Monika H. Egerer

Landscape and Local Habitat Correlates of Lady Beetle Abundance and Species Richness in Urban Agriculture

Abstract Landscape surroundings and local habitat management affect patterns of insect biodiversity. Knowing which landscape and local factors are more important for insect species diversity informs landscape and local scale land management, yet can be challenging to disentangle. We sought to identify 1) which landscape factors surrounding, and 2) which local habitat factors within urban community gardens influence patterns in lady beetle (Coccinellidae) abundance and species richness. We assessed lady beetle abundance and taxonomic diversity, garden habitat characteristics, and the surrounding landscape composition in 19 gardens over two consecutive years. We found that the amount of natural area surrounding gardens at 3 km was the strongest correlate of abundance and species richness. Specifically, gardens surrounded by less natural area (gardens embedded in more urban landscapes) had higher lady beetle abundance and richness. In gardens embedded in landscapes with more amounts of natural land, local habitat features such as ornamental abundance and crop diversity may become more important for maintaining lady beetle abundance and richness. Our results suggest that within more urban landscapes, lady beetles may aggregate and accumulate in relatively resource-rich habitats like gardens. Thus, urban landscape quality and local habitat management may all interact to shape lady beetle communities within gardens.

Local- and landscape-scale land cover affects microclimate and water use in urban gardens

Urban gardens in Central California are highly vulnerable to the effects of climate change, experiencing both extended high heat periods as well as water restrictions because of severe drought conditions. This puts these critical community-based food production systems at risk as California is expected to experience increasing weather extremes. In agricultural systems, increased vegetation complexity, such as greater structure or biodiversity, can increase the resilience of food production systems from climate fluctuations. We test this theory in 15 urban gardens across Californias Central Coast. Local- and landscape-scale measures of ground, vegetation, and land cover were collected in and around each garden, while climate loggers recorded temperatures in each garden in 30min increments. Multivariate analyses, using county as a random factor, show that both local- and landscape-scale factors were important. All factors were significant predictors of mean temperature. Tallest vegetation, tree/shrub species richness, grass cover, mulch cover, and landscape level agricultural cover were cooling factors; in contrast, garden size, garden age, rock cover, herbaceous species richness, and landscape level urban cover were warming factors. Results were similar for the maximum temperature analysis except that agriculture land cover and herbaceous species richness were not significant predictors of maximum temperature. Analysis of gardener watering behavior to observed temperatures shows that garden microclimate was significantly related to the number of minutes watered as well as the number of liters of water used per watering event. Thus gardeners seem to respond to garden microclimate in their watering behavior even though this behavior is most probably motivated by a range of other factors such as water regulations and time availability. This research shows that local management of ground cover and vegetation can reduce mean and maximum temperatures in gardens, and the reduced temperatures may influence watering behavior of gardeners.

People or place? Neighborhood opportunity influences community garden soil properties and soil-based ecosystem services

ABSTRACT Soils are the foundation for cultivating ecosystem services in urban agriculture. Yet, variations in socio-environment characteristics of urbanization leads to variable soil properties and unequal distribution of ecosystem services like soil fertility. Thus, examining relationships among biophysical features and social dimensions of urban agricultural systems is necessary to understand soil functioning variation and to develop urban agricultural systems that promote equitable ecosystem service provisioning. In 25 urban community gardens in California, we examined two links between soil properties and neighborhood socio-demographics: (1) how groundcover management affects soil properties; and (2) how socio-demographics (and in particular, social advantage) can affect groundcover management and soil properties. We found that mulch groundcover improves soil fertility and water holding capacity in gardens, and that socio-demographic factors may affect people’s access to mulch to affect soil properties: neighborhoods with measures of higher mobility (e.g., greater vehicle availability), but measures of poorer public/environmental health (e.g., poorer health care access) had more soil organic matter, higher soil nutrient content, and greater water holding capacity. However, we found indicators of high functioning soils in the absence of mulch, indicating that other factors like social networks and organizational support may be important for urban agricultural ecosystem services.

Temperature variability influences urban garden plant richness and gardener water use behavior, but not planting decisions.

Urban environments are being subject to increasing temperatures due to the combined effects of global climate change and urban heat. These increased temperatures, coupled with human planting preferences and green space management practices, influence how urban plants grow and survive. Urban community gardens are an increasingly popular land use, and a green space type that is influenced by unique climate-human behavior interactions. Despite ongoing rapid temperature changes in cities, it is unknown how gardeners are adapting to these changes, and to what extent changes influence planting decisions and patterns of urban plant diversity. In this study, we monitored the variation in daily air temperatures and measured plant species richness at the garden and garden plot scale in 11 community gardens in Melbourne, Australia. We surveyed >180 gardeners to better understand the relationships between temperature variation, garden plant species diversity, and gardener management practices. We found that garden scale temperature variability is driven by regional context, and temperatures are more stable in landscapes with higher impervious surface cover. Gardeners agreed that climatic/temperature changes are influencing their watering behavior, but not their plant selection. Instead plant selection is being driven by desired food production. Yet, when comparing two bioregions, temperature did have a measurable relationship with garden plant composition in the region with more temperature variation. Temperature variability negatively related to plant species richness within garden plots, providing evidence that plant survival is related to climate at this scale in such regions. Although gardeners may be able to water more in response to regional climate changes, gardeners are unlikely to be able to completely control the effects of temperature on plant survival in more variable conditions. This suggests the inner city with more stable temperatures (albeit potentially hotter for longer due to heat island) may accommodate more species diverse gardens.

