Soil depth and precipitation moderate soil textural effects on seedling survival of a foundation shrub species

Authors: VEBLEN, KARI - Utah State University; NEHRING, KYLE - Utah State University; DUNIWAY, M - Us Geological Survey (USGS); KNIGHT, ANNA - Us Geological Survey (USGS); Monaco, Thomas; SCHUPP, EUGENE - Utah State University; BOETTINGER, JANIS - Utah State University; VILLALBA, J - Utah State University; FICK, STEVEN - Us Geological Survey (USGS); BRUNGARD, COLBY - New Mexico State University; THACKER, ERIC - Utah State University

Submitted to: Restoration Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2022
Publication Date: 4/8/2022
Citation: Veblen, K.E., Nehring, K.C., Duniway, M.C., Knight, A., Monaco, T.A., Schupp, E.W., Boettinger, J.L., Villalba, J., Fick, S., Brungard, C., Thacker, E. 2022. Soil depth and precipitation moderate soil textural effects on seedling survival of a foundation shrub species. Restoration Ecology. 30(6). Article e1370. https://doi.org/10.1111/rec.13700.
DOI: https://doi.org/10.1111/rec.13700

Interpretive Summary: Soil moisture is important for establishment in drylands. Because soil properties like depth and texture control soil moisture availability, we evaluated how coarser (sandier) soils promote deeper soil percolation of water and reduce surface evaporation, which can benefit sagebrush establishment in deep soils. Experiments were conducted on the Colorado Plateau across a range of soil textures and depths and sagebrush survival was monitored for two years in southeastern Utah on the Colorado Plateau. Under favorable precipitation conditions, we found that early sagebrush seedling survival was highest on coarser soils that also had a shallower bedrock contact. In contrast, under drier conditions, the effects soil texture and depth on survival were much weaker, yet older seedlings generally benefited from growing on coarser textured soils. Experiments also revealed that sheltering seedlings with small mesh cages improved their water status and survival. The probability of survival of containerized sagebrush seedlings in restoration projects can be improved by incorporating information about soil texture and depth into restoration planning under increasingly variable climatic conditions.

Technical Abstract: Soil moisture availability is a major determinant of woody plant growth and abundance in drylands and is particularly important for early seedling survival and growth. Soil properties strongly influence the timing, duration, and quantity of moisture available to plants, with soil texture and depth considered most influential. Previous work suggests that coarser (sandier) soils promote deeper soil percolation of water and reduce surface evaporation, which can benefit mature woody plants, especially in deep soils. It is unclear, however, how woody seedlings respond to coarser soil textures – or to the potentially interactive effects of depth (e.g., increased water availability in seedling rooting zones in shallower soils). Understanding how soil texture and depth influence seedling survival and growth is key to broadscale restoration efforts in western US drylands dominated by big sagebrush (Artemisia tridentata), particularly on the trailing edge of its distribution. We planted sagebrush seedlings across a range of soil textures and depths over two years in southeastern Utah on the Colorado Plateau. We repeated plantings across 20 study plots in a wet vs. average precipitation year at one site, and also examined broader patterns of sagebrush seedling survival during an average precipitation year in 56 study plots distributed across four sites. Under favorable precipitation conditions, we found that early sagebrush seedling survival was highest not only on coarser soils, but on soils that also had a shallower bedrock contact (e.g., 50 -100 cm). Under drier conditions, soil textural and depth effects on survival of the youngest seedlings were much weaker, but older seedlings nonetheless benefited from growing on coarser textured soils. We also found that it may be possible to improve moisture availability and increase survival by sheltering seedlings with small mesh cages. Our results provide new insights into important environmental factors that limit big sagebrush seedling survival, as well as detailed soil information that could increase the probability of survival of containerized sagebrush seedlings in restoration projects. This work illustrates the importance of incorporating information on soil texture and depth into restoration planning to maximize restoration success under increasingly variable climatic conditions.