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sources in the highlands to the The Llanos-A Neglected Grazing north. Starting as swift mountain Resource torrents, they flatten out into sluggish, muddy streams, with the C. LANGDON WIIITE and JOHN THOMPSON reduction in gradient in the low- lands. Professor and Instructor, respectively, Department of Geogra,- phy, Stanford University, Stanford, C’alifornia During the season of high rainfall these rivers swell tremendously, HE Llanos are unique in being in which the region could support overflow their banks and inundate T grasslands lying within 10 de- more cattle in the future. huge areas along their lower grees of the Equator and at eleva- reaches. There is a difference of 43 tions nowhere exceeding 1,000 feet Regional Features feet between high and low water above sea level. The region is Terrain and Drainage in the Orinoco. During the latter covered by a variety of plant asso- The Llanos comprise a huge level part of the heavy rainy season, it is ciations broadly termed savanna. to undulating alluvial plain, slop- believed that more than a third of The word was apparently first used the Llanos is inundated. The in 1535 by Oviedo in referring to flooded lands have every appear- the Venezuelan Llanos. In this ance of swamps, being soon clothed paper savannas are regarded as Perspective on a relatively un- with a rank vegetation and with plains whose dominant vegetation developed grazing resource in the water-plant growth (Fig. 2). is grass. However, when the rain- Tropics of South America-the Flooded for months at a time, fall is greater or the soils collect Llanos of Venezuela and Colombia. travel by land becomes impossible and hold more moisture, the sa- Dr. White is Head of the Depart- and human beings must move vanna may support trees growing ment of Geography at Stanford about ill dugouts. close enough to form woodland. In University and a student of Latin Duri$g the dry season,*&>he flow some savannas the grasses are tall, America for many years. Mr. of water is so drastically’ reduced in others short, corresponding ap- Thompson was born in South Amer- that many of the rivers dry up parently to zones of greater or ica and lived part of his life there. into pools and swamps. Some lesser moisture. up co;;lpletely. In this huge natural landscape .. bounded by the Andes Mountains ing south and southeastward from ,‘r Climate and the Orinoco River, the popula- the Andes to the Orinoco. As con- Rhythm . in the rainfall is the tion of both man and domestic sidered here, the region is divided’ outstand&g characteristic of the animals is small and the region is into the Eastern, Central and climate, the year being divided into not of great import. This is puz- Southern Llanos (Fig. 1). two seasons-the dry referred to zling, for superficial consideration The region is traversed by a locally as verano lasting from June of the map indicates that the number of streams having their to March inclusive and the wet- Llanos should be a truly great cattle country. It consists largely of grassland, it is relatively near the sea, from its first occupation by white men it has been used pri- marily for cattle raising, it is served by the Orinoco-one of South America’s major rivers, and the populations of both Colombia and Venezuela are badly in need of meat produced at home. Further study, however, discloses that neither country is realizing the potentialities of the Llanos for cattle production. It is the purpose 0 200 400 of t)his paper to present the high- M\LEs lights of this great grassland, to point out the reasons for its eco- nomic neglect, and to suggest ways FIGIJRE 1. MRP of northern South Anericn showing the subregions of the Llanos. 11 12 C. LASGDON WHITE ASD .JOIIN THOMPSOX invierno-lasting from .June to Oc- ducrd firrs have yielded a wide clothed with in sparsr, short-grass t,obcr inclusive. April and hZlty, vnrirt,y of plant associat,ions “vu wgctatioo of low nutritional valor. Novcmhrr and Dwxmher are trnrl- t,hc Llaoos (Fig. 3). I~owver, Hew Trach//poyon appcxs to be &ion months. The arrival sod uniformity does not, cherartrrix t,he most rommol~ form of veget,a- duration of thr seasons \&es from t,he region; new should the Llanos tion. Palms, trwn and shrubs are year to year and from place to he rgsrded solely as #‘IL great thinly scattered in the eastern place. III general t,he xet ~ra.s”n monotonous sea of waving grass”. mesa country, while a considerable shortens and the annual rainfall Grass does hold sway in some parts area of monte or chaparral or open diminishes northward. Annual pre- but trees do in others. The grass is wrub forest, overlies the nort,hcrn cipitation varies from 39 inches