Electronic Supplementary Data STRUCTURAL VARIATION IN WATER-EFFICIENT YARDS

Transcription

1 Electronic Supplementary Data STRUCTURAL VARIATION IN WATER-EFFICIENT YARDS

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4 Figure S1. Photos of select study yards show great variation in yard structure, maintenance, and plant composition. Only water-efficient yards shown here.

5 RESULTS OF HOMEOWNER LANDSCAPE MANAGEMENT SURVEY Table S1. Descriptive statistics on water-efficient yard management and the land cover change process collected from a 2014 survey of homeowners who participated in the Tempe Landscape Rebate Program (n=111). Survey Question Topic Survey Question % of Yards To the best of your knowledge, when your yard was changed to a desertstyle landscape, how was the yard Conversion process prepared? Soil amendments during conversion Litter management Irrigation frequency Irrigation type Stopped watering grass 45.2 Living grass removed (removed grass while still alive) 41.9 Stopped water and used herbicide 38.7 Used turf removal equipment (removed first 5cm soil) 22.6 Kept living grass (installed new cover over living grass) 2.0 Other 22.6 Before adding rocks or other non-grass ground cover, which of the following activities were completed? Laid down barrier (plastic sheeting or weed-blocking fabric) 22.6 Tilled soil 16.1 Added soil or compost 3.2 Watered grass or dirt 0 Added fertilizer 0 Other 9.7 Which of the following best describes what is done after maintaining the yard? Cut grass, weeds, leaves/branched and remove by bagging 92.9 Leaf-blower is used to blow off leaves, weeds, or grass 28.6 Grass clippings, leaves or weeds are left on the ground 9.5 Grass, shrubs or weeds are not cut or trimmed 2.4 Don t know 2.4 Thinking about this past summer (June-August 2013), about how often / were the plants, trees or grass in your yard usually watered? Every day 4.8 Every week (but not daily) 54.8 Every month (but not weekly) 21.4 Every season (but not monthly) 4.8 Never water 11.9 Please indicate all of the ways used to water plants, trees, or grass in your yard. Drip irrigation 71.4 A handheld hose 52.4 Watering jug/can 35.7 Sprinklers 31.0 Sprinklers on a hose 14.3 Flood irrigation 4.8 Other 71

6 ANOVA AND ANCOVA RESULTS Table S2. Results of ANOVA and ANCOVA tests. Dependent variables are represented in column titles with independent variables as row titles. All ANOVA tests were run with study yard as a random factor to control for non-independence of sampling at multiple depths. Independent variables Soil NO 3- (g/m 2 ) Resin NO 3 - (g/g resin) Resin NH 4+ (g/g resin) Organic matter (%) Landscape type Years since land cover change Patch type Shrub cover (%) Sand (%) Significant interactions & covariates * denotes p<.05 df F * df F df F 8.36* df F 7.03* df F Shrub cover: Patch type Precipitation Precipitation ub cover: Years since land cover change

7 EXTRACTABLE AND PLANT-AVAILABLE NO 3 - -N and NH 4 + -N DATA BY DEPTH Table S3. Averages of both water-efficient and turfgrass soil properties by depth. Bold values are patch-weighted averages. One SE shown in parentheses. Gravimetric soil moisture Water holding capacity Soil organic matter NO 3- -N NH 4+ -N % g H 2 O/g soil % g/m 2 g/m 2 Water-efficient yards 0.09 (.003) 0.50 (.01) 3.53 (.10) 2.38 (.23) 0.17 (.01) Between plants 0.09 (.004) 0.50 (.01) 3.41 (.12) 2.61 (.35) 0.15 (.01) 0-15 cm 0.08(.01) 0.48 (.02) 3.38 (.22) 2.62 (.65) 0.19 (.03) cm 0.10 (.01) 0.51 (.01) 3.48 (.23) 2.10 (.50) 0.11 (.03) cm 0.10 (.01) 0.49 (.01) 3.36 (.20) 3.11 (.63) 0.15 (.01) Under plants 0.09 (.004) 0.50 (.01) 3.67 (.16) 2.09 (.29) 0.19 (.02) 0-15 cm 0.08 (.01) 0.50 (.01) 3.88 (.28) 2.28 (.48) 0.16 (.03) cm 0.10 (.01) 0.52 (.01) 3.51 (.23) 1.74 (.46) 0.20 (.06) cm 0.09 (.01) 0.50 (.01) 3.63 (.32) 2.25 (.57) 0.20 (.05) Turfgrass yards 0.18 (.02) 0.63 (.03) 5.72 (.71) 0.58 (.16) 0.15 (.05) 0-15 cm 0.20 (.03) 0.67 (.05) 6.87 (1.01) 0.85 (.37) 0.21 (.12) cm 0.18 (.04) 0.64 (.07) 5.26 (1.28) 0.56 (.25) 0.08 (.02) cm 0.15 (.02) 0.58 (.05) 4.89 (1.47) 0.29 (.18) 0.16 (.06) Table S4. Averages of both water-efficient yard and turfgrass plant-available NO 3 - -N and NH 4 + -N, from resin bag assays. Shallow refers to bags that were installed at 3-6 cm, while deep refers to bags installed at cm. Bolded rows are averages across depth. One SE shown in parentheses. Plant-Available NH4+-N NO3--N mg N/g resin Water-efficient yard Between plant 0.08(0.01) 0.52(0.08) Shallow 0.10(0.02) 0.34(0.07) Deep 0.07(0.02) 0.63(0.14) Under Plant 0.13(0.04) 0.58(0.11) Shallow 0.13(0.02) 0.45(0.07) Deep 0.15(0.08) 0.80(0.23) Turfgrass Shallow 0.02(0.01) 0.21(0.06) Deep 0.01(0.01) 0.11(0.04)

8 Table S5. Average plant-available inorganic N (from mixed-exchange resins) from June to September. Bold values indicate whole-yard averages (patch-weighted by percent shrub and non-shrub cover in water-efficient yards). One SE shown in parentheses. Plant-Available NH4+-N NO 3 --N mg N/g resin Turfgrass 0.08 (.04) 0.64 (.24) Water-efficient yard <4 yrs 0.05 (.01) 0.33 (.06) Between Plants 0.12 (.05) 0.57 (.09) Under Plants 0.14 (.06) 0.65 (.14) Water-efficient yard 4-8 yrs 0.23 (.04) 1.17 (.19) Between Plants 0.20 (.08) 1.32 (.41) Under Plants 0.22 (.05) 1.22 (.37) Water-efficient yard 9-13 yrs 0.09 (.06) 0.62 (.18) Between Plants 0.15 (.03) 1.25 (.53) Under Plants 0.47 (.34) 1.09 (.29) Water-efficient yard (.02) 0.42 (.19) Between Plants 0.13 (.03) 0.68 (.86) Under Plants 0.17 (.08) 1.46 (.71) F value- Landscape type p-value- Landscape type F value- Patch type p-value- Patch type F and p-values from ANCOVA of landscape type x Patch type (with precipitation as covariate) and NO 3 - and NH 4 +