|GORNISH, ELISE - University Of California|
|AANDERUD, ZACHARY - Brigham Young University|
|Rinella, Matthew - Matt|
|ENGLUND, SUZANNE - Brigham Young University|
|JAMES, JEREMY - University Of California Agriculture And Natural Resources (UCANR)|
Submitted to: Oecologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2014
Publication Date: 2/1/2015
Publication URL: http://handle.nal.usda.gov/10113/60843
Citation: Gornish, E.S., Aanderud, Z.T., Sheley, R.L., Rinella, M.J., Svejcar, A.J., Englund, S.D., James, J.J. 2015. Altered snowfall and soil disturbance influence the early life stage transitions and recruitment of a native and invasive grass in a cold desert. Oecologia. 177:595-606. doi: 10.1007/s00442-014-3180-7.
Interpretive Summary: Climate change is predicted to result in less snow and higher snowfall variability in much of the western US. Snowfall can potentially impact seedling establishment of important rangeland species, but this topic has received little research attention. In a field study we found that deeper snowpack increased seedling establishment of both a common native bunchgrass and an invasive annual. Reduced snowpack could potentially make it more difficult to establish desirable species on western rangelands. Our results will help land managers better predict when seedling establishment is likely to occur.
Technical Abstract: Climate change effects on plants are expected to be primarily mediated through early life stage transitions. Snowfall variability, in particular, may have profound impacts on seedling recruitment; structuring plant populations and communities, especially in mid-latitude systems. These water-limited and frequently invaded environments experience tremendous variation in snowfall and the species in these systems must contend with harsh winter conditions and frequent disturbance. In this study, we examined the effects of snowpack depth and soil disturbance on the germination, emergence, and establishment of the native Pseudoroegnaria spicata and the invasive Bromus tectorum; two widely distributed grass species across the cold deserts of North America. The absence of snow in winter exposed seeds to an increased frequency and intensity of freeze-thaw cycles, and greater fungal pathogen infection. Moreover, a shallower snowpack promoted the formation of a frozen surface crust, reducing the emergence of both species (although, more so for P. spicata). Conversely, a deeper snowpack substantially recharged the soil and improved seedling establishment of both species by creating higher and more stable levels of soil moisture availability following spring-thaw. Experimental disturbance also served to decrease cumulative survival of both species across several snow treatments. Furthermore, we observed that regardless of snowpack treatment the majority of seed mortality (70-80%) occurred between seed germination and seedling emergence, suggesting that other wintertime factors or just winter conditions in general limited survival. Our results suggest that snowpack variation and legacy effects of snowpack influence emergence and establishment, but might not facilitate invasion of cold deserts.