Abstract
AbstractIn the Great Basin, native plant species Crepis acuminata Nutt. (tapertip hawksbeard) and Sphaeralcea ambigua A. Gray (desert globemallow) play crucial roles in supporting ecological stability and have growing interest for use in restoration efforts. They are recognized for their adaptability to disturbed habitats post-fire and their importance in supporting wildlife, including the greater sage-grouse and the desert tortoise. These plant species are pivotal in restoration strategies aimed at combating habitat degradation. This thesis presents two studies, one with Crepis acuminata and another with Sphaeralcea ambigua, examining the effects of biochar media amendment and varying nitrogen forms on the growth and development within a controlled nursery setting. Utilizing conifer sourced biochar concentrations (0%, 15%, and 30% by volume) combined with three nitrogen fertilizers (ammonium as (NH₄)₂SO₄, nitrate as Ca(NO₃)₂, ammonium nitrate as NH₄NO₃), we evaluated their effects on below and aboveground traits, including germination and plant height, biomass production, root architecture, and leaf fluorescence.
C. acuminata had increased germination rates with the presence of biochar, peaking at a 15% biochar concentration. This suggests that biochar can create a more conducive environment for seed germination, likely due to additional moisture retention. However, the effect appeared to diminish slightly at the highest biochar concentration, indicating an optimal range for biochar's positive impact on germination. Biochar amendments significantly decreased media electrical conductivity and increasing pH. Increasing biochar concentrations led to notable increases in total root biomass, across both species; S. ambigua exhibited significant increases in root length, area, and diameter with biochar addition, suggesting enhanced root system development and nutrient uptake capabilities. Aboveground, the responses varied between species, with S. ambigua height and leaf area responding to biochar, indicating a positive adaptation to the increased water retention and nutrient availability provided by biochar amendments. Comparatively, greater responses of C. acuminata height, leaf counts, and leaf areas were seen under the ammonium nitrate form.
These studies underscore the potential of biochar as a media amendment to bolster the growth and ecological function of native plant species in restoration efforts. By highlighting the specific responses of Crepis acuminata and Sphaeralcea ambigua to biochar and nitrogen form, this study contributes valuable insights into altering nursery practices to improve seedling development and improve restoration efforts to assist sagebrush (Artemisia spp. Nutt.) and desert communities by providing habitat for sage grouse, desert tortoise, and pollinators.