Response of leaf surfaces and gas exchange to wind stress and acid mist in birch (Betula pubescens)

Abstract

This research demonstrates that a leaf's response to acid mist is dependent on the integrity of the leaf cuticle and that significant differences in the structural and physiological disturbances in leaves can be attributable to different types of wind action. Betula pubescens Ehrh. plants were located at adjacent, but contrasting, sites to create different wind treatments: (i) direct wind action, (ii) indirect wind action and (iii) shelter from wind action (control). In combination with the wind treatments, acidic (pHs 5 and 3) or neutral (pH 7) mists were applied weekly. Wind action significantly increased visible leaf injury, microscopic cuticular lesions and cuticular conductance (g c ), but reduced photosynthetic rate (P N ) and stomatal conductance (g s ) compared to shelter. Wind action combined with acid mist was more injurious than wind action alone, but leaves sheltered from wind action were highly resistant to the damaging effects of acid mist. Direct wind action combined with pH 3 mist resulted in the highest values of g c and the greatest number of cuticular lesions. By contrast, indirect wind action combined with pH 3 mist induced most visible injury, but relatively low values of g c and few microscopic cuticular lesions. Acid mist reduced P N only when leaves had been damaged by wind action. Higher values of g c were associated both with increases in the area of visible leaf injury and with the number of cuticular lesions. Compensatory increase in P N of healthy tissue was evident in leaves exposed to combinations of wind action and acid mist.& k w d : Key words Wind · Acidic mist · Foliar injury · Cuticular integrity · Gas exchange& b d y :

Comparison of photosynthetic damage from arthropod herbivory and pathogen infection in understory hardwood saplings

“…Moreover, defenses against diVerent classes of damage such as herbivores and pathogens may not oVer cross-protection, thus exacerbating the costs of defense (Faeth 1992;Saikkonen et al 2001). Indeed, the costs of defense may be great enough that leaf abscission becomes a viable alternative to defense (Hoad et al 1998;Manter and Kavanagh 2003).…”

“…This underestimate comes primarily from the diVerence between the direct eVect of herbivory (consumption of photosynthetic tissue) and the indirect eVect-reduced photosynthesis in tissues not directly damaged by the herbivore (Welter 1989;Zangerl et al 2002). In addition to herbivorous arthropods, pathogens (Hood et al 1990;Osmond et al 1990;Faeth 1992) and physical damage (Hoad et al 1998;Hunter and Forkner 1999) can further reduce photosynthesis in natural ecosystems. For example, the reduction of stomatal conductance and photosynthesis by fungal infection of oak leaves directly reduces growth (Luque et al 1999;El Omari et al 2001).…”

Changes in wind regime around a nickel–copper smelter at Monchegorsk, northwestern Russia

“…These data suggest that wind stress can not be ignored when discussing the factors that affect plant performance in heavily contaminated habitats. Moreover, barren soils produce a large amount of dust, which may further enhance foliar damage via the impact of wind-borne particles (Hoad et al 1998). Thus, the observed decline of forests in contaminated habitats, although presumably triggered by pollution, could not be attributed to toxic effects of pollutants alone: initial forest disturbances (felling for the building of the city, fires around the city), combined with an absence of natural recovery (hampered by unfavourable changes in abiotic environment), through secondary effects may enhance further disturbance in a positive feedback fashion (Perkins et al 1987;Rigina and Kozlov 1999).…”

“…Although the impact of winds on plant growth is obvious (Wadsworth 1960;Grace 1977;Lawton 1982), and experimental studies have clearly demonstrated that wind stress may interact with sulfur dioxide and acid mist, leading to higher foliar damage of windexposed plants (Brennan and Leone 1968;Ashenden and Mansfield 1977;Hoad et al 1998), the possible changes in wind regime have been generally neglected in discussions on mechanisms of plant damage around the point emission sources: all the adverse effects were routinely ascribed to the toxicity of pollutants. However, we found that sheltering improved the performance of birch seedlings in heavily polluted industrial barrens (Kozlov and Haukioja 1999); there is also other indirect evidence suggesting a significant contribution of wind regime to shaping the vegetation pattern in heavily contaminated areas (Kozlov 1997;Rigina and Kozlov 1999).…”

Monitoring the damage to epicuticular waxes at silver birch (Betula pendula Roth.) in the changing air pollution spectrum of the Ore Mountains

“…In case of damage to the assimilatory apparatus by air pollution, functional disturbances and fi nally also abnormalities in the morphology of leaves occur fi rst. These disturbances refl ect largely physiological processes (Hoad et al, 1998). The plant epidermis with cuticle and waxes are damaged as the fi rst due to the infl uence of external factors on the plant (Tuomisto and Neuvonen, 1993).…”