Ecology of Malolotja Nature Reserve in Eswatini, on the eastern escarpment of southern Africa

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Malolotja Nature Reserve ( and and and lies along the northwestern border of Eswatini (

It is ecologically similar to the eastern edge of the Highveld (, which - strictly speaking - lies several hundred km to the west.

The following description of this conservation area is based on an unpublished report written by Ken L Tinley in 1978, in support of a proposal to upgrade the nature reserve to the status of national park.


Imagine yourself near Forbes Reef (, on the ridge dividing the valleys of the Inkomati ( and Mbuluzi ( streams.

You view the landscape to the north, which falls within Malolotja Nature Reserve. More specifically, you view the confluence of the ravines of the Inkomati and the Malolotja streams.

The skyline, from left to right, consists of the Silotwane range, with the Shokohla range in the distance; then the Makonjwa range, rising to the blunt peak of Josefskop (1757 m a.s.l.); then the Emlembe range, with its even blunter peak at 1852 m a.s.l. The middle distance consists of steep, treeless slopes. Trees are confined to drainage lines and the tor-fields traversing the crests of the low hills in the foreground, a few kilometres from where you stand.


Catena on Ngwenya range, in the south-western sector of the Park, near the iron ore mine (

Catena on granite in eastern sector of the Park:

  • at highest altitudes, treeless grassland
  • on upper slopes, patches of thicket on tor-fields of Bornhardt cores (
  • on mid-slopes and lower slopes, treeless grassland on pink to red, sandy latosol. The surface is extremely resistant to erosion when bared, especially in areas influenced by dolerite. The subsoil deeper than 1 m grades into a layer of friable, leached kaolinite, which erodes extremely rapidly if exposed

Catena on eastern slopes of Ngwenya and Silotwane ranges:

Catena in ravines:

Floors of ravines:

  • marshes and peat-bogs on organic hydromorphic soils, built up by fen peat, produced by hygrophilous sedges and grasses


Please see

Over most of Malolotja Nature Reserve, the bedrock consists of quartzites and conglomerates. Granites occur along the eastern sector, near the main road to Piggs Peak ( The northern Makonjwa valley is formed on phyllites, greywackes and cherts. Intercalated with these are small outcrops of serpentinites and schists.

All these rocks weather to a mainly sandy texture. The main soils in Malolotja Nature Reserve are yellow and red ferralitic soils (, mostly of a sandy or sandy clay texture.

Piercing the above metamorphic rocks are dolerite dykes of various dimensions. Here, the soils are red latosols, more loamy than those described above.


As interpreted by Tinley (1978):

Treeless grassland in Malolotja Nature Reserve is generally associated with either

  • poor drainage, or
  • latosols, where any seasonal waterlogging in summer is followed by edaphic drought in winter.

Woody vegetation is generally associated with moist but well-drained (aerobic) sites and substrates.


  • treeless grassland predominates over all aspects of the rounded terrain of hills and valleys, on substrates with either seasonal waterlogging or extreme seasonal variation in moisture, and
  • thicket/forest, by contrast, is confined to substrates with moderate moisture, viz. the incised heads of valleys, rock outcrops, sinkholes, and streambanks.

"Most of the thicket/forest habitats which occur on the valley sides are in relatively fresh donga incisions of old valley head vleis, indicating that they are young developing communities, and not relics as is prevalently thought. Although the sharp edges of most thicket/forest habitats is due to the singeing by annual fires, their spatial patterns are determined primarily by perch-based dispersion of seeds and by soil moisture balance" (Tinley 1978).

According to the vegetation classification system of Acocks (

Most of Malolotja Nature Reserve is covered by the Piet Retief Sourveld division (Acocks Type 63) of the Highveld Grassland formation.

The second-largest area is occupied by the Northeastern Mountain Sourveld (Acocks Type 8), on lower parts of the upland in the escarpment zone,

The smallest area is occupied by Lowveld Sour Bushveld (Acocks Type 9), confined to the main river valleys and the tor-field outcrops.


