Forests ponderosa

The term ponderosa-Jeffrey type is a general term that includes a mosaic of five subtypes described by McBride on the basis of species dominance. These subtypes are ponderosa pine forest, ponderosa pine-white fir forest, ponderosa pine-Jefh y pine forest, Jeffry pine forest, and Jeffrey pine-white fir forest. The injury by oxidant air pollutants is most intense in the types dominated by ponderosa pine and less intense in the Jeffry pine types. In the field plots of these various types, the average area covered by shrubs is only 3.8% in the ponderosa types, but 26% in the Jeffrey pine types. ... 

Axelton, E. A. 1967. Ponderosa pine bibliography through 1965. U. S. Forest Service Res. Paper lNT-40. 

Browne, F.L. Brenden, J.J. Heat of Combustion of the Volatile Pyrolysis Products of Fire-retardant-treated Ponderosa Pine. Res. Pap. FPL 19. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory Madison, WI, 1964. 

Stark et o/. and Miller et reported that oxidant (ozone) injury to ponderosa pine predisposed the trees to later invasion by pine bark beeides. The beetles increase the rate of decline and may be the final cause of tree mortality (see Chapter 12). It is possible that oxidant stress in other parts of the country contributes to insect infestation in forest areas. Weber (personal communication) has shown that ozone and mixtures of ozone with sulfur dioxide (0.25 ppm, 4 h/day) can decrease the population of four nematodes associated with soybean. These... 

Even that kind of information is not available for forest species. Other than chronic injury to white pine (associated with ozone, sulfur dioxide, and their mixtures), no clearly defined examples of chronic injury from ozone have been reported for eastern forests, and no information is available on PAN. It is of interest that both Virginia and jack pine appear more sensitive than white pine to acute ozone exposures, but chronic symptoms have not been observed in either species. The relationship between oxidant dose and injury in the San Bernardino Mountains area suggests that ponderosa pine is moderately to severely injured in areas that receive oxidant at above 0.08 ppm for 12-13 h each day (Chapter 12). Ponderosa pine seems to be the most sensitive western pine, but in some areas Jeffrey pine is about as sensitive. White fir, incense cedar, and sugar pine all appear more tolerant, even to the high oxidant concentrations in the San Bernardino Mountains. PAN may play some role in the chronic responses noted in the western forest species, particularly by broadleaf deciduous trees and some shrubs. 

Field surv have confirmed oxidant injury to ponderosa pine and associated species at numerous locations in the Sierra Nevada foothills east and southeast of Fresno. Oxidant measurements at ground stations and by instrumented aircraft show late-aftemoon peaks of transported oxidant on the western slopes of the Sierras. Limited measurements by instrumented aircraft suggest the development of a layer of oxidant approaching the forested mountain slopes between 610 and 1,829 m during the late afternoon. A very weak inversion or isothermal layer may serve as a reservoir of oxidant, which is advected to the mountain slope in the southern coastal air basin, as suggested by Edinger. Considerable concern has been registered about air quality in the Lake Tahoe basin, where local development may cause adverse oxidant concentrations. ... 

The recent history of the mixed-conifer forest of the San Bernardino Mountains has be n analyzed. This analysis included an initial inventory of ecosystem components and processes, as indicated in Figures 12-8 through 12-12. The inventory emphasizes ponderosa and Jeffrey pines, the most dominant species in the climax community, and is... 

Wildfire is a very important factor in western forest ecosystems. In the San Bernardino Mountains, the fire frequencies were determined by McBride and Laven in two stand types before and after 1893, when the area was first set aside as a forest preserve and fire protection began. Before 1893, the average interval between fires in ponderosa stands was 12 yr after 1893, it was 24 yr. The comparable numbers for Jeffrey pine stands were 16 and 38 yr. The buildup of heavy fuels due to ozone-caused mortality and fire protection results in hotter fires, and the thinning of the tree canopy results in increased rates of fire spread. Hotter fires decrease tree survival. Moisture interception by condensation in living tree crowns would decrease as the stands became thinner, thus causing some sites to be drier. ... 

In the San Bernardino Mountains, our goals have been to describe the terrestrial vertebrate community within this mixed-conifer forest, particularly in relation to ponderosa and Jeffrey pine stands, and to determine the effects of oxidant air pollutants on this community. The possible interactions of vertebrates in this system are shown in Figures 12-8 through 12-12. 

Thus, tree squirrels are a major source of loss of seeds of ponderosa, Jeffrey, and sugar pine and of black oak acorns. Vertebrates, then, can have a major effect on the reproduction of these species, particularly because the gray squirrel is only one of numerous species in this forest that feed on coiner seeds and acorns. 

