Estoques de biomassa em diferentes cenários de uso da terra ao norte de Manaus, Amazônia Central brasileira

The high primary productivity of secondary vegetation (capoeira) and the large extent and continued presence of this land cover in the agricultural landscape of Amazonia indicate the capacity of this vegetation to absorb substantial amounts of carbon from the atmosphere. In order to calculate these flows and stocks of carbon and to remunerate the environmental services of secondary vegetation, indirect models of biomass estimation are needed that are adapted to the range of sucessional conditions in each region. We investigated the effects of different forms of land use among rural settlers on aboveground biomass estimates and the chronological progression of biomass accumulation in abandoned pastures in small rural properties in the Tarumã Mirim settlement near the city of Manaus in Central Amazonia. We developed mathematical models using total height and diameter at breast height of all plants and indices related to the use history of the land to estimate plant biomass in 24 plots used by rural settlers. Biomass data were obtained using destructive sampling of all plants with diameter at breast height > 1 cm in secondary vegetation ranging from 1 to 15 years of age that had been used as pasture and agriculture. With these data we developed monospecífic allometric equations for 13 species and multispecífic equations for a group of 121 species of trees, for a group of 12 species of bushes and for dead plants that remain standing. We also developed indirect methodologies of estimate biomass stocks in capoeiras through less-difficult nondestructive methods. The rate and the accumulation of biomass from the 3rd to the 21st year of age of secondary vegetation established in degraded pastures were indirectly appraised using the allometric equations we developed. A continuous inventory of the degraded pastures was carried out annually in permanent plots in capoeiras with three different use intensities. Both the amount of accumulated biomass and the florístic richness in abandoned pastures are higher when the areas had been subjected to less time under grazing. The biomass stock is determined more by the intensity of previous use than by the age of the capoeira. Along course of succession the rates of biomass accumulation are not linear, there being a high degree of interannual variation, with stagnation and even biomass loss in the secondary vegetation plots during years with severe droughts. Variation of capoeira management practices by settlers with different profiles also affected the biomass accumulation. Settlers who were living in cities prior to moving to the rural area showed poor knowledge of capoeira management practices and burned the capoeira too early (< 2 years of fallow time). At this age the capoeira has not produced enough biomass to increase soil fertility and to maintain it over the long term. These urban-originated settlers do not associate the practice of fallowing with the recovery of soil fertility through natural regeneration. This study contributes to the understanding of biological and social factors that determine sucessional processes in the agricultural landscape of central Amazonia.A alta produtividade primária e a ampla distribuição da vegetação secundária (capoeira) na paisagem agrícola da Amazônia indicam o potencial desta cobertura vegetal de absorver quantidades significantes de carbono da atmosfera. Para poder calcular estes fluxos e estoques de carbono e remunerar os serviços ambientais da vegetação secundária deve-se usar modelos indiretos de estimativa de biomassa ajustados às amplitudes de condições sucessionais de cada região. Foram investigados os efeitos de diferentes formas de uso da terra nos estoques e nas taxas de acúmulo de biomassa das capoeiras originadas de agricultura e pastagens abandonadas de propriedades rurais do Assentamento Tarumã Mirim e em áreas de pastagens degradadas abandonadas da Estação Experimental da Embrapa (AM), na Amazônia Central. Foram desenvolvidos modelos matemáticos a partir da altura total, diâmetro à altura do peito (DAP) e histórico de uso da terra em 24 capoeiras para estimar a biomassa de árvores e o estoque de biomassa de áreas de vegetações secundárias. Dados de biomassa foram obtidos por metodologia destrutiva através da pesagem de todas as plantas com DAP superior a 1 cm em capoeiras com idades de 1 a 15 anos originadas de áreas de agricultura e pastagens abandonadas. Com estes dados foram desenvolvidas equações alométricas monoespecíficas para 13 espécies e equações multiespecíficas para um conjunto de: 121 espécies arbóreas; 12 espécies arbustivas; e plantas mortas que permanecem em pé. A taxa e o acúmulo de biomassa do 3o ao 21o ano de idade de vegetações secundárias estabelecidas em pastagens degradadas foram avaliados indiretamente com as equações alométricas desenvolvidas. Medições contínuas das pastagens degradadas foram realizadas anualmente em parcelas permanentes de capoeiras com três diferentes intensidades de uso. A biomassa acumulada e a riqueza florística em pastagens abandonadas são maiores quanto menor o tempo em que a área foi submetida ao pastejo. O estoque de biomassa foi determinado mais em função da intensidade de uso do que da idade da capoeira. Ao longo da sucessão as taxas de acúmulo de biomassa não são lineares, tendo grandes variações interanuais. Nos anos em que a seca é crítica há estagnação e até perda de biomassa nas parcelas de vegetação secundária. Variações nas práticas de manejo de capoeira entre agricultores também afetam o acúmulo de biomassa. A maioria dos agricultores assentados que não têm origem agrícola não associam a prática de pousio à recuperação da fertilidade do solo através da regeneração natural. Considerando o valor irrisório por tonelada de carbono pago pelo mercado internacional e a média da extensão da área de vegetação secundária por propriedade de 0,91 ha e a duração media de pousio de 1,9 anos no Assentamento Tarumã Mirim, o que uma família rural lucraria pelo carbono acumulado pela capoeira não representaria compensação financeira suficientemente atrativa. Se o mercado passar a ter um valor diferenciado para o carbono fixado pela agricultura familiar, e considerar os plantios agroflorestais e, principalmente, o desmatamento evitado, a comercialização do carbono agregaria valor às atividades produtivas sustentáveis. Este trabalho contribui com o entendimento dos fatores ecológicos e sociais determinantes dos processos sucessionais na paisagem agrícola da Amazônia Central

