Where we work

Omatjenne sunset

We have been working on termite mounds in Namibia since 1998, when our project was first funded by Earthwatch. The first phase of the project was based north of the northern Namibia town of Outjo, on the farm Namatubis, which was generously opened to us by the farm owner, Mr Freddie Pretorius.

After an interlude from 2001-2004 (when our work shifted to South Africa and the primitive mound-builder Trinervitermes, we returned to Namibia in 2004, this time to the Omatjenne Agricultural Research Station, part of the Namibia Ministry of Agriculture. We have had extraordinary support there, including housing, logistics and the freedom to roam a 17,000 hectare extent of relatively pristine acacia savanna (with lots of termites).

Here are some facts about Namibia, Omatjenne and the termites that live there.

About Namibia

Namibia has one of the most diverse termite faunas of southern Africa. The genus that interests us, Macrotermes is represented by four species.

Namibia is a semi-arid country that is characterized by a steep gradient in mean annual rainfall that ranges from tropical wet forest in the northeast to the hyperarid Namib desert on the coast and southwest. Macrotermes are found mostly in the tropical summer rainfall regions of the country, in habitats where the mean annual rainfall is as low as 250 mm.

Namibia rainfall

The video below is a useful introduction to the country of Namibia. It was prepared as part of a proposal to the SUNYESF Board of Trustees to develop Omatjenne as a field campus in Africa for the College.

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About Omatjenne

The Omatjenne Agricultural Research Farm is situated 25 km west of the northern Namibia town of Otjiwarongo. It is situated on the Omatjenne River, which runs northwest from the higher plains near Otjiwarongo, and drains ultimately to the Ugab River to the north. Here is a Google Earth Image of the area.

Here is some closer satellite imagery from Google Earth that shows more details. The dotted box on the top map indicates the extent of the image below.

Omatjenne

The farm has a varied history. It was formally demarcated as a private farm in 1907 following the expulsion of the Herero and Himba herders that were the region’s traditional inhabitants. Following the farm’s commercial failure, it was taken over by the Southwest Africa administration as a government-managed irrigation scheme, centered around the construction of the Omatjenne Dam. Many remnants of this scheme are visible around the farm today.

Omatjenne dam

The Omatjenne Dam today

In the late 1920’s, the farm was used for resettlement of the poorer contingent of Angolan Dorsland Trekkers, who had become disillusioned with Portuguese rule there and wished to return to Namibia. By the late 1930’s, this venture had also failed. The subsequent structural failure of the Omatjenne Dam in the 1950s ended forever any hopeful schemes for tillage agriculture on the farm.

Through a variety of accidental circumstances, the farm began to be employed as a holding/quarantine area for various indigenous breeds of livestock, beginning in the 1950’s, with a consignment of Damara sheep confiscated from herders trying to avoid livestock control lines. Managing this flock proved to be useful for research purposes, and in the 1980’s the farm’s livestock husbandry activities were expanded to include cattle breeds. The farm’s principal mission today is managing breeding stocks of the several indigenous breeds of sheep, goats and cattle that are currently farmed in Namibia.

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Historical rainfalltemp and hum

Omatjenne climate

Omatjenne has a tropical pattern of rainfall, which means dry cold winters and warm summer rainfalls, mostly in the form of thundershowers.

Rainfalls at Omatjenne are highly seasonal, as they would be in a semi-tropical savanna. The mean annual rainfall at Omatjenne from 1950-2004 is 418 mm, 87% of which comes in the months of December through April. Also as expected, annual rainfalls vary widely from year to year.

We measured rudimetary weather for at 15 min intervals for roughly 30 months. Winters were cool to very cold, with nighttime temperatures often falling below freezing. Because humidity was very low, winter frosts and dewfalls are rare. Spring brings the hottest temperatures, although dry conditions continued to prevail. Humidity steadily increased during the spring, however, which produced sporadic springtime rainfall episodes. Summer temperatures cooled slightly with the onset of summer rains. Late summer and early autumn brought further cooling, along with a fairly abrupt transition to dryer conditions coincident with the end of the rainy season, typically by April or May.

Annual (vertical) and daily (horizontal) variation of temperature and humidity are plotted to the right as color-coded isotherms and isopleths. Maximum daily temperatures are commonly in the early afternoon around 15h00, and coldest temperatures commonly occurred just prior to sunrise. As expected, daily march of relative humidity is out of phase with the daily march of temperature, with low humidity during the high air temperatures of the day and elevated night-time humidity during the cooler temperatures then. During the winter, humidity was very low during the day, and, despite the cold temperatures, remained low at night, signifying the very dry air that prevails in winter in northern Namibia. Higher humidity prevailed in the summer: consequently, there were frequent summer dewfalls.

During the rainy season, rainfalls are episodic and correlated with intervals of high daytime humidity. Rainfall episodes also correspond to a moderation of air temperatures. During this study, annual rainfalls were higher than the historic average. For the 2004 rainy season, cumulative rainfall totaled 534 mm, roughly 110 mm higher than the 50-year historical average. The 2005 rainy season was still wetter, with a cumulative rainfall of 572 mm, largely due to a single exceptional rainfall event of nearly 72 mm, which also was the heaviest during the course of this study. The 2006 rainy season was slightly dryer than 2005, with a cumulative rainfall of 555 mm. The heaviest rainfall event in that year was about 45 mm.

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savanna

Grassland

Aloes

wetlands

Omatjenne habitats

The farm is approximately 17,000 ha in extent and sits on the northern margins of Namibia's thornbush savanna biome.

The vegetation is mostly acacia savanna (a), with the most common species being Acacia tortilis and A mellifera (Mimosoideae). Boscia (Capparaceae) and Grewia (Tiliaceae) are also common tree species.

Around the central part of the farm are several grassy fields used for hay production, which contain abundant populations of termites (b).

Several granitic ridges also run through the farm (c), which host abundant populations of aloes along their tops, probably Aloe littoralis (Liliaceae, Mopane aloe, Mopanie-aalwyn).

Finally, there are small patches of ephemeral wetland located along the Omatjenne River upstream from the Omatjenne Dam (d). These are common gathering points for game and nesting sites for birds in the rushes that are common there.

Finally, to the west is the Paresisberg, an extinct caldera, which acts as an inselberg and supports many interesting species (below).

Paresisberg

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The termites of Omatjenne

The principal attraction of Omatjenne are the termites. We have surveyed these extensively and they are abundant on the 17,000 hectares of the farm. Here is a map of more than 900 of them in the fields nearby the station's headquarters.

Termites at Omatjenne

There are two confirmed species of Macrotermes on the farm,. and perhaps three. These are Macrotermes michaelseni (a), which build mound with conical bases and tall vertically-oriented spires (which point to the sun's average zenith), and Macrotermes natalensis (b), which build low mounds without the tall spire. We believe, but have not confirmed, that there is a third species that builds massive mounds and that are found in the lowlands of the Omatjenne River, upstream from the dam, We believe these are Macrotermes subhyalinus (c).

mound types

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Termite pages

Termite home

Structure

Endocasting

Social homeostasis

Nest temperature

Water homeostasis 1

Water homeostasis 2

Water homeostasis 3

Fungal symbiosis

Fungal symbiosis and water 1

Fungi and water homeostasis 2

Gas exchange 1

DC vs AC Gas Exchange

Gas exchange 2

Gas exchange 3

Gas exchange 4

Omatjenne

Team Omatjenne

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