Spread of African Pasture Grasses to the American Tropics1

Spread of African Pasture Grasses to the American Tropics Item Type text; Article Authors Parsons, J. J. Citation Parsons, J. J. (1972). Spread of African pasture grasses to the American tropics. Journal of Range Management, 25(1), 12-17. DOI 10.2307/3896654 Publisher Society for Range Management Journal Journal of Range Management Rights Copyright © Society for Range Management. Download date 03/10/2021 04:34:23 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/647510 Spread of African Pasture Grasses variably they are more palatable to livestock than the native American to the American Tropics1 species, and more productive. Such adaptability to grazing clearly must JAMES J. PARSONS be related to their simultaneous evolutionary development with Professor of Geography, Department of Geography, University of California, Berkeley. grazing animals in their areas of origin during the late Pliocene and Pleistocene. Highlight the north coast of Colombia, on the There are no data on how much Andean spurs of eastern Venezuela, Most of the economically important of Tropical America today supports pasture grasses of the tropics have in the interior of Brazil, on the is- a grass cover. It is a patchwork originated in Africa. Introduced into lands of the Greater Antilles-today quilt. Excluding the Amazon basin, the New World, they have often be- one sees pasture lands stretching to come naturalized, spreading rapidly it must approach 40 per cent. What the horizon, interrupted only by and widely. Six species have been part of this surface supports natu- scattered palms, remnant woodlots, principally involved in this massive ralized African species is not known. ecologic invasion. With the aid of man or linear rows of trees planted Although the vegetation maps may the face of much of the continent is originally as live fences. The tropi- not show it, grass, whether volun- gradually being changed from forest cal forest of Latin America, so long to productive grassland. teer, planted, or simply encouraged considered inviolate, is under seri- by man, is the most widespread of ous and sustained attack on count- all cover types over much of the The once limitless forests of less fronts and it must now be con- continent. Most pastures and ex- humid tropical America are rapidly sidered an important question tensive tracts of so-called savanna being converted to grasslands. Areas whether it will long endure (Stern- are, in fact, a mixture of native and newly cleared of selua or montana berg, 1968). introduced grasses. are cropped for a few years, then Tropical Africa-especially An- A half dozen species of Gramineae planted to perennial African grasses gola, Rhodesia, and the Transvaal have been principally involved to to’ form “artificial” pastures. These -has been an independent center date in this African invasion: generally have been aggressively of development for a number of colonizing species, readily dissemi- sown forage grasses, including vir- Guinea grass (Panicum maximum Jacq.), Para grass (Brachiaria mu- nated either by seed or cutting, and tually all of the important ones that they have become widely natural- may be considered truly tropical tica (Forsk.) Stapf), molasses grass (Melinis minutiflora Beauv.), jara- ized. Agriculture is thus but a (Hartley and Williams, 1956). Most temporary stage in the process by of these are said to have evolved gua (Hyparrhenia rufa (Nees) Stapf), Kikuyu grass (Pennisetum which forest is being converted to from woodland or forest margin clandestinum Hochst.), and, most potreros, especially where grazing habitats (Cooper, 1965). Although pressure, set fires, and the purpose- originally they appear to have had recently, Pangola grass (Digitaria decumbens Stent). The first two ful cutting or uprooting of aggres- quite restricted distributions in have been longest in the Americas sive woody species promote the Africa, they are today found over dominance of grasses over second- wide areas of ‘derived’ savanna sur- and are probably the best known and most valued, although some of growth vegetation (rastrojo). There face that once supported trees. In- is a surge and ebb to the forest- troduced into America, these grasses the later arrivals have been more aggressive colonizers. grassland boundaries thus created, have proven to be explosively ag- but the relentless sweep of the gressive, invading and holding vast Guinea Grass colonos axe is producing an ever- areas wherever they have received widening sea of grass. Where once minimal support by man. For most Guinea grass (Panicum maxi- stood great tracts of lowland forest of them numerous subspecies or mum), a tall growing clump-former -along the Pan American Highway ecotypes have been recognized, but that may be propagated either by in Mexico and Central America, on little is known regarding their dif- seeds or cutting, is undoubtedly the fering ecologic