Ecophysiological responses and sensitivity of 39 woody species exposed to air pollution.

This study aims to test the sensitivity of thirty-nine 1 to 2-year-ol d woody species planted in pots and exposed to heavily polluted and relatively clean sites for 5 months during growing season in Nanhai, Foshan, Guangdong Province. Evaluation on p ossible effects of air pollution on plants and their acclimation strategies were made on the basis of gas exchange measurements using LCA-4 photosynthesis system. Air monitorin g data showed that the polluted area received remarkably higher sulfation rate, fl uoride concentration and total suspended particles than the clean site, which significa ntly exceed the emission limit of National Standard. Net photosynthetic rate(Pn), transpiration rate(E), stomatal conductance(gs) differed among species and decreased for most species in the pol luted area. Pooled data showed that Pn and E were linearly correlated with gs to some extent at the relative clean site and polluted area,suggesting that most species showed possibility to adapt the pollution stress by simultaneously controlling photosynthesis and transpiration. The corre lation of the Pn with gs (or E with gs) had been weakened (or enhanced) under pollution stress, w hich demonstrated the unparallel and complexity in changes of Pn and E with gs, and t he diversity of acclimation strategies among different species. Based on the change in Pn, E and water use efficiency (WUE), plants can be ranked as follows by their sensibilities to air pollution:species that exhibited high sensibility included Lysidice rhodostegia, Manglietia glauca , Erythrophloeum fordii, Altingia chinensis, Artocarpus hypargyreus, Manglietia hainannensis, A quilaria sinensis and Ormosia pinnata; species showing moderate sensitivity were Iieritiera pa rvifolia, Magnolia delavayi, Fagraea ceilanica, Manglietia insignis, Artocarpus styracif olius, Heteropanax fragrans, Saraca chinensis, Machilus salicina, Annona muricata, Tern stroemia gymnanthera, Dolichandrone cauda-felina, Artocarpus nitidus subsp. lingnanens, C assia fistula, Camellia semiserrata, Tsoongiodendraon odorum, Osmanthus fragrans, Ilex rotu nda, Elaeocarpus japonicus, Spathodea campanulata, Mesua ferrea, Myrsine seguinii; a nd those showing low sensibility were Actinodaphne pilosa, Machilus chinensis, Kigelia af ricana, Gordonia axillaries, Camellia japonica, Ficus microcarpa var. fuyuensis, Ficu s microcarpa, F. annulata, F. religiosa and Tutcheria spectabilis.