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Li Q.,Chinese Academy of Forestry | Jia Z.,Chinese Academy of Forestry | Zhu Y.,Chinese Academy of Forestry | Wang Y.,Chinese Academy of Forestry | And 3 more authors.
PLoS ONE | Year: 2015

The Gonghe Basin region of the Tibet Plateau is severely affected by desertification. Compared with other desertified land, the main features of this region is windy, cold and short growing season, resulting in relatively difficult for vegetation restoration. In this harsh environment, identification the spatial distribution of soil nutrients and analysis its impact factors after vegetation establishment will be helpful for understanding the ecological relationship between soil and environment. Therefore, in this study, the 12-yearold C. intermediaplantation on sand dunes was selected as the experimental site. Soil samples were collected under and between shrubs on the windward slopes, dune tops and leeward slopes with different soil depth. Then analyzed soil organic matter (SOM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP) and available potassium (AK). The results showed that the spatial heterogeneity of soil nutrients was existed in C. intermedia plantation on sand dunes. (1) Depth was the most important impact factor, soil nutrients were decreased with greater soil depth. One of the possible reasons is that windblown fine materials and litters were accumulated on surface soil, when they were decomposed, more nutrients were aggregated on surface soil. (2) Topography also affected the distribution of soil nutrients, more soil nutrients distributed on windward slopes. The herbaceous coverage were higher and C. intermedia ground diameter were larger on windward slopes, both of them probably related to the high soil nutrients level for windward slopes. (3) Soil " fertile islands"were formed, and the "fertile islands" were more marked on lower soil nutrients level topography positions, while it decreased towards higher soil nutrients level topography positions. The enrichment ratio (E) for TN and AN were higher than other nutrients, most likely because C. intermedia is a leguminous shrub. © 2015 Li et al.

Liu L.-Y.,Chinese Academy of Forestry | Jia Z.-Q.,Chinese Academy of Forestry | Zhu Y.-J.,Chinese Academy of Forestry | Li H.,Chinese Academy of Forestry | And 3 more authors.
Forest Research | Year: 2012

Salix cheilophila is one of the main shrub species for afforestation in Alpine Sandland of Gonghe Basin, Qinghai Province. Stable isotope technique was used to test the δD and δ18O value of rain, well water, branch xylem and different soil depth of 5-, 9- and 25-year-old S. cheilophila plantation, and then the differences of main water source among the three S. cheilophila stands with different ages were analyzed. Also, the δ13C value of leaves was tested to evaluate the water use efficiency (WUE) of the S. cheilophila stands. Comparison of δD and δ18O showed that 5-year-old S. cheilophila used the water in 10-50 cm soil infiltrated from rainwater; 9-year-old S. cheilophila consumed relatively deep soil water, including 20 cm infiltrated from rainwater and 30-50, 150 cm replenished by ground water; and 25-year-old S. cheilophila used 10-20 cm soil water infiltrated from rainwater and 50 cm soil water replenished by ground water. The difference of leaf δ13C value among 5-, 9- and 25-year-old S. cheilophila stands was significant; 5-year-old S. cheilophila has exclusively high WUE, whereas that of 9-year-old and 25-year-old stands were similar. The water source and WUE suggest that 9-25 years old S. cheilophila was in steady period.

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