PROTECTION OF SHADE TREES. 331 



CAUSES OF THE PRESENT CONDITION OF THE SHADE TREES OF 



NEW HAVEN. 



The unsatisfactory condition of many of the shade trees in 

 the squares and streets of New Haven is due to a number of 

 causes acting together; no single one of them being chiefly 

 responsible for the damage. A brief statement of these causes 

 follows : 



i. Old Age. 



Many of the trees in New Haven are of very great age. 

 For example, the sycamore near the corner of College and 

 Elm Streets, the last of a row which once bordered the Green, 

 was set in 1759 and many of the elms on the Green were 

 planted in the year 1787. 



While under favorable conditions some of these trees may 

 last for many years longer, their age must necessarily tell 

 against them in their struggle for life under any circumstances. 



2. Lack of Water and Air about the Roots. 



All trees need to stand in ground which is sufficiently open 

 to the air and suitably watered. The exclusion of either air 

 or water from the soil is surely and quickly fatal. It is a 

 matter of common observation that a filling of earth two or 

 more feet deep about thrifty, mature trees will damage or kill 

 them. The covering of earth works this injury simply by 

 excluding air from the active rootlets. 



The conditions of city life seem to require that streets and 

 sidewalks should be made hard and as nearly impervious to 

 water and incidentally to air, as may be. As a result, the 

 trees standing on or close by the streets are greatly limited 

 in their supply of both water and air by the water-tight and 

 air-tight covering above their roots. 



3. Lack of Plant Food. 



The soil in a large part of the city is a light leachy sand, 

 naturally unfertile and for more than a hundred years the 

 tree roots have been constantly taking the available plant food 

 out of it. A part of this matter assimilated by the trees remains 

 permanently in the wood and by far the larger part goes into 



