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Rcfcrcntx Area No. ? <br />Crncr trcttls for 12c1•crencc Arca d? di(Tcr from the otlxv rcfcrcnoe arras, in Ihrt rnrcr of rll vegetation <br />~tcgoncs incratscd sharply lxtwcett 1996 and 1999 Thts is tfuc to the fact that the heltlutc flat was <br />topso8ed and soeded m the fall of I'ri)7, and 1998 was the lust growtng season. The ern cr increase from <br />199810 199') rcflcx;ts nwluranon of plants that acre seedlings in 1998. Vcgclation st:mds in the other <br />reference artrs had btxn socdcd at IGtV five years poor to Otc initial sampling. Since 1999, total vegetation <br />cover and non-noxtous fort cover have remaitwd relatively stable, while grass cover Ims incrrased.:utd <br />noxtous wval cover Itas agntficantly dvtlined (Figure S1 <br /> Figure 5 - Beltllne Reference Area •3 Absolute <br /> Cover Trends; 1998-2001 <br />~ 60 0% . Absolute <br />c 50 0% --- Noxious Cover <br />~ <br />~ 40 0% <br />30 0% ~ Absolute Grass <br />~ <br /> - <br />Cover <br /> 20 0% _ « Absolute Forb <br />~ <br />Q 70 0% Cover <br />----- <br />~ 0 0% ~ -t-Total4epetatlon <br /> 1998' 1999 2000 2001 Cover <br />2(X11 absolute and relmne emer by species and category is prcscmtd m Table 9 Absolute and rclauve <br />cover sample means b}' categon and year arc prcscuttvl m Table 11) lkrause I'ri)8 was the first growing <br />swson, etfccts oC spmymg arc ntaskcxl by gmwih and nwtumuon of ind,v~dual plants, and as such <br />compunson of 1998 absolute cover values with subsequent yclr absolute Dover values Is not mcantngful. <br />Rrlnn,r cover. a measure of spites composition, does allow for hmutd, w•tthm category companson <br />lxtwccn 1998:md Inter years. Cover summon tahlc-s for 1998, l9'», and 2(NMt arc included in the <br />n~spccxivc D'v1G Annual 14'txxt Sampling Rcporl Based on rcludve cover, the domin;tnt noxious spaics to <br />1998 wcrc the biennials plumclcss thtstlc 1 I S ~°6), and musk thtstlc (10.3°in), with oxeye drtsy the <br />rern:uning noxious species sampled (?.r.°~) Rclauve corer of plumdess thistle roughly doubled between <br />1998 anti 1999, bul dtxhncd sharply belwcen 1999 and 21NNt, and was not cncountcrcd by cover sampling <br />m 2tNt L Musk thistle was not cncountcrud by cover samplingrfter 1996 (tins-tdcnuficauon of plumclcss <br />thtstlc seedlings as musk thtstlc in 19'+8 is a possibthh) Carutda thistle was first encountcrcd in 21NNt. and <br />wits a minor sttmd component to both 2000 and 2tN) I Itclauvc coca of oxeye daisy rcrrtatntxi rchttivcly <br />stable rn cv the couru of the slttdv. <br />Bchsecn 1999 and 21X1 I, ohsolute cover of noxious spceies tlwlintxl from I G.S% to 2.3°/q while absolute <br />guts wvcr trtcrcasal from 14 i'!a to 29 ?~•; "fhe response of plumclcss thtstlc, which dn:brtat from IS,Ogo <br />absolute cover in 1999, to a ?°!, cover m :(NN) oriel lw/° cover m 2txt I , is the reason for the a•er-all dochnc <br />to noxious spa-ics cover A ntunhcr of grass species conuibutcd to the inacase to sbsolute cover of <br />grassy rn•cr the pcnod. Absolute cover of non-noxiats fofis has remained n:ltttivcly sl:tMe since 1999, <br />w iUt no readily apparrnt effects of spraying on indreidual species or the category as a whole <br />Noxious species density tLzltncd sharply bchvccn 1996 and 2tN11, and renmmcd low to 1tN11, due to the <br />responxe of the noxious thistle spoctcs its illusuatcd to Figure r, Although thistle spoetcs wcrc not <br />separated in the density estimate. it atrt be inferred based on the cover darn that the dramatic da;line <br />rellectcxl the rcsTxinse of plumclcss lhisilc and (possibly) musk thistle ihtrile denary sample mean <br />tioclmed by approximately 95^% from 1'»6 to 21Nt 1, fmm l U] plants per squ;uc meter l0 0. s pmts per <br />squ:ue mctt7 Oxt7c daisy density was sampled ooh in 1999 and 2tN)I, and dcrtstty rcmvncd stnblc at the <br />rclutivcly low Irnrl of 1. I playas per squam meter to I'riri) urd I ? plains per square meter in 2tN) I <br />