Ponderosa pine damage

Fig. 8-3. Relationship between Los Angeles Basin s urban sources of photochemical smog and the San Bernardino Mountains, where ozone damage has occurred to the ponderosa pines. The solid lines are the average daily 1-hr maximum dose of ozone (ppm), )uly-September 1975-1977. Source Adapted from Davidson, A., Ozone trends in the south coast air basin of California, in "Ozone/Oxidants Interaction with the Total Environment.". A ir Pollution Control Association, Pittsburgh, 1979, pp. 433-450.

A number of histologic and histochemical changes in current-year needles of ponderosa pine were detected after five to seven daily exposures to ozone at 0.45 ppm for 12 h each day. Chloroplasts and carbohydrate stain accumulated in the peripheral portions of mesophyll cells concurrently, the homogeneous distribution of proteins and nucleic acids was disrupted, and add phosphatase activity increased. Cell wall destruction occurred in mesophyll cells after appredable intracellular damage. 

Larsh, R. N., P. R. Miller, and. L. Wert. Aerial photography to detect and evaluate air pollution damaged ponderosa pine. J. Air Pollut. Control Assoc. 20 289-292. 1970. 

FIGURE 12-14 Topographic projection, San Bernardino Mountains, showing how ponderosa pine (PP) and Jeffrey pine (JP) in major study sites are distributed in six injury classes according to seasonal dose of total oxidant. A, dead, 0 B, very severe, 1-8 C, severe, 9-14 D, moderate, 15-21 , slight, 22-28 F, very slight, 29-35 C, no visible damage, 36 +. Reprinted with permission from Kickert et al. 

Early studies suggested that injuiy to ponderosa pine was similar in all size classes, but Cobb and Stark later reported higher mortality rates in understoiy ponderosa pines (9-12 in., or 22.9-30.5 cm, in diameter) than in larger size classes. The probable effect of tree mortality on stand composition can be anticipated to some extent from an example of the present species and size-class composition, as shown in Table 12-5. In this severely damaged stand in the ponderosa pine-white fir subtype, nearly 50% of the overstory and about 22% of the understory is ponderosa pine. 

Stark, R. W., and F. W. Cobb, Jr. Smog injury, root diseases, and bark beetle damage in ponderosa pine. Calif. Agric. 23(9) 13-15. 1%9. 

Ozone and related oxidants are estimated to be responsible for about 95% of the annual 130 million crop loss caused by air pollutants in the United States. Reports have indicated that ozone can seriously damage important crops such as spinach, beans, petunias, citrus, tobacco, soybeans, and alfalfa, and forest trees such as Eastern white pine and Ponderosa pine. 

Tjhotochemical oxidant air pollution—chiefly ozone—was first identified in 1962 as the agent responsible for the slow decline and death of ponderosa pine (Pinus ponderosa Laws.) trees in southern California (I). Work on identifying this source of damage can be traced to the mid-1950s it was described as chlorotic decline (2). 

This paper describes the present stand composition, degree of injury, and mortality in ponderosa pine in relation to the concentrations of oxidant air pollution in a heavily damaged area and points out some possible physical and biological factors associated with oxidant-induced changes in community composition. 

Until fairly recently, the only firm reported gaseous pollutant damage of this kind was confined to North America and to special situations where particularly high pollutant concentrations were found. The best known example is the extensive downwind damage caused by SO2 emissions from the Sudbury nickel smelter in Canada and secondly in the San Bernadino Mountains in California, where 75% loss of 30-year-old ponderosa pine found were extensively damaged by the high ozone and possibly PAN photo-oxidant concentrations of the Los Angeles area. 

Pines. Calorimetric studies of growth rates and temperature responses have not been employed to examine pine trees. Two studies were conducted to analyze effects of air pollutants on the respiration properties of Ponderosa and Jeffrey pine needles. Bower [104] used one-cm needle segments and demonstrated a correlation between the extent of ozone damage, measured as the number of lesions on the needles, and isothermal metabolic heat rates. He also measured increases in metabolic heat rates resulting from acid and nitrate deposition on the needles. Momen et al. [105] conducted a more controlled study of acid rain and ozone effects on Ponderosa pine with defined applications to plantation grown plants. In seedlings, metabolic heat rates increased in response to ozone and combinations of ozone and acid rain. Mature tree metabolic activities showed no response to ozone, acid, or combinations of the two. No studies were made to determine whether metabolic efficiencies were altered by these treatments. Thus the results show that calorimetry can be used to monitor pollutant effects on trees, but more definitive experiments must be done to identify how the ob.served responses relate to growth and survival of the trees. 

Under environmental conditions in the Stanislaus National Forest, in central California, which may or may not be comparable with those in the southern California mountains, long-term observations of seedling regeneration indicated ponderosa and sugar pines were favored by removal of the overstory, understory, and ground competition white fir was favored by a light overstory which prevented frost damage (18). In that study, incense cedar was selectively removed by cutworms (Noc-tuidae), which made it difficult to assess the comparative effect of the physical environment on survival. 

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