March. 19811 LAND SURVEY OF DURHAM 15 



spcoiul class i)astnf(' Itut iiol for mowinji', as it is washed flat. The 

 swamps a>"t' ih)\v alinosi all wasic land. 



Meadows used foi- pastui-e, swamps with liardwood frrowtli on them 

 and oilier partly tlooded areas which are heing used are classified as 

 thouji'li the water were not Ihei'c The water is sliown on such areas 

 ou the map by the symbol representing a bunch of grass, with the same 

 coloring and wording as for dry land. 



Tabulated Results 



The figures for which the survey was ma(h^ are presented in a series 

 of tal)les and diagrams and used as a basis for the discussion. The 

 basic tabk^ is No. '^. in which the total area occupied by lands of each 

 type is shown with subdivisions. The acreage of each class of wood- 

 land is recorded and cross-totaled for each age to show the acreage of 

 the types and of each density class, as well as the grand total for the 

 age. In the same way the totals along the bottom of the table show 

 the total acreage for each type while those along the side show the totals 

 for each age. The sum of these gives the total acreage of the town. 

 Other figures, as the amount of merchantable timber, may be obtained 

 by adding subtotals in this table. 



All other tables are directly or indirectly based on this one. Table 

 1. for instance, merely records the totals found at the bottom of Table 

 3. with percentage figures included to make them more easy to compare. 



Table 4 was compiled as described previously to show the amount of 

 timber per acre and also the total for the whole town for each class. 

 This is given in board feet for pine and cords for hardwoods. Where 

 there were hardwood saw logs they were recorded in the table as board 

 feet of hardwoods. Totals of hardwood, pasture and pine types are 

 given, with subtotals by age classes. There are some irregularities 

 in the table — there is a figure for pine lumber in the hardwood 50-year 

 class, for instance, even though this is classed as a purely hardwood 

 stand. In classes with only a few acres the plots were too few to get 

 good averages. These irregularities should tend to balance each other 

 so that the total estimate would not be affected appreciably. 



Table 2 classifies the hayland and pasture roughly according to their 

 productivity and estimates the annual yield for each type. 



The age class distribution diagram (Fig. 3) shows the acreage of the 

 three types of woodland for each age. The number of acres is shown 

 by the horizontal distance, and the age by the vertical. The figure in 

 each block gives the acreage for that type and age. Evidently, pine 

 lots over 45 years old, and hardwoods over 30, are unusual. Below 

 these ages, assuming that most of the gray birch will be replaced by 

 pine, there is about an equal acreage in each of the age classes for both 

 pine and hardwoods ; that is, there is about as much 10-year as there 

 is 20-year, etc. This would mean that as soon as one class becomes 

 merchantable and is cut, it would be replaced by an equal area of the 

 class below. This is called a "normal" stand. However, some hard- 

 wood lands and some pasture will grow up into pine lands, so that this 

 balance is not as even as it looks. 



