Chicago Botanic Garden Fall 2019

chicagobotanic.org 27 highest quality plants will be replanted at area sites. “ e plants are there, and they come back,” Evans says. “We have been able to demonstrate that there is a seed bank, and it is very diverse. I think the most exciting thing is that these results could be extrapolated throughout the forest preserves of northern Illinois, and we could potentially see this vernal pool story turn from a sad story to a very happy story.” According to a 2017 U.S. Forest Ser- vice report, 28 percent of the Chicago Wilderness Region’s urban tree popu- lation is made up of buckthorn. But Evans’s preliminary ndings show that the plant community looks much more diverse below ground, where seeds of blue ag iris ( Iris virginica schrevi ) , hop sedge ( Carex lupulina ) , buttonbush ( Cephalanthus occidentalis ) , and other native plants are lying in wait for the right conditions to emerge; namely, soil free of invasive buckthorn. “ is project could show an e cient, cost- e ective way for land managers to re- establish native vegetation without the need for reseeding,” Evans says. Dr. Kramer points out that healthy ver- nal pools, found locally at restored for- ests, such as Somme Woods in North- brook and the Garden’s McDonald Woods, are only inundated with water from spring to midsummer, drying out after a crucial period in the frogs’ life cycles when they lay eggs that become tadpoles. Warmer seasonal tempera- tures and drier conditions resulting from climate change are likely to dis- turb the timing and abundance of these pools and heighten the need for inter- ventions to ensure that frogs have the habitat they need to reproduce. “Frogs couldn’t reproduce successfully without these ponds. In a lake or a river, where there are sh, the tadpoles would get eaten,” Kramer says. Ecologists generally agree that forest preserves with more plant species are better at cleaning air, siphoning water from ood-prone residential commu- nities, and recovering after disturbanc- es, but how plant diversity in and around vernal pools directly impacts frog populations is an understudied area, particularly in the Midwest. Evans’s work has begun to shed light on the ecological conditions under which seeds survive and germinate in the face of exotic invasion—a process that var- ies widely by soil conditions. Previous Garden research found few native seeds remaining in buckthorn-invaded soils in drier habitat, but Evans’s research shows an exception for wetland plants. “Wetland seeds have developed the ability to persist a long time in wet soil with an impregnable seed coat layer that prevents rot from occurring,” Evans says. In a subsequent experimental study, Evans will delve deeper into vernal pool ecology, drawing soil samples from deeper underground and using the nursery’s aquatic tanks to grow seeds. Paolo Ramirez, a student in the Re- search Experiences for Undergraduate students program (REU), will help an- alyze the soil seed bank at three depths. If all goes as predicted, Evans expects upper levels of the soil to contain high levels of invasive species but deeper lev- els to reveal evidence of a diverse seed reservoir preserved from a time before buckthorn invasion and European set- tlement, when the planet was friendlier to frogs. He plans to present his results in his thesis defense in May 2020. “I think this is a great example of what we’re trying to do more of—closing the loop,” Kramer says. “Not only doing the research, but collaborating with land managers in Cook County to identify priority questions and nding ways to answer them, and then using those projects to give graduate students opportunities to build their skill sets and present their results to the commu- nities that will use them.” Learn more chicagobotanic.org/research A partnership with the Garden, Forest Preserves of Cook County, and Shedd Aquarium targets threat- ened ecosystems. Far left: Vernal pool. Left: spring peeper. Center: Western chorus frog tadpole © Mike Redmer. Right: Matt Evans and REU intern Paola Ramirez.