This study examined the early growth and water use of tree plantations established on a marginalized irrigated cropland in northwest Uzbekistan, where salinization of agricultural soils is widespread due to shallow saline groundwater tables. During the first two growing seasons in 2003-2004, the tree stands consisting of Elaeagnus angustifolia L., Populus euphratica Oliv., and Ulmus pumila L. were irrigated with 80 mm year(-1), and, in 2005, were left to rely on the shallow (0.9-2.0 m deep) groundwater with a salinity of 1-5 dS m(-1). Soil salinity increased but remained within the range of moderate-to-strong (4-14 dS m(-1)) during the three years. In the course of the growing season, plantations transpired 0.1-7 mm day(-1) in 2003 and 1-13 mm day(-1) in 2004-2005, as determined with the Penman-Monteith model. In the absence of irrigation, the annual stand transpiration averaged 1250, 1030, and 670 mm for E. angustifolia, P. euphratica and U. pumila, respectively. In 2005, the leaf area index of E. angustifolia ranged from 5 to 10, surpassing that of the other two species more than two-fold. Differences in canopy conductance and transpiration were significant among the tree species and the decoupling coefficient at no time exceeded 0.3, indicating strong physiological control of transpiration. The vigorous juvenile growth and high transpiration under deficit irrigation and after irrigation was terminated, suggested that afforestation with well-adapted tree species is a viable land use option for degraded cropland. The plantation responses to increasing soil salinity must be monitored to determine potential leaching demands in the long run.
experimental tree plantation established on degraded cropland The irrigation treatments included: (1) drip irrigation applied at a ‘‘deficit’’ rate (80 mm year 1), (2) drip irrigation applied at a ‘‘full’’ rate (160 mm year 1), and (3) traditional furrow irrigation applied at the deficit rate. The furrow irrigation was applied fortnightly whereas the deficit and full drip applications were scheduled respectively once and twice a week. The irrigation took place only during the first two growing seasons (2003–2004) and was ceased thereafter. The plantations consisted of two local species, Russian olive (Elaeagnus angustifolia L.) and Euphrates poplar (Populus euphratica Oliv.), both naturally occurring in the riparian forest of Amu Darya delta, and Siberian elm (Ulmus pumila L.), which was introduced during last century and has been widely planted within the irrigated area since.
|Climate change impacts||Effect of Nbs on CCI||Effect measures|
|Biomass cover loss||Positive||The growth parameters such as tree height and The leaf area index ... served as indicators of the tree performance during the first two years of plantation establishment|
Khorezm Region of Uzbekistan, at 418650 N latitude, 608620 E longitude (altitude 102 m a.s.l.). The region is an oasis within the transition zone of the Karakum and Kizylkum deserts and located in the lower reaches of the Amu Darya River, about 250 km south of the remainders of the Aral Sea (Fig. 1).