Abstract Detail

Ecological Section

Foxx, Alicia J. [1], Kramer, Andrea [2].

Variation in population level rooting traits in Elymus elymoides and its potential ecological role.

Root traits provide important information on functional plant attributes yet are rarely integrated into the knowledge base of appropriate plant material selection for restoration. Furthermore, the impacts of population level variation in root traits of restoration material have been overlooked. For these reasons the root distribution and structure of seedlings from twelve populations of Elymus elymoides spp. elymoides (squirreltail) were quantified using agar as a growth medium. Squirreltail is a native perennial bunchgrass frequently used in restoration in the Colorado Plateau that has been shown to exhibit significant among-population variation in many above- and below-ground traits. The root growth of all squirreltail populations was compared to growth in seedlings of Bromus tectorum, an annual invasive grass found on the Colorado Plateau with a dense fibrous root system that proficiently sequesters soil water and outcompetes most native plants. Results showed significant variation among squirreltail populations in root length, main root axes number and lateral root axes number. Two squirreltail populations were chosen for use in a greenhouse study imposing competition from cheatgrass and a water stress gradient. One squirreltail population (Ashley National Forest, UT collection), whose seedlings had a similar number of main root axes and lateral axes as cheatgrass, represents direct spatial overlap of soil resources with cheatgrass, and thus may acquire more resources. The second population (Fishlake National Forest, UT collection), whose seedlings had fewer main root axes and lateral axes than cheatgrass, represents indirect soil resource overlap with cheatgrass. While all squirreltail seedlings died under cheatgrass competition, a time of death analysis showed that the Ashley squirreltail population persisted longer than the Fishlake population suggesting that seedling traits such as a more robust root system positively influences seedling establishment. The water stress gradient revealed differing allocation strategies and plastic responses to water stress in each population: the Ashley population allocated more biomass to roots and had a stronger plastic response to water stress while the Fishlake population allocated more biomass to aboveground growth. These results suggest that asymmetries in rooting structures of seedlings of different populations are indicative of asymmetries in rooting structure of the adult plant. This understanding of among-population variation in root traits, and its potential implications for growth and survival in competitive or stressful conditions, can be used to select appropriate native plant materials that can improve native plant restoration outcomes in cheatgrass-dominated sites.

1 - Northwestern University & The Chicago Botanic Garden, Plant Biology and Conservation, 1000 Lake Cook Road, Plant Conservation Science Center, Glencoe, IL, 60022, USA
2 - Chicago Bo, Plant Conservation Sciences, 1000 Lake Cook Road, Plant Conservation Science Center, Glencoe, IL, 60022, United States

Keywords:
Elymus elymoides
Population variation
Phenotypic plasticity
Root structure.

Presentation Type: Oral Paper:Papers for Sections
Session: 47
Location: Clearwater/Grove
Date: Tuesday, July 29th, 2014
Time: 2:45 PM
Number: 47004
Abstract ID:715
Candidate for Awards:None