Reduced Diversity and Complexity in the Leaf-Litter Ant Assemblage of Colombian Coffee Plantations

Coffee agroecosystems have recently undergone a dramatic intensification in Colombia, a megadiverse country, especially in terms of the nature of shade cover. We tested for changes in the composition, ecological associations, and diversity of ants (Hymenoptera: Formicidae) along a gradient of intensification of coffee production in the Colombian Andes. We surveyed 16 farms in two regions, classified into four management types: (1) forest (no agriculture), (2) organic polygeneric shaded coffee, (3) monogeneric shaded coffee, and (4) sun coffee (unshaded). Forty sampling units (20 1-m 2 plots on the ground and 20 coffee bushes) were established at each farm between 2001 and 2002. We sampled with a mini-winkler litter extraction technique and through visual searching. Organic polygeneric shaded-coffee plantations contained significantly higher ant species richness, and their ant assemblages resembled the forest patches more than any other management type. The number of statistically significant associations among ant species dropped with production intensification, as did the number of ant species involved in such associations. The network of ant associations in shaded systems transformed into an extremely simplified network in sun coffee, with a few dominant ants extending almost entirely throughout the crop. Intensification of coffee agriculture not only caused loss of litter ant species (especially forest species) but also a reduction in the complexity of the ant assemblage in the leaf litter of this agroecosystem.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74649/1/j.1523-1739.2005.00062.x.pd

Throughfall and soil properties in shaded and unshaded coffee plantations and a secondary forest: a case study from Southern Colombia

In Colombia coffee production is facing risks due to an increase in the variability and amount of rainfall, which may alter hydrological cycles and negatively influence yield quality and quantity. Shade trees in coffee plantations, however, are known to produce ecological benefits, such as intercepting rainfall and lowering its velocity, resulting in a reduced net-rainfall and higher water infiltration. In this case study, we measured throughfall and soil hydrological properties in four land use systems in Cauca, Colombia, that differed in stand structural parameters: shaded coffee, unshaded coffee, secondary forest and pasture. We found that throughfall was rather influenced by stand structural characteristics than by rainfall intensity. Lower throughfall was recorded in the shaded coffee compared to the other systems when rain gauges were placed at a distance of 1.0 m to the shade tree. The variability of throughfall was high in the shaded coffee, which was due to different canopy characteristics and irregular arrangements of shade tree species. Shaded coffee and secondary forest resembled each other in soil structural parameters, with an increase in saturated hydraulic conductivity and microporosity, whereas bulk density and macroporosity decreased, compared to the unshaded coffee and pasture. In this context tree-covered systems indicate a stronger resilience towards changing rainfall patterns, especially in mountainous areas where coffee is cultivated

Composting to control the leaf-cutting ant atta cephalotes l. (hymenoptera: formicidae)

Leaf-cutting ants, Atta and Acromyrmex, are the most important defoliating herbivores in the tropics. In this study, field assays were conducted to compare the effects of two non chemical methods on survival and activity of Atta cephalotes (Formicidae: Myrmicinae) nests. A total of 83 A. cephalotes active nests were randomly assigned to one of three treatments: 1) compostable material introduced and processed into the soil of ant nests; 2) conventional mechanical mixing of the ant nests soil; 3) untreated ant nests. After three months the percentages of dead nets were 26.5, 9.63 and 3.61 using manure compost, mechanical, and control, respectively. A repeated measurement analysis of variance showed significant difference between ant colonies for both treatments, composted and mechanical mixing, with respect to the untreated treatment, given the disruption of foraging trails, mound openings, chambers and tunnels. The strongest effect was observed with the compostable material. Based on its effect on A. cephalotes (Formicidae: Myrmicinae) nests and potential soil enrichment, compostable treatment could be a sustainable and ecologically sound management practice if proper conditions are given at the site. Las hormigas cortadoras de hojas, Atta y Acromyrmex, son los herbívoros más importantes en los trópicos. En este estudio se comparan los efectos de dos métodos no químicos sobre la sobrevivencia y actividad de nidos de Atta cephalotes (Formicidae:Myrmicinae). Un total de 83 nidos activos de A. cephalotes fueron asignados de forma aleatoria a uno de tres tratamientos: 1) incorporación de un material compostable al suelo; 2) remoción y mezcla de la capa superficial del suelo (método convencional) y 3) placebo o control (sin tratamiento). Después de tres meses, los porcentajes de nidos eliminados con cada uno de los tratamientos fueron 26,5; 9,6; y 3,6; respectivamente. Un análisis de varianza de medidas repetidas mostró una diferencia significativa entre las colonias de hormigas sometidas a los tratamientos compostado y remoción mecánica en relación con el placebo. Esto debido a la destrucción de las pistas de forrajeo, de las aberturas, cámaras y túneles. Sin embargo, el más fuerte efecto fue observado con el compostado. Basado en estos resultados sobre los nidos de A. cephalotes y su efecto potencial de enriquecer el suelo, el tratamiento compostado puede representar una práctica sustentable y ecológicamente amigable en el control de hormigueros de Atta

