We've lived with severe droughts for many years now. Mulch is good, because it shades the soil (reducing effect of the blazing sun), but one thing I've noticed...sometimes very thick mulch will actually prevent moisture getting down to the soil if it's not enough watering in a single instance. That can mean that a 1/4 inch rain shower or watering won't help the plants very much. When the soil and subsoil are completely utterly dry, it is also difficult for the soil to wick water downward, instead there can be runoff early on during rainstorms. Watering techniques that get the water down directly to the soil in areas with thick mulch help. Drip irrigation during hours the sun isn't out is best. Xeriscape plants do much better, but must be established before they're able to endure the drought conditions. As for trees...the trees with higher water requirements will have severe damage or die first...that's logical. The local native trees should normally do well, but after years of severe drought, we even lost many of those. The worst of the effects on your trees will be most obvious the year AFTER the worst part of the drought. The year after our hottest and driest year, dead and dying trees were falling all over...some onto houses or cars...thank God we were spared that, because the trees closest to the house survived somehow. If a tree near a house is obviously dead, cut it down and start over. Any kind of shading for plants helps. I've used sunblock materials over some kind of framework. Then for smaller plants, I use things like plastic crates (plastic milk crate type thingies). Those very large patio type umbrellas help to shade plants temporarily. A really cloudy, shady day is a great blessing here during the summer (May through September I consider to be our summer). A rainy day is even better!
