BULLETIN" 791, U. S. DEPARTMENT OF AGRICULTURE. 



The second- weed stage is characterized by a fairly well decom- 

 posed soil. The improved condition of the rock as a habitat for 

 plants which results from the formation of soil is obvious. This is 

 particularly evident when we recall that the rate of succession is 

 largely determined by the moisture conditions of the substratum. 



r 



< 



V. 



Deep rooi-ed or' denssly 

 fufi-ed rs-fher shallow 

 rooi-ed perennia/ grasses, 

 Q-then i^eqe-f-oi'ion B/rnoai' 

 entirely lacking. 

 {Final or Climax SfaqeJ 



Lo<3n7y, -f/ne gr^fe//y so// 



r/cfj in organic matter,- 

 airji/,3b/e moisture content 

 /?,g/i. 



Perennial IrerAs, chief /y 

 weeds^ tviYh scattered st<ind 

 of aggressive gr<^sse s.- 

 sometimes <?/7 occ^siona/ 

 shruS in e'videnc^. 

 (■Second iVeed St^ffeJ 



/-oamy, s/ight/y grcffe/ly 

 %joi/ ivit/i moderate amount 

 of organic matter sfai/- 

 ab/ejmo isture content 

 moderate to /iigh. 



£'dr/y maturing annuals 

 and stiat/otv rooted short 



/iyed perennial tieribs. 

 (r/rst l^eed JtageJ 



Graiiel/y /oan7,soi/ poor in 

 organic matter; ayai/a6/e 

 moisture content moe/- 

 erate to /o>v. 



f^gjiaceous Licfrens Snd 

 Afasses ynith sparse stand of 

 ear// maturing annual herbj 

 (Transitional StageJ 



Course, grafeZ/y s-em/- 

 c/ecomposed rocA_. iSfa//- 

 ab/e moisture ;content /«><*- 



i4/gae and Crustaceoas Ocliens 

 (/nit/al or P'lO/yser .Stc^gsJ 





S^re roc/r -format/on. 

 (^/r7/t/<s/ /^eco/npios/tibn-J 



l^/^Gi^TA T/H'£- P'/fAS£- 



I 



^O/l P/tAJ£- 



i/e6eTA T/\/£ litto JoiL roff/^A r/od 



Fig. 1.- 



-Plant succession or the development of vegetation wliere grass constitutes the 

 climax or subclimax type. 



The soil upon which the second-weed stage develops, being mod- 

 erately well impregnated with organic matter, is fairly moist 

 throughout the growing season. This condition permits the estab- 

 lishment of a stand of perennial herbs of varying density, the weedy, 

 unpalatable species often predominating. These, in addition to an 

 admixture of bunch gTasses and often of turf -forming species as well, 



