SAMPLE PLOTS IN SILVICULTURAL RESEARCH 51 



where, the angle mirror is perhaps as rapid and efficient an instru- 

 ment as can be obtained. 



The scale of the map should be chosen with regard to the quantity 

 of detail required and the density of the stand. A scale of 2 to 4 

 inches to the chain is usually sufficiently large for plots of one-fourth 

 acre or more. A convenient scale that is readily divisible expedites 

 the work and lessens the danger of mistakes. Measurements can 

 be plotted easily and accurately when an engineer's scale rule is used. 



Trees may be shown on the map by dots or by special symbols that 

 distinguish trees to be cut and trees to be left, crown classes, species, 

 sprouts, and seedlings, etc. Or abbreviations placed near the tree 

 position may be used to indicate any one of these. 



When the trees bear numbers, the numbers should always be shown 

 on the map, preferably just below the tree positions. These num- 

 bers on the map should be checked against those on the tree-record 

 sheets to make sure that none has been omitted. Diameters may be 

 written in or may be shown by the relative sizes of the symbols used. 

 To enter much detail on the map may cause confusion and lessen the 

 map's usefulness. The map legend should fully explain each symbol 

 used. 



A crown map, in addition to showing the positions of the boles, 

 shows the vertical projection of the tree crowns, thus presenting 

 graphically the shade conditions on the plot. Crown maps are of 

 more value for several-storied than for single-storied stands. Com- 

 parison of crown maps made before and immediately after treat- 

 ment shows the effect of treatment on crown density, and comparison 

 of the latter with subsequent maps shows the development of the 

 crowns of the trees left. Because of the length of time required to 

 prepare a crown map, such a map should be prepared only if its 

 value is clearly demonstrable. 



Tree crowns may be mapped by plotting 3 or 4 points at the edge 

 of each crown and then sketching in its shape. These points are 

 located most easily if an assistant to the mapper stands directly 

 under the edge of the crown and the mapper determines the distance 

 and direction from the assistant's position to the tree bole. In 

 stands with irregular crowns, 1 or 2 assistants can locate points and 

 measure distances while the mapper is sketching. 



The crown map should represent the stand as seen from above. 

 The highest crowns should be outlined with solid lines; the crowns 

 of the second level may be outlined with broken lines, those of the 

 third level with lines of crosses, etc. An arrow should be drawn 

 from the position of the bole to the position of the crown edge 

 wherever the relationship is not clearly evident on the map. 



Since the crowns of trees on the isolation strip surrounding the 

 plot affect those of trees on the plot, a fringe of the former should 

 be included in every crown map. 



In many studies it may be desirable to indicate on a plot map the 

 locations of bare areas, piles of slash, logs, skid trails, etc. The 

 purpose of the study will largely govern the extent to which these 

 details should be shown. 



As the value of the map depends upon its accuracy, care in plotting 

 is essential. 



Reproduction quadrats may be mapped by essentially the same 

 method that has been outlined for plots. The quadrat may be 



