RESUMEN
Tropospheric ozone (O(3)) was first determined to be phytotoxic to grapes in southern California in the 1950s. Investigations followed that showed O(3) to be the cause of foliar symptoms on tobacco and eastern white pine. In the 1960s, "X" disease of ponderosa pines within the San Bernardino Mountains was likewise determined to be due to O(3). Nearly 50 years of research have followed. Foliar O(3) symptoms have been verified under controlled chamber conditions. Studies have demonstrated negative growth effects on forest tree seedlings due to season-long O(3) exposures, but due to complex interactions within forest stands, evidence of similar losses within mature tree canopies remains elusive. Investigations on tree growth, O(3) flux, and stand productivity are being conducted along natural O(3) gradients and in open-air exposure systems to better understand O(3) effects on forest ecosystems. Given projected trends in demographics, economic output and climate, O(3) impacts on US forests will continue and are likely to increase.
Asunto(s)
Contaminantes Atmosféricos/toxicidad , Ozono/toxicidad , Árboles/efectos de los fármacos , Animales , Clima , Ecosistema , Exposición a Riesgos Ambientales/efectos adversos , Monitoreo del Ambiente/métodos , Insectos/fisiología , Oxidantes Fotoquímicos/toxicidad , Pinus/efectos de los fármacos , Pinus/genética , Pinus/fisiología , Populus/efectos de los fármacos , Populus/genética , Populus/fisiología , Investigación/tendencias , Medición de Riesgo/métodos , Árboles/genética , Árboles/fisiología , Estados UnidosRESUMEN
Seedlings from four loblolly pine (Pinus taeda L.) families were exposed in open-top chambers to charcoal-filtered air (CF), non-filtered air (NF) or air amended with ozone to 2 times ambient (2×). Two of the families used were selected for their tolerance to fungi associated with Southern Pine Decline while two were selected for their susceptibility. Seedlings were treated with five inoculation treatments: no wound (NW), wound only (W), wound + media (WM), Grosmannia huntii (GH) and Leptographium terebrantis (LT). After 118 days of exposure (AOT40 = 31 ppm-hr(-1) for 2× ozone) seedling volume, dry matter, chlorophyll content, water potential and lesions were measured and analyzed using ANOVA procedures. Our results indicate that seedlings selected for their susceptibility to root infecting ophiostomatoid fungi were also more sensitive to ozone. Overall lesion length was greater on seedlings exposed to elevated ozone concentrations but was not specific to either root infecting ophiostomatoid fungi.