Quintais agroflorestais indígenas em área de savana (Lavrado) na terra indígena Araçá, Roraima
Data
2008
Autores
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Instituto Nacional de Pesquisas da Amazônia
Resumo
Foram estudados quintais agroflorestais (“sítios”) da Terra Indígena (T.I.) Araçá (5 comunidades), nas savanas de Roraima (Lavrado), com o objetivo de analisar a composição, riqueza, diversidade, dominância e os fatores que influenciam a presença de espécies arbóreas e arbustivas nos quintais, bem como avaliar a evolução da fertilidade dos solos dos quintais em relação ao ambiente natural de savana. Nos 60 quintais estudados foram encontradas 79 espécies, sendo que 45 são produtoras de frutos comestíveis. O limoeiro (Citrus aurantifolia Swing.), o araçazeiro (Psidium guineense SW.) e a mangueira (Mangifera indica L.) foram as espécies mais abundantes nos quintais, com 13%, 13% e 11% do total de indivíduos, respectivamente, e também umas das espécies mais freqüentes, presentes em 90% e 62% e 93% dos quintais, respectivamente. A maior parte dos frutos é utilizada para auto-consumo, porém em 40%, 15% e 8% dos quintais é realizada a comercialização do limão, da manga e da laranja, respectivamente. Tanto a riqueza de espécies quanto o número total de plantas está diretamente relacionado com a área e a idade dos quintais (p<0,01). As espécies plantadas nos quintais são geralmente adquiridas através de trocas e doações entre familiares e conhecidos, sendo que cada espécie pode ter uma ou mais procedências, sendo as principais delas a própria T.I. Araçá (75%) e a capital Boa Vista (49%). Das espécies presentes nos quintais, 21 nasceram espontaneamente, e foram mantidas nos quintais por oferecerem alguma utilidade, principalmente por produzirem frutos comestíveis, como é o caso de 46% dessas espécies. Dos 60 quintais estudados nas 5 comunidades, 15 foram escolhidos aleatoriamente para coleta de solos, realizando-se uma estratificação por idade, que dividiu os quintais em: quintais novos, com 0 a 10 anos; quintais estabelecidos, com 15 a 35 anos; e quintais antigos, com mais de 40 anos. Em cada quintal amostrado, foi também efetuada uma amostragem em uma área de Lavrado (savana) adjacente ao quintal, para servir como referência (testemunha) da qualidade do solo antes da implantação do quintal. A coleta de solos foi feita em 3 profundidades (0 a 10 cm, 10 a 20 cm e 20 a 30 cm). A maior parte dos quintais e áreas adjacentes possui solos arenosos. Foi encontrada relação positiva entre idade do quintal e teores de cálcio, potássio, magnésio, fósforo, zinco e matéria orgânica, mostrando que esses teores aumentam no quintal com o passar do tempo. Comparando com a área de Lavrado adjacente, nos quintais novos já é possível observar um maior teor de nutrientes, no mínimo em uma comunidade ou profundidade, sendo o fósforo o principal deles. Nos quintais estabelecidos e antigos, há um número ainda maior de situações em que a diferença entre quintal e área adjacente é significativa. A maior parte dos solos de quintais estabelecidos e antigos apresentou teores considerados médios de magnésio (entre 0,2 e 0,8 cmolc kg -1 ) e teores considerados altos de zinco (mais que 1,5 mg kg -1 ) e fósforo (entre 3 e 7 mg kg -1 ). O ferro apresentou poucas diferenças significativas entre quintal e área adjacente, em quintais de todas as idades. Tanto o solo dos quintais como o das áreas adjacentes possuem baixa toxidez por alumínio (menos que 0,5 cmolc kg -1 ). Em geral, os quintais apresentaram baixos teores de matéria orgânica (menos que 15 g kg -1 ), provavelmente devido à textura arenosa da maior parte dos solos. A análise de agrupamento de cluster considerou semelhantes os quintais estabelecidos e antigos, representando o grupo com os maiores teores de nutrientes e sugerindo que o tempo de habitação dos quintais estabelecidos (entre 15 e 35 anos) já é suficiente para proporcionar incrementos semelhantes aos dos quintais antigos (mais de 40 anos). Os incrementos nas características químicas dos solos dos quintais da T.I. Araçá se devem principalmente às práticas de deposição de resíduos orgânicos e de queima de resíduos vegetais em pequena quantidade, associadas à diversidade de espécies e ciclagem de nutrientes mais fechada e otimizada.