Índice de intensificación agrícola y conservación vegetal en bosques y cafetales colombianos con diferentes estrategias de manejo

Los bosques húmedos premontanos (bh-pm) presentan alto grado de deterioro por efecto de la intervención antrópica, principalmente por actividades agrícolas y ganaderas. Dada la pérdida de conectividad en estos paisajes fragmentados, es prioritario estudiar la contribución de agroecosistemas cafeteros a la diversidad regional. Este estudio evaluó la diversidad florística de cafetales y estimó del índice de intensificación agrícola (IA) en dos estrategias agronómicas de café y en bosques en La Meseta de Popayán, Cauca, Colombia, en altitudes entre 1600 y 1750 m. Se midieron 13 variables de la vegetación tales como riqueza, densidad y estructura arbórea en 20 sitios de muestreo: ocho cafetales a plena exposición, ocho con sombrío y cuatro bosques de referencia. Se determinó que la diversidad florística disminuyó en función del IA, donde las variables relacionadas al componente arbóreo y epífito fueron las que más aportaron a la medición de la IA. La composición arbórea estuvo conformada principalmente por especies pioneras que son relevantes en la conservación y restauración regional. Se concluye que el IA aplicado a estos agroecosistemas ayuda a medir el grado de intervención antrópica; que los cafetales con sombra y parches de bosque son fuente de biodiversidad vegetal, de hábitat y de conectividad entre los paisajes Andinos fragmentados; y que la aplicación del IA en cafetales resulta en una herramienta útil para examinar hipótesis sobre sostenibilidad y conservación.Premontane humid forests (pm-hf) are severely degraded from anthropogenic disturbance derived from agricultural and livestock. Given the loss of connectivity among forest patches, it is necessary to study how agroecosystems, especially because an important part of biodiversity would be present in these agroecosystems. Because there is a loss of connectivity throughout these fragmented landscapes, it is necessary to develop studies on the contribution of coffee agroecosystems to biodiversity. This study evaluated plant diversity and estimated the agricultural intensification index (AI) in two coffee agronomic management strategies and forests at La Meseta at Popayán, Cauca, Colombia between 1600 and 1700 m. Thirteen local variables related to plants, such as richness, coffee density, arboreal structure, were evaluated in 20 sampling sites: eight sun coffee, eight shaded coffee plantations and four reference forests. The study found that floristic diversity decreased in function of AI, where the variables related to the arboreal component were the most sensitive to the IA measurement of intensification change. Arboreal composition consisted mainly of pioneer species, which are relevant for conservation and regional restoration purposes. It is concluded that the AI, applied to these agroecosystems helps to measure the degree of anthropogenic disturbance. Shaded coffee and forest patches are sources of plant diversity, of habitat and landscape connectivity in the highly fragmented Andean coffee landscapes; the application of the intensification index in coffee crops may constitute a useful tool to examine hypotheses related to sustainability and conservation

