﻿AN ECONOMIC STUDY OF ACACIAS. 13 



GOLDEN GATE PARK, SAN FRANCISCO. 



The best evidence of the adaptation of nearly all of the Australian 

 acacias to the sandy soil of the California seacoast, clear down to the 

 ocean beach, directly exposed to heavy gales and dense salt fogs, is in 

 Golden Gate Park, San Francisco, where they have been chiefly in- 

 strumental in making a magnificent park out of a waste area of drifting 

 sand. The planting during the past 40 years furnishes the best record 

 of the successful use of acacias in reclaiming sand dues that exists. 

 At the present time there are superb thickets and copses of acacias, 

 thoroughly established and naturalized, so that they require no culti- 

 vation. Not only that; they are extending themselves from year to 

 year, within a stone's throw of the Pacific Ocean, and fixing the va- 

 grant sands. Further inland similar thickets are changing to acacia 

 forest, capable of yielding firewood and timber. 



The planting began in 1870, and the stock used was chiefly for 

 ornamental purposes. Trees from this first experiment are now stand- 

 ing in the older portions of the park — magnificent specimens of A. 

 melanoxylon and A. decurrens. But even with this earliest planta- 

 tion, some were set out on the sand hills to the west, simply as an 

 experiment. 



The westernmost 730 acres of this famous park consisted of great 

 shifting dunes of sterile sea sand. The larger native growths were 

 scattered evergreen scrub oaks and willows in the hollows between the 

 barren sand hills. Often the dunes would drift over the willows and 

 oaks and kill them. The struggle of these plants is clearly shown by 

 the fact that lupin roots have been traced downward for more than 25 

 feet in the sands, while the roots of the willows have been followed 

 for more than 100 feet from the main stems. 



While many of the original acacias have been removed for one 

 cause or another, this still remains a wonderful object lesson in 

 acacia planting. Some trees have been taken out in the necessity 

 for thinnings ; 6thers have had to give way to new driveways as they 

 reclaimed the sands, thus making it possible to extend the cultivable 

 portions of the park. The buildings for the Midwinter Fair of 1893 

 and the shelter tents for the homeless after the earthquake and fire 

 of 1906 further diminished the thickets and groves, yet the arboretum 

 contains the only California specimens known to the author of 

 Acacia discolor, A. capensis, and A. coccinea. 



These complete and long-continued tests indicate that the shrubby 

 Australian acacias will cover sand dunes rapidly and efficiently and 

 will furnish firewood in from 8 to 10 years from seed. While all 

 this stock was nursery grown and transplanted, experiments in other 

 places seem to indicate that seed can be sown directly on such sand 

 slopes, and that the expensive nursery and transplanting practice, 