Secondary vegetation in central Amazonia: Land-use history effects on aboveground biomass

Growth of secondary forest (capoeira) is an important factor in absorption of carbon from the atmosphere. Estimates of this absorption vary greatly, in large part due to the effect of different land-use histories on the estimates available in the literature. We relate land-use history to aboveground biomass accumulation of secondary vegetation in plots on land that had been used for agriculture (unmechanized manioc and maize) and for pasture in small rural properties in the Tarumã-Mirim settlement near Manaus in central Amazonia, Brazil. We evaluated influence of (a) age of the second growth vegetation, (b) time of use as agriculture or pasture and (c) number of times the area was burned. Biomass data were obtained by destructive sampling of all plants with diameter at breast height >1. cm in 24 parcels of secondary vegetation ranging from 1 to 15. years of age in abandoned pasture (n= 9) and agriculture (n= 15). As compared to secondary vegetation in abandoned agricultural fields, vegetation in abandoned cattle pasture (the predominant use history for Amazonian secondary vegetation) grows 38% more slowly to age 6. years. Number of burns also negatively affects biomass recovery. Applying the growth rates we measured to the secondary forests reported in Brazil's Second National Communication to the United Nations Framework Convention on Climate Change suggests that carbon uptake by this vegetation is overestimated by a factor of four in the report. © 2015 Elsevier B.V

