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Figure 6 -Beltline Reference Area #3 <br />Noxious Species Densities <br />ar`r 15 <br />f 10 _ +Thistles per <br />a y i sq. meter <br />z ~ U ~ ~-Oxeye daisy <br />w per sq. meter <br />1998 1999 2000 2001 <br />21x11 nouous wu~ dcnstn data is pnscn(cd in Table I I. 1'ablc 12 fists densny sample means for ttowous <br />thtales, oxeye duis~, and noxious spuctes ~rombtned, for each year of the study. <br />~Le~r~nce Area ho 4 <br />Figure 7 dcpavs the dratmtic iNGal dtxhrtc m noxious spxia cover ttbscn~cd at the bclthnc ouWopc <br />lxttsrcn 1998 and I °M9. In 1998, dtc dcnsitr of noxious µ'txxlt was so great that a dClLgh count sus not <br />attempod Absolute cover of noxious spectcs d~ Unai from 4 LO% in 199:1 to Ll1°o m I')99, and has <br />rcrnairted low (7.A"'o in 21x)1) In 1998, twv glecies accountal for the bulk of the nouous cover. oxeyt <br />daisy (21'sol and pluntclc thtstlc (Ir.°.o) In 2(101, lhrsc wcrc the only two notwus spcci~ sampled. cash <br />rnntribuung I .tM/o cover Cuna~ thtstlc ~sas a minor component of the nand pch year. rnnmbuting :^~~ <br />absolute cm cr to I'>`)A and 3°o absolute cosrr m 21100. <br />Flqure 7 • Boltline Reference Area q4 Absolute <br />Cover Trends; 1998.2001 <br />80 0% ~ I-+-Total Vcyetatwn <br />7 0 0 °~( - ---, Cove r <br />0 0/. -Noxious Cover <br />50.0 n, - - <br />40 0°~-. - y .-Grass Cover <br />30.0°/ - <br />20,0°.~ - ~--Non-Noxious Forb <br />10.0°h Cover <br />0.0% -+-6hrub Cover <br />1998 1994 2000 2001 <br />2rxt1 at>,solute and relative cover by spores and ptegon is pt>»setlted in Table I? Table 14 presents <br />a!>solute and relative crover sample means by category for cash year of the study. ~'ss Illustrated in Ftgurc 7, <br />t11e most sharply defined responsc~c arc t11e drantauc decline in roxious splxi~s cover, and the contesting <br />tttcrctsC to grass cm~er (from 10.0% in 1998 to Sri°io In :1x11). A number of grasses conlnbUtcd to the <br />