A comparison of Bromus tectorum growth and mycorrhizal colonization in salt desert versus sagebrush habitat

Authors: HAUBENSAK, KAREN - Northern Arizona University; D'ANTONIO, CARLA - University Of California; EMBRY, SAUNDRA - University Of Nevada; Blank, Robert - Bob

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2014
Publication Date: 5/1/2014
Citation: Haubensak, K., D'Antonio, C., Embry, S., Blank, R.R. 2014. A comparison of Bromus tectorum growth and mycorrhizal colonization in salt desert versus sagebrush habitat. Rangeland Ecology and Management. Available: http://dx.doi.org/10.2111/REM-D-12-00024.1.

Interpretive Summary: The exotic annual grass, cheatgrass, has recently invaded low elevation salt desert communities in the Great Basin. To more fully understand soil and plant factors, which facilitate the invasion of cheatgrass, seeds of cheatgrass from salt desert and upland sagebrush communities were growth in both salt desert and upland sagebrush soils. Overall, cheatgrass grew more poorly in salt desert soils than sagebrush soils, but rapid early root growth and higher incidence of flowering of salt desert seeds may be an important population control allowing cheatgrass to invade harsh salt desert environments.

Technical Abstract: Cheatgrass has recently invaded marginal low elevation salt desert habitats across the Great Basin, USA. We tested the hypothesis that cheatgrass seed produced in populations from the more stressful salt desert versus upland sagebrush habitats should grow differently in salt desert soils compared to adjacent upland sagebrush soil, and vice versa. We evaluated growth, incidence of flowering, and arbuscular mycorrhizal fungi (AMF) colonization of plants grown in the soils from which their seeds were collected versus in the reciprocal soils from the nearest sagebrush or salt desert site in three large basins in northern Nevada. Simultaneously we characterized the different soils in terms of nutrient cations, bicarbonate phosphorus (P), net nitrogen (N) mineralization, % carbon (C) and N, soil texture, and dry-down characteristics. We found that salt desert soils were generally more nutrient poor, more saline, with higher % sand than their upland (sagebrush) counterparts. The most dramatic plant responses to soil and seed source were: (1) aboveground biomass of mature plants was lower in most salt desert soils compared to sagebrush soils, or it was lower in plants grown from salt desert-seed; (2) root:shoot ratios were lower in plants grown in salt desert soil across two of three basins and irrespective of seed source; (3) there was a higher percent of flowering individuals from salt desert seed sources at harvest, irrespective of soil source; (4) AMF colonization of plants was depressed by salt desert soils; and (5) seed source exerted a strong influence on AMF: sagebrush-originating plants grown in sagebrush soils had greater AMF colonization compared to salt desert soils but salt desert-originating seedlings had very low AMF colonization rates irrespective of the soil they were grown in. These results suggest that both population level and soil-based controls are important as this widespread weed moves into marginal habitat.