Highest altitudes:

Most of the terrain in Malolotja Nature Reserve is below 1830 m a.s.l. Only the highest parts of the Ngwenya range are likely to provide habitat for the short grasses of montane grassland. e.g. Festuca ( and and Merxmuellera (

Medium altitudes:

The main type of treeless grassland in Malolotja Nature Reserve is the Piet Retief type (Acocks type 63). This vegetation is usually < 50 cm high, the flowering stalks reaching 80 cm.

These grasslands are dotted by termitaria, mainly of Trinervitermes (

These termitaria form relatively nutrient-rich microsites in an otherwise nutrient-poor landform, and feature small patches of the lawn-forming grass Cynodon dactylon (

Where there is continual grazing and the termitaria are eroded, the resulting flattened patches support enlarged lawns of C. dactylon, with diameters up to 7-10 m.

Typical grasses include:

Lowest altitudes:

Patches of tall treeless grassland occur in moist sites on the floors and sides of valleys. These consist of

All these grasslands are subjected to annual fires. Some areas are also burnt in mid-summer, i.e. twice per year.


Large, bare rock-faces occur mainly in the eastern sector, where exfoliating domes of granite occur.

In these and other areas of bare rock, a large variety of herbaceous and woody plants occurs in the joints and crevices. Typical examples include Xerophyta and Aloe, and the striking, red-flowered Streptocarpus dunnii (

Lower down in some valleys, tree cycads (Encephalartos paucidentatus), reaching heights of 6-7 m, occur in the crevices of otherwise bare (except for lichens) rock-faces.


Savannas occur

  • at high altitudes (Protea rouppelliae up to 3 m high),
  • on tor-fields, at medium to low altitudes and
  • in valleys.

Savanna on tor-fields includes the following trees, spaced more than three crown-diameters apart:

Savanna in valleys contains, e.g.


Riverine forest:

Narrow tracts of streambank forest occur in a few areas, e.g. the gorge below Malolotja Falls. These consist mainly of tall trees of Breonadia salicina (

Additional spp. of trees include

In the headward-eroding streambeds are lines of S. cordatum or tree-ferns (Cyathea dregei, In the lower valleys, above the level of the riverine trees, there are thickets, formed by scandent Senegalia ataxacantha ( and B. galpinii.

Thicket on rock outcrops:

This forms patches, in which typical spp. include:

Thicket on sinkholes:

Many of the spp. listed above also occur where the soil surface has collapsed above underground pipe drainages. Here, one of the first colonisers is the tree-fern, Cyathea dregei.

Thicket on termite mounds:

A few small patches of thicket occur on mounds of Macrotermes (, on the lower slopes of the Malolotja and Inkomati drainages. Their species-composition is unrecorded.

Southern afrotemperate thicket (allied to :

This type is floristically similar to thicket on rock outcrops. It is restricted to a few small patches, occurring

  • in west-facing ravines of the Ngwenya range, and
  • at higher altitudes, at the heads of valleys on east-facing aspects of the Makonjwa range, in the north of Malolotja Nature Reserve.

Additional spp. include


The most extensive areas of marsh and acidic bog, remaining intact, are on then southern margin of Malolotja Nature Reserve.

Two large areas of valley sedge peat occur, viz.

  • in the headwaters of the Malolotja river/stream, and
  • at the source of the Mbuluzi river/stream.

These herbaceous bogs support a large variety of plants, among which sedges, orchids, and lilies are abundant.

Typical of the bogs is a flowering sequence, in which each species, or group of species, shows a temporary visual dominance.


All the grasslands in Malolotja Nature Reserve are poor as pastures. This is because the soils are leached and nutrient-poor, producing fibrous, protein-poor plant matter.

