I have heard this meme before… trees take up more water from the ground than a single family residence. That is not the issue. The issue is how that water is then used to help or hurt the environment.
Trees provide some of the most important and primary ecosystems functions necessary for a healthy planet, such as:
Forests play a critical role in the water cycle by capturing, storing, and transferring water, and enabling its gradual discharge over time. This reduces flooding by reducing storm water run off, which reduces flood peaks, and returns moisture to the atmosphere. Infiltration improves water quality and recharges ground water. Forests are the gold standard for storm water management.
Trees clean our air. In one year, one acre of trees can remove 2.6 tons of carbon dioxide or the equivalent of what one car driving up to 8,700 miles produces. In one year, that same acre of trees produces the amount of oxygen consumed by 18 people annually. One tree alone produces nearly 260 pounds of oxygen per year. Trees sequester many other pollutants from the air, including nitrogen dioxide, sulfur dioxide, ozone, and carbon monoxide. They also provide wind buffers and noise and light buffers important in residential areas.
Shade and Reduced Energy Costs
Trees, both dead and alive, lower stream temperatures and allow fish to survive, take cover, find food, etc. They also shade homes and tree canopies reduces interior temperatures, making air conditioning less necessary.
Dead trees are recycled into the rich soils of the PNW forest and provide food for plants on the ground level. Also recycles dead plant matter on forest floor into useful soil.
Trees prevent soil erosion, which keeps our water clean, reduces sediment loading and reduces landslide risk.
Trees, again, dead and alive, are an important source of habitat for many animals and promote biodiversity.
Food and Fiber Source for humans and other species
Source of natural medicines and pharmaceuticals
Source of recreation, relaxation and scenic beauty
Important cultural values for indigenous peoples
Contrast With Residential Development:
People like Doug, and Kris Halterman, who asked the question, only think in terms of money and financial gain, so this document from earthjustice addresses the economic benefits of trees, as if the above ecoservices were not enough.
But now, let us turn our focus to what having houses in a watershed do. By removing trees and vegetation, they reduce all the above benefits, which might explain why permanent harm occurs to watersheds when impervious surfaces exceed 10%. The use of herbicides and household chemicals pollutes the ground water and surface water, cars, wood burning and diesel equipment causes air quality impacts. Biodiversity is lost as habitat becomes fragmented. While there is a good return of household water used, it is not filtered and cleaned in the same manner as a fully forested condition. Water is sometime returned through a septic system. And if this home is used as a hobby farm, the impacts escalate. If a drinking well is used, then there is a permanent loss of groundwater recharge, which effects in stream flows.
Attempting to compare water use by a house versus a tree is about the worst argument possible, but apparently, not enough people either know or care about this, because I did not hear the booing and hissing that accompanied other unpopular subjects.
Removing a tree is a serious matter and it really needs to be treated as such in our county codes and zoning laws. Again, this is something that should have been covered in a section on vegetation in the Critical Area Ordinance, but was not. Currently, we only really protect near shore and aquatic plants and do too little for terrestrial species. And let us be clear…the GMA [Growth Management Act] Hearings Board spoke loudly that protected species in a habitat conservation area includes plant and tree species.
Trees really matter. They are holy. They must be protected and preserved. We must always keep and protect wildlands with their dense forested areas.