Restoration of under-represented native plants in coastal dunes of Baldwin County, Alabama (Physalis and Asclepias Production and Out Planting) Cooperative agreement F16AC00430 Final Report 1. Project Investigators Mack Thetford, Associate Professor Debbie Miller, Professor Department of Environmental Horticulture Department of Wildlife Ecology and Conservation, West Florida Research and Education Center West Florida Research and Education Center University of Florida University of Florida 5988 Highway 90, Building 4900 5988 Highway 90, Building 4900 Milton, FL 32572 Milton, FL 32572 [email protected] [email protected] 2. Project Description During the Deepwater Horizon event, dunes were significantly harmed by the response activities on Bon Secour National Wildlife Refuge. This project contributed to the effort to offset injuries. The Trustees to some degree had restored dunes that occur in the project area already. However, monitoring results of that restoration effort reveal an absence of less common, but highly desired species that create diversity necessary for proper ecological function of the dunes. The project has improved the ecological services dunes provide to animals that live there. The plant species that were selected for this project are native components currently under-represented in the project area and are important for many pollinators, butterflies and beach mice. The goal of this project was to propagate the target species and outplant in targeted areas. Specific objectives of the project were to: 1). Develop propagation (seed and cuttings) and production techniques for Physalis angustifolia (ground cherry) and Asclepias humistrata (Sandhill milkweed) plants for restoration; 2). Outplant both species with various methods to identify production/planting methods to achieve 50% survival of plants in dunes at 180 days after planting; and 3) Conduct a baseline assessment of extant Physalis and Asclepias. Seeds were germinated in greenhouses of the University of Florida, West Florida Research and Education Center and transplants grown in a variety of container types in both greenhouse and outdoor nursery production systems. Seedlings of both species were planted through stratified periods during fall of 2016 to winter of 2017. Additionally, a baseline assessment of extant Physalis and Asclepias was established through standard sampling techniques. The ultimate goal was to develop sufficient information to develop a grower’s manual that documents specific steps used for propagation, production, and outplanting of Asclepias humistrata and Physalis angustifolia. Monitoring the planting success is foundational to the purpose of the project. To increase the understanding of how to propagate these rare but important plants, the project generated data related to survival rates in the greenhouse and in the natural environment. The objective of 50% survival to 180 days was monitored, document, and reported. Survival rates were determined through systematically subsampling the project area in quadrats typical of dune vegetation monitoring. Page 2 of 25 Asclepias humistrata (sandhill milkweed) Asclepias humistrata (sandhill milkweed) is found in areas with dry, sandy soils throughout the southeastern USA. It supports a diversity of insects, including the monarch butterfly. It is a well-documented host for the larvae of monarch butterflies as they fly north from central Mexico to the eastern USA. This plant sends up shoots with flowers that senesce (die-back to the ground) upon the production of fruit or when environmental conditions become detrimental to growth. There is typically a massive shoot emergence event from spring to summer, often followed by shoot senescence for many individuals with a smaller shoot emergence event in the fall. Plants may or may not have above ground shoots through the hottest parts of summer and throughout the winter. These growth events often are in sync with (and are an important food source) for monarch butterfly migratory patterns. This plant is a multi-stemmed, subsucculent, perennial herb that forms a deep taproot. It has an ascending to prostrate growth form and its shoots can reach up to 1m long. Leaf color is variable, ranging from green to purple, and has pink veins. The leaf has an opposite arrangement, entire margin, and is sessile. Flowers are white to pink to lavender and are arranged an umbel in the axils of upper leaves or at the terminals of the stems. Little is known on how to propagate, produce and outplant these plants. Little is known about the population ecology of Asclepias humistrata including information on factors influencing the locations of extant populations. From a restoration perspective, little empirical information is available on how to propagate, produce, and successfully outplant this plant. The goal of the following document is to describe the populations characteristics, and present knowledge on the development of propagation, production, and outplanting techniques for Asclepias humistrata within the Bon Secour National Wildlife Refuge in