TRANSPORTE DE SEMILLAS POR HORMIGAS EN BOSQUES Y AGROECOSISTEMAS GANADEROS DE LOS ANDES COLOMBIANOS

Ants are important functional agents in natural ecosystems and tropical agroecosystems. Seed movement by ants may result in dispersal or post-dispersal events, affecting diaspore survival probabilities in cattle agroecosystems undergoing ecological rehabilitation. In that case, ants could be determining in the course of succession. Activity and diversity of soil foraging ants was compared in nine plots classifi ed in three land use systems: forest, treeless pasture, and intensive silvopastoril system with Leucaena leucocephala. Transects with 10 stations separated by 10m from each other were established. In each station the diversity of ants was evaluated using tuna baits, and as a separate event, deposits were offered, each one with 15 seeds from three different plant species. We found 27, 18, and 12 morphospecies of ants in forests, treeless pastures and intensive silvopastoril systems, respectively. Twentysix percent of the seeds were removed by ants in the fi rst two hours. The removal frequency was significantly lower in silvopastoril systems suggesting that the type of management of this cattle system does not promote seed movement by ants. The greatest diversity of ants transporting seeds was found in forests and in all the cases more than 50% of the arillated seeds of the native plant Siparuna aspera was removed. It is suggested that, in cattle systems where some of primary seed dispersers have been lost, ants can offer seeds movement services that might alter the survival probability of diaspores.Las hormigas son importantes agentes funcionales en los ecosistemas naturales y agroecosistemas tropicales. El movimiento de semillas por hormigas puede resultar en dispersión o postdispersión afectando la probabilidad de supervivencia de diásporas en agroecosistemas ganaderos en proceso de rehabilitación ecológica, en cuyo caso las hormigas podrían ser determinantes en la sucesión. Se comparó la actividad y diversidad de hormigas forrajeras del suelo en nueve lotes clasificados en tres usos de la tierra: bosque, pastura sin árboles, y sistema silvopastoril intensivo con Leucaena leucocephala. En cada lote se estableció un transecto con 10 estaciones separadas 10m entre sí. En cada estación se evaluó la diversidad de hormigas con cebos de atún, y como evento separado se ofrecieron depósitos, cada uno con 15 semillas pertenecientes a tres especies vegetales. Se encontraron 27, 18, y 12 morfoespecies de hormigas en bosques, pasturas sin árboles, y silvopastoriles intensivos respectivamente. El 26% de las semillas fueron removidas por hormigas en las primeras dos horas. La remoción fue significativamente menor en silvopastoriles sugiriendo que el tipo de manejo de este sistema ganadero no favorece el proceso de movimiento de semillas por hormigas. Se encontró mayor diversidad de hormigas transportando semillas en bosques y en todos los casos más del 50% de las semillas ariladas de la planta nativa Siparuna aspera fueron movidas por hormigas. Se sugiere que en sistemas ganaderos, donde se han perdido algunos dispersores primarios, las hormigas puedan prestar servicios de movimiento de semillas que podrían alterar la probabilidad de supervivencia de las diásporas

Dataset associated with "Land use conversion to agriculture impacts biodiversity, erosion control and key soil properties in an Andean watershed"

