汾河流域植被覆盖度时空特征与地形因子的关系

Relationship Between Temporal and Spatial Characteristics of Vegetation Coverage and Topographic Factors in Fenhe River Basin

[目的]研究汾河流域植被覆盖度在时间以及空间上的变化特征,及其与地形因子的关系,为汾河流域的绿色发展提供科学依据。[方法]基于MODIS NDVI遥感影像数据,选取汾河流域2005—2020年中的2005,2009,2013,2017,2020年数据,采用像元二分模型估算汾河流域15 a的5个时期的植被覆盖度;结合线性趋势分析研究汾河流域植被覆盖度的时空变化特征;结合DEM数据探讨植被覆盖度与地形因子的关系。[结果] 2005—2020年汾河流域的植被覆盖度总体呈现增加趋势,植被覆盖度均值超过60%,其中主要以中、中高和高植被覆盖度为主,沿着吕梁山脉和太行山脉的植被覆盖度状况良好。从地形因子对植被覆盖度的影响来看:(1)随着高程的不断增加,汾河流域植被覆盖度不断增高,在2 000 m以上的地区植被覆盖度较高;(2)随着坡度的增大,汾河流域植被覆盖度在不断提高,在大于12°的地区覆盖度达到最大;(3)坡向与汾河流域植被覆盖度关系较小,植被覆盖变化呈现平缓趋势,但在阴坡覆盖度较高。[结论]汾河流域植被覆盖状况良好,植被生长状况逐年变好,地形因子是植被生长的重要影响因素。

[Objective]The spatiotemporal variation characteristics of vegetation coverage in Fenhe River basin and their relationship with topographic factors were studied in order to provide a scientific basis for the green development of the basin.[Methods]Based on MODIS NDVI remote sensing images data,five years(2005,2009,2013,2017 and 2020)of data for the Fenhe River basin from 2005 to 2020 were selected.A pixel dichotomy model was used to estimate the vegetation coverage of Fenhe River basin over the past 15 years.The spatio-temporal variation characteristics of vegetation coverage in Fenhe River basin were studied combined with linear trend analysis.Associated with DEM data,the relationship between vegetation coverage and topographic factors was discussed.[Results]The vegetation coverage of Fenhe River basin demonstrated an increasing trend from 2005 to 2020,with an average of more than 60%,mainly medium,medium-high,and high vegetation coverage.The vegetation coverage along the Lüliang Mountains and Taihang Mountains was in good condition.The impact of topographic factors on vegetation coverage could be summarized as:①Vegetation coverage in Fenhe River basin increased continuously with increasing vegetation,and was greatest in areas higher than 2000 m in elevation.②Vegetation coverage in Fenhe River basin increased with increasing slope,and the coverage reached maximum values in areas with slopes greater than 12°.③There was little correlation between slope aspect and vegetation coverage in Fenhe River basin.Changes in vegetation coverage showed a gentle trend,but coverage was higher on shady slopes.[Conclusion]Vegetation coverage in Fenhe River basin is good,and vegetation growth is getting better year by year.Topography is an important factor affecting vegetation growth.