Topic 3 Planning biodiversity and tools for controlling its development in green roofs

We need an ecosystem approach, which can help to:

To apply an ecosystem approach, we must first identify the benefits and where they come from. Then we must understand how different planning or resource-use choices will affect these ecosystem services. Involving people in decision-making and in getting things done is vital.

This high-level event, co-organized by the United Nations Environment Programme and the Portuguese Presidency of   the Council of the European Union (EU), with the support of   the Geneva Environment Network, focused on exploring the multiple benefits of Nature-based Solutions (NbS) for cities, highlighting opportunities and challenges to advance and scale up NbS, from local action to global solutions, accelerating impact in 2021 and beyond.

Key actions in applying an ecosystem approach:

As the global climate changes, human well-being, ecosystem function, and even climate itself are increasingly affected by the shifting geography of life.

Climate-driven changes in species distributions, or range shifts, affect human well-being both directly (for example, through emerging diseases and changes in food supply) and indirectly (by degrading ecosystem health). Some range shifts even create feedbacks (positive or negative) on the climate system, altering the pace of climate change.

The key factors affecting biodiversity on green roofs are identified with an assessment system with following proposed six major factors:

1 Species diversity and richness

2 Substrate type and depth

3 Plants species selection

4 Connectivity to natural vegetation

5 Green roof ratio

6 Ecologically responsible development

UN Environment Programme World Conservation Monitoring Centre

The design features, different substrates and planting regimes are considered in the proposed system

Substrate or growing media is crucial for green roof plants. Green roof systems with a variety of substrate depths and vegetation types tend to have higher spider, beetle, and bird diversity.

The use of natural, local soils and substrate can assist biodiversity, as well as benefit regional and endangered species because local species have already adapted to that particular soil environment. The substrate depth is often a good indicator of future successes in biodiversity for green roofs. Other factors such as pH value and organic constituents for substrate will affect the growth of green roof plants and thus the colonization of various vertebrates and invertebrates.

Calcareous and sedum species are the common plant species for extensive green roofs. Native plant species is preferred in particular region as the roof can mimic the regional habitat environment and thus attract the species to colonize based on the naturalness. For the non-native plant species, they are selected for building up intensive green roofs which may attract some rare species. Selection of the plant species for green roofs depends on which target species of vertebrates and invertebrates are expected to attract to the site of interest, and is very important to determining whether  biodiversity enhancement is achieved.

Sedum spurium. This is another perfect groundcover, an herbaceous and deciduous plant with beautiful colors depending on the cultivar. It can grow in any soil type and can tolerate a few hours of shadow a day. It is 10 to 15 cm tall, with bright green leaves that turn red when the cold season arrives. It blooms in summer with red, pink, or white flowers.

It is believed that proximity of green roofs to the nearby naturalized zones or landscape can contribute a positive influence on biodiversity. Good habitat connectivity can overcome the adverse effects (species extinction) brought by the habitat fragmentation and modification during the urban development.

The aim is to engage green roofs and create green corridors which allow a continuum among ecosystems around the city and the itself. This connection among spaces and species would allow green roof practitioners in the city the interchange of information about evolution of populations, sharing seeds and knowledges gained daily, etc. The support of local public governments with specific local planning, help of public servants, rules for ensuring biodiversity and tax reduction for green roofs owners is also welcome

Conceptual design where

  • A) represents a landscape resistance map in which thicker lines represent higher levels of movement,
  • B) represents green roof as patches of suitable habitat, and
  • C) is the result of combining A) and B), where darker colors represent more importance to landscape connectivity in terms of the amount of movement the corridor supports and the quality of habitat it connects.

Article: Developing an open-source toolset to improve landscape connectivity planning

Matrix to control biodiversity

A simple system is proposed for the biodiversity self assessment of green roofs. The system consists of 6 major factors as shown in Table in following page and the respective criteria for the score are described. The overall scoring is the sum of the credit marks and a proposed rating is given in each concept. This assessment system is useful to building designers and developers who would like to evaluate biodiversity in green roof projects.

Other Matrix: the subject of Nature’s Matrix is conservation of biodiversity, but it differs from other books by proposing a radically new approach based on recent advances in the science of ecology plus certain political realities.

The analysis in Nature’s Matrix is based on the linking of three key political :  crisis of biodiversity loss, food and agriculture and political unrest in rural areas

Total score: 4-7 Fair, 8-10 Good, 11-14 Excellent