Collaborative Research: Islands in the Stream: The critical role of bryospheres in small streams and river networks

About This Grant

Many headwater streams have mosses present, yet these plants are rarely included in current conceptual models of stream ecology. Bryophytes, including mosses, liverworts, and hornworts, are common in small streams where they can provide critical habitat for other aquatic organisms, and store large quantities of carbon, nitrogen, and phosphorus. This project will study the role of stream bryophytes as hotspots of freshwater biodiversity and nutrient cycling, with a particular focus on how bryophyte presence in small streams may have large impacts on water quality downstream. The project supports fifteen or more early career researchers across all career stages and multiple institutions. The research team will disseminate findings to broader audiences at conferences, local homeowners’ meetings, and field trips, and is partnering with the Hubbard Brook Research Foundation and a local school to develop environmental science curricula (5th-12th grades) that enable young students to examine and study mosses in nature. The research uses three complementary approaches to evaluate how and where aquatic bryophytes contribute to the structure and function of headwater stream ecosystems. First, researchers will experimentally remove bryophytes from two stream segments within the Hubbard Brook Experimental Forest (New Hampshire) to directly measure the impact of bryophytes on nutrient uptake, organic matter storage, and in-stream biodiversity. Second, the research team will conduct a regional survey of moss abundance and freshwater biodiversity across 50 headwater streams across the White Mountains National Forest that vary widely in stream pH. Results from both experimental and survey efforts will be used to parameterize a stream network model to estimate the effects of bryophytes on nutrient dynamics at river network scales and to predict the impact of bryophyte loss on river nutrient cycling. The project will inform our understanding of how bryophytes support freshwater biodiversity by providing flow and drought refugia and enhance stream nutrient cycling through their high surface area and capacity to trap and sequester materials. By initiating new, long-term records of moss cover at Hubbard Brook, this effort will inform our understanding of how droughts, extreme floods, and river ice affect moss cover over time. In addition to training of postdoctoral researchers and undergraduate students, and outreach to grade school students, this project will enhance understanding of processes that maintain clean freshwater streams, an essential and limited resource for U.S. citizens. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.