▁hect are ▁nature ▁reserve , ▁the ▁Rh ine ▁delta ▁offers ▁habitat ▁for ▁numerous ▁plant ▁species . ▁R ip arian ▁for ests , ▁scattered ▁me adows , ▁re ed ▁b eds ▁and ▁grass ▁b eds ▁are ▁the ▁most ▁e colog ically ▁valuable ▁rural ▁habit ats . ▁Lar ge ▁flat ▁water ▁zones ▁and ▁special ▁locations ▁such ▁as ▁d ams ▁and ▁rud eral ▁areas ▁increase ▁b iod iversity . ▁So ▁far , ▁around ▁ 6 0 0 ▁flow ering ▁plants ▁and ▁f ern s ▁have ▁been ▁detected , ▁with ▁several ▁species ▁in ▁all ▁of ▁Austria ▁or ▁in ▁Central ▁Europe ▁under ▁threat . ▁ 3 3 ▁species ▁of ▁the ▁area ▁are ▁considered ▁lost ▁or ▁have ▁become ▁ext inct . ▁These ▁include , ▁for ▁example , ▁the ▁water w heel ▁plant , ▁a ▁car n iv orous ▁aqu atic ▁plant , ▁the ▁r ar ity ▁of ▁which ▁once ▁led ▁Ferdinand ▁I ▁of ▁Bulg aria ▁to ▁the ▁Rh ine ▁delta ▁several ▁times . ▁The ▁decl ine ▁in ▁species ▁is ▁primarily ▁caused ▁by ▁d rain age , ▁intens ified ▁land ▁use ▁and ▁river ▁engineering . ▁However , ▁there ▁is ▁also ▁a ▁number ▁of ▁new ▁species ▁in ▁the ▁fl ora ▁of ▁the ▁Rh ine ▁delta , ▁especially ▁from ▁America ▁and ▁Asia , ▁that ▁mainly ▁inhab its ▁artificial ▁locations ▁such ▁as ▁the ▁Rh ine ▁d ams . ▁ ▁Tour ism ▁ ▁Das ▁R he ind elt ah aus ▁(" the ▁Rh ine ▁delta ▁house ") ▁ ▁The ▁R he ind elt ah aus ▁is ▁the ▁service ▁point ▁and ▁conservation ▁station ▁of ▁the