ECOLOGICAL SUCCE--1"\. 145 



However, no >uch arrangement of foil- has been found in 

 the^e pond-. No attempt to ascertain whether or not they are 

 present ha- been made. 



2. Relntion to Clinidtic L'hun^c^. As ha- l>cen indicated, sued 

 .-ion is dm- to changes in condition- which make- it impo--il)le 

 lor a gi\en 'jnmp of or-ani-m- to continue to live at a certain 

 !" ality. Accord:n-]\ . -nch a group .-radii, dly di-appear- and 

 i- .r 'dually -iid .-died l'\ Mip which is adapted to the new 



condition 



The ch in c'nidition- rdenvd to arc climatic or phv-io- 



graphie dial ad other- independent of ph\>iograph\" and 



din; Tin- l.i-t type of ch > usually due to the action of 



tin isms themselves. The-e hn-e force- nia\ act separateK- 



ther. Tin-! 5 probably the more common. In ca-e 



tin- li lioth the ' -i..n and the 



-ii' "t 5] l-icalit\- might lie pa.rtl\- due !< 



migration of a succession! Narthorsl '70. lid,- \\'ann- 



ing, '09, lound that the -il- imderK 'ing moors 



areofarcti< 'undra plant-. I: ial dispersal arctic-tundra 



plant- and animal- \\ere -n. - .-.nd a nciali-d 



animal-, and I .\ d. . :lnnii- 1 1 1 animal- Adam-. 



- 



'<itit>n oj // i ! ' a/ - s '/c - essi 



1 pointed out thr lact th.it there i- lrei|iietul\ a 



hori/oina! -ioiial - ! diltt -rent a. 



'ed \\ith c..nlimiou- ph\ -! 'graphic pr- . -nch a- the 



depo-iti.-i id alonj Tlie di.t^ram Fig i illustrates 



licith thi' liori/mual and \eriical -erie- ! c. mdin'i >n- with wln'di 



\\ella\el'eelldealil ' 'Ol I 11 f t 1 H f poi II I ed OH I that ll'e 



hon/uinal series \ plain i "in muni tit - nm-t Near a close ( < "1-igical 



mMaiH'e or lie pt.K n't ,ill\ identical \\ith the \ertical -. ii< - of 



pa-t plant com mini hie- \\ Inch ha\e -ncceeded om- allot her o\ er a 



^i\eii loc.tlitN in the older part of the hori/ontal -eric-. lie 



pointeil out further that the hori/ontal -eric- may lie taken as 



an index of \\hat the vertical Series ha- lieeil. lie \\oiild e\t cpt 



the tir-t Si - of plant communities which occupied a locality 



at the cl'i-e o| the ic. gi aid \\hich a- ha- ln-eti -tated. an- 



ic plant-. Thc-e arctic plant-, ho\\e\er. nm-t iia\e attd N d 



