关键词: 养分再吸收效率, 植被恢复, 草本植物, 枯落物, 叶片

Abstract: Four remote sensing images from Landsat TM/ETM⁺/TIRS in 1987, 2000, 2006 and 2013 were used to invert the land surface temperature (LST) of Golmud oasis. The LST values were normalized and the grade figures of LST were obtained. Then the transition matrix of the grade figures of LST from two adjacent dates was constructed. Furthermore, the normalized vegetation index (NDVI) and land use/land coverage change (LUCC) were used to analyze the spatiotemporal variation and the causes of cold island effect in Golmud oasis. Overall, in the last 27 years, the LST in the oasis presented a spatial pattern of lower temperature center in high vegetation coverage and it ascended from the center to surrounding areas. Oasis cold island effect was significant, and had a strongweakstrong variation. There was a remarkable negative correlation between normalized surface temperature (NLST) and NDVI that coincided with the changes of the cold island effect, indicating that the vegetation played an important role in the cold island effect. The area increased for farmland and woodland in 2000, decreased for farmland and water bodies in 2006, and increased for farmland, woodland and urban greening in 2013. Woodland, farmland, grassland and water bodies had the priority position in the lowest three grades of LST, and their temperature reduction roles were of significance in maintaining the stability of oasis cold island effect.

Key words: vegetation recovery, herbaceous plant, leaf, nutrient reabsorption efficiency, litter