Effects of Landscape Manipulation on Human Behavior, Knowledge, and

Social Organization in an Urban Ecosystem

David Casagrande1, Scott Yabiku2, Elizabeth Farley Metzger2, Diane Hope2, Corinna Gries2, Kelli Larson2, Nancy Grimm2

1 – Western Illinois University, 2 – Arizona State University

Project Overview This research represents the human dimension of a multidisciplinary experiment to study the reciprocal relationships between humans and different types of residential landscaping in metropolitan Phoenix, Arizona. Researchers at ASU’s Global Institute of Sustainability (GIOS) Central Arizona-Phoenix Long Term Ecological Research (CAP-LTER) Project have secured an agreement with the ASU-Polytechnic campus to landscape selected clusters of faculty, staff, and student family housing in the North Desert Village housing area. CAP-LTER researchers are selectively varying the landscaping of 24 single-family units with 6 units clustered in each landscape type. The remaining 122 units are receiving no landscaping other than a gravel ground cover. A cluster of six of the non-landscaped houses serve as an observational control.

In contiguous groups of six, single-family units received one of four treatments that vary landscape design and water delivery: 1. Mesic / irrigated (high water use plants and turf grass, with irrigation) 2. Oasis / mixed (a mixture of high and low water use plants and turf grass, with both drip irrigation and sprinkler systems) 3. Xeric / drip (low water use plants without turf grass, with a drip irrigation system) 4. Native / minimal (plants native to the Sonoran Desert, with minimal watering)

5. Control (no landscaping other than gravel)

Bio-physical variables of analysis include above- and below-ground floral and faunal species assemblages, plant biomass and primary productivity, soil respiration and composition, and microclimate. Human variables include behavior, social networks, environmental attitudes, perceptions of landscapes, demographics and residence histories. Pre-treatment measurement of variables and landscape installations were completed in Fall 2005. Post-intervention measurement of variation within the different treatments and control began in Spring 2006 and will be repeated at regular intervals. Here, we present initial findings and hypotheses from our analysis of pre-treatment data.

ConclusionsPre-treatment human social data indicate that outdoor recreational behavior leads to denser social networks, and residents expressed preferences to recreate in lush microclimates with high evapotranspiration and plant biomass. Residents’ abilities to identify photos of flora and fauna were uniformly low. We hypothesize that knowledge of the flora and fauna will increase more in the mesic areas than native desert as recreational behavior supports formation of social networks. This research also suggests that living longer in the arid Southwest does not in itself lead to favorable perceptions of desert landscaping. Instead, shifts in perceptions are probably highly influenced by social networks. These quantitative data are being supplemented by qualitative analysis of rich narratives elicited during interviews, which will deepen our understanding of changes in this social system. This experimental study is unique in its ability to elucidate causal effects of biophysical variables on human knowledge, behavior and social organization. Because landscaping treatments will include both manipulated and control neighborhoods, the project will be one of the few studies to examine the relationship between the biophysical environment and human behavior in an experimental, yet at the same time realistic, setting.

North DesertVillage in itscurrent condition

NativeXericOasisMesic

A digital picture of an actual residence at North Desert Village was altered to represent each of the four treatment landscapes. Residents were shown these pictures and were asked, “On a scale from 1 to 4, how much do you like this kind of yard?”

1. Dislike very much2. Dislike somewhat3. Like somewhat4. Like very much

ANOVA results from 55 survey respondents indicate significant variation in rating scores across treatment landscapes (p<.0001). Comparisons using Tukey’s method (alpha=.05) show that respondents rated Mesic and Oasis significantly higher than Xeric and Native.

Implication: Despite living in the Sonoran desert, respondents overwhelmingly prefer landscapes with higher water requirements.  If these findings generalize to the greater Phoenix area, this may suggest difficulty in convincing residents to avoid landscapes with high water use.

Mean Scores by Treatment Scenario

0

0.5

1

1.5

2

2.5

3

3.5

4

Mesic Oasis Xeric Native

Me

an

Sc

ore

Behavior and Social Networks

Residents were asked to estimate frequencies of their outdoor recreation. These were cross-checked with direct observations of behavior using time allocation spot surveys. Residents also answered a series of questions about the density of social networks within each of their six-house clusters. Recreational behavior was significantly correlated with network density (p<0.05). Note that these data precede the landscape alterations.

Implication: Outdoor recreation leads to stronger social networks in which ecological information and perceptions of landscapes are likely to be shared.

Ecological Knowledge

Using photographs and illustrations, residents were asked to name 10 plant and 6 bird species, and identify them as native to the Sonoran desert or introduced. Knowledge was uniformly low, with only 42% of questions answered correctly (SD = 8%). Long-term residents of the Southwest performed no better than recent immigrants (t = 0.15, df = 50, P1-tailed = 0.44). Respondents correctly identified native vs. introduced status more often than names. Consistent with the cognitive literature, knowledge focuses on a few charismatic species like the saguaro cactus and road runner.

Implication: Overall low knowledge and a focus on ecological characteristics like plant spines and leaf size may help explain low preferences for native landscaping.

Length of Residence and Perceptions of Desert Landscaping

We were surprised to find that the longer people lived in metropolitan Phoenix, the less they preferred desert landscaping for homes. Responses to the survey question “The natural desert is beautiful” indicated that long-term residents were as likely to appreciate the natural desert as short-term residents. But they were also more likely to make statements like: “I have lived in Arizona all my life. I love the desert, in its place,” or “You get tired of it when you’ve lived here all your life. It’s beautiful when you’ve been gone for awhile.”

Implication: Length of residence in the Southwest may not affect perceptions of natural desert, but appears to increase the belief that the desert does not belong in home landscaping.

Preferences for Different Types of Landscapes

Socio-ecological Relationships

Spearman r = 1.00; n = 5; P < 0.01

TreatmentRanking of Reported

Behavior (adults)Ranking of Social Network Density

Control 2 2Oasis 5 5Mesic 3 3Xeric 4 4Desert 1 1

Percent Correct

Plants Name Nativesaguaro 93 95Mexican fan palm 50 91bougainvillea 49 67palo verde 25 98eucalyptus 16 69creosote bush 15 98lantana 5 69Arizona ash 3 65brittle bush 2 73ironwood 2 98

Percent Correct

Birds Name Nativeroad runner 84 98gambel’s quail 44 69Gila Woodpecker 32 58cactus wren 21 65house sparrow 19 29starling 4 36

Linear Regression Results Predicting Preference Rating of Four Landscape Designs

1 2 3 4Xeric Desert Oasis Mesic

Beta SE Beta SE Beta SE Beta SESocialization: Years lived in Phoenix -0.02* 0.01 -0.02* 0.01 -0.01 0.01 0.01 0.01Aesthetics: Belief that desert is beautiful 0.15 0.10 0.23* 0.12 -0.01 0.10 -0.04 0.09Values: New Ecological Paradigm -0.01 0.23 -0.16 0.27 0.17 0.22 -0.48* 0.21Demographics:

Respondent is female -0.35* 0.20 -0.32 0.23 -0.08 0.19 0.11 0.18Number of children aged 0-6 in household -0.07 0.08 -0.1 0.09 -0.01 0.08 0.13* 0.07Respondent education (1-8 scale) 0.01 0.07 0.04 0.08 0 0.07 -0.04 0.06

Intercept 2.31* 0.78 2.31* 0.90 3.04* 0.76 5.15* 0.70

R-Squared 0.21 0.25 0.04 0.19

N 55 55 55 55*p<.10, two-tailed tests