3.2.2 Seedbed Conditions 



Mnistiire. As early as 1923, Akerman 

 described in detail the importance of swamp 

 microrelief in providing suitable cedar seedbed. He 

 observed that only the logs, stumps, or hummocks 

 that are above water during the spring high-water 

 periods form favorable seedbeds, but seedlings 

 starting there may die from lack of moisture during 

 later dry periods. However, seedlings growing in 

 lower places frequently drown during subsequent 

 high-water periods. Akerman concluded that see- 

 dlings sprouting at intermediate positions had better 

 survival than those starting either at the highest or 

 lowest spots. He found that root development by the 

 end of the first growing season began to make see- 

 dlings drought-resistant, but they remained suscep- 

 tible to drowning until after the second growing 

 season, when many were more than 30 cm tall. 

 These observations have been repeatedly corrobo- 

 rated (e.g., Korstian and Brush 1931 ; Little 1950). Lit- 

 tle (1950) determined experimentally that seedlings 

 survive in hollows only when they are above the water 

 table. 



Seedbed . Suitable substrates include rotten 

 wood, peat, and Sphagnum moss. Hardwood and 

 shrub leaf litter and pine needles inhibit cedar ger- 

 mination to less than one per cent. Seeds may ger- 

 minate in mineral soil, but non-organic soil is not as 

 favorable as hardwood swamp peat, where rates are 

 as high as 49%, and dominant first-year seedlings are 

 more than three times taller than on mineral sub- 

 strate. The floor of a wetland previously supporting 

 Atlantic white cedar is the most favorable substrate. 



Ugtil. Relatively open conditions are neces- 

 sary for healthy growth of C. thyoides seedlings, al- 

 though they may survive for 1 to 3 years under a 

 mature cedar canopy, where light intensity averages 

 4% to 6% of full sunlight. Canopy thinning enables 

 white cedar seedlings to live longer, but they are still 

 out-competed by shrubs and other trees. At a light 

 intensity of 77%, initial growth of seedlings was 

 double that at 16% light, and almost quadruple that 

 at 2% intensity (Little and Garrett, in press). Warm 

 open areas, such as cleaned clearcut cedar stands, 

 abandoned cranberry bogs, recent burns over water- 





if 



Figure 1 9. Morphology of Chamaecyparis thyoides. A, B, H, and Q are reduced in size; all others are magnified 

 (from Korstian and Brush 1931). 



A-C. 



D-G. 



H. 



I. 



J-0. 



R 



Q. 



R-X. 



Y 



Branchlet with pistillate flowers. 



Pistillate flowers (longitudinal and cross sections). 



Branchlet with staminate flowers. 



Tip of H, magnified. 



Anthers bearing pollen sacs (surface and section views). 



Cross section of stamen attached to filament. 



Branchlet with mature fruit. 



Branchlet showing arrangement of leaves, glands on scales. 



Mature cones (top, side, and dissected views) with seeds intact and discharged. 



28 



