Species and Population-Level Variation in Germination Strategies of Cold Desert Forbs Sarah C Barga and Elizabeth A Leger Natural Resources and Environmental Science University of Nevada, Reno

Seed dormancy is a common life history trait Why? Persistence during unfavorable conditions Reduction in seedling competition Match timing of germination with resource availability

Factors shaping the evolution of seed dormancy Environmental variability Range size and dispersal distance Avoid competition with other species

Germination syndromes of cold desert forbs Winter germinators Facultative winter germinators Spring germinators

Practical applications of species specific knowledge Learn how to break dormancy for seed increase Understand when to seed certain species (fall vs. spring) Understand variation among populations -- are some more dormant than others?

We investigated 10 Great Basin forb species and asked: What are the dominant germination strategies? How much within-species variation exists in germination cues? What characteristics correlate with variation within a species? – Environmental characteristics – Species characteristics

11 mi. Seed Collection 2-3 populations each ~50 plants per population Collections throughout the season Seed viability testing Reno Carson City

Seed Collection 10 species 6 annual and 4 perennial plants

Seed Collection (cont.) 10 species 6 annual and 4 perennial plants

° Seed Treatments Factorial seed treatments varied the following: After-ripening temperature (hot, cool) Cold stratification (2 C for 0, 2, 4, or 6 weeks)

Data Analysis Survival Analysis Number of seeds germinated Timing of germination Time (Days) Probability of Not Germinating

My Questions What are the dominant germination strategies? How much within-species variation exists in germination cues?

Some species had significant after-ripening preferences

Half were able to germinate at 2 C …thus identifying them as winter germinators °

Species level differences in germination strategies Gilia inconspicuaChaenactis douglasii Time (Days) Probability of Not Germinating Time (Days)

Probability of Not Germinating Time (Days) Generalist germination strategies Agoseris grandifloraCryptantha pterocarya

Time (Days) Probability of Not Germinating Time (Days) Some species possessed high levels of seed dormancy Mentzelia albicaulisPhacelia hastata

We found population level differences in germination strategies Nine species had population-level differences! Some more dramatic than others

Time (Days) Probability of Not Germinating Time (Days) We found population level differences in germination strategies Crepis intermediaGilia inconspicua

In Summary... Four species remain dormant during summer conditions (AGGR, MIGR, PHHA, CHDO) Five species can germinate in the winter (AGGR, BLSC, COPA, CRPT, MIGR) Three species prefer fall seeding (CRIN, CHDO, PHHA) Two species prefer spring seeding (GIIN, MEAL) Nine species had population-level differences - all but COPA

Can population-level variation be explained by species characteristics? Quantify population-level variation within each species Species characteristics – Range size – Environmental variation Total annual precipitation Climate water deficit Is variation in these factors correlated with increased population-level variation? Total Annual Precipitation (in) Species A Species B

Habitat Distribution Modeling Collinsia parviflora Gilia inconspicua

Other Related Work Seed bank dynamics in sagebrush steppe – Type of disturbance – Intensity of disturbance Is there restoration potential in the soil seed bank?

Seed bank diversity so far!

Thank You! Brittany Trimble, Lyndsey Boyer, Travis Allen, Vicki Thill, and Brianna Koorman Great Basin Native Plant Project Seeds of Success Nevada Native Plant Society University of Nevada, Reno Ecology, Evolution, and Conservation Biology Program

Questions?

Species Specific Details SpeciesAfter Ripening (Hot/Cool) Winter Germinator Spring Germinator Population Differences Number of Pops/Seeds Annual or Perennial Agoseris grandifloraHotYes 3/2400Perennial Blepharipappus scaberNoneYesNoYes2/1600Annual Chaenactis douglasiiCoolNoYes, ColdYes3/2400Perennial Collinsia parvifloraNoneYes No3/1800Annual Crepis intermediaNoneNoYes, ColdYes3/2200Perennial Cryptantha pterocaryaNoneYes 3/1300Annual Gilia inconspicuaNoneNoYes, No ColdYes3/2200Annual Mentzelia albicaulisNoneNoYes?Yes3/2400Annual Microsteris gracilisHotYes 3/800Annual Phacelia hastataHotNoYes?Yes3/1400Perennial