130 



John F. Pagels, Leonard A. Smock and Stephen H. Sklarew 



Table 6. Mean percent abundance, standard error, and range of riparian canopy 

 trees at the streams where S. palustris was found in Virginia, 1974-1993. 



Species 



Mean 



SE 



Range 



Betula lutea 



29 



3 



22-35 



Betula lenta 



13 



4 



0-24 



Acer saccharum 



10 



2 



4-17 



Tilia americana 



9 



4 



0-22 



Prunus serotina 



7 



3 



0-14 



Acer rubrum 



6 



4 



0-18 



Fagus grandifolia 



6 



3 



0-14 



Tsuga canadensis 



6 



2 



0-9 



Fraxinus sp. 



3 



2 



0-8 



Quercus rubra 



3 



1 



0-7 



Robinia pseudo-acacia 



2 



1 



0-6 



Carya sp. 



<1 



<1 



0-2 



Picea rubens 



<1 



<1 



0-2 



Standing dead trees 



6 



2 



0-9 



MACROINVERTEBRATE COMMUNITY 



Taxonomic composition and richness were very similar among all 

 streams (Table 7). Taxonomic richness ranged from 26 to 28 taxa, but would 

 have been considerably higher had individuals in the dipteran family Chirono- 

 midae (midges) been identified to genus. The macroinvertebrate communities of 

 all of the streams were dominated by species of midges (Diptera), stoneflies (Ple- 

 coptera) and mayflies (Ephemeroptera). Non-midge taxa common at most 

 streams included stoneflies in the families Leuctridae and Perlodidae; the mayfly 

 families Heptageniidae, Ephemerellidae, and Baetidae; and the caddisfly fami- 

 lies Philopotamidae and Hydropsychidae. Although biomass of macroinverte- 

 brates was not measured, these taxa no doubt dominated the macroinvertebrate 

 biomass because of their generally large size. 



DISCUSSION 

 In Virginia, Pleistocene remains of S. palustris are known from Natural 

 Chimneys in Augusta County, elevation 414 m (Guilday 1962), and Clarks Cave 

 in Bath County, elevation 456 m (Guilday et al. 1977). Indicative of the boreal 

 nature of the sites where S. palustris now occurs, certain other boreal species 

 with highly disjunct populations in the southern Appalachians remain associates 

 of S. palustris in Virginia, but also no longer occur in the environs of the Natural 



