Culture&Territories#3

CeiED | CULTURE & TERRITORY
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hardly suitable for this purpose. The common conditions are characterised by
confined space, lack of soil or substrate, temperature and water supply problems,
plant diseases forced by environmental impacts and the pressure by human use.
Solutions should be not only technically feasible but also cost effective. In view of
these challenges, in the last decades different and feasible solutions were developed
and optimized. Greening formerly vegetation-free site brings back a piece of nature
and, in some cases, creates a recreational space for people. For a long time, the
selection of plant species was mainly focused on functional and design criteria.
Nevertheless, the greening of formerly vegetation-free sites can be meant as an
improvement in terms of biodiversity. An indicator is the settlement of further
“unplanned” animal species - insects and birds in particular. Vegetation technology has
no direct influence on the occurrence of insects and other animal species, but it may
enhance biodiversity by offering forage plants and nesting opportunities. This
imposes further demands, which can be illustrated taking again a green roof as an
example: From the viewpoint of biodiversity even a simple extensive planting, e.g.
dominated by self-sustaining Sedum species, means a considerable improvement
in comparison to a bare hard roof surface. In order to meet biodiversity goals,
specific types of green and planting schemata have to be considered. A survey
of wild bee species on several green roofs in Hannover, Germany, revealed that a
balanced offer of forage plants and nearby habitat structures is required to increase
the number of wild bees (Witt, 2016). Such further requirements may result in
constructive modifications, as each specific type of green roofs requires tailored
construction techniques and substrates. While the technical requirements for
vegetation in general, such as structural layouts and composition of substrates are
widely known, there is a lack of information in terms of biodiversity specific
requirements. Specifying such requirements are tasks of other disciplines, like
species nature preservation and protection, which again, highlights the need of
interdisciplinary research.
Maintenance is another main concern in vegetation technology. Professional maintenance
is fundamental consideration not only to keep a green structure healthy but
also to enable it to deliver the environmental and aesthetic benefits for which it was
implemented. A demand for an ecological oriented maintenance arose in recent
decades, particularly in public domains. In public opinion, this may be seen as just a
concession to financial constraints, but in practice, this is often quite different. In fact,
greenspace maintenance targeted on biodiversity goals requires a good concept,
well-trained personnel, and adequate machinery, sometimes resulting in even higher
costs. An ecological oriented maintenance can include different actions, from banning
of pesticides and other environmentally unsound activities, differentiated cutting and
inspections frequency to different machinery, etc. For instance, changing the type of
maintenance by reducing the frequency of grassland mowing enables the conversion
from lawns into rich wildflower meadows, thus offering numerous insect habitats.