Abstract Detail



Ecology

Huebner, Cynthia [1], Thomas Van-Gundy, Melissa [2], Underwood, Christopher [3].

Comparison of Seedbank Composition over a Gradient of Pyrophilic Vegetation.

Seedbanks of second-growth deciduous forest soils are often more like the early-successional old-fields that preceded them than the existing understory vegetation. Seedbank compositions provide a record of past disturbances, the legacies of which may last for 150 years.  Our goal was to determine if sites dominated by fire-adapted vegetation have seedbank compositions different from sites lacking fire-adapted plants and if these species differences support a fire history.
Three sites were selected within the Monongahela National Forest, WV to represent three pyrophilic zones based on percent-pyrophilic-witness tree cover:  Low (0-10%), Medium (40-50%), and High (80-90%).  Sites were 80+ years and southwest-facing slopes.  Four 15x15-cm and 6-cm deep soil plugs were collected outside a 1-m2 plot every 10 m along two 50-m transects. Samples were grown in a greenhouse for five months.  Cover of all understory plants including tree seedlings under 1 m were determined from each 1-m2 plot on the transects.  We used nonmetric-multidimensional scaling (NMS), multi-response permutation procedure (MRPP), and indicator species (IS) analysis to compare the species compositions of the seedbanks and existing understory vegetation by pyrophilic zone. Soil cores were taken using a single-root auger in 10-cm increments at three, equidistant points along each transect at an average depth of 22 cm). Charcoal abundance and species identifications were determined.
Preliminary soil charcoal amounts supported the three pyrophylic zones. The NMS had a stress value of 8.7 and the MRPP chance-corrected within-group agreement with group defined by pyrophilic zone was less than that with group defined by vegetation type (seedbank vs existing vegetation).  Though the species compositions within both group types were significantly different, those of the pyrophylic zones were more similar than those of the vegetation types.  The most important IS of the existing vegetation was Melampyrum lineare var. latifolium in the High zone.  Hieracium paniculatum, Dichanthelium latifolium, and Robinia pseudoacacia were the most important seedbank IS in the High zone. Though only in a few plots, Convallaria majalis var. montana was found in the High zone existing vegetation.  Melampyrum lineare var. latifolium, C. majalis var. montana, the Dichanthelium spp., R. pseudoacacia, and S. nitida (IS in both seedbank and existing vegetation) are often associated with fire. 
Both the seedbank and existing vegetation had plant species reflective of their pyrophylic zone type.  These results support the inferred fire history based on witness trees as well as current vegetation characteristics associated with fire in the understory.


1 - Northern Research Station, USDA Forest Service, 180 Canfield St., Morgantown, WV, 26505, USA
2 - Northern Research Station, USDA Forest Service, 459 Nursery Bottom Rd, Parsons, WV, 26287, USA
3 - University of Wisconsin-Platteville, Environmental Science and Conservation, 257 Gardner Hall, Platteville, WI, 53818, USA

Keywords:
Pyrophilic
Nonmetric Multidimensional Scaling
indicator species
Fire-adapted
Soil seed bank.

Presentation Type: Oral Paper
Number: ECO4001
Abstract ID:161
Candidate for Awards:None


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