Trophic relations in an agroecosystem of the Sabanas region, Sucre, Colombia (original) (raw)
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Relaciones tróficas en un agroecosistema de la región Sabanas, Sucre, Colombia
Pastos y Forrajes, 2019
El objetivo de este estudio fue definir las relaciones tróficas existentes en el agroecosistema de una granja en la región Sabanas, Sucre, Colombia. Se partió de estudios anteriores en la granja y de observaciones de campo entre los años 2014-2017. Se recopiló información de las especies, la cual permitió agruparlas según su hábito alimenticio en trofoespecies. El flujo de energía se demostró mediante una matriz binaria de interrelaciones, y se analizaron los datos diseñando una red trófica. Se identificaron seis órdenes, dos familias, ocho géneros y 166 especies. De estos grupos se establecieron 11 categorías tróficas: productores, herbívoros, nectarívoros, granívoros, insectívoros, carnívoros, omnívoros, descomponedores, hematófagos, frugívoros y carroñeros, distribuidas en 48 trofoespecies. La red trófica presentó densidad de conexiones de 3,25 y un valor de conectancia de 0,13. Se concluye que la red trófica de los agroecosistemas permitió diferenciar los patrones fundamentales ...
Using trophic hierarchy to understand food web structure
Oikos, 2009
Link arrangement in food webs is determined by the species' feeding habits. This work investigates whether food web topology is organized in a gradient of trophic positions from producers to consumers. To this end, we analyzed 26 food webs for which the consumption rate of each species was specified. We computed the trophic positions and the link densities of all species in the food webs. Link density measures how much each species contributes to the distribution of energy in the system. It is expressed as the number of links species establish with other nodes, weighted by their magnitude. We computed these two metrics using various formulations developed in the ecological network analysis framework. Results show a positive correlation between trophic position and link density across all the systems, regardless the specific formulas used to measure the two quantities. We performed the same analysis on the corresponding binary matrices (i.e. removing information about rates). In addition, we investigated the relation between trophic position and link density in: a) simulated binary webs with same connectance as the original ones; b) weighted webs with constant topology but randomized link strengths and c) weighted webs with constant connectance where both topology and link strengths are randomized. The correlation between the two indices attenuates, vanishes or becomes negative in the case of binary food webs and simulated data (weighted and unweighted).
Community-wide trophic cascades and other indirect interactions in an agricultural community
Basic and Applied Ecology, 2003
A current goal in ecology is to elucidate the relative roles of primary and secondary consumers versus plant resources in determining community structure and dynamics. The complexity and diversity of terrestrial communities has been hypothesized to strongly influence the strength of these topdown and bottom-up forces, and in turn, trophic interactions are predicted to have significant consequences for species diversity within trophic levels. To examine the relative strengths of top-down and bottom-up trophic interactions and their relationship to arthropod diversity in an agricultural ecosystem, we conducted experiments in two alfalfa fields with different management regimes in which we manipulated light availability, nutrients, and arthropod abundance. We employed path analysis to examine how variation generated by these manipulations influenced top-down and bottom-up trophic pathways, focusing on alfalfa productivity and the abundance and species richness of arthropods. These analyses revealed a number of complex interactions between treatments and each of the three trophic levels. Shade structures had a strong effect on enemy, herbivore, and plant trophic levels, but much of the effect on plant biomass appeared to be mediated indirectly through changes in enemy and herbivore abundance. Potential positive effects of nutrient addition on alfalfa biomass were negated due to increases in abundance of soil microbes in the intensively managed field and herbivores in the weedy field. In the intensively managed, low arthropod abundance field, alfalfa biomass increased with herbivore diversity. However, in the lightly managed fields, herbivore diversity, which increased significantly with nutrient addition, reduced alfalfa biomass. The indirect top-down and bottom-up effects uncovered in this experiment were strong, but were not limited to the classic trophic cascades that have been the subject of intense recent investigation.
