Monday, August 13, 2012

Landscape Ecology of DAMBOS in Kundelungu

In my last BLOG entitled: The Conservation Values and Risks to the Kundelungu & Upemba Ecosystem I said there would be three or four more posts to better illustrate photographically the landscape ecology (Biotopes) specialists recognize here.  We will start by looking at aquatic sub-types on the High Katanga Plateau then we'll work down-slope toward the Mid-Plateau/Hills and to the the lower Basins/Valleys. we will focus on three topographic ELEVATION and ALTITUDE ZONES OF INTEREST which includes the following areas:
a) Above > 1400 meters (cool/cold and more humid savannas and forests)
b) 1000 >1400 meters (Mid-plateau valleys & hills with drier forests and savannas)
c) 600 > 1000 Meters (mid-plateau valleys and basins with larger lakes, major rivers, and wetlands).
d) Below 600 Meters (large lakes and basin with extensive flooded forests and wetlands)

Note again the map produced by the  Royal Museum for Central Africa in Tervuren Belgium-- Carte d’Occupation du Sol (small version below  and larger PDF Version HERE).

In their map, they recognize only  three aquatic habitats.  The elevation/altitude aspects is somewhat apparent but not as clearly defined as we believe it needs to be.  Their aquatic land classes are:

a) Open Water  (lakes, ponds, etc).
b) Wetlands (all sub-types lumped together). 
c) Dense (humid) Forests) i.e. those on hydromorphic soils--flooded/swampy forests.  

But, as mentioned earlier, within these broad categories there are several sub-types of habitats recognized by ecologists who have studied Katanga (see the website--Biodiversité Végétale du Katanga and also web resources by a local environmental NGO--BAK).  We feel these sub-types are important to recognize and some are quite unique.  I'm sure you’ll be impressed with the beauty and diversity of landscapes, habitats, communities, and species (Biotopes) found here.  

So what are some of the sub-types worth pointing out?  We would include: rivers, streams, waterfalls, rapids, riparian woodlands, springs, gallery forests and Dambos (more below).  All of these specialized habitats or Biotopes are where biologists can identify unique communities for research, and tourists would find exciting places to photograph and explore.  

A Brief Overview of General Landscape Ecological Relationships in Katanga:

The website--Biodiversité végétale du Katanga--points out that though the Katanga landscape may give the appearance of monotonous sameness, in fact, there are important differentiating factors that need fleshing out including: climate, topography, biogeography, and soil.  All these factors are crucial to understanding Katanga's Landscape Ecology (see more HERE).  To simplify the somewhat technical language (in French) below is a map of the ELEVATION ZONES that will help clarify ecosystem relationships as we summarize the key factors that explain habitats and ecosystem relationships.

In biogeographical terms, Katanga is in the Zambesian Region of Endemism--in essence the Southern Miombo Woodland Ecoregion talked about in our earlier post (see also Bruce Byers report 2001).  In climatic terms the fact that Katanga has a rather lengthy dry season (5-8 months) and because rainfall varies significantly from about 650 to 1550 mm depending on relief (altitude), this means that topography explains more of the plant and  vegetation dynamics seen here than latitude or longitude by themselves.  

For example, the highest plateau (Marungu) exceeds 2400 meters in altitude and Kundelungu-Berge (GPS: -9.776459° &  27.781677°) attains a height of 1700 m /(5577 ft).  In practical terms this means that the Katanga High Plateau (see  PDF Map of both parks HERE) can experience very cool to cold temperatures during the peak of the dry season (even frosts) which affects whether certain species of trees loose their leaves or not and greatly reduces the frequency and intensity of fire as well (more later).  

In terms of soil and geology, much of the region has large areas of basement Precambrian crystalline rocks (gneiss, granite and schist) which have been exposed, eroded, and redeposited that is transported around the region by wind and water as reworked sediments.  The dominant type of soils are the deeply weathered red and yellow laterites (sols ferralitiques rouges et jaunes ) underlying most surface/topsoil layers which are remnants of a long geological history--that is also where the mineral wealth comes from.  But there are some very specific unusual soils on many of the highest plateaus--which we would like to focus on because that is the heart of Kundelungu National Park.  It is also wise to remember that the geology of Africa is very complex and Africa is a very big place (see AEON Graphic HERE); there is much more to learn about how "earth history" has affected life (humans as well as plants and animals) in Africa.  

Of particular interest in soils are patches of sandy sediments redeposited by wind and water from an earlier geological phase known as the Plio-Pleistocene or the so-called Kalahari  Desert Sands.  Depending on location these soils are better drained and thus provide a good place for specific kinds of grasslands (Steppe/Grass Savannas).  On other sites there are more clayey soils, and again, depending on drainage or erosion history, provide unique environments for specific types of small "mushroom-like" Termite Mounds.  And, in the lower valleys and basins, there are deep wetland soils (hydromorphic soils) that also add significant variability--and with also unique Gigantic Termite Mounds.  All this adds up to providing a large amount of local variation  in ecological niches that make the parks a great place to visit and study.  And now, to the visual/photo survey that will introduce you to the landscape ecology of Kundelungu and Upemba National Parks.