adaptations and the most widespread. It is also known 1 This research has been supported by mechanisms for them (Torres, 1954). as hierba de India (Colombia), the Geography Branch, Office of The role of genetic variability, in- priuilegio or xacatdn (Mexico), and Naval Research, and the Center for cluding polyploidy, in the evolution capim coloniao (Brazil). Its estab- Latin American Studies, University of lishment in the West Indies appar- California, Berkeley. This is a revi- of these invasive species remains to sion and extension of an earlier paper, be investigated. It is noteworthy ently dates from the seventeenth “The Africanization of the New World that all appear to have the ability century. In 1684 Hans Sloane, Tropical Grasslands,” which appeared to respond to higher soil nutrient founder of the British Museum, col- in Tiibingen Geographische Studien, 34: 141-153 (1970). Received February levels than those encountered in the lected and described a “Scotch 6, 1971. regions from which they came. In- grass” in Barbados, and later in 12 AFRICAN GRASSES 13 ment of most of the north-side parishes is wholly owing to the introduction of this excellent Jamoico 17th C.? grass, which happened by acci- dent about 50 years ago . .” Its spread throughout the West Indies was apparently rapid. The first scientific description of the grass, in 1786, was from a specimen collected in Guadeloupe, where it was said to have become naturalized Panicum maximum Brochioria mutica (“In insula Guadeloupe sponte GUiNEA crescit”). By the end of the century it was described as being “exten- sively cultivated” in Antigua, where it had been introduced from Ja- maica. As early as 1813 it had reached Mississippi, approximately the northern limit of its range in the New World (Weintraub, 1953). Guinea grass appears to have been introduced to New Granada (Colombia) from Jamaica in 1797 (Restrepo, 1963). Here, too, it is reported to have been looked upon at first as only a curiosity, a source Hyporrhenia rufa Melinis minufiflora JA RAGUA GORDURA of bird seed. Its large scale cultiva- tion was initiated in the area of Guaduas (Cundinamarca) in the FIG. 1. The spread of sonle African pasture grasses into the New World tropics. # (1823) = place of collection and date of first scientific description of species. middle Magdalena Valley in the 1830’s where it created a major land-use revolution. One observer Jamaica (Sloane, 1707, p. 106). He the seed might have arrived from called it “a true miracle grass,” sug- labeled it “gramen paniceum maxi- Brazil, with which Barbados had gesting that the unknown person mum or paniceum vulgare.” He fairly close associations at the time. responsible for its introduction to described it as 4-5 feet tall with But to be sure that Sloane’s grass that region deserved a statue “as thick nodes at six-inch intervals on was indeed Panicum maximum we high as New York’s Statue of Lib- the stalk, being: need to examine his collections in erty, illuminated by night . so as London. “Planted in moist ground all to be visible throughout the vast over the island for provision for Bryan Edwards, the historian of area of the new haciendas of the cattle, but grows wild . in the Jamaica, writing prior to 1794, was tierra caliente that it has made pro- north side [of Jamaica] and in enormously impressed with the ductive” (Rivas, 1946). It was also part of Barbadoes called Scot- rapid spread of “Guinea grass,” but from Jamaica that it reached Cen- land, whence the name. After he, like several other observers, tral America, apparently sometime its being found very useful in attributed its presence in the West around the middle of the 19th cen- Barbadoes, and had been there Indies to a casual introduction from tury. Extensive planted pastures of planted for some time, it was Africa to Jamaica in 1740 or 1741 Guinea grass began to appear in brought hither [Jamaica] and is by the captain of a slave ship who Guatemala about this time, re- now all over the island in the had intended it for use as bird seed. moister land by river sides, portedly introduced by way of the planted after the manner of Multiple introductions seem quite Soconusco coast of Chiapas (Es- sugar canes.” likely. Commenting on the revolu- ponda, 1888). In 1870 “great zacat6n tionary impact of the grass, he ob- potreros full of fat cattle” were de- Such an early English introduction served (Edwards, 1801, p. 253): scribed as one of the principal arms would fit into a pattern of fairly “ . Most of the grazing and widespread introductions of eco- of wealth of that republic. In breeding farms, or pens, through- nomic plants to the West Indies southern Mexico, too, it provided out the island [of Jamaica] were the basis for a greatly expanded from West Africa, for many slave originally created and are still ships made Barbados their first and supported by this invaluable livestock industry.

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