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Though North America9s boreal forest contains some of the largest remaining intact and wild 29 ecosystems in the world, human activities are systematically reducing its extent. Consequently, forest 30 intactness and human influence maps are increasingly used for monitoring and conservation planning in 31 the boreal region. We compare eight forest intactness and human impact maps to provide a multi-32 model assessment of intactness in the boreal region. All maps are global in extent except for Global 33 Forest Watch Canada9s Human Access (2000) and Intact Forest Landscapes (2000, 2013) maps, although 34 some global maps are restricted to areas that were at least 20% treed. As a function of each map9s 35 spatial coverage in North America, the area identified as intact ranged from 55% to 79% in Canada and 36 from 32% to 96% in Alaska. Likewise, the similarity between pairs of datasets in the Canadian boreal 37 ranged from 0.58 to 0.86 on a scale of 0-1. In total, 45% of the region was identified as intact by the 38 seven most recent datasets. There was also variation in the ability of the datasets to account for 39 anthropogenic disturbances that are increasingly common in the boreal region, such as those associated 40 with resource extraction. In comparison to a recently developed high resolution regional disturbance 41 dataset, the four human influence datasets (Human Footprint, Global Human Modification, Large Intact 42 Areas, and Anthropogenic Biomes), in particular, omitted 59-85% of all linear disturbances and 54-89% 43 of all polygonal disturbances. In contrast, the global IFL, Canadian IFL, and Human Access maps omitted 44 2-7% of linear disturbances and 0.1-5% of polygonal disturbances. Several differences in map 45 characteristics, including input datasets and methods used to develop the maps may help explain these 46 differences. Ultimately, the decision on which dataset to use will depend on the objectives of each 47 specific conservation planning project, but we recommend using datasets that 1) incorporate regional 48 anthropogenic activities, 2) are updated regularly, 3) provide detailed information of the methods and 49 input data used, and 4) can be replicated and adapted for local use. This is especially important in 50 landscapes that are undergoing rapid change due to development, such as the boreal forest of North 51 America. |