One of the most unique aquatic habitats are the DAMBOS and associated small marshes, ponds, patch forests.  Dambos are small seasonally-flooded savannas found in very small low-lying, poorly-drained depressions on the High Katanga Plateau (see photos below).   In these minute depressions or on very flat surface areas, excessive water accumulates in the rainy season, and, because of underlying clay or laterite layers that impedes good soil drainage, the soil is often waterlogged.  Yet during the rather intense and longer dry season, the soil dries up thus making it hard for shallow-rooted shrubs or bushes to grow.  

But along the edges where there is a little more topography i.e. high spots) deep-rooting trees may survive and particularly farther down slope where the water in groundwater may seep out as springs allowing patch forests and riparian woodlands to form.  In sum, many of the variations in plant types (woody vs herbaceous plants) and even insects (presence of specific types of termite mounds or ant hills) can help explain landscape ecology along with, of course, the impact of fire, and animal predation and grazing effects.

Above (left) is a "termite bush savanna" (on clayey soils) after fire has gone through just a few weeks before.  Note how shrubs and grasses come back quickly.  Above (right) are some of the few Zebra left (maybe 29 total) in all of Upemba and Kundelungu Park--in fact that maybe all that are left in the DRC!  In the 1980s there were thousands!  Assessing what is their real status is another issue needing investigation as well as figuring out whether there is still ONE ELEPHANT in KUNDELUNGU as some guards say there is.  But this yet to be confirmed!

When there were large herds of ungulates--antelope, Kudu, Water Buck, Lechwe and so on--and of course large charismatic mammals and predators such as lions, elephants, zebra, leopard--when the entire ecological pyramid (food chain) of plants and animals was intact (maybe last in the mid-1980s ??) the animals affected what plants were eaten/grazed and thus also impacted the balance of species and communities.  Assessing how it has change and how fast is an important issue that needs research.

Bush Savanna taking over to the east of
Katwe Station from former Grass Savanna   

But, of course, with the disappearance of the large animals--particularly elephants during the 1990s--some of the old time guards say the grasslands are now getting invaded by more bush (which is a very good hypothesis to investigate).  In addition, with more poaching, tree-cutting, fire, and other human activities, and with the park management system no longer functioning as it should--this also has changed the ecological balance.  In sum, there is a lot to understand and unravel, if the "original" ecosystem is to be re-established!

Why are Dambos Important?

For your information, Dambos have been studied by NASA elsewhere in East Africa  where they were found to be key to understanding the possible transmission of animal and even human diseases such as RIFT VALLEY FEVER (see photo of a Dambo in Kenya).  But, again the complexity of factors involved is quite amazing.  Scientists have now also found that climate history factors such as El Niño and a similar (yet lesser-known) climate disturbance called the Indian Ocean Dipole  may explain a lot.  Katanga was one of the regions surveyed for this disease in the 1930's but not much has been done on it this since then in the Kundelungu and Upemba ecosystems and it is a problem worth exploring further as well.  

How does Fire change the Story?

We also need a better understanding of fire ecology in both parks.  Scientists now know fire frequency and intensity caries considerably  with climate cycles and will likely be affected by climate change.  Fire history and Miombo ecosystems have been studied more extensively just across the border from Katanga in Zambia (see work by by Valérie Trouet  who is with the University of Arizona Tree-Ring Lab) .  It is likely that similar studies in Kundelungu could be very helpful for understanding past, present, and future landscape ecology and threats to its environment by normal climate variability as well as future climate change.  

Here are some photos of a few of the Dambos in Kundelungu National Park.

In the two photos above you can see a Dambo just north of Katwe Station in Kundelungu National Park. Note the flattened grass which was floating in the water during the wet-season and which at the peak of the dry season is now left bare and dessicated.  In the distance (up on slightly higher-ground on well-drained KALAHARI SANDS is a TALLGRASS SAVANNA.   

Groundwater can still be reached by some deep-rooted trees (under favorable conditions)--see photos below (left) where Robert Ford is taking a GPS point.  This is where local park rangers have dug a well during the dry-season.  In the background is a large tree that stays green throughout the year because it can reach the groundwater and it is also on better drained soils.  

The lowest point in the Dambo becomes a small pond or Mare/Marais (in French) or temporary marsh/pond during the wet-season.  The trail below (photo at right) leads along higher-ground on the edge of the Dambo toward the SPRING and PATCH FOREST at Katwe Station which is the primary source of drinking water.  Springs and associated patch forests or larger GALLERY FORESTS, in both Upemba and Kundelungu are understood by local guards as prime wildlife habitat for birds and amphibians as well as ungulates and mammals.

Katwe Spring and Dense Patch Forest 

The Katwe Spring and Patch Forest seen from along trail leading from the 
settlement the Dambo where tallgrass has grown on better-drained soils above the Dambo

A Dambo along the road to Lofoi Falls (more later)--photo taken by Bertand Loriod.  Again note the patch forest in the distance which is the location of another SPRING.  See also the larger tree growing to the left of the low-point in this Dambo--just where it can reach groundwater year-around but still high enough for better root aeration.  Again, minute local soil and topographical relations explain much of what is observed along with seasonality in fire and rainfall.

Below is a GOOGLE EARTH IMAGE of the Katwe Dambo and surrounding forests, savannas, springs, and streams.  Some of the other BIOTOPES that can be clearly seen on the image, e.g. Tallgrass Savanna, Bush Savanna, Patch/Gallery Forest, Riparian Woodland, Termite Mound Savanna on clayey soils.  I have put PLACEMARKS at places where we have ground-level photos.

Robert Ford, Rockville Utah

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