2019
The edaphic mesofauna performs essential functions in the soil such as the recycling of nutrients and formation of its microstructure. The objective of this research was to characterize the edaphic mesofauna in five grassland agroecosystems of Granma province, Cuba. To this end, contrasting agroecosystems were selected in terms of soil type, grassland and productive purpose ("Estación de Pastos", "Ojo de agua", "El Triángulo", "El Progreso" and "Cupeycito"). The pitfall traps were used, with a 0.003 % detergent solution. The individuals were extracted and counted and placed in vials, with 70 % ethanol, for later identification. Individuals belonging to two classes, four orders, six families and seven genera were found. The Collembola order was the best represented with five genera. Only in the third sampling there was a significant influence of the season detected on some of the studied variables, specifically for each agroecosystem. The Shannon index showed values lower than 1.35; while the dominance indexes showed values close to or higher than 0.5 in most cases. It is concluded that the richness and abundance of the edaphic mesofauna in the studied grassland agroecosystems was low and very variable in both climatic periods. Individuals belonging to the trophic categories of predators and detritivores were found which showed a variable relative abundance, in each agroecosystem and sampling performed; except in the "Estación de Pastos" where there was a predominance of predators.
Potencial De Ecoinovação Em Agroecologia
Revista Brasileira de Gestão e Desenvolvimento Regional
No contexto da crise ambiental, o presente estudo teve como objetivo identificar e analisar o potencial de ecoinovação na produção agroecológica no Brasil, mediante o mapeamento da procura por informações tecnológicas da parte dos usuários na plataforma de acesso ao Serviço Brasileiro de Respostas Técnicas (SBRT). Para tanto, optou-se pelo uso da metodologia de investigação quantitativa, a partir do levantamento de respostas técnicas e dossiês técnicos relacionados às palavras-chave "sustentabilidade" , "desenvolvimento sustentável" e "meio ambiente" na coleção do segmento da agricultura, que contém 2068 documentos técnicos. Como resultados da pesquisa, foram recuperados 79 respostas e dossiês, o equivalente a 3,8% do total da amostra documental, tendo sido acessados por 1628 usuários, representando 41% do número total de acessos únicos à coleção. Com relação à informação tecnológica contida nesses documentos, 38% estão associados à agricultura orgânic...
Frontiers in Sustainable Food Systems, 2023
The simplification of the landscape as a consequence of the decrease in biodiversity and the adoption of monoculture production systems has led to a significant decrease in the provision of ecosystem services in the territory. The conversion of agroecosystems requires the adoption of agroecological techniques, which aim to design the agroecosystem as an integrated part of a vegetation matrix of the landscape, interconnecting the different production systems with the agricultural landscape. In order to measure the degree of connectivity of agroecosystems with the landscape, we used the Main Agroecological Structure (MAS) method, which was applied to 36 small agroecosystems of vegetable, livestock and fruit producers, which generally presented a low degree of connectivity. This allows us to evaluate the potential of these systems for agroecological transition, since being present in a moderately complex agricultural landscape gives important advantages over a more simplified system, allowing these producers to dispense with the use of many energy subsidies. This evaluation allows a first approximation to the quantification of the landscape matrix and will allow a comparison between agroecosystems or an evaluation of the evolution of the MAS over time. It is necessary to complement the MAS by quantifying the ecosystem services that may be associated with it.
Empirically Characterising Trophic Networks
Ecological Networks in an Agricultural World, 2013
Food webs in agricultural systems are complex and trophic linkages are difficult to track using conventional methodologies. Here, we review three alternative approaches that allow empirical assessment of feeding interactions: DNA-based techniques, and stable isotope and fatty acid analyses. DNA-based methods, namely multiplex PCR and nextgeneration sequencing, allow identification of food types and host-parasitoid linkages, resulting in taxonomically highly resolved feeding networks. Stable isotopes and fatty
Revista Agroecossistemas
Este artigo resume um esforço colaborativo de seis anos durante o qual o CIPAV e pecuaristas da cidade de Riberas del San Juan (Cimitarra, Santander) projetaram e implementaram sistemas silvipastoris e agroflorestais com o objetivo de melhorar a produtividade pecuária e gerar condições adequadas para a conservação da biodiversidade e serviços ecossistêmicos. Este processo fez parte do Projeto Vida Selvagem (PVS), uma iniciativa para a conservação de cinco espécies ameaçadas de extinção em Magdalena Medio. Na paisagem desmatada de Riberas del San Juan, as práticas de pecuária geraram forte degradação do solo, os fragmentos florestais foram destinados a se tornar novos pastos e os fazendeiros tinham uma visão negativa das árvores e florestas. O componente do PVS coordenado pelo CIPAV teve como foco a conservação da peroba-rosa (Aspidosperma polyneuron Müll. Arg.) e outras árvores em perigo de extinção local. No entanto, as condições do terreno e da comunidade de Riberas del San Juan n...
