Local and Landscape Factors Affecting Biodiversity in Urban Community Gardens in Seattle

https://scholarworks.seattleu.edu/fss-2019/1005/thumbnail.jp

Revalorando viejas prácticas mayas de manejo de plagas del maíz almacenado para la agricultura del futuro

We present results of a series of studies documenting and evaluating traditional knowledge of pest in stored grains among Mayan farmers. We performed 257 interviews in five communities in the Chiapas highlands and in three communities in the Guatemalan highlands. Sithophilus zeamais and Sitotroga cerealella were the most commonly reported insects. Fifty % of farmers use the pesticide aluminum phosphide or malathion, often in inappropriate ways. However they still employ several traditional management practices, the majority of which are preventative (local varieties, strict harvest dates, drying maize before storage, lime application, incorporation of repellent plants and cool, dry granaries). We conducted experiments to test the efficacy of these practices. The use of traditional yellow corn variety, the incorporation of Piper auritum leaves and lime in the storage, and dry, cool storage room seem to reduce pest attacks. We communicated our findings through workshops inviting young farmers to try the techniques invented by their ancestors. A survey performed a year after the workshops suggested that the workshops induced positive changes in young farmers’ attitudes towards traditional practices. The principles of Maya traditional knowledge of stored grain protection have potential for application to organic agriculture and for food security in one of the domestication centers of maize, two priorities for today’s and tomorrow’s agriculture.Se presentan los resultados de una serie de estudios para documentar y evaluar el conocimiento tradicional de manejo de plagas en granos de maíz almacenado entre agricultores mayas. Se realizaron 157 entrevistas en cinco comunidades de Los Altos de Chiapas y tres comunidades del altiplano guatemalteco. Sithophilus zeamais y Sitotroga cerealella fueron los insectos más comúnmente reportados. El 50% de los agricultores usa insecticidas, muchas veces en una forma inapropiada. Sin embargo aun utilizan varias prácticas tradicionales de manejo, que son en su mayoría de carácter preventivo (variedades criollas, fechas estrictas de cosecha, secado del maíz antes de guardarlo, aplicación de cal, e incorporación de plantas repelentes y utilización de graneros fríos y secos). Se establecieron experimentos para probar la efectividad de estas prácticas. El uso de variedades criollas amarillas, la incorporación de hojas de Piper auritum, y un lugar seco y frío para el almacenamiento parecen ser prácticas efectivas para reducir el ataque de plaga. A través de talleres se divulgaron los resultados de la investigación, con el fin de invitar a los jóvenes agricultores de la región a probar las prácticas que inventaron sus ancestros. Una encuesta realizada un año después de los talleres sugiere que los talleres provocaron cambios positivos entre los jóvenes y su actitud hacia las prácticas tradicionales. Los principios del conocimiento tradicional maya para la protección del maíz almacenado tienen potencial para la agricultura orgánica y la seguridad alimentaria en uno de los centros de domesticación del maíz, dos prioridades de la agricultura de hoy y el mañana

Social Context Influence on Urban Gardener Perceptions of Pests and Management Practices

Community gardens are important urban green spaces with a variety of social and ecological benefits, one of which is access to healthy food. Similar to rural agriculture, the quantity and quality of the food produced can be compromised by pest damage. In fact, many urban gardeners report crop damages caused by vertebrate and invertebrate pests. Yet, because the food produced in community gardens is mostly for self-consumption and thus not under market quality standards, the damage thresholds and the point when gardeners perceive a pest problem and how they decide to manage it, may greatly vary from gardener to gardener. Here, we investigated how socio-demographic factors and experience affect whether gardeners report having a pest problem and which pest management practices they use. We surveyed 187 gardeners from 18 different urban community gardens in three counties in the California central coast, USA. We also collected information about gardener socio-demographic factors (age, gender, ethnicity), as well as education, and years of experience in agriculture. The majority of gardeners reported having pests in their plots but their ethnicity, the amount of time they spend in the gardens, and whether they work in agricultural-related employment or not influenced the likelihood of reporting pests. We found that the majority of gardeners use curative, non-synthetic practices for managing pests, but that some use preventive practices and some don't do anything to control pests. The likelihood of using practices that are curative depended on gardeners' ethnicity, the amount of time they spend in the gardeners, and their gender. Our results suggest that the agricultural knowledge of urban community gardeners and the practices they use varies greatly and that, in order to be successful, extension programs may need to take this diversity into account when promoting the agroecological paradigm in urban agricultural (UA) systems

Land tenure security and luxury support plant species and trait diversity in urban community gardens

Urban ecological communities are shaped by an array of environmental and physical factors that include climate, biogeography, species interactions, dispersal, and ecological filters at the habitat and landscape scales. In addition, many social dynamics, decision-making processes, and other social characteristics, such as development, policy, government actions, as well as socioeconomic status of residents – the so-called ‘luxury’ effect – may also play strong roles in shaping which species occur within the urban context. This interaction between ecological and social drivers may impact species richness and may also influence functional traits and functional diversity, with important implications for ecosystem services provided within urban spaces. Urban agroecosystems provide food and other well-being benefits to urban residents, and are valuable green spaces in the city that provide refuges for biodiversity. Despite this fact, one of the biggest risks to gardens is insecure land tenure. While plant communities within gardens may be shaped by gardener demographics, food cultures, and ecological processes, little is known about how factors such as luxury and land tenure security may impact plant diversity, plant functional traits, and functional diversity, as well as species and trait composition. In this study, we ask how garden physical features, luxury, and land tenure security influence plant species richness, functional diversity, and species and trait composition within gardens in the California central coast. We surveyed vegetation, assessed plant traits related to growth form, plant defense, and floral characteristics, and collected information on multiple factors associated with land tenure and luxury. We found that land tenure secure gardens had higher plant and crop richness. Variables associated with garden luxury boosted ornamental plant richness, flower abundance and height, lowered crop richness, and strongly impacted plant species composition. Garden plot size negatively correlated with plant species and functional richness and relative abundance of trees. Weed species richness was not impacted by any social or physical feature examined. Thus overall, in community gardens, cultivated plants, and their traits, are strongly shaped by the socioeconomic factors of land tenure security and luxury as well as the spatial distribution and size of garden plots, with important implications for both conservation and ecosystem services provided by garden habitats within cities

The Community Ecology of Herbivore Regulation in an Agroecosystem: Lessons from Complex Systems

AbstractWhether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem

Perennial grasslands enhance biodiversity and multiple ecosystem services in bioenergy landscapes

Agriculture is being challenged to provide food, and increasingly fuel, for an expanding global population. Producing bioenergy crops on marginal lands—farmland suboptimal for food crops—could help meet energy goals while minimizing competition with food production. However, the ecological costs and benefits of growing bioenergy feedstocks—primarily annual grain crops—on marginal lands have been questioned. Here we show that perennial bioenergy crops provide an alternative to annual grains that increases biodiversity of multiple taxa and sustain a variety of ecosystem functions, promoting the creation of multifunctional agricultural landscapes. We found that switchgrass and prairie plantings harbored significantly greater plant, methanotrophic bacteria, arthropod, and bird diversity than maize. Although biomass production was greater in maize, all other ecosystem services, including methane consumption, pest suppression, pollination, and conservation of grassland birds, were higher in perennial grasslands. Moreover, we found that the linkage between biodiversity and ecosystem services is dependent not only on the choice of bioenergy crop but also on its location relative to other habitats, with local landscape context as important as crop choice in determining provision of some services. Our study suggests that bioenergy policy that supports coordinated land use can diversify agricultural landscapes and sustain multiple critical ecosystem services

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition

The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies