Comparison of morphological and physiological characteristics and water use of plantation species for combating desertification in Mongolia
Afforestation is considered as one of the best solutions for combating desertification, but it requires lots of management efforts and has serious side effects such as groundwater depletion. Thus selection of proper tree species and finding the minimum management requirements are essential in arid area plantation. Morphological and physiological properties and water use of Populous sibrica and Ulmus pumila, which were planted at Korea-Mongolia Green Belt Plantation in Lun soum, Mongolia in 2008, were compared to provide information for proper irrigation scheme and better species selection by examining the effects of irrigation densities on growth and water use of two species. Leaf morphological characteristics, such as leaf area (LA), specific leaf area (SLA) were measured with a scanner and calculated for individual leaves. Physiological characteristics were measured by using the Li-6400 to different water irrigation regimes (ambient+2L, ambient+4L) of P. sibirica, U. pumila L. Sap flow measured by Thermal dissipation probes (Granier type sap flow sensor) then estimate stand transpiration.
In morphological properties, P. sibica had larger leaf size and higher specific leaf area (SLA) than U. pumila, however, irrigation rates effected positively on the SLA of U. pumila only and not on the leaf size of both species. Photosynthetic characteristics like maximum photosynthesis rate (Amax), maximum carboxylation rate (VCmax), and maximum electron transport rate (Jmax) showed no difference in two species. In addition, VCmax and Jmax of both species had the same linear relationship of°°. In addition, Water use of P. sibirica was higher than U. pumila, but difference disappeared of seasonal variation. These results indicated that U. pumila is more adaptive species on dry condition than U. pumila due to its small leaf size, low SLA, and low water use on season. However, irrigation rates had no considerable effect on tree morphophysiological characteristics of both species. Further analysis of transpiration by species under different irrigation rates is on the way to give useful insights for plantation management without side effects such as soil water depletion.