The Endangered City Forest
The city forest is the most important and most visible natural resource in the urban environment. Yet, in our cities, the trees our grandparents planted are dying and are not being replaced. In American cities, an average of only one tree is planted for every four that are removed.
In addition, harsh urban conditions mean that trees in cities face early death. Struggling to grow in compacted soil, roots are deprived of air, space and nutrients. Polluted air clogs
tree leaves with dirt and toxins and car doors slam into tree trunks, damaging living tissue. Some trees become bulletin and graffiti boards. Planting spaces are often not carefully considered or prepared. As a result, urban trees live an average of 32 years and downtown trees only 8 to 10 years. During their short lives, city trees are often malnourished and
diseased. Adequate health care for trees is not typically available. Since most species take 40 years to mature, the greatest environmental and economic benefits are never realized.
The national hoopla you've heard about tree planting has left the impression that trees are growing out our ears! Many of the thousands of free seedlings handed out at events have ended up in garbage cans. And many of those that were planted have died because they were the wrong tree in the wrong place. Add to that the problem of city tree budgets continuing to shrink because of decreased revenues and demands for other city services. The fact is, we are losing trees faster than we are replacing them. Did you know:
• Large cities are losing trees four times as fast as they can be replanted.
• Between 90 million and 100 million trees must be planted each year over the next decade to develop and maintain the nation's urban forest.
• Only 17 percent of US cities have a master tree plan.
• A study by the American Forestry Association shows that in one-third of 20 cities surveyed, only one tree was planted for every eight trees removed.
• The average life of a street tree is as little as 8 years, compared with 40 years or more for trees removed from urban stresses.
• The chief causes of urban tree mortality are poor planting practices and improper tree care.
• The number of trees per person has declined by 13% during the past 9 years.
• An average of 80% of trees in cities live on private property.
• One million acres of forest are lost to city growth each year.
• There is enough room along city streets in California to at least double the current number of street trees.
• California's urban forests are becoming shorter because cities are planting more short-statured trees; as the urban forest is downsized, many of the ecological benefits that large
trees provide will be diminished or lost.
• The average annual expenditure per city street tree is $17.
• Over one quarter of city tree removals are due to hardscape damage.
• The diversity of tree species in most cities is dangerously low.
In San Jose:
• Over 20,000 city street trees died or were damaged during the freeze of 1989.
• The City manages 250,000 street trees along 2,500 street miles.
• Only 25% of the urban forest - primarily street and park trees - is the City's responsibility: the remainder is under the care of private property owners.
• The average annual maintenance expenditure per street tree until 1992 was $6.00; budget cuts have decreased this amount further for 1993.
•San Jose does not yet have a master tree plan, tree inventory or tree commission.
• San Jose has a new citizen-based tree program (Our City Forest).
• The total estimated increase in San Jose property values due to street trees is $750 million.
• An estimated $45 million dollars in sidewalk damage has resulted largely from planting "the wrong tree in the wrong place".
• A recent US Forest Service study has identified over 100 tree species suitable for planting in San Jose.