nationally endemic animals are found here (refer Table 2.2 below). But these figures do not accurately reflect the true biological value of the savanna ecosystem. For example, the savanna ecosystem covers a large part the Lubombo Mountains. Within this ecosystem, there are 7 species of plants (e.g. Encephalartos lebomboensis, Euphorbia keithii and Aloe keithii) and 3 species of vertebrates (Platysaurus lebomboensis, Leptotyphlops telloi and Cordylus warreni) that are endemic to the greater Lubombo mountain range (including South Africa and Mozambique). This uniqueness of the Lubombo Mountains is lost in the current analysis which is bound by political (and not ecological) boundaries. In terms of conservation status, 71 species of threatened plants occur here compared with 161 and 53 species in the grassland and forest ecosystems, respectively. The savanna ecosystem, therefore, is highly diverse, but endemism is low and relatively few species (with the exception of large mammals such as antelopes and their predators) are threatened. From a resource utility perspective, however, 66% of the commonly used plant species occur here (refer Table 2.2).

The savanna ecosystem occurs over a range of altitudes between 100 - 900 m. The specific type of savanna vegetation present at a site depends on geography, soils, impact of herbivores and fire, as well as human impact. The highest altitudes occur in the west (adjacent to the grassland ecosystem), dropping gradually to the lowest altitudes in east, but rising again in the far east as a result of the Lubombo Mountains. At higher altitudes (500 - 900 m), the vegetation is characterised by tall grassveld with scattered trees and is generally located on steep slopes or rolling hills. 

Typical grasses include Hyparrhenia hirta, Hyperthelia dissoluta, Heteropogon contortus, Cymbopogon excavatus, Panicum maximum and Themeda triandra. 

Typical trees and shrubs include Acacia spp., Sclerocarya birrea, Vangueria infausta, Syzygium cordatum, Canthium spp., Gymnosporia buxifolia, Dichrostachys cinerea, Rhus spp., Pterocarpus angolensis, Lannea discolor, Annona senegalensis, Combretum spp., Faurea rochetiana, Euclea spp. and Bauhinia galpinii. 

At altitudes between 250 - 500 m, the savanna ecosystem is typically broadleaved woodland on steep to gentle slopes. 

Typical trees and shrubs are similar to the higher altitude savannas but also include include Ficus sycomorus, Peltophorum africanum, Albizia versicolor, Terminalia sericea, Grewia spp., Gymnosporia senegalensis, Ziziphus mucronata, Trichilia emetica and Lonchocarpus capassa. 

At the lowest altitudes (100 - 300 m), the savanna ecosystem is located on basaltic plains and typically supports an Acacia woodland. Typical grasses include Panicum maximum, Themeda triandra, Eragrostis spp., Bothriochloa insculpta, Cenchrus ciliaris, Digitaria spp. and Eustachys paspaloides. 

In terms of trees, Acacia nigrescens is often dominant in the northern parts, while A. tortilis is generally dominant in the south. Other typical trees and shrubs include Ziziphus mucronata, Sclerocarya birrea, Spirostachys africana, Gymnosporia spp., Dichrostachys cinerea, Euclea spp., Ozoroa engleri, Grewia spp., Bolusanthus speciosus, Combretum imberbe, Balanites maughamii and several species of Acacia.

Savanna vegetation is not immutable and may be altered rapidly by changes in, inter alia, fire regime. Both the frequency and intensity of fire are important factors. Furthermore fire intensity is affected by grazing. As grazing intensity increases, grass cover (which is the primary source of fuel for fires in savanna ecosystems) decreases. This has the effect of reducing the intensity of fire. The elimination of hot (high intensity) fires results in the increased survival of saplings and is termed bush encroachment. Although not as yet quantified, large areas of the savanna ecosystem are suffering from bush encroachment. Bush encroachment is often associated with a decrease in species richness, and is therefore not desirable.

The predominant biological resources currently utilised or potentially available from this ecosystem are similar to that available in the grassland ecosystem but include fuel and timber (Table 2.3 below). The magnitude to which each of these biological resources has been, or currently is being, utilised varies extensively depending on land use. In protected areas biological resources are generally utilised at low levels, but poaching is a concern in certain areas (most commonly with regard to the illegal harvesting of medicinal plants and bush meat). 

