Word: smog
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Swept east by wind, the city's smog is killing the forest's majestic ponderosa pines at the rate of 3% a year. Incense cedar and white fir have also suffered. In all, the smog has caused moderate to severe damage in 60% of the forest's 160,000 acres of pines. Last week loggers began cutting down dead trees in the hardest hit 1,000 acres...
...Forest Service officials first began to notice a peculiar yellowing of needles on on the the San Bernardino trees in the 1950s. Not until the early 1960s was the cause of the disease traced to smog. "Photosynthesis is inhibited almost immediately," says Paul Miller, a plant pathologist with the Forest Service at Riverside. In controlled experiments, smog concentrations of as little as .15 ppm. caused a 20% inhibition of photosynthesis within 60 days. The reality is grimmer. On hot summer days, the smog level in the San Bernardino forest can reach .5 ppm. The average is .20 to .25 - enough...
Present plans call for selling diseased ponderosas to lumber companies and replacing them with nearly 70,000 giant Sequoia and sugar pine trees, which are thought to be more resistant to smog. Meantime, the smog rolls on, doubtless affecting the forest in other ways that are not yet known...
Near Lake Arrowhead, about ten per cent of the Ponderosa pines, about 1,300,000 trees, have died from the L.A. smog. Ponderosa pines reign over the Western forests. They're often two hundred feet all, with ten-inch-long needles. They are the oldest trees with the longest roots. In a sense, they hold the forest together. After a forest fire, grass begins to grow, which is soon replaced by bushes, like mountain mahogany and thimbleberry. Fast growing poplar trees shade out the bushes, like quaking aspens. After about a hundred years, the coniferous forest again dominates the area...
...hour journey runs a straight course toward San Francisco along the rice fields, olive groves and vineyards of the Sacramento and San Joaquin valley. Gradually slowing, the Cal Zephyr chugs under an increasing number of highway bridges and then, at the outskirts of the metropolis, finally fades into the smog of civilization...