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Landscape dynamics result from forestry and farming practices, both of which are expected to have diverse impacts on ecosystem services (ES). In this study, we investigated this general statement for regulating and supporting services via an assessment of ecosystem functions: climate regulation via carbon sequestration in soil and plant biomass, water cycle and soil erosion regulation via water infiltration in soil, and support for primary production via soil chemical quality and water storage. We tested the hypothesis that patterns of land-cover composition and structure significantly alter ES metrics at two different scales. We surveyed 54 farms in two Amazonian regions of Brazil and Colombia and assessed land-cover composition and structure from remote sensing data (farm scale) from 1990 to 2007. Simple and well-established methods were used to characterize soil and vegetation from five points in each farm (plot scale). Most ES metrics were significantly correlated with land-use (plot scale) and land-cover (farm scale) classifications; however, spatial variability in inherent soil properties, alone or in interaction with land-use or land-cover changes, contributed greatly to variability in ES metrics. Carbon stock in above-ground plant biomass and water infiltration rate decreased from forest to pasture land covers, whereas soil chemical quality and plant-available water storage capacity increased. Land-cover classifications based on structure metrics explained significantly less ES metric variation than those based on composition metrics. Land-cover composition dynamics explained 45 % (P < 0.001) of ES metric variance, 15 % by itself and 30 % in interaction with inherent soil properties. This study describes how ES evolve with landscape changes, specifying the contribution of spatial variability in the physical environment and highlighting trade-offs and synergies among ES. (Résumé d'auteur

Some years after their establishment, areas of pasture planted to Brachiaria and other African grasses in the Brazilian Amazon region show a continuous decline in forage and animal productivity. If no remedial measures are taken, plant cover decreases, the areas become invaded by weeds and the soil becomes compacted. However, this process is not yet well understood. A series of evaluations was implemented in a 20-year-old pasture located on a representative cattle ranch in Rondônia state to estimate the botanical composition, standing phytomass (including leaf litter), macrofauna species richness and microbial biomass to characterize the soil biological conditions of a pasture site about to degrade and before rehabilitation practices were adopted. The aim was to characterize the type and degree of degradation already completed to record the baseline against which the results obtained by restoration practices could be compared. Soil C, N and available P stocks were 20.4 Mg C ha-1 , 1.5 Mg N ha-1 and 8.3 kg P ha-1 respectively, higher than under natural forest and close to those found in productive pasture sites. Physical and chemical analyses did not indicate effective degradation. Woody species dominated by trees and shrubs such as Tabebuia spp., Erisma uncinatum and Vismia guianensis occupied 15-18% of the total area. Babaçu palm (Orbignya phalerata Mart) covered 12%, herbaceous weeds 4-11%, while the rest (mean 63.5%) contained a mixture of Brachiaria brizantha and Pannicum maximum. The high biomass accrual and the diversity of species suggest that the soil is still able to support a productive forage grass cover. Biomass above ground, including litter layer, totalled 131 Mg DM ha-1 , or 42% of original forest. High standing biomass in the experimental area can be attributed to insufficient and/or inapropriate weed control since the early stage of pasture installation. Reformation of the study site would implicate a potential above-ground input of about 130 Mg C ha-1 (C/N = 49; C/P = 744), besides another 6.4 Mg C ha-1 derived from root biomass decomposition. The most frequently found invertebrates were the termites (368 ind m-2), restricted to the 0-10 cm layer, while earthworms (204 ind m-2), ants (152 ind m-2) and Coleoptera (146 ind m-2) were found to a depth of 30 cm. The presence of so-called ecosystem engineers indicates that this population, probably comprising anecics and rhizophagous species, is related to the high root and litter density. The average number of representatives is more comparable with sites undergoing regrowth of secondary vegetation than with degraded pastures. Microbiological evidence indicates that the pasture studied constitutes an unstressed system about to accumulate organic matter in the soil.

Resumo:A citricultura encontra-se disseminada por todo o território nacional, com grande importância econômica e social para diversos Estados. No Estado do Pará as lavouras caracterizam-se pelo pouco uso de insumos e adoção de práticas culturais inadequadas. O trabalho teve como objetivo avaliar, por meio da diagnose foliar, o estado nutricional de pomares da microrregião do Guamá, submetidos a três manejos do solo. Foram selecionados seis pomares representativos, todos com plantas de laranjeira 'Pera' (Citrus sinensis (L.) Osbeck), enxertadas sobre limoeiro 'Cravo' (Citrus limonia Osbeck), levando em consideração três manejos. Para todas as amostras foram coletadas folhas de ramos com frutos de 2-4 cm de diâmetro nos diferentes quadrantes das plantas e em duas épocas. As maiores limitações nutricionais dos pomares foram o P, independente da época, nos níveis de manejo baixo e médio, enquanto as limitações em relação ao K ocorreram, principalmente, no manejo baixo, nas duas épocas. Em relação aos micronutrientes, o Zn, pela deficiência nas plantas, se apresentou como o mais limitante, seguido do Mn, enquanto para o Fe verificou-se nível alto e excessivo.Abstract: Orange trees are grown throughout Brazil and have great economic and social importance for various States. Orchards in the Brazilian State of Pará were selected according to the level of technology used for management. The aim of the study was to assess, by means of leaf diagnosis, the nutritional status of citrus orchards in the Guamá microregion, with three different levels of soil treatment. Six orchards representative of the micro-region were selected, all with sweet orange trees (Citrus sinensis (L.) Osbeck), grafted onto lemandarin trees (Citrus limonia Osbeck), with three levels of soil treatment. For all the samples, leaves were taken from branches bearing fruit of 2-4 cm in diameter, from different quadrants of the plants and on two separate occasions. The greatest nutritional deficiency in the orchards was in phosphorus, regardless of the time of the sampling, where there were low or medium levels of soil treatment, while potassium deficiency occurred mainly where there was a low level of treatment, again irrespective of when the sample was taken. In relation to micronutrients, the plants were most commonly found to be deficient in zinc, followed by manganese, while iron was found in high or extreme levels. ARTIGOwww.ajaes

SUMMARYPasture is the main form of land use in Amazonia. Over time the pasture grass loses vigor and yields decrease, indicating a certain degree of degeneration. The main causes of degradation are lack of pasture maintenance and subsequent weed infestation, the choice of regionally unsuitable forage species and excessive grazing. The main purpose of this study was to evaluate the impact of different recovery managements on soil chemical properties and grass yield of a degraded pasture in Rondônia. For this purpose, an experiment was installed in October 2001, consisting of five treatments: C = control; HA = harrowing + NPK + micronutrients; HE = Herbicide + NK + micronutrients; R = No-tillage rice + NPK + micronutrients; and S = No-tillage soybean + PK + micronutrients. The following N, P and K sources were used: ammonium sulfate for N, calcined phosphate for P and potassium chloride for K. The experiment was arranged in a randomized block design with four replications. The shoot dry matter yield of the grass was analyzed as of the (1

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RESUMONa região amazônica, pastagens formadas e conduzidas de forma inadequada perdem a produtividade durante os primeiros anos em razão de superpastejo, ausência de adubação e de manutenção e emprego de espécies inadequadas para as condições edafoflorísticas da região. O objetivo deste estudo foi quantificar as modificações ocasionadas por diferentes sistemas de manejo nos atributos físicos de um Latossolo Vermelho-Amarelo (

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