at of the hunch type and is not, matted half of these plains. Ciudsd Bolivar to 52 inches st as are our prairie and strppe (knrrnlizing on the IAmos San Fernando dc Apure. Nearly grasses. In the Central Llanos grasses, it may he said that thry all of this rain falls during the sir whew the water table is suficiently have low nutritional value. While months hlay to October inclusive. high, as along the Apurr and Portu- the succulent, glrcn ne\v growth at During the dry season the shade gucsa rivers, the grasses arc greeu the beginning of the wet season temperature3 approach maximas in and palatable for stork the year and following fires is eaten hy the the middle and low 90’s. Monthly round. Green meadow also may be stock, the large, coarse mature grasses become hard and unpalata- ble with progression of the dry season. Bwause t,hr Ilitneros believe that liring improves the vegetat,ion, they burn off large arcas during the dry witson. Art,ually this pruc- tier is partly rrsponsiblc for the poor quality of the forage, particu- larly in thr Eastern Llanos. Hcrc infwior grasses whirh are more resistant to elimination by fires, are replacing the better grasses. One of the biggest hurdles t,” range improvrmcnt t,o date has bern the difficulty in finding grasses other than the nat,ive variet,y t,hnt can stand the extremes of climate. Causes of the Llanas Them is no agreement among averages arc 10’ to 20’F. lo\\w. m3en as concentric rings of vegeta- botanists, ecologists and geogra- During this season the northrast, tion about an evaporating flood or phers regarding the origin and trade winds blow almost, ~“11. senpagc-created lagoon, but t,he causes of the Llanos <:over. One stsntly making the period more shallow-root,ed plants dry UP school of thought considers the hearable to man than the wet quickly its the vatcr recedes. HOW savanna vegetation to be a climat,ic season. In the latter season, though ever, the coarse, hardy grasses WC climax formation; another as an monthly averages are 4’ to 9’F. able to endure the severe rondi- edaphic climax dependent on spr- lower, the combination of higher tions. cial soil conditions. Both views, relative humidity and of reduced Scattered throughout t,he grassy however, agree that the silwmna air movement results in higher area are swh trees as chaparro, landscapes WPR pre-Columhiall, but sensible tcmprraturrs. Even during IllWXy, alcornoqw and copaibn. that the grasses grew murh taller the hrief spells of dry weather that Streams are almost always borderd then than n”\v. interrupt the wet season, there is by gallery forests. In plavcs occur Schimpcr (1903) defines the cli- little relief from its discomforts. small forests called “matas” by t,he matic requirements of a savanna to natives and h&s of moriches be an annual precipitation of 35 to Natural Vegetatim which foIlox\- strramlets and which %59inches (90&1.50 rm.), an rffPctive The variations in climatr, soils the inhahitantri call “morichales”. 4- to 3.month dry seas”,, and a and terrain alone with man-in- Murh of the Eastern Llanos is range in t,hr mont,hly mean t,erw LL.ZSOP A SE(:LECTF,D GRAZING RESOURCE 13 Another \-ir!v on the distrilmt,ion of SR\~RIIIIIIS holds that, n-e do llot know whether t heir oo~u~wn~! corre- spends to the real ecological UN- ditions. This school asserts that man, through periodic Inmrirrg and grazing, is the cause. A. Aubrevillr (19-19) doubts that, t,here iu a spr- rific savanna climate in the tropics. Myers (1933) regards the Llnnos vegetation as a fire-climax, although he h&eves soil conditions may also he involved. However, so litt,le is known scirnt,ificnlly regarding South American soils t,hat it is unsafe t,o speculate regarding this fnrtor. The authors believe that, the chief d&ermining fact,ors for the savanna cover of the Llanos are not always the same; t,he evidencr of climatic dominance is not rvery- x-here decisive. The range of cli- Occupancy of the Llanos Missionaries first entered the matic conditions under which the Colonial Per,od Llanos near the end of the sixteenth savanna occurs in this part of When the Spaniards arrived in century. They encouraged the In- South Amcrirn, the abrupt bound- this part of the New World, they dians to grow native and intro- ary hetwren forest, and SBV&IIIIR, found the Llanos (particularly the dwed crops, to raise livestock and and t,he presence of savanna eastern half) occupied hy small to develop crafts. Their success is pockets betwren zones of for& all numhrrs of Indians cngngcd in at,tested to by the results-the t,cnd to rhallengc the thesis of patch farming, hunting, fishing and Capuchins had herds numbering climatic theory.

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