A Naturalist's Travels on the Congo-Zambezi Watershed Author(S): S

A Naturalist's Travels on the Congo-Zambezi Watershed Author(s): S. A. Neave Source: The Geographical Journal, Vol. 35, No. 2 (Feb., 1910), pp. 132-144 Published by: geographicalj Stable URL: http://www.jstor.org/stable/1776946 Accessed: 10-05-2016 23:10 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://about.jstor.org/terms JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Wiley, The Royal Geographical Society (with the Institute of British Geographers) are collaborating with JSTOR to digitize, preserve and extend access to The Geographical Journal This content downloaded from 132.203.227.63 on Tue, 10 May 2016 23:10:39 UTC All use subject to http://about.jstor.org/terms 132 NATURALIST'S TRAVELS ON THE CONGO-ZAMBEZI WATERSHED. The noteworthy facts, that this 'glacier lies at a much lower level than the corresponding portions of other glaciers around it, that it is composed of fully formed ice, while they are deeply covered with snow and neve, and that it is enclosed on all sides by high mountain walls, in which the direct observation of those who have been entirely around it has disclosed no opening, as well as the indications afforded by the condition and size of the glacier itself, supply more conclusive evidence that it is enclosed only by and ends only in its own basin, than the disbelief of Sir Martin Conway, who has never seen the glacier nor any of its barriers, except the south Hispar wall, which, according to his own testimony, has no opening at this part. A NATURALIST'S TRAVELS ON THE CONGO-ZAMBEZI WATERSHED.* By S. A. NEAVE, M.A., B.Sc. Oxon. THE following notes are the result of more than four years' wanderings in Northern Rhodesia and the Katanga region of the Congo Free State. Some of the country here discussed has already been dealt with by Mr. L. A. Wallace, the present administrator of North-West Rhodesia, in the Journal of thisSociety for 1907, pp. 369 sqq. He has there described the main geographical and geological features of the country very fully. lt may, however, be of some interest to supplement his excellent account with some notes on the faunistic features of this part of Africa--more especially as I was fortunate enough to travel some considerable distance through a contiguous area in the Congo Free State, a region which does not come within the scope of Mr. Wallace's paper. Before dealing with the local conditions, it is necessary to shortly review the general distribution of the fauna of Africa south of the equator. The South African subregion has usually been considered to be bounded to the north by the Zambezi river, on the east, and by the Cunene river on the west, and this is, no doubt, roughly correct. It is, however, of great interest to observe that whilst the tropical species of the equatorial zone (I am here more particularly referring to butterflies and other insects) have spread down the east coast as far as Durban, they do not on the west extend much below the Kwanza river in Angola, a difference of 20? of latitude. This is no doubt mainly due to the high central plateaus on the eastern side of the African continent in this latitude being remote from the sea-coast, wlhilst on the west, in Angola, the lowlying coast-belt is vastly narrower. On the west side the advance of a tropical fauna to the south is also much checked by the very dry climate which obtains on the coast- belt in southern Angola and to the south of it. This great central plateau is often hundreds of miles wide, and in this latitude its long * Read at the Royal Geographical Society, November 22, 1909. Map, p. 224. This content downloaded from 132.203.227.63 on Tue, 10 May 2016 23:10:39 UTC All use subject to http://about.jstor.org/terms NATURALIST'S TRAVELS ON THE CONGO-ZAMBEZI WATERSHED. 133 axis runs roughly east and west, so that it would be possible to travel from German East Africa to within 200 miles of the coast in Angola without descending below 4000 feet above sea-level. The Congo-Zambezi watershed forms the backbone of the central portion of this plateau. To demonstrate that the high land which forms this watershed is an important barrier to the advance of the western tropical fauna is the chief object of this paper. Before entering into the details of the area under discussion it will, I think, be convenient to subdivide it into three very natural divisions. These are (1) The low ground in the Zambezi basin. (2) The Congo-Zambezi watershed and the high ground on either side of it. (3) The low ground in the Congo basin. The first of these divisions, so far as Northern Rhodesia is concerned, is limited to the valley of the Luangwa river and to a small portion of the mid-Zambezi valley. The vast proportion of this area lies below 2500 feet, and only comprises higher ground towards the borders of Nyasaland and Portuguese South-East Africa. The fauna and flora of this lowlying area are quite distinctive compared with that of the rest of Northern Rhodesia. The mammals, birds, and insects found in the Luangwa valley are mainly those which occur in the lower Zambezi valley and much of the south-east coast region of Africa. There are also present a few species which, though not known to occur south of the Zambezi, have already been recorded from Nyasaland. As an example of these latter may be instanced the pretty little love- bird, Agapornis lilianse, Scl. A very large proportion of the Luangwa valley consists of broad alluvial flats through which the river flows. The bed of the river is very wide, the sandy banks often having an edging of phragmitis reed, the white plumes of which are very effective at a distance. A close acquaintance, however, with this plant is not desirable on account of its spear-like blades. The Luangwa valley exhibits a very different appearance at the different seasons of the year. At the height of the rainy season the river is a wide and turbulent waste of muddy waters, and often over- flows its banks. At this time the flat stretches of alluvial soil in the neighbourhood of the river are singularly unpleasant to travel over. On these flats the soil largely consists of a peculiarly tenacious and impermeable clay of a dark grey colour. The huge cracks which form in this clay during the dry season are rapidly filled up by the first heavy rains. When this has once taken place the whole country soon becomes water-logged, and, when once in this condition, even a slight shower will produce standing water everywhere. When making a journey up the Luangwa river in Febi4ary and March, 1908, I was This content downloaded from 132.203.227.63 on Tue, 10 May 2016 23:10:39 UTC All use subject to http://about.jstor.org/terms 134 NATURALIST'S TRAVELS ON THE CONGO-ZAMBEZI WATERSHED. much astonished at the extent of the floods. It was an extraordinary sight to see huge stretches of " mopane" forest standing in from 6 inches up to 3 or 4 feet of water. This tree, a species of Copaifera, the " ironwood" tree of Livingstone, is a remarkable one and highly characteristic of this area; in fact, so far as North-Eastern Rhodesia is concerned, it is confined to the basin of the Luangwa river. More particularly in the low ground of the valley large stretches of forest composed almost entirely of this tree are met with. This is an unusual character in the African woodland or forest, which is much more generally composed of a great variety of trees. It is perhaps here well to point out that dense forest formed of large trees as opposed to woodland is distinctly uncommon in any of the areas under discussion, though, as we shall see later, it occurs occasionally in the Congo basin. A very large proportion of the whole country, more especially the hilly areas, is more or less uniformly covered by rather thin woodland, the majority of the trees being of moderate size. In the " Mopane " forest but little grows beneath the trees and in the clearings among them except short and not very vigorous grasses. This, perhaps, is due to the peculiar conditions of the soil. To grow successfully in a heavy clay which is water-logged in summer and baked as hard as a rock in winter, no doubt requires considerable specialization. The "mopane " trees seem peculiarly adapted to these conditions, but do not as a rule grow to a very large size, nor with very straight trunks. This rather discounts the commercial value of their timber, which is, however, very hard, and said not to be attacked by termites. The living tree is strangely inflammable. The natives take advantage of this peculiar character. In order to fell one of these trees, they insert a burning stick into a crevice in the trunk. The tree will then begin to smoulder, and will fall burnt through the trunk within some twenty-four hours, and then, if left to itself, will lie smouldering on the ground for days.

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