A century from now researchers will gather data from a forest in Maryland to see how, during the previous 100 years, varying levels of species diversity affected its development and how the forest reacted to climate change. The information researchers garner could be critical for conservation, and they will have Smithsonian scientists who planted the entire forest back in 2013 to thank.
Scientists at the Smithsonian Environmental Research Center in Edgewater, Md., are turning 60 acres of farmland into an experimental forest and watching it grow for 100 years. With the help of volunteers, they planted 24,000 tree saplings of 16 species in fields once used to grow tobacco and corn. This was the initial step in a long-term research project called BiodiversiTree.
The saplings are divided into 120 plots across the fields―some plots holding 12 species, others with only four or just a single species. The main goals are to see if a forest with high diversity, versus low, is healthier; how species respond to a changing climate; and whether a native forest is better than agricultural lands at filtering out nutrients and pollutants in a watershed of the Chesapeake Bay.
“Species are going extinct faster than they ever have before, the climate is rapidly changing, and yet humans still depend on forests and other ecosystems for basic goods and services,” said John Parker, ecologist at SERC and lead scientist for BiodiversiTree. “It’s critical for future generations that we understand the implications of these changes.”
While the project is designed to last more than a century, researchers will not have to wait that long to start seeing results. Within the next few years scientists will begin tracking how different combinations of species grow, die, bury carbon, absorb nutrients, resist enemies and drought and enhance forest diversity overall. This will begin to shed light on how a diverse forest functions relative to a species-poor forest.
An underlying challenge for all the saplings, regardless of their plot and species combination, is the ground they are planted in.
“The fields we are planting have been in continuous corn for more than 30 years,” said Whitney Hoot, project coordinator for BiodiversiTree. “Without crop rotation or other best-management practices, a continuous corn monoculture depletes the soil of nutrients, and results in reduced topsoil. As these trees grow, we will be able to analyze the changing soil quality and observe the impacts that a secondary forest can have on the restoration of degraded farmland. We have a great opportunity to restore the quality and fertility of the depleted soil.”
While the soil may not be ideal, the study’s location is. It is a significant watershed to the Chesapeake Bay and allows scientists to examine one of the growing forest’s main functions as a water filter. The root systems of a forest keep soil porous and allow water to filter through various layers. This helps remove toxins, nutrients and sediment before the water enters streams, rivers and in this case, the Chesapeake Bay.
Crops like corn, which grew on the site before, require a lot of fertilizer to foster growth. Now the scientists will continually test the water quality in the main stream linking the site to the bay and see if it changes as the young forest and its root system grow over time.
Once the last remaining saplings are planted next week, the team will put small cages around each sapling to protect them from deer, start sampling the soil and the plants to assess baseline conditions, and do it all again in about three years from now to try and answer a fundamental question in these changing times: Does diversity matter?