• Energy Research

Although ecosystem services have been intensively examined in certain domains (e.g., forests and wetlands), little research has assessed ecosystem services for the most dominant landscape type in urban ecosystems—namely, residential yards. In this paper, we report findings of a cross-site survey of homeowners in six U.S. cities to 1) examine how residents subjectively value various ecosystem services, 2) explore distinctive dimensions of those values, and 3) test the urban homogenization hypothesis. This hypothesis posits that urbanization leads to similarities in the social-ecological dynamics across cities in diverse biomes. By extension, the thesis suggests that residents’ ecosystem service priorities for residential landscapes will be similar regardless of whether residents live in the humid East or the arid West, or the warm South or the cold North. Results underscored that cultural services were of utmost importance, particularly anthropocentric values including aesthetics, low-maintenance, and personal enjoyment. Using factor analyses, distinctive dimensions of residents’ values were found to partially align with the Millennium Ecosystem Assessment’s categories (provisioning, regulating, supporting, and cultural). Finally, residents’ ecosystem service priorities exhibited significant homogenization across regions. In particular, the traditional lawn aesthetic (neat, green, weed-free yards) was similarly important across residents of diverse U.S. cities. Only a few exceptions were found across different environmental and social contexts; for example, cooling effects were more important in the warm South, where residents also valued aesthetics more than those in the North, where low-maintenance yards were a greater priority.

AbstractDespite growing recognition of the role that cities have in global biogeochemical cycles, urban systems are among the least understood of all ecosystems. Urban grasslands are expanding rapidly along with urbanization, which is expected to increase at unprecedented rates in upcoming decades. The large and increasing area of urban grasslands and their impact on water and air quality justify the need for a better understanding of their biogeochemical cycles. There is also great uncertainty about the effect that climate change, especially changes in winter snow cover, will have on nutrient cycles in urban grasslands. We aimed to evaluate how reduced snow accumulation directly affects winter soil frost dynamics, and indirectly greenhouse gas fluxes and the processing of carbon (C) and nitrogen (N) during the subsequent growing season in northern urban grasslands. Both artificial and natural snow reduction increased winter soil frost, affecting winter microbial C and N processing, accelerating C and N cycles and increasing soil : atmosphere greenhouse gas exchange during the subsequent growing season. With lower snow accumulations that are predicted with climate change, we found decreases in N retention in these ecosystems, and increases inN2OandCO2flux to the atmosphere, significantly increasing the global warming potential of urban grasslands. Our results suggest that the environmental impacts of these rapidly expanding ecosystems are likely to increase as climate change brings milder winters and more extensive soil frost.

Significance This paper offers conceptual and empirical contributions to sustainability science in general and urban-ecological studies in particular. We present a new analytical framework for classifying socioecological measures along a homogenization–differentiation spectrum. This simple 2 × 2 matrix highlights the multiscale nature of the processes and outcomes of interest. Our application of the conceptual framework produces needed empirical insights into the extent to which land management appears to be homogenizing in differing biophysical settings. Results suggest that US lawn care behaviors are more differentiated in practice than in theory. Thus even if the biophysical outcomes of urbanization are homogenizing, managing the associated sustainability implications may require a multiscale, differentiated approach.

After policy change, educational programming has been cited as one of the most powerful tools for improving food systems and decreasing food waste. University students represent a population in which emerging habits, skills, and identity may be targeted easily and changed through on-campus educational programming. To understand how to best implement programming on impacts of food, food waste, and related issues, the factors that underlie students’ behaviors related to food waste must be understood. We analyzed factors that influence food waste–related behaviors within a university student population to understand the potential for improving targeted, school-based food waste diversion programming. Four hundred and ninety-five students were surveyed to: (1) identify self-reported knowledge, attitudes, and behaviors related to food waste; (2) explore underlying factors driving food waste–related behaviors through exploratory factor analysis (EFA); and (3) understand the interactions between factors within a regression framework. Participants reported that they most often left food on their plate because it did not taste good or they had overestimated portion size. A majority of participants already performed many food waste reduction behaviors, and were both interested in taking action and aware that their efforts could make a difference. Food management skills, compost attitudes, sustainability attitudes, and reported household food waste were correlated, in various ways, with both intent to reduce and reported food waste reduction behaviors. Opportunities for improving university-related food waste programming through this data are explored.

