Abstract:One hundred and twenty-five woody plant species (including infraspecific taxa) grown in pots and in the wild were investigated to evaluate their sensitivity responses to air pollution in Foshan and Guangzhou. The investigations were based on the differences of plant growth parameters (plant height, basal diameter, crown area, leaf area, number of new leaves increased and leaf cast), physiological characters (including net photosynthetic rate, chlorophyll fluorescence characters, leaf cell membrance leakage rate and chlorophyll content) and plant injury tolerance. All the plants studied were exposed to polluted environments with combined pollutants such as acid rain, sulphide, fluoride and dust in industrial area, heavy traffic density area and residential site. As results all the plants were classified into three categories: (1) most tolerant species (35 species); (2) less tolerant (41 species); (3) most sensitive (49 species). The accumulation level of S, F and Pb in leaves of 48 species were also determined. A list of garden plants concerning sensitivity response to pollutants is given. The results can provide useful information for urban greening in similar atmospheric environments.

Abstract:Based on pollution tolerant tree species growing in the areas of Pearl River Delta of Guangdong Province, the stem, branch, bark and leaves of 52 species were used to determine the contents of moisture, crude fat, crude ash and caloric value for the selection of fire resistant trees. Species with moisture content ≥40%, crude fat ≤20‰ and crude ash ≥5% are considered to be fire resistant species, viz, Ilex rotunda, Sterculia anceolata, Ficus microcarpa, Prunus phaeosticta, Artocarpus nitidus subsp. lingnaensis, Garcinia multflora, Semiliquidamobar cathayensis, Osmanthus matsumuranus, Cettis tetrandra, Bischofia javanica, Gironniera subaequalis, Liquidambar formosnana, Chukrasia tabularia, Altingia chinensis, Cleidiocarpon cavdleriei, and Kigelia pinnata. Among the above-mentioned species, the first six had caloric value lower than Schima superba (control). It is suggested that these 6 species are most fire -resistant plants for urban forestry in the regions.

Abstract:One- to two-year-old seedlings of 38 woody species were potted in Wuxing (WX) and Dongcun (DC) villages near ceramic industry area in Foshan city, Guangdong Province, and in Botanical Garden in Guangzhou as control site. The experiments were carried out from June 2002 to May 2003. Injury symtoms of the leaves, leaf cast and the increment of the number of leaves, as well as the growth vigour of these species grown under air pollutants of fluoride, sulfide and acid rain were measured and compared. The results obtained from the sensitiveity of plants to the pollutants exhibited three catergories of plant species. (1) Most tolerant species include Camellia japonica, Camellia semiserrata, Ficus microcarpa var. fuyuensis, Ficus microcarpa, Osmanthus fragrans, Ficus annulata, Ficus religiosa, Tutcheria spectabilis, Actinodaphne pilosa, Heteropanax ragrans. (2) Less tolerant species are Lysidice rhodostegia, Erythrophloeum fordii, Kigelia africana, Cassia fistula, Ormosia pinnata, Manchamia cauda-felina, Artocarpus nitidus subsp. lingnamensis, Fagraea ceilanica, hex rotunda, Rapanea neriifolia, Artocarpus hypargyreus, Artocarpus styracifolius, Gordonia axillaris, Koelrcuteria bipinnata, Manglietia glauca, Machilus chinensis, Spathodea nilotica. (3) Most sensitive species include Mesua ferrea, Tsoongiodendron odorum, Aquilaria sinensis, Elaeocarpus japonicus, jacaranda mimosifolia, Heritiera parvifolia, Pterocarpus indicus, Machilus salicina, Saraca chinensis, Manglietia hainanensis, Michelia chapensis. The results could provide scientific basis for selection of plant species for urban forestry in the environments with similar air pollution in tropical and subtropical regions.

