Seedling growth was not affected by green needle and litter leachates. There was 

 an indication that duff and bark leachates may, under certain conditions, slightly re- 

 duce root weights, but the results were not reproducible. Seedlings grown in Hoagland's 

 solution also exhibited reduced root weights. 



Field Soil Bioassay 



Materials and Methods 



This experiment was conducted twice, experiment A in the summer of 1974 and ex- 

 periment B in the summer of 1975. Because of differences in the experimental design, 

 each will be discussed separately. 



In experiment A, the upper 5.0 cm of soil was collected from five areas in the 

 open and five areas under pine canopies. Each of the 10 different soils was sifted 

 twice through a 2.0 mm sieve to remove large pieces of organic matter and then placed 

 into 10 greenhouse pots C4-inch size) . Fifteen stratified and sterilized ponderosa 

 pine seeds were planted into each pot, and the pots were randomly placed in the green- 

 house. All soils were given equal volumes of tap water at periodic intervals as needed. 

 The germination was recorded for 15 days, and then all but the largest three seedlings 

 were removed from each pot. The remaining three seedlings were harvested after an add- 

 itional 16-day growing period. The biomass of both roots and shoots was measured after 

 ovendrying at 70°C for 48 hours. 



Experiment B was very similar to A in that soils were collected from five open 

 areas and from five areas under pine canopies. However, in experiment B, the upper 

 15 cm of the soil was lifted from the ground with minimal disturbance and placed 

 directly into 6-inch green house pots. Three replications were taken from each of the 

 10 different collection sites. Each pot was saturated with tap water and planted with 

 30 stratified and sterilized ponderosa pine seeds and randomly placed in the greenhouse. 

 All pots were given equal volumes of water at intervals as needed. Germination and 

 initial growth was observed for 21 days when all but the largest seven seedlings were 

 removed from each pot. These seedlings were grown an additional 56 days, at which time 

 they were harvested, and the root and shoot weighed after drying 70°C for 48 hours. 



A series of subsamples from the two soil groups were taken for nutrient analysis. 

 The concentration of eight cations was measured by atomic absorption. The various 

 treatment subsamples could not be paired statistically, so a nested experiment analysis 

 of variance was used and followed by the Newman-Keuls test. 



Results and Discussion 



Although the experimental design was different between A and B, the results were 

 essentially the same. In both A and B, the germination of pine seeds in soils col- 

 lected from the openings was significantly greater than the germination of pine seeds 

 in soils collected beneath a pine canopy (table 6). Although germination of the canopy 

 treatment was significantly lower than the opening treatment, it was certainly not a 

 drastic difference. Since both treatments received equal amounts of water and sunlight 

 and were, therefore, influenced by similar temperatures, soil factors, would have to 

 account for germination differences. 



It was observed that the canopy soil contained larger amounts of organic matter 

 than the opening soils, even in experiment A where the soils were sieved twice. Soil 

 surfaces in which the seeds were planted, dried quite rapidly after watering. It is 

 possible that the higher amounts of organic matter in the canopy soils created greater 

 moisture tensions that reduced germination. 



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