We have presented several testable hypotheses for potential mechanisms of interaction between host plants, biotic stress factors and acid deposition. In the instance of leaf- or bark-infesting or -feeding insect species, or foliar or stem pathogens, the potential for significant interaction with acid deposition is particularly high as these pest organisms spend important segments of their life cycles on the surfaces of plants. Phytophagous soil arthropods and root-infecting microorganisms are less likely to the influenced by acid deposition than are surface organisms. Soil organism influence would only follow acid deposition induced alteration in soil pH or chemistry or altered host resistance. The potential for biotic stress agent interaction is judged to be higher in forest ecosystems than in agricultural ecosystems not receiving intensive pesticide applications, as pest management would overwhelm and generally preclude meaningful acid deposition-biotic stress interaction. The threshold range of ambient pH above which little adverse influence on insect or microbial pest activity is anticipated is pH 3.5-4.0.
425.3 (Saure Niederschläge) 442 (Parasitische (höhere) Pflanzen. Kletterpflanzen und Epiphyten) 443 (Pilze und Bakterien) 174.7 (Coniferae [Siehe Anhang D]) 176.1 (Dicotyledoneae [Siehe Anhang D]) 453 (Insekten [Für die weitere Unterteilung siehe Familien unter 14 oder alternativ (beschrieben nach Regelfall 1d in der Einleitung) können die Nummern alphabethisch nach Familien und Arten unterteilt werden (Appendix C)])
