Description
Mean Species Abundance (MSA) is an estimate of the mean abundance of original species relative to their abundance in undisturbed ecosystems. The MSA is generally an indicator for biodiversity as it measures the abundance of original species in relation to the ecosystems in which they exist. A score of 0 means that the area has been completely destroyed. A score of 1 means that the area is largely intact. These layers contain the area-weighted mean MSA for watershed regions at different HUC levels.
Technical Description
The Mean Species Abundance (MSA) metric serves as an indicator of the intactness of local biodiversity. MSA values range from 0 to 1, with 1 indicating a completely intact species assemblage, and 0 indicating the local extinction of all original species. MSA is determined by comparing the current abundance of individual species under certain pressures to their abundance in an undisturbed or natural reference state. The calculation includes only those species that are present in the undisturbed state, and disregards any increase in species abundance from the reference to the impacted state. This approach prevents the indicator from being skewed by species that thrive in disturbed habitats. The MSA data is produced using the GLOBIO model by Schipper et al., 2020 which assesses local terrestrial biodiversity intactness using the mean species abundance (MSA) indicator, which is influenced by six human pressures: land use, road disturbance, fragmentation, hunting, atmospheric nitrogen deposition, and climate change. At the heart of the model are established quantitative relationships between these pressures and their impacts, derived from comprehensive terrestrial biodiversity databases.
This specific historical layer evaluated the MSA for 2015 using the known land use and land cover data and the six human pressures causing the loss of biodiversity. The study estimated a global area-weighted mean MSA of 0.56 for 2015 (Schipper et al., 2020).
This Collection holds the area-weighted mean MSA for watershed regions at different HUC levels. Lake
watersheds are removed prior to calculation of the weighted averages. For more
information on the MSA itself, see the STAC Collection spatiafi-biodiversity-msa-historical-baseline-v1.0.
This dataset contains the following fields:
- weighted_average_msa: The area-weighted mean MSA value for the watershed region at the specified HUC level.