The effect of drainage height on plant-species composition on a semi-arid green roof system

2021 ◽  
Vol 67 (3-4) ◽  
pp. 149-155
Author(s):  
Har'el Agra ◽  
Hadar Shalom ◽  
Omar Bawab ◽  
Gyongyver J. Kadas ◽  
Leon Blaustein

Abstract Green roofs are expected to contribute to higher biodiversity in urban surroundings. Typically, green roofs have been designed with low plant diversity. However, plant diversity can be enhanced by controlling resource availability and creating distinct niches. Here we hypothesize that by using different drainage heights during the short plant-growing season in a semi-arid green roof system we can create distinct niches and plant communities. Our experiment took place at the University of Haifa, north Israel. We tested three different heights of drainage outlet: 10 cm under the surface of the substrate (Low), 1 cm under the surface of the substrate (Medium) and 3 cm above the surface of the substrate (High) on plant species-composition in green-roof gardens. Grasses cover was higher in High and Medium drainages while forbs cover was higher in Low drainage. Species richness was the highest in Low drainage while diversity indices showed the opposite trend. We conclude that by changing the height of the drainage we can create different niches and change species composition in a short time period of one growing season. This way we can create more diverse green roof communities and enhance biodiversity in urban areas, particularly in semi-arid regions.

2011 ◽  
Vol 40 (2) ◽  
pp. 175-196
Author(s):  
ERIK JONES ◽  
THERESA MILLER ◽  
JEREMY MONSMA ◽  
JILLIAN PUSZYKOWSKI ◽  
JOANNE WESTPHAL

ABSTRACT This paper describes plant species composition and coverage changes that occurred on an extensive (shallow) green roof system exposed to direct solar exposure and steep roof conditions over time. The green roof system, installed in August, 2005, involved a pre-seeded, manufactured mat product that initially was vegetated with twelve plant species. During the interim between installation and data collection for this paper, no maintenance, fertilizer, or irrigation was applied, despite the fact that observable differences in plant coverage were noted. In April, 2009, undergraduate student researchers revisited the green roof system and examined the green roof for species composition and absolute plant cover. These data were compared to a control area where solar incidence and slope were comparable to the conditions found on a flat roof system. This paper reports on the findings of this study, and offers insight to the types of modifications in extensive green roof technology that may be necessary if extensive green roof application is to be useful for steep roof conditions in cold climate environments.


2017 ◽  
Vol 76 (5) ◽  
pp. 1081-1089 ◽  
Author(s):  
Cristina M. Monteiro ◽  
Cristina S. C. Calheiros ◽  
Paulo Palha ◽  
Paula M. L. Castro

Green roof technology has evolved in recent years as a potential solution to promote vegetation in urban areas. Green roof studies for Mediterranean climates, where extended drought periods in summer contrast with cold and rainy periods in winter, are still scarce. The present research study assesses the use of substrates with different compositions for the growth of six aromatic plant species – Lavandula dentata, Pelargonium odoratissimum, Helichrysum italicum, Satureja montana, Thymus caespititius and T. pseudolanuginosus, during a 2-year period, and the monitoring of water runoff quality. Growing substrates encompassed expanded clay and granulated cork, in combination with organic matter and crushed eggshell. These combinations were adequate for the establishment of all aromatic plants, allowing their propagation in the extensive system located on the 5th storey. The substrate composed of 70% expanded clay and 30% organic matter was the most suitable, and crushed eggshell incorporation improved the initial plant establishment. Water runoff quality parameters – turbidity, pH, conductivity, NH4+, NO3−, PO43- and chemical oxygen demand – showed that it could be reused for non-potable uses in buildings. The present study shows that selected aromatic plant species could be successfully used in green roofs in a Mediterranean climate.


2016 ◽  
Vol 42 (1) ◽  
pp. 72-83 ◽  
Author(s):  
R. Scholtz ◽  
I. P. J. Smit ◽  
C. Coetsee ◽  
G. A. Kiker ◽  
F. J. Venter

2012 ◽  
Vol 7 (4) ◽  
pp. 73-84
Author(s):  
D. C. Toland ◽  
C. P. West ◽  
M. E. Boyer

Plant selection and establishment are critical components for green roof health and success. Plant palettes (sets of plant species selected for specific conditions) for green roofs vary in their ability to confer benefits depending on the species make-up and their adaptation to particular environments and climates. The response of various species to climatic factors on rooftops is unknown for the Ozark Highlands region. The objective of this study was to compare plant survival and spread in three growing medium treatments (course and fine texture with compost and fine texture with no compost) installed as part of a green roof system. The study was performed on a green roof system at the University of Arkansas in Fayetteville over 3 years. Data were collected on 13 species installed in September of 2006 and surveyed on three dates thereafter: April 30, 2007; May 19, 2009; September 10, 2009. The treatments with added compost had statistically greater vegetated cover (from 73 to 87%) compared to the fine medium without compost (36 to 43%). In most cases the spread of individual plants was not significantly different between treatments. Results indicated that rooting medium containing compost increased survival and overall vegetated roof coverage, and identified various potential green roof plant species for the Ozark Highland environment. Two species, Sedum middendorffianum var. diffusum and Sedum spurium ‘Roseum’, did particularly well in all treatments. One species, Sedum kamtschaticum, did well only in the treatments with compost.


Land ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1334
Author(s):  
Dominik Gößner ◽  
Milena Mohri ◽  
Justine Jasmin Krespach

Green roofs have proven to be a space-saving solution to mitigate peak temperatures and control floods in urban areas through evaporative cooling and storm water retention. To encourage a sustainable city design with large-scale green infrastructure networks, a better differentiation between the diverse existing green roof systems is needed. The aim of this study is to demonstrate differences among green roof systems based on comprehensive microclimatic measurements on four small experimental roofs and to assess differences in evapotranspiration with a partial least square regression. The results show that short-wave solar radiation, relative humidity and water availability are the most important drivers of evapotranspiration. The roof system with permanent water storage maintained significantly higher substrate moisture compared to the other roofs and produced peak evapotranspiration rates of 4.88 mm d−1. The highest total evapo-transpiration of 526 mm from April to September was recorded for the roof system with the thickest substrate layer and grass vegetation. In summer, the shallowest roof showed the highest substrate temperature and air temperature at vegetation level. These findings highlight the importance of specifying the characteristics of the various green roofs in order to turn them into useful planning tools for the design of climate-change-resilient cities.


2020 ◽  
Vol 23 (6) ◽  
pp. 1227-1238
Author(s):  
Jason M. Aloisio ◽  
Matthew I. Palmer ◽  
Amy R. Tuininga ◽  
J. D. Lewis

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