Where in Arizona is this dog p[ark

It is in Safford Arizona.

First, kudos to lazygardens for asking the very first question that should be asked. I'm ashamed to admit I might have jumped in without asking it and been so very wrong in my assumptions and suggestions.

Second, I don't know enough about your area to give specifics and unfortunately your Coop Exchange and MG programs are not productive.

My advice: Pick from the native trees to your area. And make it a mix of species. Uniform will just look unnatural. Natives should not need watering once established (2-4 years). May need to shield young unestablished trees of any type from urine the first few years. Natives should be resistant to disease and pests. Natives should be adapted to the soil of your area therefor no fertilizer needed and are likely nitrifiers. Natives will attract native birds for the amusement of people and their four legged masters.

Planting consider shading, shading pattern throughout the year and throughout the day, prevailing winds and wind block, proper planting and swaling.

Care of Desert Adapted Plants
http://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1048.pdf

Selecting, Planting and Staking Trees
http://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1402.pdf

ZONE 12
Arizona's intermediate desert

The crucial difference between Arizona's intermediate desert (Zone 12) and the low desert (Zone 13) is winter cold. But though the intermediate desert averages only five more freezing nights than the low desert (20 in Tucson compared with 15 in Phoenix), it has harder frosts spread over a longer cold season. Zone 12 averages about eight months between freezes, nine months between killing frosts of 28ðF or lower. Zone 13, on the other hand, averages more than 11 months between killing frosts, when it gets them at all. Extreme low temperatures of 6ðF have been recorded in Zone 12.

The mean maximums in July and August are 5 or 6ðF cooler than the highs of Zone 13. Many subtropicals that do well in Zone 13 aren't reliably hardy here, but succeed with protection against the extreme winters. Although winter temperatures are lower than in Zone 13, the total hours of cold are not enough to provide sufficient winter chilling for some deciduous fruits. From March to May, strong winds (to 40 miles per hour) can damage young tender growth. Windbreaks help. Here, as in Zone 13 and the eastern parts of Zone 10, summer rains are to be expected and can be more dependable than winter rains.

Trees like Mesquite (all species), Afghan Pine, Chitalpa and many Acacia species do well here.

Reference towns include Tucson, Wickenburg, Safford, and Florence

http://aztrees.org/az-climate-zone-12.html

Your MG contact: Graham Co. Bill Brandau 928-428-2611 wbrandau@cals.arizona.edu

Here is a link that might be useful: desert survivors

Carob tree meets the first three criteria

I'll take exception on #3. My carob is just about the messiest tree I have - and have ever had. It's messy in Dec/Jan with flower drop, it's messy in July-Sep in pod drop and it's messy all year long with leaf drop. And then there's all the birds that like to roost and poop. Sorry nutrocker, it's a messy bugger.