Modifying landscape connectivity by reducing wind driven sediment redistribution, northern Chihuahuan Desert, USA

TitleModifying landscape connectivity by reducing wind driven sediment redistribution, northern Chihuahuan Desert, USA
Publication TypeJournal Article
Year of Publication2015
AuthorsRachal DM, Okin GS, Alexander C., Herrick JE, Peters DC
JournalAeolian Research
Start Page129
Date Published06/2015
Accession NumberJRN00641
ARIS Log Number291337
Keywordsaeolian transport, connectivity, desertification, sediment redistribution, short lived radionuclides, shrub encroachment

Shrub encroachment into perennial grasslands is occurring in many arid and semi-arid parts of the world. As shrubs displace perennial grasslands, bare patches coalesce to enhance soil erosion and sediment fluxes by wind and water transport. Reducing the connectedness of these sediment transport pathways could slow or stop grassland loss by limiting sediment redistribution. To test this hypothesis, sediment retention structures, hereafter called “Connectivity Modifiers” (Con-Mods), were placed within bare gaps of existing shrublands on two sites: the basin floor and a bajada at the Jornada Basin USDA-  LTER in southern New Mexico. Short-lived radionuclide (210Pbex, 137Cs, and 7Be) and sediment collectors were used to determine if these structures are affecting seasonal aeolian sediment transport within bare gaps. Con-Mods contained 30 to 50% higher surface radionuclide activities than control plots on the basin floor. However, there was no detectible difference between surface activities for the structures and control plots on the bajada site. Net sediment flux rates at 10 cm height indicate a loss of -2.5 to -14.2 g m-2 d-1 for both landform units for the monsoon season (Jul-Nov), while the basin floor site was the most responsive in reducing sediment transport by collecting 16.5 g m-2 d-1 over the windy season (Dec-May). This study demonstrates that changes in connectivity by wind can influence sediment movement. Altering sediment transport through bare gaps could influence ecosystem state changes in arid and semi-arid systems; thereby increasing the likelihood of recruitment of native grasses and other herbaceous plants.