Tang Hong, Zhang Lin-Tong
College of Forestry, Gansu Agricultural University, Lanzhou 730070, China.
Huan Jing Ke Xue. 2025 Jun 8;46(6):3645-3655. doi: 10.13227/j.hjkx.202401244.
Lanzhou is a typical banded plateau river valley city. This study provides a reference for vegetation restoration， soil and water conservation， and ecological environmental protection of the plateau river valley city. It also supports the sustainable development of Lanzhou. Using remote sensing image data from 2000 to 2020， we analyzed the spatial and temporal trends of vegetation NDVI during the growing season in Lanzhou. We employed the R/S index， Sen slope analysis， MK test， and coefficient of variation to conduct our analysis. Additionally， we used geodetic probes to comprehensively analyze the effects of both natural and anthropogenic factors on the spatial variation of vegetation NDVI. The results indicate that： ① From 2000 to 2020， the vegetation NDVI in the anthropogenic area was mainly of medium grade， with a growth rate of 0.004 8 a. The trends observed were 'insignificant degradation' and 'continuous degradation'. ② The vegetation in the inactive area showed mainly medium-low and low grades of NDVI， with a growth rate of 0.005 8 a， indicating a trend of 'not significantly improved' and 'continuously improved'. The stability of vegetation growth was poor. ③ In Lanzhou， the NDVI of the vegetation in the improvement area accounted for 83.5%， while the degradation area accounted for 16.3%. The high fluctuation change area accounted for 51.1%， and the low fluctuation change area accounted for only 5.7%. ④ Soil type， vegetation type， and precipitation were natural factors that affected vegetation change. Meanwhile， land use type and population density were anthropogenic factors that also had an impact on vegetation change. ⑤ In the factor interaction analysis， vegetation type and precipitation were the main factors affecting the spatial distribution of vegetation NDVI， and slope， slope direction， population density， GDP， agricultural value added， and industrial value added were the indirect factors. ⑥ Based on the analysis of various factors， it is evident that the optimal soil type was drench soil， the preferred land type was woodland， the suitable vegetation type was coniferous forest， and the ideal elevation range was between 3 500 to 3 671 meters. Overall， the NDVI of vegetation in Lanzhou was in the middle to low grade， and the growth stability of the vegetation was relatively poor. However， there is a trend of improvement for the future. In contrast， the vegetation growth stability was higher， and the vegetation NDVI grade was higher in the anthropogenic area， while the non-anthropogenic area had lower vegetation growth stability and NDVI grade. Soil had the greatest influence on vegetation growth， making it a key challenge for ecological management in Lanzhou. This highlights the need to consider human activities when assessing vegetation growth. Anthropogenic factors have a slow but steady impact， surpassing other factors in their influence.
兰州是典型的带状高原河谷城市。本研究为高原河谷城市的植被恢复、水土保持和生态环境保护提供参考，也为兰州的可持续发展提供支撑。利用2000年至2020年的遥感影像数据，分析了兰州生长季植被归一化植被指数（NDVI）的时空变化趋势。采用重标极差（R/S）指数、森斜率分析、曼肯德尔（MK）检验和变异系数进行分析。此外，利用地理探测器综合分析自然和人为因素对植被NDVI空间变异的影响。结果表明：①2000年至2020年，人为活动区植被NDVI以中等等级为主，年增长率为0.004 8，呈现“不显著退化”和“持续退化”趋势。②非活动区植被NDVI主要为中低等级和低等级，年增长率为0.005 8，呈现“未显著改善”和“持续改善”趋势，植被生长稳定性较差。③在兰州，植被改善区NDVI占83.5%，退化区占16.3%。高波动变化区占51.1%，低波动变化区仅占5.7%。④土壤类型、植被类型和降水量是影响植被变化的自然因素。同时，土地利用类型和人口密度是影响植被变化的人为因素。⑤在因子交互作用分析中，植被类型和降水量是影响植被NDVI空间分布的主要因素，坡度、坡向、人口密度、国内生产总值、农业增加值和工业增加值是间接因素。⑥基于各因素分析，最优土壤类型为淋溶土，最优土地类型为林地，适宜植被类型为针叶林，理想海拔范围为3500至3671米。总体而言，兰州植被NDVI处于中低等级，植被生长稳定性较差，但未来有改善趋势。相比之下，人为活动区植被生长稳定性较高，植被NDVI等级较高，而非人为活动区植被生长稳定性较低，NDVI等级较低。土壤对植被生长影响最大，是兰州生态治理的关键挑战。这凸显了在评估植被生长时考虑人类活动的必要性。人为因素影响缓慢但稳定，其影响力超过其他因素。
