﻿Tn'es of New York Htale 393 



lrv(!l, cfc,.), fitid IcMTJiiii cfiiisi' furtlKM" iiiodificnlion of tlioso tyfXiH. 

 Jt is gcMcnilly conceded lliat Mk; rjiirif;!!! lu'ccssjiry for forest 

 growth is about the; suhm; as thai, i-c(|iiii-('d for a<^ficult,iin' willioiit 

 irr"i<jfatiori, that is, from 20 21 inches. Jiut pnu'lpitation is (h)- 

 j)en(l<!nt on such pliysiogi-jiphic f(!atui'es as (a) proximity to tJio 

 ocean or other large bodies of wat(!!', (b) monntain ranges athwart 

 th(^ rain bearing' winds wliieh necessitate; a. cooling of the air arul 

 Jieavi(!r raiid'all, and (cj location within or n(!a,r the track of 

 cyelonic storms. With equal temperature the kinds of tri'es ati<l 

 forest typ(!S vary with prc^i^ipitation. This ac(!Ouut,s larg(!ly for 

 the fact that tlie (Jreat IMains and the Great iiasin of the United 

 States are forestless though not treeless. The plant belts whieh 

 owe their origin primai'ily to latitude are gnv'itly modified in the 

 United States owing to varying temperatures bi'ought about by 

 toi)ography and by wide extremes in annual precupitation. 



TRANSCONTINENTAL BELTS OR LIFE ZONES 



In th(! (l(!velo[)tri(jnt of the natural r•esollr(•(^s of the United States, 

 particularly the agrieultui-al resonre(;s, it was (!a,rly recognized 

 that North Ameritta (!ontaine(l seven transcontinental belts or life 

 zones, each again divisible into a large numbcn- f)f minoi- Horal- 

 faunal ar(!as. TIk'Sc; zones, as ilelincd by .\Iei-fi;iirit areas follows: 



I. The Boreal Region 



1. The Arctic-Alpine Zone — The far north beyond the 

 limit of tree g!"0wth and in the United States, high inoun- 

 tains above timber line. Zone of the polar l)ear, musk ox, 

 reindeer- and of arctic poppy, dwarf willow, etc., in north 

 polar regions. 



2. The JIudsonian Zone ln(;lud(!S thc! norther-n parM, of 

 the boreal eonifer forest stretching from Labrador to Alaska. 

 In eastern Unit(!d States it is limited to the cold summits 

 of the high(!st mountains from noi-thern New Knglafid to 

 western North (Jarolirui. 



3. 'i'he (y'anadian Zone - Includes the; southern and most 

 valuable part of t,h<! trariscontinental boreal conifer forest 

 in Canada and pai-ts of Maine, N<nv Hampshire and 

 Michigan, (!xt(!nding southward along tin; Appalacrhian 

 highlands to w(;steiTi North Carolina and Tennessee. Zone 

 of red spruee, balsam fir, paper biich and mountain ash. 



T M(!rrluiii, C. Hurt. lAt,' /hips iiikI ('ri.p ZoimH. f. S. lUol. Survey, ISiill 10, 

 181)8. 



