Effects of soil texture on establishment and growth of a deep rooted native and non-native plant

Effects of soil texture on establishment of deep rooted plants are poorly understood in semiarid and arid regions where land degradation is occurring. Climate change predictions suggest drier conditions will occur in the West especially in lower elevation grassland and shrublands which may alter vegetation communities. My goal was to answer how will establishment and growth of a native and non-native deep rooted plant change over a fine to coarse soil texture gradient. I conducted greenhouse and field experiments to assess soil textures effect on deep rooted plant establishment. For both the greenhouse and field experiment the soil texture gradient consists of four amended soils: 90% sand (6% clay), 80% sand (12% clay), 70% sand (19% clay), and 54% sand (29% clay).;In the greenhouse I evaluated the effects of nitrogen availability on a native shrub Artemisia tridentata (Nutt. ssp wyomingensis ) Beetle & Young (Wyoming big sagebrush), an introduced C3 grass (Agropyron cristatum (L.) Gaertn. (crested wheatgrass) and a non-native perennial forb Linaria dalmatica (L.) Mill (Dalmatian toadflax). Plants received either no nitrogen treatment, low nitrogen treatment (equivalent to 2 gN/m2) or a high nitrogen treatment (6 gN/m2). Biomass was collected after three months and my results show nitrogen treatments had no affect on Wyoming big sagebrush biomass, but Dalmatian toadflax and crested wheatgrass were affected by soil texture and nitrogen treatments.;In the field I evaluated the effect of soil texture on establishment and growth of Wyoming big sagebrush and Dalmatian toadflax. Soil sensors monitored depth of soil water and bi-weekly height measurements monitored plant success. Half of Wyoming big sagebrush plants were harvested at the end of one growing season to measure biomass and my results show fine soil textures produced the largest biomass and coarse soil textures produced the least biomass. Wyoming big sagebrush growth rates did not differ statistically across soil textures as 2010 precipitation was above average.;However, in 2009 soil texture significantly affected the number and length of Dalmatian toadflax branches. Once established, soil texture had no statistical significance on Dalmatian toadflax although plant height was greatest on coarse soils and smallest on fine soils. Soil moisture decreased substantially in early 2009, but the observed decrease in 2010 occurred later.;My results provide insights into understanding deep rooted plant success across a soil texture gradient. Examining the influence soil texture has on soil moisture can help us understand the advantage deep rooted plants may have over shallow rooted plants in particular climatic and soil texture conditions.