When openings have been left in walls, these are filled with soil, offering immediate growing opportunities for plants. On built walls without openings, the start for plants is slowest. The mortar has to be weathered to a certain extent before it is ready for plants, a process that may take many years. Once the environment is amenable to it, fern spores can be blown in or seeds can be smeared on the surface using some clay or old manure. On dry walls or in flat situations, sowing or planting is obviously much easier. When a number of desired individuals have been established they will usually propagate and distribute themselves, for example species such as Linaria cymbalaria, Corydalis lutea and C...>
Category The Dynamic Landscape
Whereas vegetation of organic and mineral soils have been dealt with in the preceding sections, this section is about more unusual substratums and soils, such as inorganic materials, like bricks or rocks that are found in many shapes—walls, broken rubble, lava, minestone and slate—and very shallow soils situated or created with the former as its base. With these rocky materials, all sorts of habitats and substratums may be created. They will initially look very artificial and barely natural, but they may lead to very special, unusual and surprising results. The most interesting characteristic of these materials is their suitability for creating special reliefs and gradients, impossible to achieve with normal soils...>
In other locations, vegetations of Calluna vulgaris, Erica tetralix or Andromeda polifolia that have become increasingly shaded are taken over by Empetrum nigrum, Vaccinium vitis-idaea or V. myrtillus. One vegetation aspect silently transforms into the next. On a spot where Vaccinium macrocarpus has been growing for over 30 years, with a mat of mosses and stems as thick as 10 cm, Gentiana pneumonanthe, which formerly flowered there by the thousands, is gradually disappearing completely. It does not tolerate the competition of the thickening moss-and-stem mat and is pushed out. Long before this stage is reached, Empetrum nigrum, Erica tetralix and Calluna vulgaris have established themselves, in addition to the usual unwanted species...>
Plants belonging to the heather family may be kept in good shape for years by the two elementary maintenance measures of weeding and trimming. In addition to weeding out unwanted species, annual trimming will keep the vegetation vigorous and will extend its vitality to a very long period. Without such maintenance measures, however, vegetation types like these may rarely be preserved.
The same is valid for ground covers composed of crowberry or billberry (Empetrum or Vaccinium spp.), but since trimming is, in this case, not required or tolerated, it will only rarely be necessary. When its vitality is reduced as a result of old age, frost or if a snow cover was trampled, Vaccinium vitis-idaea and V...>
After suitable initial conditions have been created, one starts with a soil that is free from vegetative weeds—as usual, but even more important, in this particular case. Calluna vulgaris and Erica tetralix can be sown or planted out. Using a mixed method is generally successful, i. e. planting out a few plants that are allowed to self-seed, thus creating a gradually closing vegetation. The seed of Calluna is ripe by November, Erica tetralix seed a little earlier. When it is preferred to start by sowing a dry heath vegetation, the trimmed-off heather heads containing the ripe seeds are distributed over the plot immediately allowing the seed to fall out on the spot...>
Species of the heather family (Ericaceae) lend themselves perfectly to the creation of heath vegetations, which are more or less closed vegetations of dwarf shrubs taking on the role of the herbaceous layer, with a strong spatial impact in open areas. In it, members of the heather and crowberry (Empetraceae) families may be combined with fine low shrubs, such as Salix repens, Genista spp., and somewhat taller species, such as Ulex, Sarothamnus, Myrica and Juniperus. In addition, one may establish some of the most refined and subtle herbaceous indigenous species. A number of vegetation forms may be discerned, with the characteristics and the atmosphere of:
– dry heath
– wet heath
Heath and bog vegetations are best realised on poor acidic soils: sand, poor loam or peat...>
When this type of maintenance by mowing with a scythe is carefully and strictly adhered to, the reed will, in the long run, disappear completely, with the Sphagnum-Polytrichum vegetation, including the aforementioned species, transforming into a vegetation of dwarf shrubs from the heather family (Ericaceae). This anthropogenic vegetation is called ‘veenheide’. Its formation may be encouraged by sowing Vaccinium oxycoccus and V. macrocarpus, Erica tetralix, Calluna vulgaris, Vaccinium vitis-idaea and Empetrum nigrum. As soon as they appear, one should start mowing at a slightly higher level to encourage their proliferation and further development. In general, it will not be feasible to stop mowing altogether...>
Reedland that does not receive a steady supply of nutrients will display an increasingly thinner vegetation and will lose shape, with the vegetation becoming more open. Only at the waterside will the vegetation keep its height, since nutrients are provided via the water. Mowing in the long run has such a fertility reducing effect that the reed vegetation will be transformed into low-fertility grassland. One may then switch to summer mowing, as in wet flower meadows. In Sphagnum reedland turning into low-fertility grassland, one should be mowing through the Sphagnum layer, just above the substratum. In this manner, the Sphagnum layer stays in good condition, and at the same time it prevents the mosses (Polytrichum spp.) present in this layer from dominating...>
Reed vegetations growing in water do not require yearly mowing in order to remain in good shape. Especially in deeper water, they may survive for a long time without human intervention. Its charm and its natural value as a habitat for birds, mammals, etc., lies mainly in the rough, naturalistic impression it evokes. This is valid even more in larger expanses, and its aesthetic value during winter can be considerable. Yet it may be advisable to now and then mow ‘over the ice’ when the ice floor allows this, and to carry off the reed produced. It cleans the vegetation up and improves the aesthetics.
The maintenance of reed vegetations on land consists of the yearly mowing in November to January. Less valuable reedlands may be mown as late as the end of March...>
One of the best-known marsh vegetations is reedland. In shallow (20-60 cm) water and on rich soils, reed (Phragmites australis) may provide simple but very characteristic and, on a larger scale, attractive vegetation with its own atmosphere and beauty. Creating a suitable habitat for reed is done as follows: the soil is dug down until, or slightly under, the water table. On bare soil one does best to plant out reed cuttings. Since reed germinates under special conditions only—for example in wet, muddy situations on soils that have gone dry shortly before, in spring or summer—and as one usually cannot meet these requirements, planting out cuttings is the most successful approach...>