Science of the Seasons

Summer 2019

In the summer, nature gets busy replenishing the larder in endlessly diverse ways. Plants are converting energy from sunlight into the energy that will nourish them throughout the year. Bees are busy collecting nectar and converting it to honey to feed to the hive. The entire food chain is fully engaged in either consuming prey or avoiding becoming prey.

As part of a shared landscape, people contribute both for good and for not-so-good to nature’s busiest season. Check out our stories on research that found doing less yard work benefits pollinators and other research that is finding that the chemicals that keep us safe from the sun’s rays are an emerging concern for aquatic ecosystems.

Science Summer Reads


Aquatic Contaminants of Emerging Concern

Anne Timm collecting samples of oysters.Across a multitude of brands and sun protection factors, or SPFs, sunscreen plays a key role in keeping us safe in summer. While it protects people from harmful ultra-violet rays, sunscreen is less beneficial when it reaches aquatic ecosystems.

Researchers are finding ample evidence that the pharmaceutical products that keep people healthy are entering our water systems and impacting aquatic wildlife. The UV-filter chemicals in our suncreens are estrogenic chemicals that interfere with the biological processes in some wildlife resulting in intersex fish (having both male and female reproductive tissue) and bird egg shells becoming weak. Both of these conditions result in reproductive failure for area wildlife.

Anne Timm is a research aquatic ecologist with the Northern Research Station in Baltimore, Maryland, where she collaborates with the University of Maryland Baltimore to understand how sunscreen and other pharmaceuticals that wind up in water are affecting aquatic organisms. Working with her partners, Timm developed a “quick, easy, cheap, effective, rugged and safe” method, or QuEChERS, to detect bioaccumulation of contaminants of emerging concern in stream and coastal ecosystems.

QuEChERS has been used to assess the presence of contaminants of emerging concern in crayfish of urban streams, crayfish produced by the aquaculture industry, coral in Hawaii, and oysters and crab of the Chesapeake Bay. Application of the method to oysters in the Chesapeake Bay will enable managers to prioritize oyster restoration activities and assess ecosystem health to maintain significant coastal resources.


How much are you willing to not do on behalf of bees?

An Eastern bumble bee (Bombus impatiens) on a lawn flower at one of 16 study sites in Springfield, Mass., where researchers found that letting lawns get a little longer benefits bees.Throughout the United States there has been growing concern over widespread population declines of bees and other pollinators due to habitat loss. Research by a USDA Forest Service scientist and her colleagues suggests that with a little less lawn mowing, “lawn flowers” such as dandelions and clover would grow tall enough to flower and be a source of food for pollinators.
Research ecologist Susannah Lerman and her collaborators explored whether different lawn mowing frequencies (1, 2 or 3 weeks) influenced bee abundance and diversity in herbicide-free suburban yards in Springfield, Mass. In a study published in the journal Biological Conservation titled “To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards,” Lerman and her colleagues suggest that improving pollinator habitat can be as easy as mowing the lawn every 2 weeks instead of weekly.

Throughout the 2-year study, the researchers conducted tick surveys to determine whether reduced mowing might increase the presence of ticks in yards; they did not find a single tick in lawns in the study area. The study is published in the journal PLOS One titled “Lawn mowing frequency in suburban areas has no detectable effect on Borrelia spp. vector Ixodes scapularis (Acari: Ixodidae)

The United States has an estimated 40 million acres of lawn, including residential yards, athletic fields and golf courses, making lawn management a potentially significant tool in efforts to preserve pollinators.

Selected Research Stories


Selected Publications


The publications listed below do not represent every study related to spring; for a more complete list of NRS publications, please visit our Publications page at: http://www.nrs.fs.fed.us/pubs/

Lerman, Susannah B.; D’Amico, Vincent. 2019. Lawn mowing frequency in suburban areas has no detectable effect on Borrelia spp. vector Ixodes scapularis (Acari: Ixodidae). PLOS ONE. 14(4): e0214615-. https://doi.org/10.1371/journal.pone.0214615.

Lindsey, Greg; Qi, Yunlei; Gobster, Paul H.; Sachdeva, Sonya. 2019. The 606 at three: Trends in use of Chicago's elevated Rail-Trail. Proceedings of the Fábos Conference on Landscape and Greenway Planning. 6(37). 14p.

Roach, Melissa C.; Thompson, Frank R.; Jones-Farrand, Todd. 2019. Effects of pine-oak woodland restoration on breeding bird densities in the Ozark-Ouachita Interior Highlands. Forest Ecology and Management. 437: 443-459. https://doi.org/10.1016/j.foreco.2018.12.057.

Janowiak, Maria K.; D'Amato, Anthony W.; Swanston, Christopher W.; Iverson, Louis; Thompson, Frank R., III; Dijak, William D.; Matthews, Stephen; Peters, Matthew P.; Prasad, Anantha; Fraser, Jacob S.; Brandt, Leslie A.; Butler-Leopold, Patricia; Handler, Stephen D.; Shannon, P. Danielle; Burbank, Diane; Campbell, John; Cogbill, Charles; Duveneck, Matthew J.; Emery, Marla R.; Fisichelli, Nicholas; Foster, Jane; Hushaw, Jennifer; Kenefic, Laura; Mahaffey, Amanda; Morelli, Toni Lyn; Reo, Nicholas J.; Schaberg, Paul G.; Simmons, K. Rogers; Weiskittel, Aaron; Wilmot, Sandy; Hollinger, David; Lane, Erin; Rustad, Lindsey; Templer, Pamela H. 2018. New England and northern New York forest ecosystem vulnerability assessment and synthesis: a report from the New England Climate Change Response Framework project. Gen. Tech. Rep. NRS-173. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 234 p. https://doi.org/10.2737/NRS-GTR-173.

Lerman, Susannah B.; Contosta, Alexandra R.; Milam, Joan; Bang, Christofer. 2018. To mow or to mow less: Lawn mowing frequency affects bee abundance and diversity in suburban yards. Biological Conservation. 221: 160-174. https://doi.org/10.1016/j.biocon.2018.01.025.

Luo, Tianxiang; Liu, Xinsheng; Zhang, Lin; Li, Xiang; Pan, Yude; Wright, Ian J. 2018. Summer solstice marks a seasonal shift in temperature sensitivity of stem growth and nitrogen-use efficiency in cold-limited forests. Agricultural and Forest Meteorology. 248: 469-478. https://doi.org/10.1016/j.agrformet.2017.10.029.

Wolfe, David W.; DeGaetano, Arthur T.; Peck, Gregory M.; Carey, Mary; Ziska, Lewis H.; Lea-Cox, John; Kemanian, Armen R.; Hoffmann, Michael P.; Hollinger, David Y. 2018. Unique challenges and opportunities for northeastern US crop production in a changing climate. Climatic Change. 146(1-2): 231-245. https://doi.org/10.1007/s10584-017-2109-7.

Livingston, William H.; Kenefic, Laura S. 2018. Low densities in white pine stands reduce risk of drought-incited decline. Forest Ecology and Management. 423: 84-93. https://doi.org/10.1016/j.foreco.2017.12.047.

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Last Modified: June 20, 2019