Vegetation in Vanhankaupunginlahti Bay Area

Most of the vegetation in Vanhankaupunginlahti bay is treeless wetlands, bordered, in many areas, by black alder groves. The clearly predominant and striking vegetation is the reed bed. It seems monotonous, mainly the common reed meeting the eye, but many other plants and different vegetation zones exist within it. The structure  - height, density and coarseness - of the reed bed varies as well. The bottom may be muddy and boggy, or quite dry. Other type of vegetation may be completely absent or quite lush, even predominant. The reed beds have been classified into eight different types.

Many open ponds can be found hidden among the reeds, although they are being overgrown and are diminishing in size. Hardly any submerged or floating aquatic vegetation exists due to the poor quality of water. In the open water areas, submerged vegetation mainly occurs in close proximity to reed mace, as this particular species of vascular plant has the ability to filter and, thus, purify the drainage water.

Land in the Helsinki region, rises by around 30 cm every 100 years. In addition, decomposing vegetation and detritus brought down by the river lower the water level of the bay. Along the shores of Vanhankaupunginlahti bay, new types of plants appear, to be replaced by others at intervals of around 100 years. Succession proceeds by open water turning into reed marshes and wetland meadows, and then to solid land supporting clumps of alder, woodlands and forests.

 

From shore meadows to woodlands

Shore meadows form an intermediate zone where the water and shoreline vegetation gives way to dry land and hard vegetation. The original meadows, that have arisen without human impact are scarce, and are nowadays only extensive in Purolahti. The most common species found in the shore meadows are the marsh cinquefoil and the creeping fescue.

Groves surrounding the reed bed have a greater variety of vegetation. In Hakalanniemi and Kuusiluoto, the wood sorrel and May lily groves are at their best. The dominant tree species include silver birch, European aspen, rowan and maple, the bush vegetation consisting of, for example, mountain current, Alpine elder and bird cherry. The field layer has such species as wood anemones, marsh marigolds, meadow horsetails and red campions. Hazelnut also occurs.

Many forests in Viikki -area, excluding the lush alder groves, are dominated by spruce, most of the forest growing rowan and European aspen as well. The lower vegetation in these forests consists of species like blue berry, chickweed wintergreen and wood cow-wheat. Remains of a very old spruce forest still remain in Kivinokka and Mölylä. Sturdy pines, on the other hand, stand along the dendrological path in Kivinokka, and various species of trees are displayed in the Hakala arboretum.

 

Something Special About the Fungi

Due to the nature reserve status, forests in Vanhankaupunginlahti bay area have mostly been left in peace. They are rich in old decaying trees and, therefore, host a great variety of fungi. The most visible of these are the shelf fungi (Polyporaceae) that can be seen growing in multiple colours on tree trunks and stumps.

Corticiaceae is a group of less known organisms of wood-decaying fungi. They are somewhat different from shelf fungi, as most of them are only annual and their sporophores are quite small. Some of the Corticiaceae fungi species are only visible a couple of hours after rain. In Finland, there are about 345 Corticiaceae species of which about 100 can be found in Viikki. Several of the species found in Viikki are very rare and one of them has its only known Finnish growth site in Viikki.

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