Department of Resources and Environmental Engineering, Ludong University, Yantai, 264025, P.R. China.
Sci Rep. 2020 May 26;10(1):8672. doi: 10.1038/s41598-020-65286-5.
The oasis-desert transition zone, the boundary between the desert and oasis, has special significance in maintaining oasis stability and indicating ecosystem health. The width of the boundary is one of the critical indicators to determine the sampling design and restrict findings scaling in the study of the desert oasis transition zone. Buffer analyze and focal analyze were conducted to determine the width among oasis-desert transition zone and oasis artificial sand fixation zone in Hexi corridor China. Focal analyses indicate that TCImax and TCImin can constrain NDVI of trend variation, and the effect increases with the analysis scale. On the same spatial scale, NDVI and TCI have opposite trends and have intersections. The intersection of the sandy desert transition zone is between 30-90 m, and the oasis artificial sand-fixaion zone is between 90-150 m. The width of the sandy desert transition zone is between 220-300 m, and the width increases with the increase of analysis scale. The oasis artificial sand-fixation zone is between 420 and 540 m, which decreases with the increase of the analysis scale. NDVI shows a trend of decreasing from the oasis boundary to the desert, the trend of TCI is different from that of NDVI, showing an increase from the edge of oasis to the interior of desert. The differences in the spatial distribution of NDVI and TCI can be clearly expressed, and different types of transition zones and analysis scales have their own characteristics.
绿洲-荒漠过渡带是荒漠与绿洲的交界地带，对维持绿洲稳定、指示生态系统健康具有特殊意义。边界宽度是确定采样设计和限制荒漠绿洲过渡带研究中发现规模的关键指标之一。本研究以河西走廊绿洲荒漠过渡带和绿洲人工固沙带为例，采用缓冲区分析和焦点分析方法确定了绿洲荒漠过渡带和绿洲人工固沙带的宽度。研究结果表明，TCImax 和 TCImin 可以约束 NDVI 的趋势变化，且这种约束作用随分析尺度的增加而增强。在相同的空间尺度上，NDVI 和 TCI 的变化趋势相反，存在交点。其中，沙质荒漠过渡带的交点在 30-90 m 之间，绿洲人工固沙带的交点在 90-150 m 之间。沙质荒漠过渡带的宽度在 220-300 m 之间，且随着分析尺度的增加而增加。绿洲人工固沙带的宽度在 420-540 m 之间，且随着分析尺度的增加而减小。NDVI 从绿洲边界向荒漠逐渐减小，TCI 的变化趋势与 NDVI 不同，表现出从绿洲边缘向荒漠内部逐渐增大的趋势。NDVI 和 TCI 的空间分布差异明显，不同类型的过渡带和分析尺度具有各自的特点。