On SNL, however, biological resources are used extensively. Wildlife resources (especially antelopes and their mammalian predators) have been decimated in this ecosystem. With the exception of protected areas, and areas under commercial cultivation, the remainder of the savanna ecosystem is heavily utilised for livestock grazing. On SNL, grazing pressure can be enormous and there are no mechanisms in place to prevent over-grazing. Fauna and flora are utilised both for the preparation of natural medicine and for food. This has lead to the destruction of wildlife (as outlined above), and is now contributing to the demise of medicinal plants. There is currently no mechanism in place to ensure the regeneration of what is being harvested. There appears to be an increase in the harvesting of medicinal plants, but this trade has not been quantified. It is not clear whether medicinal plants are harvested at differential rates in the different ecosystems. A major threat to this ecosystem is the continued clearing of natural vegetation for the cultivation of sugar cane. This exercise has continued unabated over the past few years despite the constraint of limited water availability. 

Another major threat to this ecosystem is the unsustainable harvesting of woody vegetation for timber and fuel wood. Harvesting of woody vegetation appears to be widespread and on the increase. Furthermore, there is no mechanism in place to ensure the regeneration of this biological resource. The selling of fuel wood along certain routes in the lowveld appears to have grown exponentially over the past decade without any apparent enforcement of control measures (such as the Flora Protection Act). As mentioned above, overgrazing and poor fire management has resulted in bush encroachment over large areas of SNL. 

The effects of this bush encroachment are fully understood, but often includes a loss of biodiversity. It has been shown that areas suffering from bush encroachment support a lower diversity of birds. Alien plant invasion is a problem in parts of this ecosystem, especially along water courses. Lantana camara, Psidium guajava and Chromolaena odorata have spread over large areas of this ecosystem, while the herb Parthenium hysterophorus is often evident in the grass layer in disturbed areas. Finally, parts of the ecosystem have been lost by way of inundation as a result of dam construction. New dam sites are still being proposed in this ecosystem.

Forests

The forest ecosystem is highly restricted, covering only 1% of South Africa. This ecosystem is characterised by woody vegetation with a continuous canopy, with the dominant vegetation consisting mostly of evergreen trees. It extends from the southern Cape along the eastern seaboard of South Africa to the Soutpansberg in the Northern Province (South Africa). 

In Swaziland, forest vegetation is usually found at moderate to high elevations mainly in the west of the country and in ravines of the Lubombo Mountains. At high altitudes, forest patches are interspersed amongst the grassland and play an important role in supporting biodiversity. Effective conservation of this ecosystem is hampered by its fragmented nature.

In a recent inventory of the forests of Swaziland using remote sensing data and field verification, the total cover of afromontane forest was placed at 11 349 ha (0.65% of the land area of Swaziland) and riparian forest at 25 207 ha (1.45% of Swaziland). In total, forests cover an estimated area of 870 km² or 5% of Swaziland (Thurland, 1999) (refer to Table 2.1 below). Only 2% of these forests are formally protected, while a further 5% are recognised as protection worthy. A quarter of these forests have been converted to some other form of land use (predominantly forestry). Considering the tiny area encompassed by this ecosystem, this figure is highly significant.

Forests are legendary for the high species diversity that they support. Although, in Swaziland, grasslands and savannas support more species in total, forests support more species per unit area. Three species of endemic plants, and no known endemic animals occur in Swaziland’s forests.

Swaziland’s forests can be divided into three broad categories, namely: afromontane forests (mostly at altitudes above 1000 m), riverine forests (mostly at altitudes below 900 m) and forests in the Lubombo Mountains. Typical plant species include Englerophytum magalismontanum, Syzygium cordatum, Syzygium gerrardii, Psychotria capensis, Diospyros whyteana, Maesa lanceolata, Cussonia spp., Gymnosporia mossambicensis, Heteropyxis spp., Peddiea africana, Scolopia spp., Trichocladus grandiflorus, Ficus spp., Dalbergia armata, Xymalos monospora, Combretum kraussi, Clausena anisata, and Rhus spp.. 

A number of rare or range-restricted species also occur here such as the cycads Encephalartos umbeluziensis and E. aplanatus. With the exception of birds, vertebrates are not well represented in forests (Table 2.2 below). However, several species of birds are restricted to forests including: Lioptilus nigricapillus, Glaucidium capense and Smithornis capensis.

Forest ecosystems generally tend to be fragile and are easily degraded by humans (Masson, 1991). Over-harvesting of woody plants quickly opens up and dries out a forest exposing it to fire. Fire, although a natural and necessary component of grasslands and savannas, has a devastating effect on forests.

The predominant biological resources currently utilised or potentially available from this ecosystem are similar to that available in the savanna ecosystem but generally excludes livestock fodder (Table 2.3 below). The magnitude to which each of these biological resources has been, or currently is being, utilised varies extensively depending on land use. In protected areas biological resources are generally utilised at low levels, but persistent poaching of certain resources is of concern (e.g. cutting of the tree Androstachys johnsonii). 

