Učna sprehajalna pot Rača v občini Moravče - Zavod RS za varstvo ...

1819?ivljenjski prostori alihabitati ob Ra;iHabitats along the Ra;astreamRača in its middle course. BetweenSelo and Stegne it cut a narrow gorgein Mesozoic limestone. We willcatch sight of it when crossing thestream at Mecetov mill.Here, we will find no arable land orhuman settlements, the only exceptionbeing the old abandoned, crumblingmills and sawmills. In its furthercourse, the Rača valley widens. Characteristichere is its shallow and meanderingbed overgrown with riparianvegetation. In this part, the stream oftenbursts its banks, which is the reasonwhy wetlands have been formedin the wider parts of the valley.On its way, the Rača flows throughnumerous meanders, hardly accessiblegorges and, again, through widerparts of the valley, where its coursecalms down and spills across the surroundingplains. The same as theRača changes its face along our trail,so the very different riparian habitatsalternate along it.Ravninska struga Ra;e.The lowland Ra;a bed.rečico pri Mecetovem mlinu.Tu ni ne obdelovalnih površin ne naselij,izjema so bili stari mlini in žage,ki so opuščeni in jih najeda zob časa.V nadaljevanju toka se dolina Račerazširi. Zanjo je značilna z obrežnovegetacijo obrasla plitka in vijugavastruga. V tem delu rečica pogostoprestopa bregove in poplavlja, nadolinskih razširitvah so zato nastalamokrišča.Rača se na svoji poti vije v številnihzavitih okljukih, čez težko prehodnesoteske, in se na dolinskih razširitvah,kjer umiri svoj tok, razlije na obvodnihravnicah. Kot spreminja Rača svojobraz ob naši poti, tako se ob njej vrsterazlični obvodni življenjski prostori.Vodotok v zgornjem delu je naravnoohranjen. Tu najdemo številne različneobvodne in vodne življenjskeprostore ali habitate, ki dajejo zavetjemnogim različnim vrstam rastlin inživali. Vzdolžno se v toku reke menjavajopredeli s hitrim pretokom inpredeli s počasnim pretokom. Razlikeso tudi v pretoku od površine do dna.Hitrost pretoka pada z globino. Zaradivečjih skal in prodnikov na dnu je tokvrtinčast. Rečni tok vpliva z odnašanjemin odlaganjem rečnega materialana zgradbo rečnega korita. Z občasnimpoplavljanjem in erozijskimi procesivpliva tudi na obliko in vegetacijskosestavo obrežja. Tako se ustvarjajoštevilni manjši in večji življenjskiprostori, ki spodbujajo rastlinsko inživalsko pestrost ob vodotoku.V toku domujejo ribe, pod kamnise skrivajo redki potočni raki, na muljastemdnu in obrežnih naplavinahnajdemo celo sladkovodno školjkopotočnega škržka.Po prodnatem dnu in večjih kamnihin med vodno obrastjo in rastlinjemse zadržujejo vodni polžki, pijavke, vrtinčarji,postranice in ličinke številnihžuželčjih vrst, katerih razvoj je vezanna vodo in obrežno rastlinstvo. Vsi tiorganizmi predstavljajo bolj neuglednoin povprečnemu opazovalcu skorajnevidno živalsko druščino, medkatero se na koncu zvrstijo še enoceličniorganizmi in bakterije. Ti bodonekoč to odmrlo druščino in celočloveško nesnago, razgradili in miner-In its upper course, the Rača has beenwell preserved. Here, we will find numerousand diverse riparian and waterhabitats, giving shelter to many differentplant and animal species. Longitudinally,sections with quick flow ratesand sections with slow flow rates alternatein its course. There are, however,differences in its flow rates at differentdepths as well: the speed of the currentdecreases with its depth. Due tothe presence of larger rocks and boulderson the bottom, the current swirls.By carrying away and depositing theriver material, the current has a strongimpact on the structure of its bed.With occasional flooding and erosionprocesses it also affects the shape andvegetation structure of its banks. Thusnumerous smaller and larger habitatsare created, which stimulate plant andanimal diversity along the stream. Thewater itself is inhabited by fishes, underthe stones the rare crayfish arehiding, whereas on the silty bottomand alluvial deposits the shell of thefreshwater Painter’s Mussel (Unio pictorum)can even be found.On shingly bottom, larger stones andin water epigrowth and plants we maycatch sight of water snails, leeches,flatworms, amphipods, and larvae ofseveral insect species whose developmentis closely associated with waterand riparian vegetation. All these organismsconstitute a more or less insignificantand to average observers almostinvisible animal »company«, in