Pesquisa Agropecuária Tropical ISSN: 1517-6398 [email protected] Escola de Agronomia e Engenharia de Alimentos Brasil Guglieri-Caporal, Adriana; Machado Caporal, Francisco José; Pott, Arnildo PHYTOSOCIOLOGY OF SOWN PASTURE WEEDS UNDER TWO LEVELS OF DEGRADATION IN BRAZILIAN SAVANNA AREAS, MATO GROSSO DO SUL STATE, BRAZIL Pesquisa Agropecuária Tropical, vol. 40, núm. 3, julio-septiembre, 2010, pp. 312-321 Escola de Agronomia e Engenharia de Alimentos Goiânia, Brasil Available in: http://www.redalyc.org/articulo.oa?id=253019612013 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative e-ISSN 1983-4063 - www.agro.ufg.br/pat - Pesq. Agropec. Trop., Goiânia, v. 40, n. 3, p. 312-321, jul./set. 2010 PHYTOSOCIOLOGY OF SOWN PASTURE WEEDS UNDER TWO LEVELS OF DEGRADATION IN BRAZILIAN SAVANNA AREAS, MATO GROSSO DO SUL STATE, BRAZIL1 Adriana Guglieri-Caporal2, Francisco José Machado Caporal2, Arnildo Pott2 RESUMO ABSTRACT FITOSSOCIOLOGIA DE PLANTAS DANINHAS DE PASTAGENS CULTIVADAS SOB DOIS NÍVEIS DE DEGRADAÇÃO EM CERRADO, NO MATO GROSSO DO SUL Cultivated pastures, in general, go through a decline process, associated with the occurrence of weeds, whose Pastagens cultivadas, de maneira geral, entram em successful management begins with the survey of species and processo de declínio, associado à infestação de plantas daninhas, their biology. This study aimed to carry out phytosociological cujo manejo exitoso começa com o levantamento das espécies surveys, during the rainy and dry seasons, in two pastures infestantes e sua biologia. Este trabalho teve como objetivo o cultivated with Brachiaria (Urochloa) spp., with cattle (AI) estudo fitossociológico, nas estações chuvosa e seca, em duas and without cattle (AII), in Cerrado (Brazilian savanna) areas pastagens cultivadas de Brachiaria (Urochloa) spp., com gado of the Mato Grosso do Sul State, Brazil. The occurrence of (AI) e sem gado (AII), em áreas de Cerrado do Mato Grosso 104 weedy herbaceous and subshrubby Phanerogams species do Sul. Foi constatada a ocorrência de 104 espécies de plantas was recorded. The families with the highest number of species daninhas herbáceas e subarbustivas de Fanerógamas. As famílias were Fabaceae (23 species), Poaceae (16), and Asteraceae (15). de maior destaque, em número de espécies, foram Fabaceae (23 Hemicryptophytes predominate with 41% of the species. The espécies), Poaceae (16) e Asteraceae (15). As hemicriptófitas species with the highest importance value and relative coverage predominam com 41% das espécies. As espécies com maiores are B. decumbens and Sida rhombifolia, in AI, and B. brizantha valores de importância e cobertura relativa são B. decumbens e and Desmodium incanum, in AII, plus Paspalum notatum, Sida rhombifolia, em AI, e B. brizantha e Desmodium incanum, in both pastures. The Shannon diversity index was 4.19 and em AII, além de Paspalum notatum, em ambas as pastagens. Os 4.43 nats, for AI and AII, respectively, indicating considerable valores de diversidade de Shannon foram 4,19 e 4,43 nats, para weed species richness. The floristic dissimilarity index between AI e AII, respectivamente, indicando considerável riqueza de AI and AII, obtained from the Euclidian distance, is 0.7468, espécies. O índice de dissimilaridade florística entre AI e AII, indicating just a few species in common (44%). In the dry obtido a partir da Distância Euclidiana, é 0,7468, o que indica season, the number of species in AI decreased 10% while in poucas espécies em comum (44%). Na estação seca, o número AII it increased 4%. de espécies em AI caiu 10% e, em AII, aumentou 4%. PALAVRAS-CHAVE: Agroecossistema; Brachiaria; ecologia KEY-WORDS: Agroecosystem; Brachiaria; flora; plant ecology; vegetal; flora;Urochloa . Urochloa. INTRODUCTION species well adapted to climate and soils (Perón & Evangelista 2004). Cerrado (Brazilian savanna) is the second Sown pastures, in general, present high initial biome in Brazil, 2 million km2, approximately productivity, however, within a few years, go through 22% of the country (Eiten 2001), covering nearly a decline process (Dutra et al. 2004). Excessive the whole Central-West region. Soils are generally stocking rate, wrong choice of forage species, and dystrophic, but well structured, often on flat or inadequate management have caused an increasing gently rolled relief, what favors cattle ranching and process of pastures degradation (Santos & Costa mechanized crops (Pivello 2006). Cattle farming 2002, Perón & Evangelista 2004, Dias Filho 2007), has expanded considerably in the region, after the which reaches 80% in the Central-West Brazilian 1970s, due to low prices of land, finance, and forage region (Perón & Evangelista 2004). According to 1. Trabalho recebido em abr./2009 e aceito para publicação em set./2010 (n° registro: PAT 6051/ DOI: 10.5216/pat.v40i3.6051). 