California black oak and white fir and less often on incense cedar in the San Bernardino Mountains. No direct effects of oxidants have been noted on the mistletoe plant itself under field conditions. The true mistletoe obtains mainly water from its host and would be indirectly affected by debilitation of die host tree. The dwarf mistletoes Arceuthobium spp.) are common on ponderosa, Jeffry, and sugar pines in the San Bernardino National Forest. They depend on their host for both water and carbohydrates. Heavily infected or broomed" branches on ponderosa or Jeffrey pines severely injured by ozone often have more annual needle whorls retained than do uninfected branches on the remainder of the tree. The needles are also greener. It can be hypothesized that the infected branch is a carbohydrate sink where a pooling of carbohydrates occurs higher carbohydrate concentrations may be instrumental in either preventing or helping to repair ozone injury to needles on the broomed branches. In the long term, stresses from mistletoe and ozone are probably additive and hasten tree death. 

Deer mice, P. maniculatus, readily find buried seeds. In forest reseeding projects, deer mice often remove 70 to 100% of the planted conifer seeds. In the laboratory, deer mice found the aromatic seeds of sugar, Jeffrey, and Ponderosa... 

Site of Investigation. The site of investigation was the Coconino National Forest. The Coconino National Forest is the largest contiguous ponderosa pine forest in North America. 

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. 

Wagner, R.G., T.D. Petersen, M.D. W. Ross, and S.R. Radosevich (1989). Competition thresholds for the survival and growth of ponderosa pine seedlings associated with woody and herbaceous vegetation. New Forests, 3 151-170. 

Aluminum reduction plants have also caused local forest destruction. In Montana, fluoride pollution killed or severely injured ponder osa pine and lodge pole pine on 8 fcm (2000A) surrounding a plant. In Washington, ponderosa pine mortality and morbidity resulted over a 130 km (50 mi ) area in the vicinity of an aluminum plant. 

Photochemical injury to ponderosa pine in the San Bernardino National Forest of California is a serious problem there. Screening for resistance to ozone is being carried on in preparation for conducting a formal breeding program (16). 

In 1969 an aerial photo survey by the U. S. Forest Service of the San Bernardino National Forest showed that 1.3 million ponderosa or Jeffrey pines (12 inches or larger, diameter at breast height) on more than 100,000 acres were affected to some degree (4). 

Figure 1. Change in a ponderosa pine during 10 years of chronic exposure to photochemical oxidant air pollution on the San Bernardino National Forest,...

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. 

The lack of pine seed production on remaining sugar and ponderosa pines in a cut-over area on the Stanislaus National Forest coupled with shade from competing vegetation allowed white fir and incense cedar to fill in the available spaces from 1923 to 1947, so that pines comprised only 5% of the reproduction by 1947 (20). 

During the past century, the conifer forests of this mountain area have been logged and burned to the extent that they have been replaced by brush or woodland chaparral (6). The inability of the conifer forest to regenerate after these events may be an important indicator of what to expect on some sites after removal of the conifer forest dominated by ponderosa pine. 

Oxidant air pollution may be eliminating only the most sensitive ponderosa pines from the forest, but there is undoubtedly suppression of the photosynthetic activity (26) and subsequent growth of the remaining trees. 

Influence on Host—Parasite Relationships. Cobb and Stark (11) have directed considerable attention to the increased incidence of attack of oxidant-injured ponderosa pines by bark beetles in the San Bernardino mountains. They suggest that ponderosa pine will nearly be eliminated from the mixed conifer forest if such attacks continue. Increased activity of other insect pests of ponderosa pine or associated conifers has not been observed. 

A mass attack of insects can cause serious devastation to crops, forests, food storehouses, etc. These invasions are usually triggered by the release of a set of pheromones. For example, upon landing on a ponderosa pine tree, the female western pine beetle, Dendroctonous brevicomis, releases exo-brevicomin 16 (Scheme 1.5) to attract males. Shortly after mating, the pioneers start to release a mixture of compounds, 17-19, which carries a sort of you are welcome message to their kinsfolk. The flow of incomers increases a hundredfold and as a result the tree is overwhelmed and killed. ... 

This region is located in the northern part of the area of West American Desert-Xerophytic Forest ecosystems, on the borderline between temperate and subtropical belt (see Figure 2). The lower slopes in this region are covered with Big Tree Forest ecosystems (Sesquoia semperviverens) on acidic Cambisols above, in drier regions, are found Pine Forest (Pinus ponderosa) ecosystems and Stiff-Leafed Oak Forest and Shmbs (formation of chaparral) ecosystems on Chromic Cambisols. 

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