Species-rich communities along watercourses
Riparian forests extend along streams and rivers. In Puch, too, we find them along the banks of the Salzach, among other places. Riparian forests are characterised by periodic, temporary flooding and high groundwater levels. With every flood, nutrient salts and sediment are introduced into the soil, which makes the floodplains particularly nutrient-rich and fertile sites and ensures a great abundance of plants. Floodplain forests are also home to a variety of animals, including insects such as wild bees, butterflies, beetles and dragonflies, as well as various species of snails, mussels, crabs and amphibians, and many species of birds, including the kingfisher, the wagtail and the woodpecker. But badgers, beavers, roe deer, otters and brown hares are also at home in the alluvial forest.
Richness in nutrients made the riparian forest a popular settlement area
Because of their richness in nutrients, riparian forests have always been considered good settlement areas. Clearing the forest made room for houses and pasture land. As the land was too wet for agriculture, at first only cattle were allowed to graze here. Later, people learned the technique of drainage and drained the meadows in order to cultivate them with less effort or to partially cultivate agriculture there.
"Treppelwege" along watercourses became important transport routes - such routes also led through Puch.
Rivers became important transport routes. In Puch, too, the name "Treppelweg" still bears witness to this in the Puch-Urstein landscape conservation area, on the banks of the Salzach. Treppelwege" are paths that were built directly on the banks of rivers and canals so that people and draught animals could pull barges (Plätten) upstream, this was called "treideln". Salt from Hallein in particular was shipped downstream, reloaded in Laufen and brought to Passau, where it was then loaded again onto larger ships for onward transport. On the way back, some of the boats were loaded with goods that were needed in Hallein and sold at the market.
The zones of natural "true riparian forests
Riparian forests are among the most species-rich biotic communities in Central Europe. However, most riparian forests have disappeared due to drainage, construction and straightening and an associated lowering of the watercourse, or are no longer regularly flooded and are thus only the remains of natural riparian forests. Sites that are actually still periodically submerged in water are now among the habitats that are particularly valuable and worthy of protection. A natural floodplain consists of three zones:
- the wood-free floodplain, where grasses and herbaceous plants grow in the shore area.
- the softwood floodplain, found directly along the watercourse and gravel banks, and
- the hardwood floodplain, which lies a little further away from the watercourse and is flooded less frequently and for a shorter period than the softwood floodplain.
In the softwood floodplain we find fast-growing woody plants such as willows, poplars, black alder and grey alder (softwoods). In the hardwood floodplain, depending on the soil and the frequency and duration of flooding, we find different hardwood tree communities, typically ash, mountain elm, lime, pedunculate oak, maple and, in the shrub layer, hawthorn, hazel, honeysuckle, weeping cherry and elder. Nowadays, floodplains are also distribution corridors for neophytes, i.e. for plant species that have been introduced since 1492, which have established themselves here under human influence and were not native before. In the area of the Pucher floodplains we find, for example, goldenrod, glandular touch-me-not and professional weed along the riverside paths.