Abstract:Air monitoring data showed that acidic sulfate and toxic fluoride were the major source of pollutants from ceramic industry in Foshan city, Guangdong Province. Thirty-five garden plant species were grown in pots at two polluted sites near ceramic factories and a relatively clean site as control to measure the growth of plant height, basal diameter, crown cover, and the complex growth rate as indexes of pollution tolerance of the species. One to two-year-old seedlings incubated in pots for about 5 months of exposure to air pollutants were examined. The results indicate that all the species tested can be grouped into three types: Ⅰ. tolerant species (Ilex rotunda, Ficus religiosa, Ficus annulata, Lysidice rhodostegia, Ficus microcarpa, Camellia semiserrata, Heteropanax fragrans, Artocarpus hypargyreus)；Ⅱ. middling tolerant species (Artocarpus styracfo1ius, Cassia fistula, Actinodaphne pilosa, Artocarpus nitidus ssp. lingnanensis, Camellia japonica, Kigelia africana, Spathodea campanulata, Mesua ferrea, Machilus salicina, Dolichandrone caudafelina, Fagraea ceilanica, Myrsine seguinii Ormosia pinnata, Koelrcuteria bipinnata, Manglietia glauca, Gordonia axillaries, Pterocarpus indicus)； and Ⅲ. sensitive species (Machilus chinensis, Manglietia hainanensis, Erythrophloeum fordii, Elaeocarpus japonicus, Jacaranda mimosifolia, Tsoongiodendron odorum, Heritiera parvifolia, Aquilaria sinensis, Michelia chapensis, Saraca chinensis).

Abstract:Seventy-five species of garden plant seedlings were potted under contaminated environment at Dongcun (DC) and Wuxing (WX) near ceramic industry sites in Foshan City, Guangdong, and at botanical garden (control). The contents of sulphur and fluorine in the leaves of the thirty-two surviving species were measured after 128 days, among which 14 species including Ficus religiosa, F. microcarpa var. fuyuensis, Lysidice rhodostegia, Carallia brachiata, Ilex rotunda, etc. had great ability to absorb air pollutants SO₂ and fluoride. Average sulphur and fluorine contents in leaves of these species pot-grown at contaminated sites were 17442 mg kg^-1 DW and 3725.9 mg kg^-1 DW, respectively, which were 1.9 times and 20 times higher than those at control site, respectively, showing that these species were more tolerant to SO₂ and fluoride pollutants.

Abstract:This study aims to test the sensitivity of thirty-nine 1 to 2-year-old 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 possible 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 monitoring data showed that the polluted area received remarkably higher sulfation rate, fluoride concentration and total suspended particles than the clean site, which significantly exceed the emission limit of National Standard. Net photosynthetic rate(P_n), transpiration rate(E), stomatal conductance (g_s) differed among species and decreased for most species in the polluted area. Pooled data showed that P_n and E were linearly correlated with g_s 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 correlation of the P_n with g_s (or E with g_s) had been weakened (or enhanced) under pollution stress, which demonstrated the unparallel and complexity in changes of P_n and E with g_s, and the diversity of acclimation strategies among different species. Based on the change in P_n, 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, Aquilaria sinensis and Ormosia pinnata; species showing moderate sensitivity were lieritiera parvifolia, Magnolia delavayi, Fagraea ceilanica, Manglietia insignis, Artocarpus styracifolius, Heteropanax fragrans, Saraca chinensis, Machilus saclicina, Annona muricata, Ternstroemia gymnanthera, Dolichandrone cauda-felina, Artocarpus nitidus subsp. lingnanens, Cassia fistula, Camellia semiserrata, Tsoongiodendraon odorum, Osmanthus fragrans, Ilex rotunda, Elaeocarpus japonicus, Spathodea campanulata, Mesua ferrea, Myrsine seguinii; and those showing low sensibility were Actinodaphne pilosa, Machilus chinensis, Kigelia Africana, Gordonia axillaries, Camellia japonica, Ficus mucrocarpa var. fuyuensis, Ficus microcarpa, F. annulata, F. religiosa and Tutcheria spectabilis.

Abstract:Several physiological parameters were compared including leaf area, cell membrane leakage rate, Fv/Fm and photosynthetic pigments content in leaves of 30 species of plants for urban greening, potted in two air polluted sites, Wuxing(WX) and Dongcun(DC), Foshan City, Guangdong Province, and one less polluted site at South China Botanical Garden in Guangzhou(BG) for control After growing for 3-5 months, the growth of leaves was inhibited and maximal photochemical efficiency of PSⅡ and content of photosynthetic pigments decreased in most plants at two polluted sites in comparison with the less polluted site. The average values of leaf area, Fv/Fm, and photosynthetic pigments content at each site were in the order of BG>WX>DC, while the average values of cell membrane leakage rate were in the contrary. Data analysis showed that leaf area was the most sensitive one to air pollution and Fv/Fm was slightly affected by different species. According to the tested parameters, it is concluded that Artocarpus hypargyreus, Ficus annulata and Camellia semiserrata are resistant species while Liquidambar formosana is sensitive one.