A visually apparent but scientifically untested outcome of land‐use change is homogenization across urban areas, where neighborhoods in different parts of the country have similar patterns of roads, residential lots, commercial areas, and aquatic features. We hypothesize that this homogenization extends to ecological structure and also to ecosystem functions such as carbon dynamics and microclimate, with continental‐scale implications. Further, we suggest that understanding urban homogenization will provide the basis for understanding the impacts of urban land‐use change from local to continental scales. Here, we show how multi‐scale, multi‐disciplinary datasets from six metropolitan areas that cover the major climatic regions of the US (Phoenix, AZ; Miami, FL; Baltimore, MD; Boston, MA; Minneapolis–St Paul, MN; and Los Angeles, CA) can be used to determine how household and neighborhood characteristics correlate with land‐management practices, land‐cover composition, and landscape structure and ecosystem functions at local, regional, and continental scales.

Evaluations of the local effects of global change are often confounded by the interactions of natural and anthropogenic factors that overshadow the effects of climate changes on ecosystems. Long-term watershed and natural elevation gradient studies at the Hubbard Brook Experimental Forest and in the surrounding region show surprising results demonstrating the effects of climate change on hydrologic variables (e.g., evapo- transpiration, streamflow, soil moisture); the importance of changes in phenology on water, carbon, and nitrogen fluxes during critical seasonal transition periods; winter climate change effects on plant and animal community composition and ecosystem services; and the effects of anthro- pogenic disturbances and land-use history on plant community composition. These studies highlight the value of long-term integrated research for assessments of the subtle effects of changing climate on complex ecosystems. unraveling this daunting complexity is long-term studies, including those in which natural elevation gradients are exploited, as a foundation for detailed studies of critical and often unexpected climate-induced changes in forest struc- ture and function. In this article, results from the Hubbard Brook Experimental Forest (HBEF) and the surrounding region are used to illustrate how long-term studies can serve as a foundation for addressing the complex interactions that ultimately determine the effects of climate change on ecosystems. We combine data from long-term (50-year) measurements of multiple aspects of climate and ecosystem structure and function to highlight important but poorly studied inter- actions that could be critical determinants of the responses of plant and animal communities, fluxes of water, element dynamics, and services in northern hardwood forest eco- systems. Our objective is to demonstrate how a combina- tion of long-term and in-depth measurements facilitates A dominant approach in climate change research has been to focus on the effects of changes in temperature and precipitation on broadscale ecosystem properties over large areas and long periods. This body of research suggests that climate change will substantially alter the distribution of species and the function of ecosystems (e.g., Iverson and Prasad 2001), with important effects on ecosystem services. These analyses are based on well-described effects of tem- perature and precipitation on the distribution and activity of organisms. However, climate change is playing out over the complex and dynamic hydrobiogeological structure of the landscape—that is, the intertwined patterns of soils, vegetation, and hydrologic flowpaths, with a spatially variable history of land use and a wide range of current human activities and concurrent environmental changes. The climate effects on ecosystem structure and function may be modified by interactions with these patterns and histories over a range of time scales. We assert that a key approach to

Low-impact development (LID) is a common management practice used to infiltrate and filter stormwater through vegetated soil systems. The pollutant reduction potential of these systems is often characterized by a single pollutant removal rate; however, the biophysical properties of soils that regulate the removal of pollutants can be highly variable depending on environmental conditions. The goal of this study was to characterize the variability of soil properties and nitrogen (N) cycling rates in bioretention facilities (BRFs). Soil properties and potential N cycling processes were measured in nine curbside bioretention facilities (BRFs) in Portland, OR during summer and winter seasons, and a subset of six sites was sampled seasonally for two consecutive years to further assess temporal variability in soil N cycling. Potential N cycling rates varied markedly across sites, seasons, and years, and higher variability in N cycling rates was observed among sites with high infiltration rates. The observed seasonal and annual changes in soil parameters suggest that nutrient removal processes in BRFs may be highly variable across sites in an urban landscape. This variability has important implications for predicting the impacts of LID on water quality through time, particularly when estimated removal rates are used as a metric to assess compliance with water quality standards that are implemented to protect downstream ecosystems.

AbstractUnderstanding the responses of terrestrial ecosystems to global change remains a major challenge of ecological research. We exploited a natural elevation gradient in a northern hardwood forest to determine how reductions in snow accumulation, expected with climate change, directly affect dynamics of soil winter frost, and indirectly soil microbial biomass and activity during the growing season. Soils from lower elevation plots, which accumulated less snow and experienced more soil temperature variability during the winter (and likely more freeze/thaw events), had less extractable inorganic nitrogen (N), lower rates of microbial N production via potential net N mineralization and nitrification, and higher potential microbial respiration during the growing season. Potential nitrate production rates during the growing season were particularly sensitive to changes in winter snow pack accumulation and winter soil temperature variability, especially in spring. Effects of elevation and winter conditions on N transformation rates differed from those on potential microbial respiration, suggesting that N‐related processes might respond differently to winter climate change in northern hardwood forests than C‐related processes.