This data set involves soil and plant variables collected from 50 farm and forest plots in a mountainous region of the Valle del Cauca Department of Colombia. Sampling was conducted in 2016 to evaluate soil biodiversity and ecosystem services provided across five dominant land uses in the region.The conversion of natural vegetation to agricultural land uses in mountainous Andean landscapes threatens an array of key ecological processes and ecosystem services. In protected areas and buffer regions that provide water to cities, it is critical to understand how interactions between plants and soil communities sustain a range of ecosystem functions, associated with nutrient recycling, soil structure, and erosion control. We sought to understand how land use conversion within a mountainous tropical forest landscape influences the diversity of vegetation and soil macrofauna communities, soil physico-chemical properties, and hydrological regulation services. Biodiversity and a suite of key soil-based ecosystem services were compared in five major land uses of the Cali River watershed: 1) annual cropping systems, 2) coffee plantations, 3) pastures, 4) abandoned shrubland, and 5) secondary forests. The diversity of woody and herbaceous vegetation, as well as soil macrofauna was assessed in each land use. Soil chemical fertility and aggregate morphology were assessed via laboratory analyses and visual separation of soil aggregates based on their origin. Infiltration, runoff, and sediment production were measured using a portable rainfall simulator. We found a decrease in the diversity of woody vegetation across land-uses to be associated with lower diversity of soil macrofauna. At the same time, agricultural management, annual crops in particular, supports the largest earthworm populations, likely due to increased organic inputs and low impact tillage, which appears not to diminish soil fertility and water infiltration. In contrast, the low soil fertility in pastures was associated with the lowest values of soil C, poor aggregation, and high bulk density, and likely reflects overgrazing, with negative implications for water infiltration and erosion. Associations between the different sets of variables, evaluated with a co-inertia analysis, highlights the hierarchical relevance of plant cover and woody diversity on ecosystem services. The biological complexity associated with intact forest cover appears to generate "bundles" of co-occurring ecosystem services, with this land use demonstrating the highest infiltration, and low runoff and sediment losses. Our findings demonstrate that forests and tree-based agricultural systems may better contribute to the provision of multiple ecosystem services, including biodiversity conservation and hydrologic regulation

Uso de acolchados (mulching) en la restauración de bosques secos en el Valle del Cauca

Dry tropical forest is one of the most severely threatened ecosystems. Despite that, efforts for its restauation are insuficient. Aso it happens with other tropical forests, exotic grasses constitute common barrier for natural regeneration. Mulching is a technique used to control weeds to avoid competition with native trees during the restauration process. The effect of two types of mulching (straw and cardboard) on growth and survival of four species of native plants(Pithecellobium dulce, Achatocarpus nigricans, Cestrum cf. nocturnum and Croton gossypiifolius= was stuied. Additionally, the effect of mulching on weeds and on soil was also studied for six months. It was  found that diameter growth was higher when straw mulching was used for treatment. This treatment  also fostered greater retention of humidity on the soil during periods of less rain precipitation for  both mulching treatments. There was a lower growth of weeds recorded as well as the appearance  of commelinaceas plants. It was concluded that mulching is a viable option for the control of exotic  grasses on the restauration areas. The reduction in the variation of soil moisture could promote growth of native plants in a long run.El bosque seco tropical es uno de los ecosistemas más amenazados por actividades humanas. Pese a eso, los esfuerzos para su restauración son insuficientes. Como en otros bosques tropicales, las gramíneas exóticas constituyen una barrera importante para su regeneración natural. El acolchado (mulch) es una técnica utilizada en el control de plantas arvenses para su evitar la competencia  con los árboles nativos durante el proceso de restauración. Se estudió el efecto de dos acolchados  (vegetal y de cartón) sobre el crecimineto y superviviencia de cuatro especies de plantas nativas (Pithecellobium dulce, Achatocarpus nigricans, Cestrum cf. nocturnum y Croton gossypiifolius).  También se estudió el efecto del acolchado sobre las arvenses y el suelo por seis meses. Se encontró mayor crecimiento en el diámetro bajo el tratamiento de acolchado vegetal. Este tratamiento también  permitió mayor retención de humedad en el suelo en el periodo de menor precipitación. En ambos  acolchados hubo un menor crecimiento de arvenses y se observó la colonización de commelináceas  sobre las áreas tratadas. Se concluye que el uso de acolchados es viable para el control de gramíneas  exóticas  en  áreas  en  restauración.  La  reducción  en  la  variación  en  la  humedad  del  suelo  puede  favorecer el crecimiento de las plantas nativas a largo plazo

