Recruitment of Large Woody debris in Headwater Streams of Great Smoky Mountains National Park: Individual Versus Mass Mortality

Field Methods:
The proposed research will address the following questions:

Q1. What is the frequency, volume, and orientation of LWD in GSMNP streams?
Q2. What is the relative dominance of individual versus mass mortality in LWD recruitment?

To address these questions, I will conduct intensive fieldwork on three streams within the park (Le Conte Creek, Baskins Creek, and Roaring Fork), which are all in the drainage area of the fire.

Q1: I will inventory all LWD for a 1-km segment of each stream. To qualify as LWD, the wood must meet the minimum dimensions (1 m long, 10 cm in diameter), must be in the active channel (the portion of the stream channel between the banks, where there is evidence that water flows at least every 1-2 years), and must be dead wood. The specific field measurements I will make include: 1) Location: I already own a survey-grade real-time kinematic global positioning system (RTK-GPS), which I will use to record locations of each piece of LWD. For LWD jams, which consist of multiple pieces of LWD that have accumulated together, I will record the location of the jam. The advantage of using the RTK-GPS is that it is highly accurate (~10 cm) and quick to record points. Also, while handheld GPS units often fail to fix a location because of poor satellite reception under dense vegetation canopies, my unit consists of a base station and a rover. The base station is set up in an open area with good satellite reception, and the rover is carried to measure points. The base station and rover can be as much as half-a-mile apart and do not require line-of-sight. If the GPS fails to get adequate satellite reception, I will instead measure relative positions of LWD using longitudinal and cross-sectional tapes. 2.) Dimensions: I will use a tape to measure the length and diameter of each LWD piece. For LWD jams, I will estimate the overall volume of the jam and the length and diameter of key pieces (the pieces that serve as anchors for additional LWD). 3) Orientation: I will note the angle at which each LWD piece is oriented (ranging from 0° for pieces oriented parallel to flow to 90° for those oriented perpendicular to flow).

Q2: I will use the method of Piégay et al. (2017) determine the likely source of recruitment of each LWD piece based on its condition. The most important characteristic will be whether it has visible burn marks or not. Also, I will record whether it has intact limbs and root-wads and if there is evidence of local bank failure, which is an indication that it was likely recruited recently by undercutting of the bank. Significant decay is a sign that the piece has been dead for many years and is a “legacy” rather than recent recruitment. Finally, when possible to determine, I will note whether the piece is from a coniferous or hardwood species. These field notes will be supplemented with photographs of each LWD piece or jam.

Locations authorized:
The fieldwork may take place along Roaring Fork (along Roaring Fork Motor Nature Trail), Baskins Creek (along Baskins Creek Trail), and Le Conte Creek (along Twin Creeks and Rainbow Falls trails).

LC1:  35°42'3.24"N,  83°30'40.25"W
LC2:  35°41'13.23"N,  83°29'55.78"W
LC3:  35°40'33.17"N,  83°29'12.41"W
BC:  35°41'12.80"N,  83°28'47.18"W

Tags: aphn, appalachian-highlands-network, ecological-framework-geology-and-soils-geomorphology-stream-river-channel-characteristics, great-smoky-mountains-national-park, grsm, ser, southeast-region, studyid-grsm-02074, woody-debris
Organization: Department of the Interior