Botanical Sciences, 2020
Agroforestry systems have cultural, economic, social, and biodiversity conservation significance and are essential for the subsistence of communities. Is there a difference in the richness, management and use of useful plants present in the agroforestry systems (home gardens, coffee plantations, and milpa)? What is the influence of sociodemographic factors on the distribution of traditional knowledge regarding plants of these systems? Las Delicias, municipality of Juquila Vijanos, Sierra Norte of Oaxaca, Mexico, from January 2016 to May 2018. Visits to three agroforestry systems and semistructured interviews with 30 families to learn how they use the plants and to calculate the use value (UV) for each species. The similarity of floristic composition between agroforestry systems and the influence of sociodemographic factors (age, gender, schooling, economic activity and language) in the traditional plant knowledge was evaluated. The methods used were chi squared and proportions analyses, and a generalized linear analysis with Poisson distribution. The three agroforestry systems consisted of 211 of useful plants; home gardens and coffee plantations had a greater similarity in floristic composition; the dissimilarity of the milpa agroecosystem is related to seasonality. The plants with higher UVs were those with multiple uses, and are found mainly in coffee plantations. Production in these spaces is complemented to satisfy the needs of the inhabitants. Gender and economic activity are factors that influence the distribution of traditional knowledge. Agroforestry systems provide a species richness differentiated for specific purposes but complementary to each other. coffee plantation, home gardens, milpa, use value. Resumen: Los sistemas agroforestales tradicionales tienen una importancia cultural, económica, social y en conservación de la biodiversidad; son esenciales en la subsistencia de las comunidades. ¿Existe diferencia en la riqueza, manejo y uso de plantas útiles presentes en los sistemas agroforestales (huertos familiares, cafetales, milpa)? ¿Cuál es la influencia de los factores sociodemográficos en la distribución del conocimiento tradicional sobre las plantas de estos sistemas? Las Delicias, municipio de Juquila Vijanos, Sierra Norte de Oaxaca, México; de enero de 2016 a mayo de 2018. Recorridos por tres sistemas agroforestales y entrevistas semiestructuradas a 30 familias, para calcular el Valor de Uso de cada especie vegetal. Se evaluó la similitud de la composición florística entre los sistemas agroforestales y la influencia de factores sociodemográficos (edad, sexo, escolaridad, ocupación e idioma) en el conocimiento tradicional de plantas, mediante pruebas de Ji cuadrada, de proporciones y de un modelo lineal generalizado con distribución Poisson. Los sistemas agroforestales estudiados conservan 211 especies vegetales útiles; los huertos familiares y los cafetales tienen una mayor similitud florística; la disimilitud del sistema milpa se relaciona con su temporalidad. Las plantas con mayor Valor de Uso fueron las que tienen múltiples usos y presentes en los cafetales. La producción se complementa para satisfacer las necesidades de los pobladores. El sexo y la ocupación están influyendo en la distribución del conocimiento tradicional. Los sistemas agroforestales proporcionan una riqueza de especies diferenciada con propósitos específicos, pero complementaria entre sí. Palabras clave: Cafetal, huertos familiares, milpa, Valor de Uso.
Categorias tróficas em uma assembléia de mamíferos: diversidade em paisagens agrícolas
Biota Neotropica, 2007
Mammals play an important role in the maintenance and regeneration of tropical forests since they have essential ecological functions and can be considered key-species in structuring biological communities. In landscapes with elevated anthropogenic pressure and high degree of fragmentation, species display distinct behavioral responses, generally related to dietary habits. The landscape of Passa-Cinco river basin, in the centraleastern region of São Paulo State, shows a high degree of anthropogenic disturbance, with sugar cane plantations, eucalyptus forests, native semideciduous forest remnants and pastures as the key habitat types in the region. We surveyed medium to large mammals in those habitats and determined species richness and relative abundance for each of the following trophic categories: Insectivore/Omnivores, Frugivore/Omnivores, Carnivores, Frugivore/Herbivores and Herbivore/Grazers. Differences in species richness and relative abundance among habitats were tested using one-way analysis of variance, followed by Tukey test, considering 1) each of the trophic categories individually and 2) the set of categories together. Between July 2003 and June 2004, 284.4 km were walked and 22 species were recorded (20 native and two exotics). Analysis of variance did not detect differences in species richness for any of the trophic categories or for the assemblage. Considering relative abundance, the analysis detected significant differences only for the whole assemblage, with the assemblage being more abundant in sugar cane plantations compared to pastures. Our results indicate that the heterogeneous landscape of the study area is dominated by generalist species adapted to use different habitat types and food items.