Effect of Habitat Type on Parasitism of Ectatomma ruidum

Eucharitidae are parasitoids that use immature stages of ants for their development. Kapala Cameron is the genus most frequently collected in the Neotropics, but little is known about the biology and behavior of any of the species of this genus. We aimed to evaluate the effect of habitat type on eucharitid parasitism and to contribute to the knowledge of the host-parasite relationship between Kapala sp. and the poneromorph ant Ectatomma ruidum (Roger) in Colombia. Twenty E. ruidum colonies were extracted from two different habitat types (woodland and grassland), and larvae and cocoons (pupae) were examined in search for parasitoids in different stages of development. Globally, 60% of the colonies were parasitized, with 1.3% of larvae and 4% of pupae parasitized. Planidia (first-instar larvae), pupae, and adults of the parasitoid were observed. All of the pupae and adult parasitoids belonged to Kapala iridicolor Cameron. All the colonies collected in the woodlands were parasitized and contained more parasitized larvae (2%) and parasitized cocoons (8%) than those collected in grasslands (4/12 parasitized colonies, 0.5% parasitized larvae, 0.8% parasitized cocoons). The relationship observed between habitat type and parasitism prevalence is a novel aspect of the study of eucharitid impact on ant host populations

Rediscovery of Omalodes (Omalodes) fassli Bickhardt, 1911 (Coleoptera: Histeridae) in Colombia and first report of the species on banana crops (Musa paradisiaca)

After 106 years, the presence of Omalodes (Omalodes) fassli in Colombia has been confirmed, and new distributional data for the country has been provided. This is the first report of the species on banana crops (Musa paradisiaca), it highlights its potential role in the control of the banana weevil, a key pest of this crop worldwide.Después de 106 años, se confirma la presencia de Omalodes (Omalodes) fassli en Colombia y se aportan nuevos datos de su distribución para el país. Este representa el primer registro de la especie en cultivos de plátano (Musa paradisiaca) y se destaca su potencial papel como controlador del picudo del plátano, plaga clave de este cultivo en el mundo

Contribución al conocimiento de las interacciones entre plantas, hormigas y homópteros en bosques secos de Colombia

Las interacciones entre plantas y hormigas y entre plantas, hormigas y homópteros se estudiaron en 248 estaciones de muestreo situadas en nueve fragmentos de bosque seco del valle geográfico del río Cauca, entre enero y junio de 1997. Se registraron 352 interacciones que involucran 91 especies vegetales, hormigas de 67 especies y homópteros pertenecientes a nueve familias. El 4 7% de las asociaciones registradas implica el uso por parte de las hormigas de diferentes estructuras de las plantas (p. e. raíces de las epífitas, domacios en los tallos, hojarasca acumulada entre ramas y hojas, brácteas y peciolos de Heliconia spp.) como refugios temporales o sitios de anidamiento. El restante 53% involucra la recolección de miel de homópteros y de sustancias azucaradas en nectarios extraflorales. asmannia auropunctata (17%), Dolichoderus bispinosus (11%) Y Brachymyrmex heeri (7%) fueron las especies de hormigas registradas con mayor frecuencia. Las plantas más utilizadas fueron Heliconia stricta (8%), Philodendron sp. nov. (7%) y Passiflora coriacea (5%). Entre las relaciones observadas, predominan las de tipo generalista, en que las hormigas explotan diferentes recursos aparentemente en forma oportunista y las plantas pueden encontrarse en buen estado a pesar de la ausencia de las hormigas.Interactions between ants and plants and those involving homopterans were studied in 248 sampling points located within nine tropical decidous forest fragments in the Cauca river Valley, between january and june, 1997. A total of 352 interactions were recorded involving 91 plant species, 67 ant species and Homoptera belonging to nine families. 47% ofthe interactions involved ants using different plant structures (such as epiphyte roots, domacia, litter collected in branches and leaves, bracts and petioles of Heliconia spp.) as nesting sites or temporary refugia. The remaining 53% involved the collection of homopteran honeydew and sugary substances from extrafloral nectaries. Wasmannia auropunctata (17%), Dolichoderus bispinosus (11 %) and Brachymyrmex heeri (7%) were the most frequently recorded ant species. Heliconia stricta (8%), Philodendron sp. nov. (7%) and Passiflora coriacea (5%) were the most heavily used plant resources. Predominant relations could be described as generalist, in which ants exploited different plant resources opportunistically and plants appeared to be healthy even without their ant occupants