New Policies for Old Trees: Averting a Global Crisis in a KeystoneEcological Structure

摘要

Large old trees are critical organisms and ecological structures in forests, woodlands,savannas, and agricultural and urban environments. They play manyessential ecological roles ranging from the storage of large amounts of carbonto the provision of key habitats for wildlife. Some of these roles cannot be replacedby other structures. Large old trees are disproportionately vulnerable toloss in many ecosystems worldwide as a result of accelerated rates of mortality,impaired recruitment, or both. Drivers of loss, such as the combined impacts offire and browsing by domestic or native herbivores, chemical spray drift in agriculturalenvironments, and postdisturbance salvage logging, are often uniqueto large old trees but also represent ecosystem-specific threats. Here, we arguethat new policies and practices are urgently needed to conserve existing largeold trees and restore ecologically effective and viable populations of such treesby managing trees and forests on much longer time scales than is currentlypracticed, and by protecting places where they are most likely to develop.Without these steps, large old trees will vanish from many ecosystems, andassociated biota and ecosystem functions will be severely diminished or lost.