Читать книгу The Outdoor Citizen. Get Out, Give Back, Get Active онлайн

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The loss of the forty million American elms remains memorable for arborists, tree wardens, and parks supervisors who are in their late forties or older. It’s important to share this history of Dutch elm disease to show how quickly the health and survival of valuable natural assets can be endangered. Today, elms are hatching a return and making a healthy comeback in many cities. Hybrid elms, which have been crossbred to incorporate the genes of other plants, are more resistant to Dutch elm disease. But other trees are in danger, particularly urban ones.

For urban trees, challenges abound, from the encroachment of overdevelopment to the toxicity of soil to neglect and vandalism. Urban trees and other city-based species live a fraction of the lifespan of their rural counterparts. One study suggested that downtown trees have an average lifespan of seven years, compared to thirty-two for suburban; another suggested thirteen years for downtown trees, thirty-seven for residential, and 150 for rural.60