NOTES 



Effkct of Ground Cover and Littf.r 



Reprvydiiction studies of western yellow pine at the Fort Valley Ex- 

 periment Station are bringing out some interesting data regarding the 

 effect of ground cover and litter. In connection with sample plot work 

 some fifty 5 by 10 foot plots were thoroughly worked up with a mattock 

 in 1914 for comparison with natural plots adjacent. This year's counts 

 almost invariably showed more seedlings of 1919 germination on the 

 natural than on the cultivated plots. The exceptions occur where a 

 considerable amount of leaf litter covers the soil. Under these con- 

 ditions the cultivated plots often contain seedlings at the rate of 400,000 

 per acre, and from 50 to 100 per cent more than the adjacent natural 

 plots. The explanation of this phenomenon lies in the fact that a 

 cover of organic matter, particularly where it has formed a thin layer 

 of mould on the surface of the soil, is a distinct aid to germination. 

 Deep cultivation destroys this cover, and also tends to increase the clay 

 content of the surface layer by bringing up clay from below. An adobe 

 soil treated in this manner becomes very compact on top after two or 

 three years. Thus, while cultivation increases the moisture content by 

 eliminating competing vegetation, it may prove detrimental to repro- 

 duction by forming a poor seed bed. This, however, is not the case if 

 the ground is seeded before it has become compacted. 



The above results are strikingly confirmed under a different set of 

 conditions in a treeless clay flat surrounded by virgin forest. This fiat 

 which is virtually a small "park" is about 150 yards in diameter. The 

 surface is smooth, free from stones and strongly compacted by over- 

 grazing. Perennial grasses have given way almost entirely to "six- 

 weeks grass" a short annual grama of small forage value. Clumps of 

 Senecio spartoides and several similar unpalatable weeds occupy about 

 15 per cent of the ground surface. Counts in the middle of this opening 

 showed 13,000 seedlings of 1919 germination per acre, while near the 

 south side, 75 feet from the edge of the timber, there were 25,000 per 

 acre. The tendency of seedlings to group themselves in and around 

 the weed slumps was so conspicuous that a plot 5 by 20 feet was charted 

 to scale, showing the location of all seedlings and weed clumps. It was 

 found that 58 per cent of the seedlings were in the weed clumps which 

 302 



