The planting of sand-binding vegetation in the Shapotou region at the southeastern edge of the Tengger Desert began in 1956. Over the past 46 years, it has not only insured the smooth operation of the Baotou-Lanzhou railway in the sand dune section but has also played an important role in the restoration of the local ecoenvironment; therefore, it is viewed as a successful model for desertification control and ecological restoration along the transport line in the arid desert region of China. Longterm monitoring and focused research show that within 4-5 years of establishment of sand-binding vegetation, the physical surface structure of the sand dunes stabilized, and inorganic soil crusts formed by atmospheric dust gradually turned into microbiotic crusts. Among the organisms comprising these crusts are cryptogams such as desert algae and mosses. In the 46 years since establishing sandbinding vegetation, some 24 algal species occurred in the crusts. However, only five moss species were identified, which was fewer than the species number in the crust of naturally fixed sand dunes. Other results of the planting were that near-surface wind velocity in the 46-year-old vegetation area was reduced by 54.2% compared with that in the moving sand area; soil organic matter increased from 0.06% in moving sand dunes to 1.34% in the 46-year-old vegetation area; the main nutrients N, P, K, etc., in the desert ecosystem increased; soil physicochemical properties improved; and soil-forming processes occurred in the dune surface layer. Overall, establishment of sand-binding vegetation significantly impacted soil water cycles, creating favorable conditions for colonization by many herbaceous species. These herbaceous species, in turn, facilitated the colonization and persistence of birds, insects, soil animals, and desert animals. Forty-six years later, some 28 bird species and 50 insect species were identified in the vegetated dune field. Thus, establishment of a relatively simple community of sand-binding species led to the transformation of the relatively barren dune environment into a desert ecosystem with complex structure, composition, and function. This restoration effort shows the potential for short-term manipulation of environmental variables (i.e., plant cover via artificial vegetation establishment) to begin the long-term process of ecological restoration, particularly in arid climates, and demonstrates several techniques that can be used to scientifically monitor progress in large-scale restoration projects.

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A field experiment was conducted to investigate root distribution, biomass, and seasonal dynamics in a revegetated stand of Caragana korshinskii Kom. in the Tengger Desert. We used soil profile trenches, soil core sampling, and minirhizotron measurements to measure root dynamics. Results showed that the roots of C. korshinskii were distributed vertically in the uppermost portion of the soil profile, especially the coarse roots, which were concentrated in the upper 0.4 m. The horizontal distribution of the root length and weight of C. korshinskii coarse roots was concentrated within 0.6 and 0.4 m of the trunk, respectively. The lateral distribution of fine roots was more uniform than coarse roots. Total-root and fine-root biomasses were 662.4 +/- 45.8 and 361.1 +/- 10.3 g m(-2), accounting for about two-thirds and one-third of the total plant biomass, respectively. Fine-root turnover is closely affected by soil water, and both of these parameters showed synchronously seasonal trends during the growing season in 2004 and 2005. The interaction between fine-root turnover and soil water resulted in the fine-root length densities and soil water content in the 0- to 1.0-m soil layer having similar trends, but the soil water peaks occurred before those of the fine-root length densities.

Abstract:More than 40 years of revegetation using mainly Caragana korshinskii at Shapotou Desert Experimental Research Station in China has established a dwarf-shrub and herbaceous cover on the stabilized sand dunes. The evapotranspiration (ET) of the dwarf-shrub C. korshinskii community and the evaporation (E) of the bare soil were measured by the auto-weighing lysimeter method during the growing seasons from 1990 to 1995. The average ET rate was 0Ð83 mm d 1 , which varied from 0Ð71 to 1Ð06 mm d 1 during the 6-year period. Monthly ET ranged from 0Ð14 to 2Ð35 mm d 1 , with a monthly precipitation (P) range of 0 to 3Ð12 mm d 1 . Monthly ET/P ratios varied from 0Ð94 to 1Ð28 and averaged 97Ð4% overall. Most of the precipitation in this area usually falls between June and September. The lowest precipitation was recorded in 1991, with most of it falling during April and May. This temporal anomaly in the precipitation resulted in the highest ET/P ratio (by 0Ð33) and soil moisture depletion (S D 31Ð5 mm) for the 6-year period. ET from the revegetated sand dunes around Shapotou under natural precipitation may account for 12Ð2% of the potential evaporation. Cumulative P and cumulative ET and E were highly correlated, with a well-defined linear relationship of ET D 0Ð80P C 10Ð0 and E D 0Ð55P C 5Ð89, with regression R 2 ranging from 0Ð953 to 0Ð985. In 1991, however, the regression equations for both ET and E were considerably different than the other years, with a steeper slope and a negative intercept resulting from the anomaly in the precipitation pattern.

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