▁research ▁and ▁a ▁unique ▁habitat . ▁These ▁for ests ▁have ▁a ▁very ▁dense ▁can opy ▁and ▁a ▁mo ist ▁under story . ▁ ▁Since ▁the ▁invasion ▁of ▁the ▁b als am ▁w ool ly ▁ad el g id , ▁discovered ▁in ▁ 1 9 5 7 , ▁F ras er ▁fir ▁mort ality ▁rates ▁have ▁been ▁ 9 0 – 9 9 %. ▁Although ▁some ▁areas ▁are ▁being ▁reg ener ated ▁by ▁young ▁f irs , ▁there ▁is ▁much ▁change ▁in ▁under story ▁composition , ▁including ▁invasion ▁by ▁both ▁wo ody ▁and ▁her b ace ous ▁species . ▁Red ▁Spr uce , ▁the ▁spr uce ▁component ▁of ▁the ▁spr uce ▁fir ▁e cos ystem , ▁has ▁also ▁been ▁suffering ▁decl ines . ▁Some ▁research ers ▁attribute ▁these ▁decl ines ▁to ▁damage ▁from ▁wind , ▁which ▁is ▁usually ▁blocked ▁by ▁the ▁f irs . ▁B als am ▁w ool ly ▁ad el g ids ▁destroyed ▁about ▁ 9 5 % ▁of ▁the ▁F ras er ▁f irs ▁in ▁the ▁Great ▁Sm ok y ▁Mountains ▁National ▁Park , ▁creating ▁" g host ▁for ests ". ▁The ▁number ▁of ▁adult ▁f irs ▁has ▁increased ▁over ▁ 3 0 ▁years , ▁with ▁C ling mans ▁D ome ▁having ▁three ▁times ▁as ▁many ▁adult ▁trees ▁as ▁of ▁ 2 0 2 0 ▁as ▁in ▁the ▁ 1 9 8 0 s . ▁▁ ▁One ▁concern ▁is ▁that ▁acid ▁rain ▁and ▁the ▁d eter ior ation ▁of ▁the ▁o zone , ▁among ▁other ▁poll ut ants ▁are ▁contrib uting