2. Universidade Federal do Mato Grosso do Sul (UFMS), Centro de Ciências Biológicas e da Saúde, Departamento de Biologia, Campo Grande, MS, Brasil. E-mails: [email protected], [email protected], [email protected]. 313 Phytosociology of sown pasture weeds under two levels of degradation in Brazilian savanna areas 313 Macedo & Zimmer (1993), a degraded pasture of unbroken native vegetation, with more than undergoes a gradual process of vigor, productivity 2,000 ha covered with cerradão and semideciduous and recovery capacity loss, becoming unable to forest, close to the capital city of Mato Grosso do overcome harmful pests effects, diseases, and weeds, Sul, Campo Grande. ending up with natural resources degradation. Correa The climate of the region, according to the et al. (2001) pointed out that pasture degradation in Köppen system classification, is Aw humid tropical the Cerrado region is often related to exhaustion subtype (mean temperature of 24ºC and mean annual of soil fertility. Dias Filho (2007) stressed that rainfall of 1,500 mm), with a rainy season in the weed proliferation in pastures is a consequence of Summer (October to April) and a dry one in the the degradation process and not its cause, and that Winter. The relief is gently rolled, with predominance weeds compete for soil nutrients, making them less of Dystrophic red Latosol (Rhodic Ferrasol) accessible to forage plants. (Embrapa 2008). The management success of a weed community Two areas (paddocks) of sown pasture were begins with the survey of weeds, in order to selected, here named area I (AI) and area II (AII). Since understand their biology and predominant species the middle 1930s, these areas, originally from Cerrado (Pott et al. 2006). So, floristics and phytosociology s.s. and cerradão, have been cleared and burned for are extremely useful tools, helping on practices pasture development, usual practices in the region. In management and weed control of different crops, the 1970s, following a regional trend, African species the first supplying a list of all weed species and of Brachiaria (Urochloa) were introduced. the second supporting the understanding of species AI has around 6 ha of B. decumbens (signal structure and dynamics, dominant populations, and grass) pasture, within approximately 100 ha the weed community, as a whole. Studies involving of paddock area, with 200 head of cattle and sown pastures weed communities were performed sometimes 20 horses. AI is limited by the coordinates by Dantas & Rodrigues (1980), Dias Filho (1990), 20º45′14,2′′S and 54º50′34,9′′W; 20º45′14,4′′S and Mascarenhas et al. (1999), Mitja et al. (2000), Dutra 54º50′32,4′′W; 20º45′26,0′′S and 54º50′35,2′′W; et al. (2004), and Tuffi Santos et al. (2004), however, 20º45′26,1′′S and 54º50′37,1′′W, and the smallest side just a few were carried out in the Central-West region of the polygon is connected to a strongly impacted (Pott et al. 2006, Silva et al. 2006). and thinned cerradão remnant. Altitude varies from The objective of the present research was the 513 m to 526 m. phytosociological study of two pastures sown in AII represents a pasture of B. brizantha Cerrado areas, with and without cattle, during the (palisade grass), 5 ha, within the coordinates rainy and dry seasons, in Mato Grosso do Sul State, 20º45′46,0′′S and 54º50′21,9′′W; 20º45′48,2′′S and Brazil. 54º50′15,2′′W; 20º45′53,8′′S and 54º50′11,9′′W; 20º45′46,5′′S and 54º50′10,9′′W, and two polygon MATERIAL AND METHODS sides are adjacent to little disturbed cerradão. Altitude varies from 509 m to 520 m. Up to September 2006, Study areas only six working oxes were kept in this paddock, which stayed without cattle from October 2006 to Nova Esperança ranch lays in the township of January 2008, over the study period. Sidrolândia, micro-region of Campo Grande, 37 km South of Campo Grande city, Mato Grosso do Sul Floristic study State, Brazil, with an approximate area of 4,000 ha, including 1,500 ha of swamp, wet grassland, Cerrado The study was performed from February 2007 grassland and scrub, and Cerrado stricto sensu, used to January 2008, during a rainy season (October as pastureland for beef cattle. to April) and a dry one (May to September). A The Nova Esperança ranch presents a great minimum of 12 months is expected for this kind of ecological importance, as it includes seven headwaters study, due to variables such as fast vegetative growth and a registered private reserve, near Serra de and complete flowering, fruit set, and dispersion Maracaju, part of the Pantanal-Atlantic Forest cycles. Monthly visits were made in order to survey ecological corridor, being one of the few remnants pasture herbaceous, subshrubby and climbing weeds, e-ISSN 1983-4063 - www.agro.ufg.br/pat - Pesq. Agropec. Trop., Goiânia, v. 40, n. 3, p.