Abstract Detail

Ecological Section

Drenovsky, Rebecca [1], Thornhill, Megan [2], James, Jeremy [3].

Environmental stochasticity, not resource limitation, drives fecundity and recruitment in perennial bunchgrasses.

A major goal of restoration ecology is to establish self-sustaining populations. Although many studies have examined the impact of resource limitation on adult plant performance, only a few studies have assessed how the maternal environment influences subsequent recruitment. Our objective was to determine how water and nutrient amendments influenced maternal plant growth and seed production, as well as survivorship and recruitment of seedlings in three perennial bunchgrass species (Elymus elymoides, Festuca idahoensis, and Pseuderoegneria spicata). All three species are commonly used in restoration projects in the Intermountain West, USA. For three years, resource amendments (water, NPK, water+NPK) were applied to the three species of naturally established perennial bunchgrasses and compared to control plants receiving no resource amendments. Maternal plant biomass was co-limited by nutrients and water (P=0.02), although the magnitude of response to resource amendment varied by species. In contrast, water and nutrient amendment had no significant effect on total seed production per plant (P>0.05), despite large and significant variation in seed production between years (P=0.01). Across all treatments, seed germination and seedling recruitment under field conditions was very low, with maternal environment (i.e., resource amendment) having no significant impact on either variable (P>0.05). Together, these data suggest that resource limitations limit maternal plant growth, but temporary increases in soil resource availability following natural disturbances or above average precipitation years may not increase plant fitness or population growth. While below ground resources may limit the growth and survival of established plants in arid systems, fecundity and population growth appear to be limited by non- below ground factors and may include complex sets of aboveground environmental conditions and cues that vary substantially across years.

Broader Impacts:

1 - John Carroll University, Biology Department, 1 John Carroll Blvd, University Heights, OH, 44118, USA
2 - John Carroll University, Biology, 1 John Carroll Blvd, University Heights, OH, 44118, USA
3 - SIerra Foothills Research and Extension Center, 8279 Scott Forbes Road, Browns Valley, CA, 95918, USA

Keywords:
fitness
fecundity
restoration
aridlands
nitrogen
Phosphorus.

Presentation Type: Oral Paper:Papers for Sections
Session: 32
Location: Marlborough B/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 2:00 PM
Number: 32003
Abstract ID:305
Candidate for Awards:None