× 1 - meter ▁back drop ▁( L imb ▁et ▁al . ▁ 2 0 0 7 ). ▁Rob el ▁et ▁al . ▁( 1 9 7 0 ) ▁developed ▁a ▁pole ▁to ▁determine ▁height ▁based ▁on ▁correl ated ▁veget ation ▁weight . ▁The ▁pole ▁was ▁d uly ▁named ▁the ▁Rob el ▁pole . ▁Rob el ▁et ▁al . ▁( 1 9 7 0 ) ▁found ▁that ▁V O ▁measurements ▁taken ▁at ▁a ▁height ▁of ▁ 1   m ▁and ▁a ▁distance ▁of ▁ 4   m ▁from ▁the ▁pole ▁gave ▁a ▁reliable ▁index ▁of ▁the ▁amount ▁of ▁veget ation ▁production ▁at ▁a ▁location . ▁H amer st rom ▁et ▁al . ▁( 1 9 5 7 ) ▁were ▁quoted ▁as ▁saying ▁" Height ▁and ▁density ▁of ▁grass ▁were ▁clearly ▁more ▁important ▁to ▁the ▁pra irie ▁ch ick ens ▁than ▁species ▁composition " ▁as ▁reported ▁by ▁Rob el ▁et ▁al . ▁( 1 9 7 0 ). ▁This ▁was ▁also ▁believed ▁to ▁be ▁true ▁for ▁the ▁sharp - ta iled ▁gr ouse . ▁These ▁key ▁aspects ▁can ▁now ▁be ▁ass essed ▁using ▁the ▁Rob el ▁pole , ▁N ud ds ▁cover ▁board , ▁and ▁Lim b ▁et ▁al . ▁digital ▁phot ography ▁method ▁effectively ▁and ▁efficiently . ▁ ▁Management ▁It ▁is ▁apparent ▁that ▁the ▁effects ▁of ▁habitat ▁fragment ation ▁across ▁all ▁habitat ▁types ▁selected ▁by ▁sharp - ta iled ▁gr ouse ▁are ▁impact ing ▁this ▁species . ▁The ▁management ▁of ▁sharp - ta iled ▁gr ouse ▁habitat ▁has ▁changed ▁over ▁the ▁years ▁from