>> dr. isabel ashton: one of the missions of thenational park service is to preserve and protect native prairie and one of the challenges ofthis is when we have invasive species, like cheatgrass or japanese brome, with these annualbrome grasses that can outcompete native species. so, we’re just beginning to collect dataon this but what we have been seeing is that in areas where we have a lot of annual bromeswe have a big reduction in native grasses - the number and abundance of them and alsothe number of wildflower species. so that’s a concern because of course, we’rehoping to protect those native plants. and in prairies, when you don’t have asmany wildflowers and grasses, there’s going to be cascading effects on things like birds,and pollinators, and other wildlife.
>> amanda: grassland ecosystems are foundon six continents and originally covered as much as 25% of the earth’s surface. the northern great plains is one of the largest grasslands in the world and also one of the most disturbed among grassland ecoregions- where 75% has been heavily altered by cultivation, fire, livestock grazing, and the introductionof invasive species. >> carl: end users at the national park service’s,northern great plains network collect and analyze natural resource data for long-termmonitoring throughout 13 park units in the northern great plains. this project focused on three of these parkunits located in south dakota - badlands national
park, wind cave national park, and jewel cavenational monument - with the goal of using nasa earth observations to remotely sensethe spatial and temporal patterns in annual brome grass abundance. >> jared: cheatgrass and japanese brome aretwo species of invasive annual brome grasses that are becoming widespread in the northerngreat plains grasslands. >> brennan hauk: another reason why bromesare great invaders is their ability to use resources available early in the spring thatnative plants can’t take advantage of. >> dr. amy symstad: one of the impacts of annualbrome species in the northern great plains that we’re really worried about is the negativerelationship that we find between annual brome
abundance and the richness of native prairiespecies. >> jared: vegetation phenology is the timingof seasonal developmental stages in plant life cycles including green-up, flowering,and senescence. cheatgrass and japanese brome begin startof season green-up in april and brown-down, or senesce in june. this phenology is earlier and distinct fromthe surrounding native vegetation. >> amanda: nasa earth observations were usedto capture this difference in phenology across the region. the modis instrument aboard the aqua and terrasatellites provides information on vegetation greenness. the usda's forwarn phenology dataset uses thisto determine the julian date of key phenological
events based on ndvi, the normalized differencevegetation index. leveraging the temporal resolution of modis,we used this to analyze patterns in the relative earliness of brome phenology and to relatethat with brome abundance. >> jared: higher resolution data provide thespatial resolution necessary to identify bromes from native grasses. with the timing of key phenological eventsidentified, 30m landsat imagery were obtained in order to classify likely regions of bromeusing in situ data provided by the national park service. additionally, we incorporated 10m sentinel-2data to improve and validate brome classification. >> carl: the national parks service can incorporatethese remote sensing methods using nasa earth
observations into the regional monitoringof invasive annual bromes and incorporate this information into the development of acomprehensive management plan for cheatgrass and japanese brome control in the northerngreat plains. >> dr. isabel ashton: they are really hard to managebecause they’re very widespread. there is some options of chemical control,but its hard to imagine that we’d have the money to spray the entire national park serviceunits or the whole northern great plains everywhere they are and they have a lot of seeds, soyou’d have to really get rid of them all.