Effect of heavy metals and environmental variables on the assimilation of CO2 and stomatal conductance of Ligustrum lucidum, an urban tree from Mexico City

《Effect of heavy metals and environmental variables on the assimilation of CO2 and stomatal conductance of Ligustrum lucidum, an urban tree from Mexico City》

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来源: URBAN FORESTRY & URBAN GREENING,Vol.42,P.72-81

语言: 英文

关键字: Air temperature; CO2 concentration; Physiological responses; Photosynthetically active radiation; Pollutants; Urban vegetation; AIR-POLLUTION; PARTICULATE POLLUTION; LEAF CONDUCTANCE; WATER RELATIONS; CARBON-DIOXIDE; PHOTOSYNTHESIS; RESPONSES; DENSITY; LE

作者单位: [Estefania Garcia-Sanchez, Irma; Barradas, Victor L.; Ballinas, Monica] Univ Nacl Autonoma Mexico, Inst Ecol, Lab Interacc Planta Atmosfera, Circuito Exterior S-N,Ciudad Univ, Mexico City 04510, DF, Mexico. [de Leon Hill, Claudia A. Ponce] Univ Nacl Autonoma Mexico, Fac Ciencias, Circuito Exterior S-N, Mexico City 04510, DF, Mexico. [Esperon-Rodriguez, Manuel] Western Sydney Univ, Hawkesbury Inst Environm, Locked Bag 1797, Penrith, NSW 2751, Australia. [Rosas Perez, Irma] Univ Nacl Autonoma Mexico, Ctr Ciencias Atmosfera, Circuito Invest, Mexico City 04510, DF, Mexico. Barradas, VL (reprint author), Univ Nacl Autonoma Mexico, Inst Ecol, Lab Interacc Planta Atmosfera, Circuito Exterior S-N,Ciudad Univ, Mexico City 04510, DF, Mexico. E-Mail: vbarrada@ecologia.unam.mx

摘要: Urban trees reduce CO2 and pollutants that represent a risk for human health in cities. In this work, we assessed the potential effect of heavy metals and environmental variables on the CO2 assimilation (A) and the stomatal conductace (g(s)) of Ligustrum lucidum, a common urban tree in Mexico City. We compared two sites with contrasting pollution levels: 1) city centre (PPI-C, high pollution level); and 2) south of the city (CU-SW; low pollution level). At each site, we measured 1) phsysiological traits (A and g(s)); 2) environmental variables (photosynthetically active radiation, PAR; air temperature, T-A; vapor pressure deficit, VPD; concentration of atmospheric CO2); and 3) morphological leaf characteristics (stomatal size and density). Concentration of the heavy metals Pb, Cd, Cr, Cu, Mn, Fe, and Zn was determined in washed (internal metals) and unwashed (external plus internal metal) leaves at both sites. CO2 assimilation at CU-SW was higher than at PPI-C. PAR had the greatest effect on A; whereas T-A and VPD had the greatest effect on g(s). Regarding heavy metals, although we found no significant differences in internal concentrations between sites, we found a lower stomatal density at PPI-C, which may indicate a response of the species to the local pollution conditions. This characteristic might be beneficial for the species, allowing it to maintain optimal physiological conditions by reducing the assimilation of pollutants. Our results suggest that L. lucidum is a well adapted species for the urban environment.