Abstract:Response of three woody species (native Symplocos lancifolia and Aporosa chinensis, and exotic Eucalyptus exserta) to air pollution grown at two experimental sites, Wuxing with ceramic factories nearby at Foshan city (WX) and control site at South China Botanical Garden (BG), was examined physiologically. Buffering capacity of S. lancifolia and A. chinensis was higher than that of E. exserta. pH in cell sap of leaves of three species was lower in WX than that in BG. After the leaves were treated with 10 mmol L^-1 NaHSO₃ under 20.5μmol m^-2s^-1 light intensity for 10 h, the photosynthetic oxygen evolution, Fv/Fm, Fv/Fo and ΦPSⅡ in all the three species decreased to some extent, most significant decrease in three parameters was found in E. exserta. The results demonstrated that there was less resistance to air pollution in E. exserta than in the other two, and it was consistent with different buffering capacity of cell sap in three species. It is suggested that the buffering capacity of cell sap in plant leaves can be a useful index in evaluating the resistance of plants to SO₂ pollution.

Abstract:Seventy-two woody plant species of 1 to 2-year old seedlings were potted at non-polluted site in South China Botanical Garden in Guangzhou. One year later, mature leaves of every species from different individuals were used for experiment of simulation of SO2 pollutant by immersing leaf discs in 20 mmol L^-1 NaHSO₃ solution at 25℃ under 20μ is mol m^-2s^-1 light intensity for 20 h, and in distilled water as control. The treated leaves were conducted for chlorophyll fluorometric assay and for buffer capacity for alkali. The resistance of plants was evaluated comprehensively by decreasing amplitude of the values of Fv/Fm and Fv/Fo after the leaves were treated with NaHSO₃ compared to the control, and by pH value in cell saps and buffering capacity of leaves. Results indicate that the resistant species are Ficus microcarpa var. fuyuensis, Artocarpus nitidus ssp. lingnanensis, Heteropanax fragrans, Tutcheria spectabilis, Ormosia pinnata, Artocarpus hypargyreus, ect., the sensitive species being Dillenia indica, Manglietia glauca, Fagraea ceilanica, Garcinia multiflora, Cassia siamea, etc.

Abstract:Multiple regression analysis was used for the investigation of the influence of air pollutants (sulfate and fluorides) on the changes in physio-ecological characteristics in the leaves of 48 plant species distributed at 8 site in Foshan city and one site in Dinghushan Nature Reserve as control. The results showed that the changes in leaf area (LA), total chlorophyll contents (Chl), cell liquid pH values (pH) and cell membrane leakage (CML) (electronic conductance) exhibited significant correlation with pollutant contents in leaves. Linear regression equation between physio-ecological changes and pollutant content in the air was Y_S=0.034X_LA-0.011X_Chl+0.017X_pH+40.0003X_CML+0.034 (r=0.99,p<0.001) for sulfation rate, and was Y_F=0.362X_LA+0.329X_Chl+0.814X_pH+0.024X_CML-4.596 (r=0.947,p<0.03) for fluorides. The application of physio-ecological changes in plants as biological monitoring indicatoss of air pollution was consistent with actual environment condition.

Abstract:With the development of the society and economy as well as the urbanization, city problem has been becoming the focus in the social and scientific communities. Urban forestry therewith has received a growing concern due to its function and contribution in the construction and development of cities and towns. In this paper, we start with the basic concept and contents of urban forestry in terms of its natural and social attributes, scopes and levels, and then compare the differences between urban forestry and traditional forestry, modern gardens in aspects of research fields, functions and properties, aims and levels of management. Based on the research data and results available, the role of urban forestry and its potentials in solving problems from urbanization are also demonstrated. According to the current status and existent problems, we propose the opportunities and challenges, and future trends of modem urban forestry.