Solar radiation measurementes and leaf area index (LAI) from vegetal covers

A method by which a physical model of the solar radiation transfer in a vegetal medium is inverted to estimate the leaf area index (LAI) for different types of vegetation is presented here, as an alternative to the destructive experiments, which are a hard task to implement on the vegetation covers. Radiation data were obtained during the dry season - 1996, at the Embrapa Experimental Station, (BR 174 - km 54, 2º 31' S, 60º 01' W), Manaus, Brazil. The method yielded convergent values for the LAI between different adopted radiation classes with more stable estimates at time when there is a predominant diffuse radiation. The application of the inversion algorithm yields the following values for the leaf area index and respective annual foliage increments:3.5 (0.35 yr.-1) for the intact secondary forest; 2.0 (0.5 yr-1) for the palm agroforestry system; and 1.6 (0.4 yr-1) for the multi-layer ones.", 'enUm método de inversão de modelo físico de penetração de radiação solar em meio vegetal para estimar o índice de área foliar(IAF) é apresentado e testado neste trabalho para diferentes tipos de vegetação, como uma alternativa aos experimentos destrutivos, trabalhosos e de difícil implementação em coberturas florestais. Os dados de radiação foram obtidos durante o período seco de 1996 na Estação Experimental da Embrapa, (BR 174 - km 54, 2º 31' S, 60º 01' O), Manaus, Brasil. O método produziu valores de IAF convergentes entre as classes de radiação adotadas, com estimativas mais estáveis para ocasiões em que há predomínio de luz difusa. A aplicação do procedimento de inversão deu origem aos seguintes valores de índice de área foliar e respectivos incrementos anuais3,5 (0,35.ano-1) para a vegetação secundária intacta; 2,0 (0,5.ano-1) para o sistema agroflorestal com palmeiras; e 1,6 (0,4.ano-1) para o sistema agroflorestal multiestratificado

Contribuição ao estudo de parasitos intestinais em dois bairros de Manaus - Amazonas

In the months of May and June a parasitological investigation was made for 1035 residents of two areas of Manaus, Amazonas. The specimens were concentrated by Faust's method, and the authors prepared the followng index of intestinal parasites in these individuals. These results were obtained: Helminths: Trichocephalus trichiurus 74%, Ascaris lumbricoides 58%, Ancylostomideae 53%, Enterobius vermiculares 1%, Strongyloides stercoralis 9%, and Hymenolepis nana 0,3%. The highest incidence of protozoan parasites has of Giardia lamblia 17%, Endamoeba coli 14%, Endamoeba histolytica 3%, Iodamoeba butschlii 2.4% and Endolimax nana 0.7%.", 'enOs AA realizaram um inquérito coproparasitológico em 1035 pessoas da cidade de Manaus, constituindo 100 famílias do bairro Coroado (511 indivíduos) e 100 famílias do bairro Colônia Oliveira Machado (524 indivíduos), com a finalidade de evidenciar a incidência de parasitoses intestinais. Cada amostra de fezes foi submetida a parasitoscopia pelo método de concentração, segundo Faust. Dentre as amostras analisadas do bairro do Coroado, 85,1% estavam parasitadas por Helmintos e Protozoários, enquanto que no Colônia Oliveira Machado esta infestação era de 90,0%

Aspectos silviculturais da castanha-do-brasil (bertholletia excelsa) em sistemas agroflorestais na Amazônia Central

This study evaluated the development of Brasil nut (Bertholletia excelsa) in agroforestry systems established on non-flooding plateaus in Central Amazonia. Three multi-strata agroforestry systems established in 1992 in degraded pastures, located at the Experiment Station of Embrapa Amazonia Ocidental, BR-174 highway, km 54, Manaus, Amazonas, were evaluated. The area had been intensively managed as pasture for six years, then abandoned for four years, and reopened with traditional slash and burn practices to plant the agroforestry systems. Species development was evaluated with measurements of survival rate, trunk diameter at breast height (DBH), total tree height, crown diameter, canopy proportion, degree of slenderness, prominence index, inclusion index and crown shape. At 12 years of age, the trees had a mean total height of 20.9 m and DBH of 37.9 cm, with an annual mean increment of 1.74 m and 3.16 cm, respectively. Mean survival was 78%, with mortality due windstorms and lightening. These observations confirm the suitability of this species to help rehabilitate degraded areas and be included in agroforestry systems

Development of forest structure and leaf area in secondary forests regenerating on abandoned pastures in Central Amazonia

