COS 44-3 - CANCELLED - Selecting seed for restoration: exploring relationships between source climate and population-level variation in germination

Abstract: Restoration practitioners are increasingly interested in including native forbs in restoration seed mixes, but more information is needed regarding critical life-history barriers to establishment, like seed germination. Many arid land forbs experience seed dormancy that is released by temperature and moisture cues; however, arid land plants also tend to be locally adapted to the environmental conditions at their population origin. Understanding relationships between seed germination cues and environmental characteristics at seed source locations can inform optimal seed selection and improve restoration outcomes. We tested population-level variation in germination characteristics across 20 populations for each of two forb species of interest for use in restoration, Chaenactis douglasii and Machaeranthera (Dieteria) canescens, to quantify differences in response to varying lengths of cold stratification (0, 2, 6, 10 weeks). Populations were selected based on variation in winter minimum temperature and aridity at source locations. We used a standard germination protocol with cold stratification occurring at 2C, after which seed was placed at 15C for the remainder of the experiment. We observed population-level differences in both the rate of germination and the quantity of seeds that germinated in response to the germination treatments and that seeds from some populations were able to germinate during cold stratification. We also found that some populations were more variable in their response to the treatments than others. We will explore how these differences relate to different characteristics at their environments of origin. We will then discuss how this information can be used to inform seed selection for restoration.