64 David R. Lenat 



Table 3. Average taxa richness by group for North Carolina Piedmont streams. Ranges 

 are rounded to integer values. 



Stream: 



# Collections: 



County: 



Cane Bolin Gates 



3 3 3 



Orange Orange Orange 



UT Lanes 

 Creek 



3 

 Union 



Long 

 Branch 



4 

 Gaston 



4-Mile 



4 



Davidson 





Group 











Range 



EPHEMEROPTERA 



8.3 



8.7 



8.7 



7.7 



8.0 



9.4 



8-9 



PLECOPTERA 



1.7 



3.7 



3.7 



2.0 



3.0 



5.0 



2-5 



ODONATA 



0.7 



0.7 



3.7 



0.7 



1.0 



1.6 



1-4 



TRICHOPTERA 



5.0 



4.0 



5.6 



2.0 



7.3 



3.4 



2-7 



COLEOPTERA 



5.0 



4.7 



5.7 



5.3 



3.7 



3.0 



3-6 



MEGALOPTERA 



2.0 



2.0 



1.3 



2.7 



1.0 



1.8 



1-3 



DIPTERA 



21.0 



13.7 



19.7 



16.0 



17.3 



14.6 



14-21 



MOLLUSCA 



3.3 



2.3 



1.7 



2.3 



1.3 



1.4 



1-3 



OLIGOCHAETA 



3.7 



1.0 



2.7 



2.3 



1.7 



1.8 



1-4 



CRUSTACEA 



1.7 



3.0 



2.7 



1.7 



2.0 



1.7 



2-3 



OTHER 



2.7 



2.0 



0.3 



0.6 



- 



- 



0-3 



TOTAL 



55.1 



45.8 



55.8 



43.3 



46.3 



44.0 



43-56 



Average Taxa Richness/ Percent Density 



Environmental assessment is often based on quantitative data from 

 a single collection or on data averaged over several collections. It may 

 be difficult to relate these data to water quality if good control informa- 

 tion is lacking. Tables 3 and 5 present average taxa richness and density 

 values from Cane Creek and make comparisons with five other rela- 

 tively unstressed Piedmont streams. All samples were taken during 

 DEM investigations. Collection methods (kicks) and identification 

 techniques were identical for all streams. From this data set, one may 

 attempt to define the normal characteristics of Piedmont stream 

 macroinvertebrate communities. 



Table 3 gives average taxa richness values in the range of 43 to 56 

 (x = 48.5). There was often a remarkable constancy at the group level. 

 For example, Ephemeroptera varied only from 8.3 to 9.4. Plecoptera 

 values were generally in the range of 2 to 4, except at 4-Mile Creek. The 

 greater number of Plecoptera in this stream, which is at a higher eleva- 

 tion, may reflect colder water temperatures. The expected number of 

 Odonata is close to the average (1.4), except at Cates Creek. This is a 

 very narrow, slow stream and might be expected to show a high propor- 

 tion of bank associated (edge) species in quantitative samples. Odonata 

 are most frequently collected in bank areas. Variations in Coleoptera 

 and Trichoptera, especially the latter, are not easily explained. Various 

 regional differences in water chemistry, temperature, and gradient may 

 be responsible. The number of Diptera, especially chironomids, had a 



