Abstract Detail

Ecology

Finch, Jessamine [1], Seglias, Alexandra [2], Kramer, Andrea [3], Havens, Kayri [4].

Effects of seed source vary among species, early life stages, and field sites for two milkweeds (Asclepias sp.).

A key consideration in ecological restoration is the sourcing of plant material. Ideal sourcing maximizes the likelihood that material is ecologically appropriate, while minimizing any negative genetic effects (e.g. swamping, outbreeding). In seed-based restoration, the first test of ecological suitability is germination and seedling emergence. A mismatch between seed traits and the conditions at the restoration site can serve as a major bottleneck to recruitment, ultimately reducing restoration quality and/or increasing costs. Despite their importance to restoration outcomes, empirically based seed transfer guidelines are not available for most species. Instead, practitioners rely on provisional seed transfer zones, derived from ecological and climatic data, which are intended as a generalized framework to guide seed sourcing for any species. To assess the utility of seed transfer zones, we investigated the effect of population and collection zone on field recruitment for two native congeners (Asclepias incarnata, A. syriaca). Populations (n=18) were sourced from three collection zones and sown at two field sites in the Midwest U.S. We used germination bags and grid-seeded plots to assess variation in germination, emergence, establishment, and performance. Magnitude and direction of source effects varied among species, life stages, and field sites. For A. incarnata, germination rates and aboveground biomass were greater for southern populations, while seedling emergence was greater for northern populations (P < 0.001). Interestingly, germination, emergence, and biomass of A. syriaca displayed no significant difference among seed sources. Emergence timing, seed source, and field site significantly affected survival for both species (P < 0.001). Overall, survival increased with latitude of population origin at the northern site, but slightly decreased with latitude at the southern site. Variation in early life stages among collection zones was considerably more pronounced for A. incarnata than A. syriaca, suggesting that restoration establishment of A. incarnata is more sensitive to seed sourcing. However, seed sourced from within a single collection zone did perform similarly, indicating that current zones appropriately delineate some degree of intraspecific variation. Implications of these results will be discussed in the context of the ongoing monarch habitat restoration effort and seed sourcing guidelines.

1 - Chicago Botanic Garden, Plant Science And Conservation, Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
2 - Denver Botanic Gardens, 909 York Street, Denver, CO, 80206, United States
3 - Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022, United States
4 - Chicago Botanic Garden, 1000 Lake Cook Rd, Glencoe, Illinois, 60022, United States

Keywords:
Seed Germination
emergence
restoration
seed sourcing
milkweed
seedling recruitment.

Presentation Type: Oral Paper
Session: 31, Ecology Section - Population Biology
Location: 106/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 1:45 PM
Number: 31002
Abstract ID:922
Candidate for Awards:Ecological Section Best Graduate Student Paper