VEGETATIONAL ANALYSIS 



51 



a point. Under such conditions, there is often a strong temptation 

 to shift a plot a few feet or more to include or exclude a desired or 

 undesired species or condition. 



FlG. 20. Diagrammatic profile along a transect on the dunes at Ft. Macon, 

 N. C. Physiographic-vegetational zones are indicated. Transect was 110 

 meters long and horizontal scale is one-half the vertical. 



188 



102 t 103 



PEAK OF REAR DUNE 



. FlG. 21. Portion of field-mapped transect along profile shown in Figure 

 20 from 97 m. through 104 m. across the transition from Zone 4 to Zone 5, 

 where dominance changes from Andropogon to Uniola. The symbols indi- 

 cate A—Andropogon, U— Uniola, H—Heterotheca, C—Cenchrus, Oe— Oeno- 

 thera, L—Leptilon. Such a map gives accurate quantitative data for each spe- 

 cies as well as a visual record of changes ki vegetation associated with habitat. 

 See Table 1. 



Transects— A transect is a sampling strip extending across a 

 stand or several stands. It is most often used when differences in 

 vegetation are apparent and are to be correlated with one or more 

 factors that differ between two points. From a flood plain of a 

 river to the adjacent upland there would be marked changes in 

 moisture conditions, and in such a place a transect can be useful 

 for determining the range of moisture requirements of individual 



