Selecting Potential Moss Species for Green Roofs in the Mediterranean Basin

Ricardo Cruz De Carvalho,Cristina Branquinho,Zulema Varela,Teresa Afonso Do Paço

doi:10.3390/urbansci3020057

Ricardo Cruz De Carvalho, Cristina Branquinho + Show 2 more

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https://doi.org/10.3390/urbansci3020057

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Abstract

Green roofs are important infrastructures to address the effects of climate change in urban areas. However, most studies and applications have been done in cooler and wetter regions of the northern hemisphere. Climate change will lead to more extreme weather events, such as increased drought and decreased precipitation with intense flash rain events. Increase desertification is expected especially in the Mediterranean Basin, where in summer, radiation and temperature are high and water is scarce. Therefore, while vascular plants increase water consumption in green roofs during warmer periods, mosses present themselves as potential candidates due to their poikilohydric nature, responding to the environmental availability of water, completely drying out and recovering upon rehydration. Although criteria for the selection of vascular plants adapted to the Mediterranean and suitable for green roofs have been developed, no information is available regarding the selection of mosses based on scientific criteria. Here we propose selection criteria for moss species based on ecological preferences according to Ellenberg’s values and help to define moss traits suitable for a nonirrigated, nature-based green roof that tolerates the Mediterranean climate. The main result is a table of potential candidate mosses that can be either used as standalone or in conjunction with vascular plants to decrease water usage and/or manage stormwater through an easily applicable selection methodology. For green roof practitioners, we proposed that acrocarpous mosses exhibiting turf/cushion life forms and colonist or perennial life strategies best fit the requirements for such a green infrastructure in extreme climate regions with scarce water resources.

Highlights

The Mediterranean climate is characterised by mild wet winters, autumns and springs with variable temperature and precipitation, and warm to hot, dry summers that are typical of semiarid climates [1]
It is the first time that Ellenberg’s values of ecological preferences are used in the selection of mosses for use on green roofs in the Mediterranean and, as we can see in Table 1, these preferences reflect perfectly their functional traits, as expected, since according to the literature, life form, growth form and life strategy are related to plant strategy, climatic factors and land use [24,28,29,30,37,39]
Acrocarpous mosses are commonly found in open dry sites, while their pleurocarpous counterparts are more common in moist shady locations [44]

Summary

Introduction

The Mediterranean climate is characterised by mild wet winters, autumns and springs with variable temperature and precipitation, and warm to hot, dry summers that are typical of semiarid climates [1]. Nowadays, against a background of climate change with extreme temperatures (high and low) and precipitation (scarce or very intense flash rain events), drought periods occur in the whole Mediterranean Basin, in summer, and in winter. Green roofs are plant-based spaces that mimic shallow substrate rock outcrops or meadow habitats. They are placed on a waterproof layer on top of houses, factories, offices and other buildings, and complement the ecosystem services provided by other types of green spaces in urban areas [5,6,7,8]

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