Tree canopy myxomycetes and new records from ground sites in the Great Smoky Mountains National Park

Castanea, Jun 2003 by Snell, Kenneth L, Keller, Harold W, Eliasson, Uno H

ABSTRACT

Thirty-five tree species, represented by 240 individuals, were climbed during two three-week periods in June, July, and August of calendar years 2000 and 2001 in the Great Smoky Mountains National Park. The double rope climbing technique was used because the climbers could advance to higher levels in the tree canopy. Maximum-sized mature trees in old growth park areas were sampled up to 40 m. Bark samples were cultured in moist chamber cultures. Ninety-five myxomycete species were obtained from the tree canopy mostly from the following tree species: Fraxinus americana (white ash), Quercus alba (white oak), Liriodendron tulipifera (yellow poplar), Acer rubrum (red maple), and Pinus strobus (white pine). We report here 52 new records from the tree canopy, 7 from ground sites, bringing to 212 the number of myxomycete species known from the Park. Comatricha penicillata is recorded for the first time outside of the type locality in Japan. This is the first upper tree canopy list of myxomycete species from the Park. The Myxomycetes represent the only group of cryptogams with species only known from the tree canopy.

INTRODUCTION

The Great Smoky Mountains National Park (GSMNP) comprises more than 210,566 ha and is a refuge for one of the richest and most diverse biota in the temperate regions of the world. It has the largest remaining tracts of old growth forest in the eastern United States, estimated at 40,000 ha, which has resulted in its designation as a National Park, June 15, 1934, an International Biosphere Reserve, October 26, 1976, and a World Heritage Site, December 6, 1983. The park forms the boundary between eastern Tennessee and western North Carolina.

A new research initiative, the all Taxa Biodiversity Inventory (ATBI), under the rubric of a non-profit organization Discover Life in America (web site at www.discoverlife.org) represents a research effort to inventory all life forms in the park. The initial sampling plan developed by the ATBI established 20 one-hectare study plots located in major habitats throughout the park. Site selection was based on major forest/vegetation types, elevation, and relative accessibility. No previous study had collected myxomycetes from the tree canopy. The high canopy of the old growth forest allowed collection from many heights, occasionally over 40 m. The GSMNP is home to five forest types; spruce-fir, northern hardwood, cove hardwood, hemlock, and pine-oak forests (Whittaker 1956).

Hagelstein (1940) published an abbreviated list of Myxomycetes collected during the 1939 Mycological Society of America foray. A complete list of 64 species was published by Linder (1941). Weiden (1951) added 21 species to the park records. A preliminary list of 30 new myxomycete records for the park was published in Inoculum by Counts et al. (2000). These myxomycetes were gathered in two separate forays from June 19 to July 6 and July 31 to August 17, 2000, mostly from the tree canopy. Recently Stephenson et al. (2001) added 75 new myxomycete records, but 15 of these species were duplicates published earlier by Counts et al. (2000).

Study area

The GSMNP was selected for this study because of its favorable climatic conditions, variety of habitats, and high plant and fungal diversity. Moderate temperatures, ranging from 4[degrees] to 23[degrees]C at lower elevations, and an average yearly rainfall ranging from 140 to 216 cm (Shanks 1954) make the park an excellent environment for myxomycetes.

METHODS

Field Methods

Individual trees were selected from geographically different areas of the park, but due to access and climbing restraints, random selection was not practical. Acceptable trees exceeded 21 meters in height and allowed sampling from the ground continuously to near the top. Tree selection was often limited by climbing hazards such as poison ivy [Toxicodendron radicans (L.) Kuntze], dead branches, or overall limb structure.

Canopy bark samples were collected using the double-rope climbing technique. In this technique, a thin plastic slick-line tied to a weighted throw bag was thrown or shot, using a large slingshot, over the highest possible substantial branch. Once the bag and line were lowered to the ground, a climbing rope was tied to the slick-line, which was used to pull it over the branch or tree crotch. One end of the climbing rope was tied to the climbing saddle, as well as the end of a short length of rope called the split tail. The other end of the split tail was tied into a friction knot around the standing end of the climbing rope. When the climber pulled down on the standing end, he/she was pulled upward as the rope slid around the branch. The friction knot was advanced with each pull, holding the climber's position and leaving both hands free to sample from the bark. The double-rope technique also allows the climber to advance the rope to higher branches, often reaching to near the top of the tree (Jepson 2000).

Samples were taken at roughly three-meter increments as the climber advanced upward. Bark was scraped or pried from the trunk using a large knife, taking care not to damage the underlying living tissues of the tree. Efforts were made to sample from all sides of the trunk. All samples were collected from living parts of the tree and placed in paper bags (approximately 1000 cm^sup 3^), on which height and tree number were recorded. Trunk diameters at breast height (DBH = 1.5 m) were measured for each tree, and voucher specimens of leaves were gathered for their positive identification. Each climber used an elevation line marked off in 0.3 m increments to determine tree height measurements. Trees were tagged with numbers, and Global Positioning System (GPS) readings were taken for each climbing site location. In addition, a site description including most recent rain and current weather conditions was recorded.