SPATIO-TEMPORAL ANALYSIS OF LANDSCAPE PATTERNS IN THE CATOLÉ WATERSHED, NORTHERN MINAS GERAIS1

ABSTRACT The aim of this study was to quantify the spatio-temporal changes in land use/ cover (LULC), as well as analyze landscape patterns over a 20-year period (1995 - 2015) in the Catolé watershed, northern Minas Gerais State, using landscape metrics. The LULC maps were obtained using Landsat 5 and 8 data (Processing level 1) through supervised classification using the maximum likelihood classifier. Seven thematic classes were identified: dense vegetation, sparse vegetation, riparian vegetation, cropland, planted forest, bare soil, and water. From the LULC maps, classes related to the natural landscape (dense, sparse, and riparian vegetation) were grouped into forest patches, which was then ordered by size: very small (< 5 ha); small (5 - 10 ha); medium (10 - 100 ha); large (100 ha); and a general class (no distinction of patch size). Then, metrics of area, size and density, edge, shape, proximity and core area were calculated. The dense vegetation portion of the study area decreased considerably within a given time, while the portion of cropland and bare soil increased. Overall, in the Catolé river basin, the total area of natural vegetation decreased by 3,273 hectares (4.62%). Landscape metrics analysis exhibited a reduction in the number of very small patches, although the study area was still considered as fragmented. Moreover, a maximum edge distance of 50 m is suggested for conducting studies involving core area metrics in the Catolé watershed, as values above this distance would eliminate the very small patches.

摘要 本研究以米纳斯吉拉斯州北部的卡托莱流域为研究区，借助景观指数（landscape metrics），量化分析了1995-2015年这20年间的土地利用/覆被（Land Use/Cover, LULC）时空动态变化，并解析了流域内的景观格局。研究通过最大似然分类器（maximum likelihood classifier）开展监督分类，利用陆地卫星5号、8号（Landsat 5/8）的处理级别1（Processing level 1）数据生成了LULC地图。研究共识别出7个主题类别：茂密植被、稀疏植被、河岸植被、耕地、人工林、裸土与水体。从LULC地图中，将与自然景观相关的类别（茂密植被、稀疏植被、河岸植被）合并为森林斑块，并按斑块面积划分为5个等级：极小斑块（<5公顷）、小斑块（5-10公顷）、中斑块（10-100公顷）、大斑块（≥100公顷）以及不区分斑块大小的通用类别。随后计算了面积、大小与密度、边缘、形状、邻接性及核心面积相关的景观指数。研究时段内，研究区茂密植被占比显著下降，而耕地与裸土占比则有所上升。整体而言，卡托莱流域的自然植被总面积减少了3273公顷（占比4.62%）。景观指数分析结果显示，极小斑块的数量有所减少，但研究区整体仍处于破碎化状态。此外，在卡托莱流域开展涉及核心面积指数的相关研究时，建议采用50米的最大边缘距离阈值，因为超过该阈值将无法统计到极小斑块。