36 STATE BOARD OF FORESTRY. 



resident population. This branch of shelter planting should be extended 

 particularly on the windward side of seaport towns, where windbreaks 

 in proper places will protect anchored vessels and facilitate shipping. 

 Windbreak planting should also be practiced in many coast localities 

 to hold the sand from drifting inland and covering up valuable agricul- 

 tural land, crops and dwellings. 



Fully grown Eucalyptus windbreaks running at right angles to the 

 direction of the prevailing winds every quarter mile across level country 

 afford effective protection. Near the foothills the lines should be closer 

 together, since the winds blowing down from the mountains gain greater 

 velocity. Through orchards they are generally located every 100 or 200 

 feet. Though a heavy wind may be swaying the tops of the trees in a 

 windbreak, usually there is hardly any stir in the air near the ground 

 within a well-protected citrus orchard. The wind is never sufficiently 

 strong to whip the foliage or injure the fruit. 



All crops protected in this way suffer less from winds than open- 

 grown crops. They remain uninjured when unprotected crops are 

 blighted, unless the arrangement of the windbreaks results in defective 

 wind-drainage and the formation of a frost hole. After a cold night, 

 during frosty winter months, the shade cast by a windbreak on the 

 eastern side of an orchard will often prevent injury from too rapid 

 thawing. 



Citrus trees are unfavorably affected by shade, hence the yield of 

 fruit of rows adjoining a windbreak is often lessened. Windbreaks on 

 the north and east sides of an orchard are less harmful than on the 

 west or south side. Under ordinary conditions the south side of an 

 orchard should be left open for wind-drainage. 



The best spacing of gum trees for windbreaks is 4 feet apart each 

 way in double rows. The trees of the second row should be planted 

 opposite the open spaces in the first row. Double, or even triple, rows 

 should be planted where the winds are severe. Triple rows will always 

 be adequate for crop protection, though shelter belts from 10 to 20 rows 

 wide may be advisable to protect from strong sea winds. 



Monterey cypress is frequently planted alternately or in double rows 

 with eucalypts to maintain a dense shelter near the ground, since the 

 gum trees clear the lower stem with later growth, giving access to the 

 winds. This combination is an excellent one, since great density is 

 united with towering height. The cypress is well adapted to this use 

 by its tolerance of shade. Cypress and eucalypts should be planted in 

 separate rows and not alternated in the same row, the cypress being 

 located on the windward side of the line, excepting on the north side 

 of a field, where it should be planted on the south side of the line to 

 receive more light. 



