Get reliable rangeland science

There are 234 indigenous tribes within 225,365 km2 of tribally managed drylands within the conterminous United States of America (USA). A national report on the carbon dynamics of US Tribal drylands argued that a knowledge gap existed for these dynamics in drylands because data, publications, and research were nonexistent. However, carbon stocks of Tribal lands have been implicitly studied, and a few explicit studies have used poor experimental design to produce questionable results. We explicitly address the carbon dynamics knowledge gap by defining Tribal dryland extent using the aridity index (AI) and a time series of Moderate Resolution Imaging Spectroradiometer (MODIS) 250-m pixel resolution net primary productivity or NPPM250, g C m-2 yr-1 from 2001 to 2019 of US drylands. We compared the 19-year mean NPP of the rangeland and cropland land uses within the tribal, public, and private land ownerships within their shared ecoregions. We compared the ecological resilience of tribal and non-tribal rangeland's NPP in response to the 2002 global change-type drought. We mapped aridity thresholds associated with land degradation and used the thresholds to identify tribal lands vulnerable to increasing aridity. We conducted these analyses at multiple scales using open-source GIS software, including Google Earth Engine (GEE) and QGIS. We found that Tribal rangeland and cropland land uses had greater productivity than non-tribal drylands. We found that Tribal rangelands had greater ecological resilience in the face of a global change-type drought than non-tribal drylands. However, we also found that with increasing aridity, 86% of the Tribal land area exhibits potential vulnerabilities that include declines in food security, species richness, canopy cover, productivity, and soil fertility. These potential vulnerabilities suggest the need for complementary field and remote sensing studies to determine the integrity of these predictions.