Diurnal pattern of leaf water potential of <i>H</i>. <i>ammodendron</i> (a, b) and <i>C</i>. <i>mongolicunl</i> (c, d) before and after irrigation for the five irrigation intervals.

<p>The data points for the 2-week interval fell between those of the 1 and 4 weeks; those of the 8-week interval fell between those of 4 and 12 weeks. Error bars represent the standard deviation of the mean.</p

Soil water content and biomass allocation of two species for 2-week irrigation interval at the TDBG and the TDSH where some <i>C</i>. <i>mongolicunl</i> have been dead.

<p>Soil water content and biomass allocation of two species for 2-week irrigation interval at the TDBG and the TDSH where some <i>C</i>. <i>mongolicunl</i> have been dead.</p

Leaf-specific apparent hydraulic conductance of <i>Haloxylon ammodendron</i> (a–e) and <i>Calligonum mongolicunl</i> (f–j) before and after irrigation with intervals of 1, 2, 4, 8 and 12 weeks.

<p>The relationship between leaf water potential and transpiration rate was best fitted by the linear function Y = A + BX, in which A represents <i>Ψ</i>₀ which is the water potential at the soil–-root interface and B represents leaf-specific apparent hydraulic conductance before and after irrigation.</p

Seasonal changes in leaf area per branch and growth rate of branch biomass of <i>H</i>. <i>ammodendron</i> (a, c) and <i>C</i>. <i>mongolicunl</i> (b, d) for the five irrigation intervals.

<p>Error bars represent the standard deviation of the mean. Different lower-case letters indicate significant differences among treatments (<i>P</i> = 0.05).</p

Diurnal photosynthesis patterns of <i>Haloxylon ammodendron</i> (a, b) and <i>Calligonum mongolicunl</i> (c, d) before and after irrigation for the five irrigation intervals.

<p>The data points for the 2-week interval fell between those of the 1 and 4 weeks; those of the 8-week interval fell between those of 4 and 12 weeks. Error bars represent the standard deviation of the mean. Different lower-case letters indicate significant differences among treatments (<i>P</i> = 0.05).</p

Diurnal pattern of transpiration for <i>H</i>. <i>ammodendron</i> (a, b) and <i>C</i>. <i>mongolicunl</i> (c, d) before and after irrigation for the five irrigation intervals.

<p>The data points for the 2-week interval fell between those of the 1 and 4 weeks; those of the 8-week interval fell between those of 4 and 12 weeks. Error bars represent the standard deviation of the mean.</p

Comparison of mean physiological and growth parameters of <i>Haloxylon ammodendron</i> and <i>Calligonum mongolicunl</i> before and after irrigation with intervals of 1, 4 and 12 weeks.

<p>Comparison of mean physiological and growth parameters of <i>Haloxylon ammodendron</i> and <i>Calligonum mongolicunl</i> before and after irrigation with intervals of 1, 4 and 12 weeks.</p

Is the Taklimakan Desert Highway Shelterbelt Sustainable to Long-Term Drip Irrigation with High Saline Groundwater?

<div><p>Freshwater resources are scarce in desert regions. Highly saline groundwater of different salinity is being used to drip irrigate the Taklimakan Desert Highway Shelterbelt with a double-branch-pipe system controlling the irrigation cycles. In this study, to evaluate the dynamics of soil moisture and salinity under the current irrigation system, soil samples were collected to a 2-m depth in the shelterbelt planted for different years and irrigated with different groundwater salinities, and soil moisture and salinity were analyzed. The results showed that both depletion of soil moisture and increase of topsoil salinity occurred simultaneously during one irrigation cycle. Soil moisture decreased from 27.4% to 2.4% for a 15-day irrigation cycle and from 26.4% to 2.7% for a 10-day-cycle, respectively. Topsoil electrical conductivity (EC) increased from 0.64 to 3.32 dS/m and 0.70 to 3.99 dS/m for these two irrigation cycles. With increased shelterbelt age, profiled average soil moisture (0–200 cm) reduced from 12.8% (1-year) to 7.1% (10-year); however, soil moisture in 0–20-cm increased, while topsoil salinity decreased. In addition, irrigation salinity mainly affected soil salinity in the 0–20-cm range. We conclude that water supply with the double-branch-pipe is a feasible irrigation method for the Taklimakan Desert Highway Shelterbelt, and our findings provide a model for shelterbelt construction and sustainable management when using highly saline water for irrigation in analogous habitats.</p></div

Soil physical properties of shifting sand and shelterbelt soil after shelterbelt has been set up for 7 years.

<p>Soil physical properties of shifting sand and shelterbelt soil after shelterbelt has been set up for 7 years.</p

Growth status of <i>Haloxylon ammodendron</i> and <i>Calligonum mongolicunl</i> in parts of the Taklimakan Desert Highway Shelterbelt.

<p>Growth status of <i>Haloxylon ammodendron</i> and <i>Calligonum mongolicunl</i> in parts of the Taklimakan Desert Highway Shelterbelt.</p