Suchergebnisse

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. ; MacroSystems Biology Program in the Emerging Frontiers Division of the Biological Sciences Directorate at the National Science Foundation (NSF) [EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 121238320]; NSFNational Science Foundation (NSF) [DEB-0423476, SES-0951366]; Phoenix [BCS-1026865]; Plum Island (Boston) [OCE-1058747]; Cedar Creek (Minneapolis-St Paul) [DEB-0620652]; Florida Coastal Everglades (Miami) [DBI-0620409] ; This work was supported by the MacroSystems Biology Program in the Emerging Frontiers Division of the Biological Sciences Directorate at the National Science Foundation (NSF) under grants EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 121238320. The work arose from research funded by grants from the NSF Long-Term Ecological Research Program supporting work in Baltimore (DEB-0423476), Phoenix (BCS-1026865), Plum Island (Boston) (OCE-1058747), Cedar Creek (Minneapolis-St Paul) (DEB-0620652), and Florida Coastal Everglades (Miami) (DBI-0620409). This research was also supported by the NSF-funded Decision Center for a Desert City II: Urban Climate Adaptation (SES-0951366). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NSF. ; Public domain authored by a U.S. government employee

In natural grasslands, C-4 plant dominance increases with growing season temperatures and reflects distinct differences in plant growth rates and water use efficiencies of C-3 vs. C-4 photosynthetic pathways. However, in lawns, management decisions influence interactions between planted turfgrass and weed species, leading to some uncertainty about the degree of human vs. climatic controls on lawn species distributions. We measured herbaceous plant carbon isotope ratios (delta C-13, index of C-3/C-4 relative abundance) and C-4 cover in residential lawns across seven U.S. cities to determine how climate, lawn plant management, or interactions between climate and plant management influenced C-4 lawn cover. We also calculated theoretical C-4 carbon gain predicted by a plant physiological model as an index of expected C-4 cover due to growing season climatic conditions in each city. Contrary to theoretical predictions, plant delta C-13 and C-4 cover in urban lawns were more strongly related to mean annual temperature than to growing season temperature. Wintertime temperatures influenced the distribution of C-4 lawn turf plants, contrary to natural ecosystems where growing season temperatures primarily drive C-4 distributions. C-4 cover in lawns was greatest in the three warmest cities, due to an interaction between climate and homeowner plant management (e.g., planting C-4 turf species) in these cities. The proportion of C-4 lawn species was similar to the proportion of C-4 species in the regional grass flora. However, the majority of C-4 species were nonnative turf grasses, and not of regional origin. While temperature was a strong control on lawn species composition across the United States, cities differed as to whether these patterns were driven by cultivated lawn grasses vs. weedy species. In some cities, biotic interactions with weedy plants appeared to dominate, while in other cities, C-4 plants were predominantly imported and cultivated. Elevated CO2 and temperature in cities can influence C-3/C-4 competitive outcomes; however, this study provides evidence that climate and plant management dynamics influence biogeography and ecology of C-3/C-4 plants in lawns. Their differing water and nutrient use efficiency may have substantial impacts on carbon, water, energy, and nutrient budgets across cities. ; U.S. National Science Foundation Macrosystems Biology Program [EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 121238320] ; This research was funded by a series of collaborative grants from the U.S. National Science Foundation Macrosystems Biology Program (EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 121238320). The authors thank La'Shaye Ervin, William Borrowman, Moumita Kundu, and Barbara Uhl for field and laboratory assistance. ; Public domain authored by a U.S. government employee

The urban heat island (UHI) is a well-documented pattern of warming in cities relative to rural areas. Most UHI research utilizes remote sensing methods at large scales, or climate sensors in single cities surrounded by standardized land cover. Relatively few studies have explored continental-scale climatic patterns within common urban microenvironments such as residential landscapes that may affect human comfort. We tested the urban homogenization hypothesis which states that structure and function in cities exhibit ecological "sameness" across diverse regions relative to the native ecosystems they replaced. We deployed portable micrometeorological sensors to compare air temperature and humidity in residential yards and native landscapes across six U.S. cities that span a range of climates (Phoenix, AZ; Los Angeles, CA; Minneapolis-St. Paul, MN; Boston, MA; Baltimore, MD; and Miami, FL). Microclimate in residential ecosystems was more similar among cities than among native ecosystems, particularly during the calm morning hours. Maximum regional actual evapotranspiration (AET) was related to the morning residential microclimate effect. Residential yards in cities with maximum AET < 50-65 cm/year (Phoenix and Los Angeles) were generally cooler and more humid than nearby native shrublands during summer mornings, while yards in cities above this threshold were generally warmer (Baltimore and Miami) and drier (Miami) than native forests. On average, temperature and absolute humidity were similar to 6 % less variable among residential ecosystems than among native ecosystems from diverse regions. These data suggest that common residential land cover and structural characteristics lead to microclimatic convergence across diverse regions at the continental scale. ; Macrosystems Biology Program at NSF [EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 1241960, 121238320]; Earth Systems Modeling program at NSF [EF-1049251]; NSF Long-term Ecological Research Program in Baltimore (BES LTER) [DEB-0423476]; NSF Long-term Ecological Research Program in Phoenix (CAP LTER) [BCS-1026865]; NSF Long-term Ecological Research Program in Plum Island (PIE LTER Boston) [OCE-1058747, 1238212]; NSF Long-term Ecological Research Program in Cedar Creek (CDR LTER, Minneapolis-St Paul) [DEB-1234162]; NSF Long-term Ecological Research Program in Florida Coastal Everglades (FCE LTER, Miami) [DBI-0620409] ; We are grateful to numerous technical staff, students, and volunteers who assisted with microclimate data collection, including Erin Barton, Matthew Camba, Emma Dixon, La'Shaye Ervin, Caitlin Holmes, Richard McHorney, Miguel Morgan, Joseph Rittenhouse, Anna Royar, Jehane Samaha, Sydney Schiffner, Julea Shaw, Anissa Vega, Elisabeth Ward, and Megan Wheeler. We also thank Darrel Jenerette for reviewing an earlier draft of this manuscript. This project was supported by several collaborative grants from the Macrosystems Biology Program at NSF (EF-1065548, 1065737, 1065740, 1065741, 1065772, 1065785, 1065831, 1241960, and 121238320), and by the Earth Systems Modeling program at NSF (EF-1049251). This work was also supported in part by the NSF Long-term Ecological Research Program in Baltimore (BES LTER, DEB-0423476), Phoenix (CAP LTER, BCS-1026865), Plum Island (PIE LTER Boston; OCE-1058747 and 1238212), Cedar Creek (CDR LTER, Minneapolis-St Paul; DEB-1234162), and Florida Coastal Everglades (FCE LTER, Miami; DBI-0620409). ; Public domain authored by a U.S. government employee