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

Brenda B Lin; Monika H Egerer; Heidi Liere; Shalene Jha; Peter Bichier; Stacy M Philpott

doi:10.1016/j.scitotenv.2017.08.091

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

Sci Total Environ. 2018 Jan 1:610-611:570-575. doi: 10.1016/j.scitotenv.2017.08.091. Epub 2017 Aug 17.

Authors

Brenda B Lin¹, Monika H Egerer², Heidi Liere³, Shalene Jha⁴, Peter Bichier⁵, Stacy M Philpott⁶

Affiliations

¹ CSIRO Land and Water Flagship, Australia. Electronic address: Brenda.Lin@csiro.au.
² Environmental Studies Department, University of California, Santa Cruz, United States. Electronic address: megerer@ucsc.edu.
³ Biology Department, Reed College, United States. Electronic address: heliere@reed.edu.
⁴ Integrative Biology Department, University of Texas at Austin, United States. Electronic address: sjha@austin.utexas.edu.
⁵ Environmental Studies Department, University of California, Santa Cruz, United States. Electronic address: pbichier@ucsc.edu.
⁶ Environmental Studies Department, University of California, Santa Cruz, United States. Electronic address: sphilpot@ucsc.edu.

PMID: 28822924
DOI: 10.1016/j.scitotenv.2017.08.091

Abstract

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 California's 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.

Keywords: Climate change; Groundcover; Land cover; Urban greening; Vegetative complexity; Water use.