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Restoration of dryland ecosystems is often limited by low seedling establishment and survival. Defoliation caused by insects and small mammals could be an overlooked cause of seedling mortality. In the sagebrush steppe, we examined the effect of seedling defoliation on the survival of perennial grasses commonly used as restoration materials. Under field conditions, seedlings of three perennial bunchgrass species (non-native Agropyron cristatum , and native grasses Poa secunda and Pseudoroegneria spicata) were defoliated at two intensities (30 % and 70 % leaf length removal) and frequencies (one or two clippings) and compared to a non-defoliated control. Following emergence the first year, clippings occurred at the two-leaf stage; a second clipping occurred 1 month later for repeated defoliation treatments. We monitored seedling survival and tillering for 2 years. We expected higher defoliation intensity and frequency to reduce survival for all species, but only a few treatments reduced Po. secunda survival. Conversely, larger-statured Triticeae (wheatgrasses) benefited from some defoliation treatments. In both years, A. cristatum survival increased with repeated defoliation at both intensities. Defoliation did not affect Ps. spicata survival in the first year, but a single defoliation in the second year resulted in increased survival. In both A. cristatum and Ps. spicata , higher-intensity defoliation reduced the boost to survival resulting from defoliation frequency. Seedlings with more tillers had greater survival probabilities, but tiller number was unaffected by defoliation. Further research may elucidate mechanisms seedlings use to compensate for or benefit from defoliation. In the meantime, managers should aim to select defoliation-tolerant species if they anticipate herbivory will be problematic for restoration sites. [ABSTRACT FROM AUTHOR]

Seed‐based restoration is one of the most difficult challenges for dryland restoration. Identifying environmental conditions that drive variation in seed and seedling mortality across similar restoration efforts could increase understanding of when and where restoration outcomes are likely to be favourable and identify new tools and strategies to improve outcomes.We asked how variation in a suite of environmental predictors influenced germination, emergence, seedling establishment and juvenile survival of four commonly sown perennial grass species across 33 seeding experiments distributed over an ~160,000‐km2 area of the Great Basin, a cold desert system in the western United States.Across experiments, we observed wide variation in the rates of four demographic transitions and wide variation in environmental conditions experienced by plants at each stage. For all species, higher precipitation during the first 30 days following seeding was associated with an increase in germination. Conversely, higher soil temperature over this same time period was associated with a significant decrease in germination and emergence, and soil temperature was associated with a substantial portion of the variation in germination and emergence probabilities observed across our seeding experiments.Within the range of precipitation variation observed, we were unable to detect a significant relationship between seedling establishment the first growing season and cumulative precipitation the first year, precipitation during the first spring growing season or annual climatic water deficit (CWD) the first year. Higher CWD the second growing season reduced seedling survival over that time period.Synthesis and applications. Our results show higher soil temperature negatively impacts grass seedling establishment. Restoration efforts should be prioritized when seasonal or subseasonal temperature forecasts indicate likely periods of below average temperatures. These results also indicate that climate warming will make restoration even more difficult, with our model estimates suggesting the 2°C increase in temperature expected in the Great Basin over the coming decades will decrease germination and emergence by about 30%. Lastly, while our field‐based approach provided insight into short‐term drivers of mortality, it did not provide insight into drivers of longer term survival, suggesting a need for further work on predicting long‐term restoration outcomes. [ABSTRACT FROM AUTHOR]

Cultivation legacies affect native vegetation in old fields of the Great Basin, USA for nearly a century after these fields are abandoned. We hypothesized that cultivation lowered soil nutrients and that this legacy would differentially impact plant performance of four representative Great Basin species. To test these hypotheses, we compared soil nutrients (C, N, P, K, Mg and Ca) between two formerly cultivated and adjacent noncultivated sites in two soil series. We then compared the plant growth and foliar nutrient content of an exotic grass ( Bromus tectorum L.), two native grasses ( Elymus elymoides [Raf.] Swezey and Achnatherum hymenoides [Roem. and Schult.] Barkworth), and a native forb ( Sphaeralcea grossulariifolia [Hook. and Arn.] Rydb) grown in these soils in the greenhouse and in the field. Only one sampling site had reduced soil nutrients associated with cultivation legacies, where most of the negative effects on plant performance were found. E. elymoides appeared to be less affected by cultivation legacies than did A. hymenoides, which had a reduced survivorship and 20 % less above-ground biomass in cultivated soils. No species, including B. tectorum, were favored by cultivation. Our findings suggest that cultivation legacies can affect plant performance of different species in different ways and that altered soil nutrients may interact with other abiotic and biotic cultivation legacies in complex ways. [ABSTRACT FROM AUTHOR]

Revegetation of degraded shrub-steppe often fails due to intense competition from weeds, highly variable environmental conditions, and limited soil moisture. The objective of this study was to test whether a commercially available seed coating and a water-retaining acrylamide copolymer hydrogel would increase seedling emergence and establishment of crested wheatgrass (Agropyron cristatum) under three watering frequencies and two soil textures. Pots were filled with one of four soil treatments: field soil, two parts field soil mixed with one part sand, field soil plus hydrogel, or field soil plus sand plus hydrogel. We seeded the pots with coated or uncoated seed and placed them in a greenhouse for 66 days. The pots were assigned one of three watering treatments: 4.5 oz (150 ml) applied one time per week, 1 .5 oz (50 ml) applied three times per week, or 0.9 oz (30 ml) applied five times per week. We recorded seedling emergence at three and six weeks. At the end of 66 days, the numbers of seedlings that survived were counted and aboveground biomass was collected, dried, and weighed. We found that uncoated seed had 1.6 times greater seedling density than coated seed. Incorporation of the acrylamide copolymer hydrogel into the potting medium conferred some benefit to emergence, biomass, and survivorship of crested wheatgrass seedlings. However, it was watering frequency that produced the most consistent influence on seedling emergence, survival, and biomass. Watering three or five times per week increased emergence more than watering one time per week, but watering one time per week generally led to greater survivorship and biomass. This suggests that the use of water-retaining hydrogels may help to overcome soil moisture limitations and improve seedling establishment during revegetation of degraded shrub-steppe. [ABSTRACT FROM AUTHOR]