The grasses are palatable to grazers only during the growing season, which occurs during the rainy summers and lasts for 3-4 months. Instead of being eaten, the grasses are consumed largely by fire.

The carrying capacity, for livestock or wild ungulates, is estimated to be one stock unit (454 kg) per hectare, and this applies only to the 4-5 months of summer.

Tinley (1978) states:

"A most important finding of long-term pasture experiments, is that mowed veld yields up to eight times as much herbage as burnt veld. In sourveld the period of palatability is extended by mowing in midsummer...Ideally, therefore, as much mowing as possible should be undertaken in preference to burning."


Tinley (1978) pointed out that perhaps the wild ungulate most suited to reintroduction in Malolotja Nature Reserve was the blesbok (Damaliscus pygargus phillipsi).

This has been borne out by the local viability of the blesbok, proven over the ensuing 45 years (

The blesbok is particularly adapted to the nutrient-poor grasslands of the Highveld, by virtue of its relatively small body size and seasonally frugal metabolism.

With respect to the springbok (Antidorcas marsupialis marsupialis,, Tinley (1978) wrote:

"We are assured by Mr Ted Reilly that springbok were recorded from the western sector of Swaziland in the past. However, the remnant springbok populations in the adjacent eastern Highveld of the Transvaal are all associated with the alkaline and saline sweetveld shortgrass pastures occurring round the margins of the isolated pan systems found in this region. Springbok do survive in sourveld, but as the animals in Mlilwane and the Krugersdorp Lion Park show, their physical condition is poor almost throughout the year, and in these areas they feed almost exclusively on the sweetveld patches of kweek, Cynodon, growing on termite mounds."


It is Ken L Tinley, not I, who performed the fieldwork for this report. My role has been to bring a long unpublished piece of work to light, by means of a complete edit and nearly-complete rewriting. Because Tinley submitted his report to the government of the then Swaziland 45 years ago, his work risks vanishing from the public record. Furthermore, the paucity of observations from Malolotja Nature Reserve in iNaturalist shows that this area has been neglected/underplayed by naturalists. I trust that this Post will help to renew interest in a reserve which failed to be raised to the status of national park, but deserves appreciation.

Posted on October 05, 2023 08:59 AM by milewski milewski


Could you please annotate the following as to whether the rocks are granitic or doleritic?

Sorry: no - the geology in these ancient rocks is complex. Everything here looks like gneiss to me. I did not notice any particularly obvious dolerite formations on our hikes. But if some gneisses were acidic and others basic I have no idea.
From the geology map ( see ) it appears that I missed lots - ruddy grass all over the place - much easier without any green cancer - e.g. in the Richtersveld!

Posted by tonyrebelo 10 months ago

With regards to Springbok, we have a small herd maybe 30 animals give or take a few that free range (likely started with 10 or so animals that were on the former Blyvoor golf course which was stripped (starting with the fence) when the mine went bankrupt), they have seemed to do fine in the sourish dolomite grassland about 50km West of Krugersdorp, they live mainly on the vast fenceless mine property which is basically land the mine was forced to buy from farmers after the de-watered the underlying aquifer (resulting in the highest density of sinkholes in SA) so the land has no economical value (other than the odd farmers cattle "straying" onto the land to graze)... But there as more satellite populations towards the west as well (Sprinkbok being the jumpers they are, these undoubtably are the result of escaped animals from game farms) although not as common as warthog in the area, they do seem to do well in the sourveld when they escape from private land (not to mention they are possibly the most common antelope found in game farms throughout the sourveld region (with blesbok))

Posted by kyle_campbell1 10 months ago

Thanks for this interesting report. I really must try to visit this place some day,

Greetings Bart

Posted by bartwursten 10 months ago


Many thanks for the interesting information re springbok.

Posted by milewski 10 months ago


I'm glad you found it interesting...

With many thanks from Antoni

Posted by milewski 10 months ago


Posted by milewski 10 months ago

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