192 ALTERNATIONS IN TIMBER-GROWTH. 



There can be no donbt but that climatic causes may have some con- 

 nection with these changes, where they occur to greater extent or in 

 more marked degree, — while the aggressive tendencies of other trees 

 may result from the exceptionally fine conditions of the places where 

 their seed may chance to fall. 



It is not unusual to observe in swamps throughout the jS'orthern States, 

 an alternation of growth taking place without human agency, but not 

 without apparent cause. Extensive tracts of tamarack [Larix ameri' 

 oana) may be seen in Northern Wisconsin that are dying out, and being 

 succeeded by the balsam tir {Ahies halsamea), which may be probably 

 caused by the partial drainage of the swamps, from the decay or re- 

 moval of a fallen tree that had obstructed the outlet. Accidents like 

 these, increasing or diminishing the moisture of the soil, may occur from 

 many causes. The construction of beaver-dams have in some cases do- 

 stroyed large tracts of timber which might very probably be succeeded 

 by other species when tlie obstruction was removed. Professor Agassiz 

 observed on the south shore of Lake Superior the very dense spruce 

 woods encumbered with fallen birch trunks, as if they had usurped the 

 place of a biich forest.^ 



Mr. Burnet Landreth, in a paper read before the American Forestry 

 Association in September, 1876, mentioned an observation upon the 

 white pine that is worthy of notice: 



A gentleman of Virginia, a friend of mine, largely interested in lands, a shipper of 

 timber from the seaboard, therefore not inexperienced, discovered in his forest explor- 

 ations what, for want of a better term, I shonld call a while-pine sciilement, in the dense 

 yellow-pine forests of the northern neck of his State. In the midst of a gronp of white 

 pines, extending over an area of five or six acres, stood a gigantic individual tree 

 96 feet high, 8 feet 4 inches in circumference three feet from the ground. There it 

 stood and stands to-day, surrounded by seedlings from 40 feet high down to seedling 

 R year old, as the boundaries of the settlement are reached, numbering in the whole 

 three or four thousand. Hore is a fact which cannot be questioned. A bird of passage 

 had evidently dropiied a solitary seed at some period long preceding, which, springing 

 up, had established itself in its now homo, far distant from the region where nature 

 Lad placed its ancestors. The meie fact of a white pine having tixed its abode and 

 prospered in a remote locality is but a trifle; but taken in connection with inferences 

 not to be ignored, its value can hardly be estimated. The proof is made patent thai 

 this tree of northern halit thrives equally well with the southern pine (of which there 

 are several species commercially classed as " Carolina") in the latter's native laud and 

 under the scorching sun of the South, opens a vista in forest-tree planting which those 

 who look beneath the surface cannot fail to appreciate. It is the index to future wealth 

 of inconceivable magnitude. 



Mr. Winslow C. Watson, of Port Kent, N. Y., in an article on " Forests, 

 their Influence, Uses, and Eeproduction,"^ notices the changes of charac- 

 ter in forests — pines being almost uniformly succeeded by a deciduous 

 wood, and the second growth on the site of a hard-wood forest being as 

 often followed by evergreens and soft-wood trees. He considers the in- 

 stances as rare and exceptional, in which the primitive forest is succeeded 

 by the same genera of trees. The most careful observation could fix no 

 rules that control these operations of nature. An instance came under 

 his own observation : 



In the course of ray explorations of Essex County, under the appointment of the 

 State Society, in 1852, I observed many singular manifestations of these caprices. In 



> Lake Supaior, p. 77. 



2 Tranaactions of New York State. Agricultural Sodetij, 1865, and separately published, 

 pp. 16. 



This writer, in presenting these and other instances of a new vegetable growth where 

 a different one had grown before, and noticing the several theories that had been ad- 

 vanced to account tor them— such as seeds long buried in the soil, and tbe like— in- 

 dulgfS in a conjecture of his own, still less tenable. We see in these examples no phe- 

 nomena ditfereut from or more difficult to explain than those already mentioned. 



