They break the wind and reduce heating costs in the winter. Trees absorb gaseous pollutants produced by our automobiles, trucks, busses, industry, home heating and other aspects of modern life. They also cleanse our air of particulate pollutants, naturally produced dust, dust from construction, and smoke particles. Trees beautify our home landscapes and city and town environments. They provide protection and nesting environments for wildlife.
Tree roots stabilize the soil, preventing wind and water erosion.
As I stated above, some trees produce pollen which can cause hay fever attacks. Of these, some are worse than others. There are some trees which do not cause hay fever. This is also true of shrubs as well. Plants such as grass, and many native plants found in New Mexico, can also be hay fever pollen producers.