A raster version of the Circumpolar Arctic Vegetation Map (CAVM)
A raster version of the Circumpolar Arctic Vegetation Map (CAVM)
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DOI：
10.1016/j.rse.2019.111297
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发表时间：
2019-10-01
影响因子：
13.5
通讯作者：
Troeva, Elena
中科院分区：
文献类型：
--
作者：
Raynolds, Martha K.;Walker, Donald A.;Troeva, Elena
土地覆盖图是理解和模拟生态模式和过程所需的基本数据层。2003年制作的北极圈植被图已被广泛用作北极苔原生物群落研究的基础地图。然而，地图的分辨率和矢量格式相对粗糙，与许多其他数据集不兼容。我们提出了一个新版本的CAVM，建立在原来的地图的优势，同时提供更精细的空间分辨率，光栅格式，并改进映射。栅格CAVM使用原始CAVM的图例、范围和投影。传说有16种植被类型，冰川，盐水，淡水和非北极陆地。栅格CAVM将绘制加拿大地盾的原始岩石-水-植被复合体地图单元划分为两个地图单元，区分以地衣和灌木为主的植被区域。与最初手绘的CAVM相比，新地图是基于对北极17个地理/植物分区的无监督分类，使用AVHRR和中分辨率成像光谱仪数据（反射率和归一化差异植被指数）和海拔数据。使用各种辅助数据将分类得到的单元建模为CAVM类型。该地图由熟悉其特定地区的专家进行了审查，包括来自加拿大，格陵兰岛（丹麦），冰岛，挪威（包括斯瓦尔巴群岛），俄罗斯和美国的CAVM的许多原始作者。光栅CAVM的空间分辨率更高，可以对水体和山区进行更详细的测绘。该模型较原CAVM模型更好地反映了植被类型分布的异质性。从6个陆地卫星场景解释随机1公里像素的准确性评估显示，平均70%的准确性，从39%的原始CAVM。灌木主导类型的分布变化最大，在山区绘制了更多的匍匐灌木冻原，而在低地地区绘制了较少的低灌木冻原。这种改进的绘图对于量化土地覆盖的现有和潜在变化非常重要，土地覆盖是模拟和监测生态系统的关键环境指标。
Land cover maps are the basic data layer required for understanding and modeling ecological patterns and processes. The Circumpolar Arctic Vegetation Map (CAVM), produced in 2003, has been widely used as a base map for studies in the arctic tundra biome. However, the relatively coarse resolution and vector format of the map were not compatible with many other data sets. We present a new version of the CAVM, building on the strengths of the original map, while providing a finer spatial resolution, raster format, and improved mapping. The Raster CAVM uses the legend, extent and projection of the original CAVM. The legend has 16 vegetation types, glacier, saline water, freshwater, and non-arctic land. The Raster CAVM divides the original rock-water-vegetation complex map unit that mapped the Canadian Shield into two map units, distinguishing between areas with lichen- and shrub-dominated vegetation. In contrast to the original hand-drawn CAVM, the new map is based on unsupervised classifications of seventeen geographic/floristic sub-sections of the Arctic, using AVHRR and MODIS data (reflectance and NDVI) and elevation data. The units resulting from the classification were modeled to the CAVM types using a wide variety of ancillary data. The map was reviewed by experts familiar with their particular region, including many of the original authors of the CAVM from Canada, Greenland (Denmark), Iceland, Norway (including Svalbard), Russia, and the U.S. The analysis presented here summarizes the area, geographical distribution, elevation, summer temperatures, and NDVI of the map units. The greater spatial resolution of the Raster CAVM allowed more detailed mapping of water-bodies and mountainous areas. It portrays coastal-inland gradients, and better reflects the heterogeneity of vegetation type distribution than the original CAVM. Accuracy assessment of random 1-km pixels interpreted from 6 Landsat scenes showed an average of 70% accuracy, up from 39% for the original CAVM. The distribution of shrub-dominated types changed the most, with more prostrate shrub tundra mapped in mountainous areas, and less low shrub tundra in lowland areas. This improved mapping is important for quantifying existing and potential changes to land cover, a key environmental indicator for modeling and monitoring ecosystems.