基于Landsat影像的春坤山自然保护区植被盖度动态变化特征

Characteristics of Dynamic Changes of Vegetation Coverage in Chunkun Mountain Nature Reserve Based on Landsat Image

为探究围封禁牧对自然保护区植被覆盖度长期动态变化趋势的影响,以包头春坤山自然保护区为研究对象,选用2013、2015、2018、2019、2021年5期的Landsat-8卫星影像数据,提取归一化植被指数,结合现场植被调查,分析保护区内部和外围放牧区植被盖度的时间、空间变化特征。结果显示:(1)2013—2021年保护区植被盖度呈整体稳定、局部退化趋势,且阴坡平均植被盖度高于阳坡;空间上呈“中部高、周边低、阴坡高、阳坡低”的分布格局,退化区域主要分布于地势低、坡度大的区域。(2)保护区内植被盖度随海拔升高呈增加趋势。(3)保护区内植被盖度年际变化与年降水量呈正相关关系,要加强对降雨少,盖度较低时期的保护区管理。(4)保护区内植被盖度显著高于保护区外(P<0.05),围封禁牧有利于植被恢复。综上所述,基于包头春坤山保护区的数据结果,建议同类保护区要加强非生长季的管理,在保护区内重视对地势低、坡度大的区域进行监测与管护。

In order to investigate the influence of enclosed grazing ban on the long-term dynamic change trend of vegetation coverage in nature reserves,by taking Baotou chunkun mountain Nature Reserve as the research object,Landsat-8 satellite image data of five periods in 2013,2015,2018,2019 and 2021 were selected to extract the normalized vegetation index,and the temporal and spatial change characteristics of vegetation coverage in the interior and peripheral grazing areas of the reserve were analyzed in combination with the field vegetation survey.The results found that:(1)From 2013 to 2021,the overall vegetation coverage of the reserve is stable and locally degraded,and the average vegetation coverage of the shaded slope was higher than that of the sunny slope;spatially,the distribution pattern is“high in the middle,low in the periphery,high on the shaded slope and low on the sunny slope”,and the degraded areas were mainly distributed in the areas with low terrain and large slope.(2)Vegetation coverage in the reserve tends to increase with elevation.(3)The interannual variation of vegetation coverage in the reserve was positively correlated with the annual precipitation,and it is necessary to strengthen the management of the reserve in the period of low rainfall and low coverage.(4)The vegetation coverage inside the reserve was significantly higher than that outside the reserve(P<0.05),and the enclosed grazing ban was beneficial to vegetation recovery.In summary,based on the results of the data from the Baotou Chunkun Mountain Reserve,it is recommended that similar reserves should strengthen management during the non-growing season and pay attention to monitoring and management of areas with low terrain and high slopes within the reserve.