1396 



AMERICAN FORESTRY 



den. These two trees were rarely found to be in good 

 condition and often were found partially if not wholly 

 defoliated. 



A group of four species comes in at this place in the 

 list, tulip, pin oak, white ash, Austrian pine. They were 

 seldom found entirely defoliated but frequently their 

 crowns were very thin. The tulip poplar sometimes had 

 line form but with small, poor foliage. 



Another group contains cottonwood, English oak, red 

 oak, scarlet oak and sycamore, and these in many cases 

 showed signs of deterioration by having dead tops, al- 

 though many are still in good condition. 



Sometimes the soil will be badly drained and will tend 

 to collect and hold too much moisture, having the 

 tendency to smother the roots of the trees by shutting 

 off all air. Then again, the soil may be shallow and will, 

 therefore, tend to dry out very quickly, thus leaving the 

 trees without water. Then the condition of the sub-soil 

 may make a great difference in the tree growth. If the 

 sub-soil is very heavy and impermeable to water and to 

 the roots of trees, it will greatly impede tree growth if 

 it is too close to the surface, or it prevents moisture from 

 coming up from below into the surface soil. Under 

 such conditions breaking up the sub-soil with dynamite 



THE WHITE BIRCH 



Nowhere is the European white birch found 

 really doing well in Central Park and here 

 it had splendid forest floor conditions with 

 plenty of shade and humus, but it did not 

 thrive despite these. 



FAST FALLING ELMS 



American elm near 59th Street, 15 inches in 

 diameter and planted on an east slope where 

 the full effect of the sun on the ground will 

 be felt most. Note the dense cover of grass 

 about the roots of the tree. 



POOR RED MAPLES 



This tree was nearly defoliated. The soil was 

 very shallow and there was a large, rocky 

 outcrop just to the left of the picture. Many 

 of the other red maples in the park are like 

 this one. 



The last class of all, containing trees which showed 

 little or no sign of any kind of having suffered contained 

 the Ailanthus, Gingko, cucumber, Norway maple, Catalpa. 



Deplorable Soil Conditions. 



Soil conditions in Central Park are undoubtedly the 

 most severe handicap to the health of the trees. Most 

 common trees desire a fairly deep, well-drained loamy 

 soil with plenty of humus (decayed vegetable matter) 

 mixed in with it, especially in the surface layer of three 

 to six inches. If too loose and sandy the rain water will 

 soon drain off and leave the trees waterless, and if the 

 soil is too heavy, like a fine dense clay, the water falling 

 on it will tend to form pools on the surface and evapo- 

 rate and be lost to the trees that way. Also a heavy clay 

 soil will tend to interfere with the growth of the roots. 



has been proved to be effective. Again, hard packing of 

 the surface soil by people walking upon it, covering the 

 soil with cement or asphalt walks or roads will tend to 

 impede tree growth. Now, many of these difficulties 

 and hindrances to tree growth exist in Central Park 

 today. Shallow soil is very common, often only a few 

 inches covering up the rock below. Heavy impermeable 

 clay is also present in places. A hard packing of the soil 

 around the bases of the trees is quite noticeable along 

 Fifth Avenue. And exposure of the soil to evaporating 

 winds and to the direct rays of the sun is everywhere 

 common. Add to this the frequent proximity of asphalt 

 walks and drives and the frequency of a dense sod of 

 grass growing under the trees, and it is easy to see how 

 difficult it is for a tree to secure normally good soil con- 

 ditions in Central Park. 