Cityscape quality and resource manipulation affect natural enemy biodiversity in and fidelity to urban agroecosystems

ContextComplex landscapes with high resource availability can support more diverse natural enemy communities and better natural pest control by providing resources and facilitating organism dispersal. Moreover, in agricultural landscapes, local agroecosystem management can support biodiversity maintenance and pest control by adding resources in less complex landscapes with fewer resources. However, we lack an understanding of how local and landscape factors interact to affect natural enemy communities and their site fidelity to agroecosystems in urban landscapes (i.e., cityscapes).ObjectiveTo better understand how local and landscape factors influence natural enemies in urban agroecosystems, we used urban community gardens as a model system to test if and how local resource manipulation and differences in cityscape quality affect natural enemy (ladybird beetles, parasitoid wasps) communities and their fidelity to urban habitats.MethodsWe performed two manipulations. First, we added local floral resources in 6 of 12 gardens situated in different cityscapes to measure differences in natural enemy biodiversity. Second, in those 12 gardens, with and without resource additions, we manipulated populations of a common natural enemy, Hippodamia convergens, to assess fidelity to the gardens.ResultsFloral resource additions increased parasitoid abundance and changed community composition, but had little effect on ladybeetle abundance, richness or site fidelity. Rather, ladybeetle fidelity to gardens was lower in gardens in low quality cityscapes with high impervious cover.ConclusionsCityscape quality influences natural enemies in and fidelity to gardens. Landscape-moderated biodiversity patterns observed in rural landscapes likely differ from urban contexts with implications for pest control.

Seed dispersal as an ecosystem service: Frugivore loss leads to decline of a socially valued plant, Capsicum frutescens

Abstract Species interactions, both mutualistic and antagonistic, are widely recognized as providing important ecosystem services. Fruit‐eating animals influence plant recruitment by increasing germination during gut passage and moving seeds away from conspecifics. However, relative to studies focused on the importance of frugivores for plant population maintenance, few studies target frugivores as ecosystem service providers, and frugivores are underappreciated as ecosystem service providers relative to other mutualists such as pollinators. Here, we use an accidental experiment to elucidate the role of seed dispersal by frugivores for maintaining a culturally and economically important plant, the donne’ sali chili (Capsicum frutescens) in the Mariana Islands. One of the islands (Guam) has lost nearly all of its native forest birds due to an invasive snake (Boiga irregularis), whereas nearby islands have relatively intact bird populations. We hypothesized that frugivore loss would influence chili recruitment and abundance, which could have economic and cultural impacts. By using video cameras, we confirmed that birds were the primary seed dispersers. We used captive bird feeding trials to obtain gut‐passed seeds to use in a seedling emergence experiment. The experiment showed that gut‐passed seeds emerged sooner and at a higher proportion than seeds from whole fruits. Consistent with our findings that birds benefit chilies, we observed lower chili abundance on Guam than on islands with birds. In a survey questionnaire of island residents, the majority of residents reported an association between the wild chili and local cultural values and traditions. In addition, we identified a thriving market for chili products, suggesting benefits of wild chilies to people in the Marianas both as consumers and producers. Our study therefore documents seed dispersal as both a cultural and a supporting ecosystem service. We provide a comprehensive case study on how seed‐dispersed plants decline in the absence of their disperser, and how to apply mixed‐methods in ecosystem service assessments. Furthermore, we suggest that scientists and resource managers may utilize fruit–frugivore mutualisms concerning socially valuable plants to gather support for frugivore and forest conservation efforts.

Agroecologies of displacement: a study of land access, dislocation, and migration in relation to sustainable food production in the Beach Flats Community Garden

ABSTRACT In this article, the Beach Flats Community Garden is used as a case study to theorize an “agroecologies of displacement.” We argue that farmers are increasingly less singularly place-based through involuntary displacement and that displacement and dispossession can shape agricultural practices in farming communities. We follow Cohen (2010), Kerssen and Brent (2017), and others in calling for the necessity to bring a historical and focused analysis of displacement, dispossession, and the dynamics of land under capitalist systems to our understanding of the articulations of food movements, in particular transformative agroecologies.