Fauna and flora are utilised both for the preparation of natural medicine and for food. This has lead to the destruction of wildlife, and is now contributing to the demise of medicinal plants. There is currently no mechanism in place to ensure the regeneration of what is being harvested. There appears to be an increase in the harvesting of medicinal plants, but this trade has not been quantified. Another major threat to this ecosystem is the unsustainable harvesting of woody vegetation for timber and fuel wood. Harvesting of woody vegetation appears to be widespread and on the increase. Furthermore, there is no mechanism in place to ensure the regeneration of this biological resource. Alien plant invasion is a problem in parts of this ecosystem, especially in riparian vegetation where Lantana, Chromolaena and Melia azedarach have secured a foothold.

Aquatic ecosystems

The aquatic ecosystem covers the smallest area of Swaziland, yet it supports a relatively high density of species (i.e. species per unit area) and plays an important role in the functioning of the other ecosystems. Riparian forest, for example, would not exist in the absence of the aquatic ecosystem. Approximately 1% of Swaziland falls under this ecosystem, a proportion similar to that of South Africa (Table 2.1). Only 2% of this ecosystem is currently protected, whilst a further 5% is regarded as protection worthy. Seven percent has been converted to other forms of use (such as commercial agriculture and damming).

Despite its small extent of coverage, the aquatic ecosystem supports a rich biodiversity. A total of 98 species of plants occur exclusively in this ecosystem. This does not reflect the full diversity supported by this ecosystem as numerous habitats in the other ecosystems require water to sustain them (e.g. riparian and riverine vegetation). Vertebrates are also well represented in this ecosystem (refer to Table 2.2 below). No endemics occur in this ecosystem and few aquatic plants are currently threatened. 

However, a significant number of aquatic vertebrates are currently threatened. These include numerous species of waterbirds whose habitats have become increasingly degraded and destroyed (Monadjem et al., in preparation). As a proportion of the total number of species occurring in the ecosystem, the aquatic ecosystem suffers the highest impact of exotic species. Nearly 10% of all aquatic plants are exotics, whilst in the other ecosystems this figure is below 3%. Although the number of exotic species does not necessarily reflect the density of exotics in an ecosystem, aquatic invasives do have the potential to completely dominate aquatic systems (e.g. Salvinia molesta).

The aquatic ecosystem differs considerably from the other ecosystems in its mode of functioning. The impact of fire and herbivory, so significant in the other ecosystems, is not as obvious in the aquatic ecosystem. Veld mismanagement, such as over-grazing, is one of the causes of erosion. This soil makes its way into the aquatic ecosystem leading to increased siltation. Since silt load affects the species composition of both fish and aquatic invertebrates (Hyslop, 1994), mismanagement of neighbouring ecosystems impacts directly on the aquatic ecosystem. Hence the state of aquatic ecosystem is often determined by the state of neighbouring ecosystems. 

Certain habitats in the aquatic ecosystem are extremely fragile. For example, the high-altitude marshes, which are generally found above 1000 m, are easily degraded by cattle grazing and trampling, and can be completely destroyed by draining (which is a relatively simple operation). Despite their fragility, these highveld marshes play an important ecological-hydrological role by, inter alia, absorbing storm water in the wet season and continuously releasing water in the dry season, thereby ensuring an adequate supply of water throughout the year.

The aquatic ecosystem is probably the least studied ecosystem in Swaziland. Little is known about the range and distribution of habitats available. The only regular monitoring conducted in this ecosystem is the African Waterfowl Census which counts waterbirds twice per annum at major wetlands throughout the country.

The predominant biological resources currently utilised or potentially available from this ecosystem are water, natural medicine and food, fisheries and products made from reeds and sedges (Table 2.3 below). Furthermore, some aquatic ecosystems, such as wetlands, are also exposed to grazing by livestock. The magnitude to which each of these biological resources has been, or currently is being, utilised varies extensively depending on land use. In protected areas there is little or no exploitation of biological resources. On SNL, however, biological resources are used extensively. 

On SNL, grazing pressure can be enormous and there are no mechanisms in place to prevent over-grazing. Wetlands are very susceptible to overgrazing and trampling by livestock, and are easily degraded. Fauna and flora are utilised both for the preparation of natural medicine and for food. This has lead to the destruction of wildlife (as outlined above), and is now contributing to the demise of medicinal plants. 

