The coupling relationship between variations of NDVI and change of aeolian sandy land in the Yarlung

There was a total of 273 697. 54 hm 2 of aeolian sandy lands in the Yarlung Zangbo River basin of Tibet in 2008. The fast development of aeolian sand lands has caused immense damages to its social and economic development, it is urgent to choose appropriate plant species for vegetation restoration of the moving sand dunes in the basin. Thus, we carried out a continuous trial of the field artificial seeding on sand dunes in the middle reaches of the Yarlung Zangbo River basin, the main testing plant species included the northern China忆 s psammophyte species and the Tibet忆 s native species. The germination, emergence, growth processes and reproduction of the testing plant species were observed from 2008 to 2011, based on these, the best suitable species on sand dunes in the alpine valley were determined, which could be used to guide the ongoing vegetation recovery and reconstruction on aeolian sandy land in the studied area. The results showed that the plant height and plant size growth of northern China忆s psammophyte species were larger than that of native psammophyte species in the field artificial seeding trial, and the species such as Artemisia sphaerocephala, Hedysarum scoparium, Calligonum mongolicum, H. fruticosum var. mongolicum and Sophora moorcroftiana all exhibited good adaptability to

We conducted a case study to examine the soil nutrients content and grain size fraction of different aeolian sandy land types in the Shannan wide valley area, middle reaches of the Yarlung Zangbo River by choosing moving sandy land, flat sandy gravel land, semi鄄fixed sandy land, fixed sandy land and sandy land on flood plain as sample plots. The mechanism how aeolian sand movement affects soil grain size fraction and nutrients content of aeolian sandy land was discussed based on field sand movement observation and wind velocity and direction data from 1980 to 2006 from the Lhasa Airport meteorological station. The results showed that 1) The soil pH value of aeolian sandy land in the study area was neutral, alkaline or strong alkaline, and soil organic matter ( SOM) and total nitrogen ( TN) content were rather low, whereas total phosphorus ( TP) and total potassium ( TK) were very high. The soil grain size fraction followed the order of sand content (53. 83% -95. 93% ) > silt content (3. 3% -40. 5% ) > clay content (0. 77% -5. 68% ) , and the clay and silt content both presented rather low. 2) The clay and silt content was highest in sandy land on flood plain (4. 02% and 27. 95% , respectively) , whereas that was lowest in semi鄄fixed sandy land (1. 35% and 5. 27% , respectively) . The clay