Homegardens were studied in the Araçá Indian Land (5 communities), in Roraima’s savannas (Lavrado), in order to analyze species composition, richness, diversity, dominance and factors that could influence the presence of tree and bush species in the homegardens, and verify changes in soil fertility in relation to the natural environment in savannas. A total of 79 species were found in the 60 homegardens studied, of which 45 species bear edible fruits. Sour Lime (Citrus aurantifolia Swing.), Araçá Trees (Psidium guineense SW.) and Mango trees (Mangifera indica L.) are the most numerous species at the homegardens, representing 13%, 13% and 11% of the total number of plants, respectively. They are also ones of the most common species, as they are present in 90%, 62% and 93% of the homegardens, respectively. Most fruits are used for self consumption; however the sour limes, mangoes and oranges are commercialized in 40%, 15% and 8% of homegardens, respectively. The number of species and the total amount of plants are related to the size and age of the homegardens (p<0, 01). Planted species are generally collected through exchanges of seeds and seedlings among family members and friends, and each species may come from one or more places, mainly from the Araçá Indian Reservation (75%) and from Boa Vista (49%). From the total number of species present at the homegardens, 21 grown spontaneously, and are kept at the home gardens because they were useful somehow, mainly because they can bear edible fruits, in this case 46% of these species. From the 60 homegardens studied in the 5 communities, fifteen were chosen randomly in order to get soil samples, and were classified in 3 categories, according to age: new homegardens (0 to 10 years old); settled homegardens (15 to 35 years old) and old homegardens (40 years old or more). As homegardens were checked, a nearby savanna was sampled too, and it was considered to be evidence, in order to compare the levels of the elements at the homegarden soils and at the nearby savanna soils. Soil sample was done at three layers (0 to 10 cm, 10 to 20 cm and 20 to 30 cm). Most of the gardens and nearby areas are sandy. There was a significant relation among the garden age and calcium, potassium, magnesium, phosphorus, zinc and organic matter, showing that these nutrients levels increase along the years. Comparing savanna nearby areas, at new gardens it is already possible to notice higher element levels, at at least one community or soil layer, phosphorus being the main element increased at these homegardens. At settled and old homegardens there are even more cases where the difference between gardens and savanna is significant. Most part of soil at settled and old homegardens showed average levels of magnesium (levels varying between 0,2 and 0,8 cmolc kg -1 ) and high levels of zinc (more than 1,5mg kg -1 ) and phosphorus (variation: 3-7 mg kg -1 ). Iron showed little changes in levels when comparison was made between savannas and homegardens of all ages. Homegardens soil and nearby areas show low level of aluminum toxicity (less than 0,5 cmolc kg -1 ). In general homegardens showed low level of organic matter (less than 15g kg -1 ), probably because most soils are sandy. The analysis of cluster grouping showed that settled and old gardens were similar. They represent the group with the highest levels of nutrients. It conveys that period of time for settled gardens (about 15 and 35 years old) is enough to produce results that could be similar to the ones present in old gardens (more than 40 years old). The increased chemical characteristics at T.I. Araçá homegarden soils are due mainly to organic residues deposition and burning small quantities of vegetal residues, associated to species diversity and a closer andamoreaoptimizedanutrientacycling.
Homegardens were studied in the Araçá Indian Land (5 communities), in Roraima’s savannas (Lavrado), in order to analyze species composition, richness, diversity, dominance and factors that could influence the presence of tree and bush species in the homegardens, and verify changes in soil fertility in relation to the natural environment in savannas. A total of 79 species were found in the 60 homegardens studied, of which 45 species bear edible fruits. Sour Lime (Citrus aurantifolia Swing.), Araçá Trees (Psidium guineense SW.) and Mango trees (Mangifera indica L.) are the most numerous species at the homegardens, representing 13%, 13% and 11% of the total number of plants, respectively. They are also ones of the most common species, as they are present in 90%, 62% and 93% of the homegardens, respectively. Most fruits are used for self consumption; however the sour limes, mangoes and oranges are commercialized in 40%, 15% and 8% of homegardens, respectively. The number of species and the total amount of plants are related to the size and age of the homegardens (p<0, 01). Planted species are generally collected through exchanges of seeds and seedlings among family members and friends, and each species may come from one or more places, mainly from the Araçá Indian Reservation (75%) and from Boa Vista (49%). From the total number of species present at the homegardens, 21 grown spontaneously, and are kept at the home gardens because they were useful somehow, mainly because they can bear edible fruits, in this case 46% of these species. From the 60 homegardens studied in the 5 communities, fifteen were chosen randomly in order to get soil samples, and were classified in 3 categories, according to age: new homegardens (0 to 10 years old); settled homegardens (15 to 35 years old) and old homegardens (40 years old or more). As homegardens were checked, a nearby savanna was sampled too, and it was considered to be evidence, in order to compare the levels of the elements at the homegarden soils and at the nearby savanna soils. Soil sample was done at three layers (0 to 10 cm, 10 to 20 cm and 20 to 30 cm). Most of the gardens and nearby areas are sandy. There was a significant relation among the garden age and calcium, potassium, magnesium, phosphorus, zinc and organic matter, showing that these nutrients levels increase along the years. Comparing savanna nearby areas, at new gardens it is already possible to notice higher element levels, at at least one community or soil layer, phosphorus being the main element increased at these homegardens. At settled and old homegardens there are even more cases where the difference between gardens and savanna is significant. Most part of soil at settled and old homegardens showed average levels of magnesium (levels varying between 0,2 and 0,8 cmolc kg -1 ) and high levels of zinc (more than 1,5mg kg -1 ) and phosphorus (variation: 3-7 mg kg -1 ). Iron showed little changes in levels when comparison was made between savannas and homegardens of all ages. Homegardens soil and nearby areas show low level of aluminum toxicity (less than 0,5 cmolc kg -1 ). In general homegardens showed low level of organic matter (less than 15g kg -1 ), probably because most soils are sandy. The analysis of cluster grouping showed that settled and old gardens were similar. They represent the group with the highest levels of nutrients. It conveys that period of time for settled gardens (about 15 and 35 years old) is enough to produce results that could be similar to the ones present in old gardens (more than 40 years old). The increased chemical characteristics at T.I. Araçá homegarden soils are due mainly to organic residues deposition and burning small quantities of vegetal residues, associated to species diversity and a closer andamoreaoptimizedanutrientacycling.
Descrição
Dissertação de mestrado defendida no Instituto Nacional de Pesquisas da Amazônia.
Palavras-chave
Sistemas agroflorestais, Roraima, Savanas, Agricultura indígena
Citação
PINHO, R. C. Quintais agroflorestais indígenas em área de savana (Lavrado) na terra indígena Araçá, Roraima. 2008. 108 f. Dissertação (Mestrado em Ciências de Florestas Tropicais) - Instituto Nacional de Pesquisas da Amazônia, Manaus. 2008.