There is currently no mechanism in place to ensure the regeneration of what is being harvested. There appears to be an increase in the harvesting of medicinal plants, but this trade has not been quantified. Wetlands have also been degraded or destroyed as a result of the construction of roads and buildings. As mentioned above, erosion is having a serious impact on the streams and rivers of the country by increasing the silt load. Soil erosion has reached critical levels in parts of the country (Mushala, 2000), and does not appear to be under control. Siltation may thus be expected to deteriorate. Further threats to this ecosystem include industrial pollution (mostly entering the Usushwana River from Matsapha Industrial Area), urban waste and agricultural chemicals. Alien plant invasion is a problem in parts of this ecosystem, especially Salvinia molesta.

2.3 Analysis of Ecosystems Using Biodiversity Criteria

The four ecosystems can be ranked in order of importance for conservation by using the internationally recognised biodiversity criteria of species richness, endemism, protection and conversion. The results of this analysis are presented in Table 2.4 below. Ecosystems are scored on the basis of how many species have been recorded in them and how many of them are endemic to that ecosystem (based on information for plants and vertebrates only). It is possible that the results of this analysis might have been different had information been available for other groups of organisms such as invertebrates. However, with a lack of critical data, this analysis had to be restricted to plants and vertebrates (as has been the case for studies in most other nations). Also included in the analysis was consideration of the area currently under formal protection, as well as the area converted to other use. The total coverage of the four different ecosystems varies by a factor of 40 (the savanna ecosystem is almost 40 times the extent of the aquatic ecosystem). Therefore, to simply express the total area under protection or conversion would not be logical. Hence, the proportion of each ecosystem protected or converted has also been applied as criteria.

It is evident from Table 2.4 that the grassland ecosystem has the highest ranking (i.e. most important from a biodiversity conservation perspective), followed by the forest and savanna ecosystems. The aquatic ecosystem ranks lowest (i.e. least concern). The results of this analysis, though potentially useful, must be read with caution. Firstly, the data on species richness and endemism are incomplete (as mentioned above). Secondly, and more importantly, this analysis is conducted at the very broad scale of "ecosystem". Within each of these ecosystems, there numerous habitats varying in their conservation status. For example, within the aquatic ecosystem, high-altitude wetlands (marshes) support a rich diversity of flora and fauna, are poorly protected and have, to a large extent, been converted or degraded. This is not reflected in the current analysis (presented in Table 2.4 below). Neither is the biological uniqueness of the Lubombo Mountains (discussed in section 2.2 above) reflected in this analysis. It must, therefore, be recognised, that while this analysis provides useful insight into the overall conservation value of the four ecosystems, it does not necessarily reflect the true diversity within each ecosystem. Finally, the influence of the aquatic ecosystem extends well beyond its boundary into that of neighbouring ecosystems. Therefore, the aquatic ecosystem plays a pivotal role in the function of many habitats in other ecosystems. This crude analysis does not reflect this either. This analysis, then, is probably appropriate for the three terrestrial ecosystems, but inappropriate for the aquatic ecosystem.

It does not come as a surprise that, of the terrestrial ecosystems, grasslands have the highest priority. On a southern Africa scale, grasslands support numerous endemics, have suffered major conversion to other forms of land use, and are poorly represented in protected areas. Forests are also of conservation concern due to the high density of species occurring in them. However, compared to grasslands, they support fewer endemics (both in Swaziland and in southern Africa), and are marginally better represented in protected areas. In southern Africa, the highly diverse savanna ecosystem is extensive, supports few endemics and is well protected. Within Swaziland, this ecosystem is better represented in protected areas than any of the other three ecosystems. However, only 5% of the savanna ecosystem is currently conserved, far short of the IUCN’s recommended 10%. Furthermore, this ecosystem is currently facing severe pressure from commercial agriculture (mostly for sugar cane cultivation). This ecosystem, therefore, should not simply be ignored on the basis of its low ranking.

Table 2.1: Status of ecosystems of Swaziland

1 Source Roques & Dobson (in lit.)
² Source Low & Rebelo (1998), but for aquatic ecosystem Fairbanks et al. (2000)
3 Source Deal et al. (2000)

Table 2.2: Species diversity by ecosystem

1 L. Dobson (in lit.)
2 Monadjem (1997b)
3 from Flora Protection Bill (2000)
4 Monadjem et al. (in preparation)
5 from SNTC website
6 Clancey (1986)

Table 2.3: Major biological resources available in, and major threats to, each ecosystem

Table 2.4: Comparison of ecosystems on biodiversity criteria

Ecosystems are ranked on a scale of 1 to 4 using biodiversity criteria of species richness, endemism, protected areas and conversion to other use. The lowest ranking (1) indicates the lowest importance for that criterion. The ecosystem with the highest total score ranks as the ecosystem with the highest priority from a conservation perspective. Where ecosystems are tied, the score is divided equally between them.