Photo 1. Kolitovica Pond on Krk Island is an example of a circle-shaped pond. The impression of a regular circle is enhanced by the drystone wall and the ring-like belts of vegetation along the shore (Photo by Patrik Krstinić)
VEGETATION ENHANCES THE CIRCULAR AND RING-LIKE STRUCTURES OF PONDS IN THE LANDSCAPE
In Part I of our report on the circular structure of ponds, we pointed out that ponds encircled in drystone walls help to make a landscape look more dramatic (see: http://www.ju-priroda.hr/zanimljivosti.asp?iddb=82). The circular shape of ponds is further enhanced by the fact that the vegetation within the pond usually grows in concentric circles. During the year the water level of ponds fluctuates, causing ring-shaped segments to appear in the ponds’ shoreline area. These segments alternatingly dry out and are flooded by water for longer or shorter periods throughout the year. A variety of plant species are adapted to these changing ecological conditions. Belts of different types of marsh and aquatic plants also grow in the ponds depending on the depth of its permanent water. Typically only aquatic plants grow in the central part of a pond, which often has no vegetation at all. This central part forms a sort of circle around which grow concentric belts of marsh vegetation.
Menkova Pond near Poljica is a lovely example of this ring-like, though not perfectly regular, distribution of aquatic and marsh plants. Because it is a permanent pond, there are hardly any plants on the surface of the water in its centre. Outward from the centre there is a belt of floating aquatic vegetation consisting of broad-leaved pondweed and duckweed, together with luxuriant submerged aquatic vegetation. Following is a distinctive ring of marsh vegetation mostly made up of densely lined stems of spikerush (Eleocharis). Between this ring and land, there are two more distinctive ring-shaped belts. The first is almost barren of vegetation, with the exception of several highly resistance plant species adapted to constant fluctuation in wet and dry conditions (a species of the parsley family, in particular), while a dense carpet of bright green bentgrass (Agrostis sp.) grows in the second, wider one.
These more or less circular and ring-like structures attract our attention every time we go out into the field to list and study the main characteristics of some 60 ponds on Krk Island, our task in the cross-border Project LOKNA.
Categories: landscape, ponds
Keywords: Menkova Pond, Krk Island, circular structures in the landscape, aquatic and marsh vegetation
Photo 2. At Menkova Pond, the circular structure is emphasized by the growth of aquatic and marsh plants. Providing there is enough water in the pond during the vegetative period, a bright-green ring of bentgrass grows around the pond. (Photo by Ivana Rogić)
Conservation and Promotion of Aquatic Biotopes – Ponds and Marsh Pools – For the Future – LOKNA
The aim of the Project for the Conservation and Promotion of Aquatic Biotopes – Ponds and Marsh Pools – For the Future (Project LOKNA) is the conservation and revitalisation of aquatic biotopes (ponds on Krk Island and marsh pools in the Ljubljana Marsh) through a joint cross-border approach to valorising, taking inventories of, revitalising and promoting aquatic biotopes.
This is the link to the Internet page of the 2007-2013 Slovenia-Croatia Operational Programme: