Are Collembola flying onto green roofs?

Abstract

<p><strong>Are Collembola flying onto green roofs?  </strong></p><p>With a worldwide urban population projected to reach 5 billion by 2030 (Véron, 2007), the roles and benefits of urban green spaces cannot be denied, like climate regulation by trees or water flow regulation (Gómez-Baggethun and Barton, 2013). If green spaces are among the new societal expectations of urban people, they also play a crucial role in preserving biodiversity in urban areas. Among them, green roofs are a great opportunity to create green space in cities as they represent 32% of cities’ horizontal surfaces (Frazer, 2005). Their installation is also perceived as a possible way to preserve biodiversity in cities. However, the effectiveness of green roofs in supporting biodiversity, especially soil biodiversity, has rarely been studied.</p><p>Thanks to different research programmes (TROL, SEMOIRS and T4P), we investigated the taxonomic and functional collembolan biodiversity in both extensive and productive green roofs as well as in ground-level urban microfarms in order to (i) evaluate the effectiveness of green roofs in supporting soil biodiversity, (ii) identify the mechanisms of colonisation by soil organisms and (iii) separate the effect of landscape and soil conditions on collembolan communities assemblages.</p><p>Surprisingly, green roofs are supporting high levels of soil biodiversity. Despite various soil characteristics (organic matter and water avaibility), no difference was found between extensive roofs and rooftop gardens concerning the taxonomical structures of collembolan communities (e.g. species richness, abundances). In contrast, there are differences concerning both taxonomic and functional compositions. Two ways of colonisation are suggested: a passive wind dispersal − the “flying” collembolans − and a settlement through compost inputs. We conclude that stakeholders should take into account the spatial connections of green roofs with other green spaces in order to support urban soil biodiversity.</p>

Land snail dispersal, abundance and diversity on green roofs

“…In this study, we find that most land snail species encountered are indeed well-documented greenhouse inhabitants (Table 2). A similar mechanism has been suggested for the dispersal of Collembola (springtails) onto green roofs via composting for roof soil enrichment [30]. If our findings are validated with further research, it could provide useful insight into the dynamics of how green roof ecosystems are created and change through time.…”

Fine-scale substrate heterogeneity does not affect arthropod communities on green roofs

“…The factors that were found to enhance biodiversity were high vegetation cover ( Schindler, Griffith & Jones, 2011 ; Gonsalves, 2016 ), larger roof size ( Berthon, 2015 ), connectivity with other potential habitats ( Berthon, 2015 ; MacIvor, 2016 ; Blank et al, 2017 ; Ksiazek-Mikenas et al, 2018 ; Wang et al., 2017 ), greater vegetation complexity (i.e., height) ( Madre et al, 2013 ; Gonsalves, 2016 ), plant species diversity ( Gonsalves, 2016 ; Kratschmer, Kriechbaum & Pachinger, 2018 ; Ksiazek-Mikenas et al, 2018 ), and greater substrate depth ( Kratschmer, Kriechbaum & Pachinger, 2018 ), or substrate depths under 10 cm or over 15 cm ( Kyrö et al, 2018 ). On the other hand, the type of green roof, extensive or intensive, ( Joimel et al, 2018 ), roof age ( Schrader & Böning, 2006 ), and vegetation cover ( Rumble & Gange, 2013 ) did not affect soil microarthropod diversity in other studies. It was suggested that habitat heterogeneity may be an important factor in increasing these species’ diversity ( Rumble & Gange, 2013 ).…”

Biodiversity of collembola on green roofs: A case study of three cities in Belgium

“…More specifically, to the best of our knowledge, only three related studies exist: Schrader and Böning, 2006;Rumble andGange, 2013 andJoimel et al, 2018 (Table 4). Given the fact that only a few studies have been performed on collembolan communities in Western Europe on green roofs, we will compare our results where possible with these studies (Schrader and Böning, 2006;Rumble and Gange, 2013;Joimel et al, 2018).…”