RE: Lots of Trees Make Those 90 Degree Summer Days Bearable With Natural ShadeAnd cuts down on air conditioner engery waste too. Another good reason for lots of trees: earthquakes and landslides .the root systems keep your home’s cement foundation from cracking easily from shifting soil. That’s why they plant them on freeway hills, to prevent landslides like last winter’s BAD ONE on Hwy 18 .it was lucky this happenned in the middle of the night or there would have been many very likely deaths, all at once too. Like the condemned waterfront homes on landslides we see frequently on the news too.