Abstract:This study aims to characterize the damage or sensitivity of different plant species growing under long-term air pollution around ceramic industrial areas, on the basis of community survey, to provide implications for restoration of heavily polluted and degraded areas in similar condition. Field survey was carried out by ten quadrats 10m×10m in area for tree layer, and eight subquadrats 5m×5m for shrub and herb layers in a hilly land semi-natural secondary forest at a rural site in Nanhai city of Guangdong Province. The forest was dominated by exotic Eucalyptus exserta and Eucalyptus urophylla, followed by native tree species, Schefflera octophylla and Bambusa gibba, with the importance value (Ⅳ) of 26.75, 17.08, 16.27 and 11.50, respectively, while all other companion species accounted for less than 30%, Based on foliage loss and the extent of injured leaf tissues, plants were categorized into: (1) dead without any leaves attached, (2) severe damage with the injured degree ranging from 60% to 100%, (3) moderate damage, 25%-60%, (4) light damage, 10%-25%, and healthy with the injured degree less than 10%. Among all tree species, Eucalyptus exserta and Pinus massoniana were the most severely damaged species, of which all individuals were dead or with only a few dead branches without any leaves attached, and then followed by Bambusa gibba and Dalbergia balansae. Although the Ⅳ was much lower for the rest companion species, but most of them showed high capacities to cope with the pollution stress. These species include Schefflera octophylla, Viburnum odoratissimum, Desmos chinensis, Syplocos lancifolia, Broussonetia papyrfera, Mallotus apelta, Aporosa dioica, Carallia brachiata, Trema tomentosa, Ficus hirta and Litsea glutinosa. Compared with species in tree layer, damages of woody seedlings, herbs or lianas growing under the canopies were largely reduced. Results from this study demonstrate that attention and concern should be made on those introduced Eucalyptus species in heavily polluted area, which had ever been considered as one of the important species for forest restoration in hilly degraded lands and planted in a wide range of areas during 1970-80s, due to its fast growing aspect. The results also demonstrate the potentials and perspectives by developing native species as target plants for restoration of degraded area, which makes a stimulus for scientists to initiate studies as a base for advancing our ability to describe the functional aspects of native species and process-based interactions with pollution stress.

Abstract:Sulfur dioxide concentration, sulfation rate and fluoride contents in atmosphere around the Nanshan district in Shenzhen were measured in summer and winter of 2000 using two different sampling methods (i.e. conventional standard sampling and static suspending piece absorption). At the same time, sulfur and fluorine contents in plant leaves were also measured. Regression analysis showed that pollutant concentrations in atmosphere were significantly correlated with the pollutant contents (x) in plant leaves. On the basis of these correlations, biomonitoring mathematical models for evaluation on air sulfation rate (y) were developed as y=0.781x-0.754 for summer and y=l.88x-2.283 for winter, whereas on air fluoride (y), y=0.363x-7.511 for summer and y=0.175x-3.461 for winter. It is suggested that the models are reliable.

Abstract:The responses of seed germination and seedling growth of rice (Oryza sativa cv. Yueza 223), wheat (Triticum aestivum cv. Gaoyun 5) and maize (Zea mays cv. Shangyu 2) to simulated acid rain were investigated by dipping seeds into solution of pH2.5, 4.5 and 5.6 made from mixtures of H2SO4 and HNO3, and into distilled water (control). Different pH (2.5, 4.5, 5.6) simulated acid rain showed no effect on seed germination of rice and wheat, but significant inhibition effect was found in the germination of maize. Seedling growth of rice, wheat and maize was inhibited by simulated acid rain. Biomass and contents of chlorophyll and carotenoids decreased to some extent in all the three crop species grown under simulated acid rain, whereas no obvious changes in Chl a/b was exhibited in these crops. There was little effect on Fv/Fm and photochemical quenching of chlorophyll fluorescence (qP) in leaves of maize grown at pH 4.5 or 5.6 of simulated acid rain, but nonphotochemical quenching of chlorophyll fluorescence (NPQ) decreased markedly, revealing that non-radiation energy dissipation in the antenna of photosystemⅡ was possibly damaged under acid rain condition.