34 BULLETIN 272, U. S. DEPARTMENT OF AGRICULTURE. 
cypress about 265 years old (Pl. VII). Outside of these successive 
age classes in the form of concentric rings, the main stand was mostly 
300 to 400 years with a considerable mixture of bays and gum. In 
logging, only a few of the larger trees in the 140-year-old class and 
practically all of the surrounding older stand were taken. 
The subsidence theory.—The theory that the Atlantic and Gulf 
coasts are gradually sinking is held by some to account for the irregu- 
lar and unsatisfactory reproduction of cypress. This theory of a 
general subsidence is one upon which authorities hold quite opposite 
views. Those who believe in subsidence indicate a rate of about 
one-tenth of a foot in a decade. Cypress seed, however, usually 
germinates the first year, and the seedling makes an average growth 
of from 10 to 18 feet in height during the first decade. The prevail- 
ingly better reproduction of cypress on low wet situations than on 
better drained or upbuilding soils, except near salt water, is an 
evidence against the adverse effect of any subsidence that may be 
in progress by either checking the incoming of reproduction or sub- 
sequently retarding its growth. The effects, if any, from subsidence at 
so slow arate would be more apt to appear in the tree during periods 
measured in centuries than during the few years of the reproduction 
stage. On upbuilding lands cypress is clearly receding before the 
hardwoods, and similarly, the best reproduction of cypress is found 
in very wet situations, where it is equally the dominating and the 
advancing species over all associated swamp hardwoods. 
DEMANDS UPON CLIMATE AND SOIL. 
CLIMATE. 
- Cypress grows in a wide range of temperature. Its natural range 
extends from below the frost lme in southern Florida northward to 
New Jersey. Its extended potential range takes it northward to a 
line connecting Massachusetts and Michigan, where it experiences 
minimum temperatures of about —20° F. More than 90 per cent of 
the total cypress stand is found at an elevation of less than 100 feet 
above sea level. In the Middle Atlantic coastal States the 100-foot 
contour marks the upper line of elevation, while over. the central 
Mississippi Basin the species prevailingly stops at an elevation of 
about 500 feet. Hundreds of miles west of the great coastal swamps 
cypress reaches large size around the edges of deep hollows on the 
Edwards Plateau of Texas at elevations ranging from 1,000 to 1,750 
feet. It appears that atmospheric moisture and rainfall both play 
an unimportant part in the distribution of cypress, as compared with 
soil moisture. 
SOIL. 
Cypress thrives in a wide variety of soils, including muck, clays, 
and the finer sands, It has been commonly reported that sandy 