The area of secondary forest (SF) regenerating from pastures is increasing in the Amazon basin; however, the return of forest and canopy structure following abandonment is not well understood. This study examined the development of leaf area index (LAI), canopy cover, aboveground biomass, stem density, diameter at breast height (DBH), and basal area ( BA) by growth form and diameter class for 10 SFs regenerating from abandoned pastures. Biomass accrual was tree dominated, constituting >= 94% of the total measured biomass in all forests abandoned >= 4 to 6 yr. Vine biomass increased with forest age, but its relative contribution to total biomass decreased with time. The forests were dominated by the tree Vismia spp. (> 50%). Tree stem density peaked after 6 to 8 yr ( 10 320 stems per hectare) before declining by 42% in the 12- to 14-yr-old SFs. Small-diameter tree stems in the 1-5-cm size class composed > 58% of the total stems for all forests. After 12 to 14 yr, there was no significant leaf area below 150-cm height. Leaf area return (LAI = 3.2 after 12 to 14 yr) relative to biomass was slower than literature-reported recovery following slash-and-burn, where LAI can reach primary forest levels ( LAI = 4 - 6) in 5 yr. After 12 to 14 yr, the colonizing vegetation returned some components of forest structure to values reported for primary forest. Basal area and LAI were 50% - 60%, canopy cover and stem density were nearly 100%, and the rapid tree-dominated biomass accrual was 25% - 50% of values reported for primary forest. Biomass accumulation may reach an asymptote earlier than expected because of even-aged, monospecific, untiered stand structure. The very slow leaf area accumulation relative to biomass and to reported values for recovery following slash-and-burn indicates a different canopy development pathway that warrants further investigation of causes ( e. g., nutrient limitations, competition) and effects on processes such as evapotranspiration and soil water uptake, which would influence long-term recovery rates and have regional implications

Conhecimento e utiliza\ue7\ue3o da floresta pelos \uedndios Waimiri-Atroari do Rio Camanau - Amazonas

Os índios Waimiri Atroari têm hábitos e costumes bastantes intactos e retiram da floresta, roça e rio os materiais necessários para a alimentação, utensílios e moradia. Este trabalho objetivou fazer um levantamento preliminar do conheciamento e utilização da floresta pelos índios. Foram inventariados todas as árvores com DAP > 6cm em cinco parcelas de 10 x 20m, localizadas 0,5km da aldeia, ao longo de um transecto abrangendo um gradiente de terra firme - baixio. Foram coletadas amostras para herbário e anotadas informações sobre uso e nome indígena. Em 0.1 hectare foram encontradas 135 árvores de 60 espécies, sendo as famílias mais comuns: Lecythidaceae, Leguminosae sensu latu, Burseraceae, Bombacaceae e Lauraceae. Noventa e cinco por cento dessas espécies eram identificadas com um nome específico na língua Waimiri Atroari e as demais receberam um nome genérico ("wiwe ') que quer dizer árvore. De uma amostra de 34 espécies sessenta e cinco por cento tinham algum uso específico. Estes dados demonstram um alto grau de conhecimento e utilização da floresta pelos Waimiri Atroari.The Waimiri Atroari retain much of their original culture and take from the forest, river, and plantations their food and most of the materials necessary fpr construction, craft, and medicines. This study attempted to quantify their knowledge and use of forest. Five quadrats of 10 x 20m (total = 0,1 hectare) were located along a transition from "terra firme" (upland) to "baixio" (stream valley). Herbarium specimens were collected from trees above 6cm DBH, and Indian names and uses were recorded. In 0,1 hectare, 135 trees belonging to 60 species were found. Lecythidaceae, Leguminosae (sensu latu), Burseraceae, Lauraceae and Bombacaceae were the commonest families. Ninety-five percent of the species received a Waimiri Atroari name, and in a smller sample (n = 34), sixty-five percent of the species had some specific use. These results show a high degree of knowledge and utilization of the forest by the Wairniri Atroari