Biologic Markers of Air-Pollution Stress and Damage in Forests (1989) / Chapter Skim
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Fungal and Bacteria Symbioses as Potential Biological Markers of Effects of Atmospheric Deposition on Forest Health
Fungal and Bacteria Symbioses as Potential Biological Markers of Effects of Atmospheric Deposition on Forest Health
Pages 217-232
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From page 217... ...
Shafer USDA Agricultural Research Service NC State University Raleigh, NC 27695-7616 The ecological role and physiological functions of the different microbial symbiotic associations, specifically ectomycorrhizae, endomycorrhizae, and actinorhizae, which occur naturally on roots of forest trees will be discussed. The effects of man-made and natural stress on tree physiological and soil processes which may cause change in (i)
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From page 218... ...
The extramatrical growth of hyphae from VAM fungi can extend beyond the feeder roots and increase the volume of soil from which these elements are absorbed. The additional nutrient absorption due to VAM fungi can result in several-fold growth increases in plants.
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From page 219... ...
Unfortunately, with the exception of the above mentioned fungi, few of the hundreds that exist in any given forest stand can be identified based on characteristics of the ectomycorrhizae. The only sure way of identifying ectomycorrhizal fungi is with their fruit bodies.
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From page 220... ...
A single species of ectomycorrhizal fungus can develop numerous biotypes or clones in a very limited area of a pure stand (Fries 1987~. Some fungi are apparently host-specific; others have broad host ranges and form ectomycorrhizae with members of numerous tree genera in diverse families.
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From page 221... ...
Thus, while prospective cells for infection in the primary nodule arise from de-differentiation of cortical cells, cells for infection in the "true nodule" that develops from the lateral roots arise from continued production of cells by the apical meristem of the lateral root. The meristem itself is not infected.
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From page 222... ...
Fungal Succession and Forest Development Terrestrial plant communities tend to be dominated by either endomycorrhizal or ectomycorrhizal plants (Moser 1967~. During ecosystem succession to climax forest in most temperate regions, the fungal associates of higher plants change from endomycorrhizal or VAM dominance in herbaceous and scrub communities to ectomycorrhizal dominance associated with trees (Rose 1980~.
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From page 223... ...
1977~. Fruit body production by these fungi, which is the main parameter used to observe succession, is also strongly influenced by season of year, rainfall amount and frequency, organic content of soil, root density, and degree of ectomycorrhizal development (Wilkins and Harris 1946~.
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From page 224... ...
The amount of photosynthate required to support a healthy and vigorous population of ectomycorrhizal fungi on roots has been estimated in only a few cases. These estimates, based on measured carbon content of fruit bodies and estimated carbon content of the fungal mantle and extramatrical mycelia (turn-over rate)
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From page 225... ...
They concluded that increased levels of Al and Mn in the acid treated soils reduced root growth, which caused a reduction in ectomycorrhizae. Numerous other researchers in other parts of Europe have reported similar depressions in ectomycorrhizae on trees with various degrees of foliar symptoms of air pollution damage (Blaschke 1981, 1982, Schlechte 1986~.
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From page 226... ...
Conversely, mycorrhizal status may appear to increase in the presence of a lateral root growth inhibitor. If root growth slows or stops, the growth rate of the fungi and roots may be more closely matched or the mycorrhizae may develop faster than new short roots can be produced.
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From page 227... ...
3. Susceptible short roots on lateral roots must be formed by the tree host before root colonization by microbial symbionts can occur.
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1986a. Changes in occurrence of basidiomycete fruit bodies during forest stand development: With specific reference to mycorrhizal species.
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1982. The effects of ozone and sulfur dioxide on respiration of ectomycorrhizal fungi.
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1977. High soil fertility decreases sucrose content and suceptibility of loblolly pine roots to ectomycorrhizal infection by Pisolithus tinctorius.
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McWha. ectomycorrhizal fungi.
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1987. Screening loblolly pine seedling responses to SO2 and O3: Analysis of families differing in resistance to fusiform rust disease.
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