青藏高原东缘半湿润沙地典型生态恢复模式的效果比较研究

草地退化与沙化直接影响草地生态系统的功能与服务，植被恢复是沙地恢复治理的重要方式之一，但是探究沙化草地典型生态恢复模式的恢复效果及模式优化研究不足。以野外调查与室内分析相结合的方法，以重度沙化草地为对照（CK），比较研究了青藏高原东缘沙地三种典型生态恢复模式（围栏封育（Fencing enclosure，FE）、布设高山柳沙障（Salix cupularis sandy barrier，SCSB）、布设高山柳沙障+种草（Salix cupularis sandy barrier plus planting grasses，SCSBPPG））对草本植物群落和土壤理化性质的影响。结果显示：（1）与CK相比，FE的地上草本盖度、生物量、Margalef丰富度指数和Shannon-Weiner多样性指数分别显著提高了13.54倍、13倍、3.09倍和1.80倍，且SCSBPPG的这些指标分别显著提高了11.24倍、10.50倍、1.05倍和0.83倍（P < 0.05），而SCSB对以上指标影响均不显著。（2）三种典型生态恢复模式对沙地的土壤容重无显著影响，而三种典型生态恢复模式0-10 cm、10-20 cm和20-30 cm土层土壤含水量变化规律一致（SCSBPPG > FE > SCSB），且SCSBPPG和FE的0-10 cm土层土壤含水量的增加最明显，分别为244.90%、176.92%（P < 0.05），而SCSB土壤含水量相较于CK无显著差异。（3）该研究区的pH在5.74-6.21之间，FE和SCSBPPG较CK显著降低了0-30 cm各土层土壤pH（P < 0.05）。此外，三种生态恢复模式0-30 cm各土层土壤有机质、全N、全P、全K含量递减变化规律为FE > SCSBPPG > SCSB，FE和SCSBPPG各土层土壤有机质、全N、全P均高于CK，且都在土层10-20 cm增幅最大，FE的最大增幅分别为243.62%、93.94%、68.97%，SCSBPPG的最大增幅分别为118.46%、45.45%、41.38%，而SCSB显著降低了各土层土壤有机质、全N和全P量（P < 0.05）。因此，在青藏高原高寒轻度沙化草地围栏封育有利于其恢复，而重度沙化草地的生态恢复需采用植灌和种草结合的模式。研究结果可为沙地的恢复治理和可持续管理提供依据。

Comparison study to the effectiveness of typical ecological restoration measures in semi-humid sandy land in eastern Qinghai-Tibetan Plateau, China

Grassland degradation and desertification directly affect the functions and services of the grassland ecosystem. Vegetation restoration is one of the essential measures for the restoration and control of sandy land, but little research has been conducted to investigate the effectiveness and optimal modes of typical ecological restorations in sandy grassland. In this paper, we combined field investigation and laboratory analysis to compare the grass community, soil physical and chemical properties between the severe sandy grassland as a control (CK) and three typical ecological restoration measures, including fencing enclosure (FE), Salix cupularis sandy barrier (SCSB) and Salix cupularis sandy barrier plus planting grasses (SCSBPPG), in the eastern Qinghai-Tibetan Plateau, China. The results are as follows: (1) Compared with CK, the grass coverage, aboveground biomass, Margalef richness index and Shannon-Weiner diversity index significantly increased by 13.54, 13, 3.09 and 1.80 times with FE, respectively, and by 11.24, 10.50, 1.05 and 0.83 times with SCSBPPG, respectively (P < 0.05); while SCSB had no significant influence on the four indexes. (2) The soil bulk density presented no significant differences among the three typical ecological restoration measures. Soil moisture distribution showed a similar pattern (SCSBPPG > FE > SCSB) in the soil layer of 0-10 cm, 10-20 cm and 20-30 cm. At the same time, soil moisture content in SCSBPPG and FE had the most significant increase in the soil layer of 0-10 cm, 244.90% and 176.92%, respectively (P < 0.05) while there was no significant difference between CK and SCSB (P > 0.05). (3) The value of pH in this study area ranged from 5.74 to 6.21. FE and SCSBPPG had significantly reduced the soil pH value of three soil layers from 0 to 30 cm compared to CK (P < 0.05). Besides, the soil organic matter, total N, total P, and total K contents of three soil layers in the soil profile under the three ecological restoration measures had the same descending order (FE > SCSBPPG > SCSB). The soil organic matter, total N and total P of FE and SCSBPPG were significantly higher than that of CK in the three soil layers, and the maximum increase came at the 10-20 cm soil layer. The soil organic matter, total N and total P of FE had the maximum rate of increase of 243.62%, 93.94%, 68.97%, respectively while that of SCSBPPG had the maximum rate of increase of 118.46%, 45.45%, and 41.38%, respectively. SCSB significantly decreased the amount of soil organic matter, total N, and total P in the three soil layers (P < 0.05). Therefore, fencing enclosure is more conducive to restore the light sandy grassland while the restoration of severe sandy grassland may need to combine shrub and grass planting measures in the Qinghai-Tibetan Plateau. Our results could provide evidences for the recovery and sustainable management of sandy land.