Alabama. MATERIALS AND METHODS Extant Populations of Asclepias humistrata The extant population of Asclepias humistrata within the dune systems of Bon Secour NWR was documented for two distinct sites within the refuge and GPS points mapped (See Figures 1-4). In summer 2017 both the Mobile Street and Fort Morgan sites were scouted for locations of Asclepias humistrata and GPS coordinates of all plants encountered were logged. A total sampling method was used with 2 observers searching the same area over time. A. humistrata were scouted in the same area as 2017 during summer of 2018 (7/21/2018-8/6/2018). An additional western portion of the Page 3 of 25 Mobile St. site was surveyed in 2018 (Figure 4). A total sampling method was used with 3 observers searching the same area over time. After mapping, plant density at each site was computed on the basis of the entire site as well as the narrower area restricted to where the plants were detected. Figure 1. Maps depicting locations of all Asclepias humistrata encountered (occurrence area) while surveying the Fort Morgan site of Bon Secour NWR (Survey area) between Page 4 of 25 mid-May and July 2017. Figure 2. Maps depicting locations of all Asclepias humistrata encountered (occurrence area) while surveying the Mobile Street site of Bon Secour NWR (surveyed area) between mid-May and July 2017. Figure 3. Nine hundred and twenty two GPS locations (922) of extant Asclepias humistrata (1 point per plant) recorded summer 2018 at the Ft. Morgan site of Bon Secour National Wildlife Area. Page 5 of 25 Figure 4. One thousand six hundred and fourteen GPS locations (1614) of extant Asclepias humistrata (1 point per plant) recorded summer 2018 at the Mobile Street site Bon Secour National Wildlife Area. A total of 1,383 plants were located in the original sample area (yellow box) with 231 plants located in the 26 hectare expanded search area summer 2018 (red box). Boxes in the figures represent a generalized search area and do not represent the exact search area boundaries. Asclepias humistrata Seed Collection Seeds were collected from mature fruits (follicles that were dehisced or dehisced upon the slight application or pressure) from plants growing on secondary dunes within 2 sites (Mobile Street and Fort Morgan) on Bon Secour National wildlife refuge from (June-August 2016; 11/23/2016; 05/2017 to 07/2017). Collected fruits had seeds extracted and fibers attached to seeds (coma) removed. Seeds were then air dried for at least 2 weeks (if not planted in greenhouse before) in paper bags at room temperature. Seeds were then stored in airtight containers until use. Initial collections in 2016 (June-August 2016) included a mixture of follicles; approximately half of the follicles contained all seeds of the fruit while the remaining half of the follicles contained only a portion of seeds as a result of seed being discharged from the follicle. Additional seeds were collected on 11/23/2016 from the Mobile Street Site and were separated on the basis of follicle condition with 234 seeds resulting from follicles with discoloration and 427 seeds collected from follicles of normal color. For this initial seed collection, all seeds encountered were collected to ensure adequate seed numbers for planned germination and production experiments. Seeds collect in 2017 occurred from spring to early summer (bi-weekly from 05/2017 to 07/2017) and only from follicles of normal coloration. Between mid-May and July 2,932 seeds were collected from the Mobile Street site and 1,513 were collected from the Fort Morgan site totaling 4,445 seeds collected in 2017. Page 6 of 25 Asclepias humistrata Propagation and Production Germination Protocol A standard germination protocol was used for all germination and production trials. A single seed is placed into a cell within a germination flat (either 72 or 244 cells/flat) containing a milled pine bark and peat-based potting substrate (Fafard 3B). Seed are placed on the surface of the substrate and covered with fine horticultural grade vermiculite to a depth approximately 1.5 times the thickness of the seed. Flats are maintained in an environmentally controlled greenhouse under natural photoperiod and watered by an overhead intermittent mist system that delivers a fine mist of water for approximately 10 seconds every 20 minutes. These time intervals are adjusted as needed based on crop age and environmental conditions. 2016 summer seeds To determine if Asclepias humistrata seeds have non-deep physiological dormancy, seeds were sown 2 (11/25/16) (n=273) or 15 (12/8/2016) (n=154) days after collection. Seeds from discolored follicles were sown (n=234) 15 days after collection. Seed were sown in 244 cell flats. Germination was defined as the appearance of the cotyledons above the soil line (Figure 5). Final germination was recorded 46 days after sowing fresh seed and 33 days after sowing stored seed (1/10/2017) and a final germination (%) calculated for each treatment group. Figure 5. Asclepias humistrata seedlings sown on 15 December 2017, picture taken on 30 April 2018.