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Multifunctionality is affected by interactions between green roof plant species, substrate depth, and substrate type

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ABSTRACT

Green roofs provide ecosystem services through evapotranspiration and nutrient cycling that depend, among others, on plant species, substrate type, and substrate depth. However, no study has assessed thoroughly how interactions between these factors alter ecosystem functions and multifunctionality of green roofs. We simulated some green roof conditions in a pot experiment. We planted 20 plant species from 10 genera and five families (Asteraceae, Caryophyllaceae, Crassulaceae, Fabaceae, and Poaceae) on two substrate types (natural vs. artificial) and two substrate depths (10 cm vs. 30 cm). As indicators of major ecosystem functions, we measured aboveground and belowground biomasses, foliar nitrogen and carbon content, foliar transpiration, substrate water retention, and dissolved organic carbon and nitrates in leachates. Interactions between substrate type and depth strongly affected ecosystem functions. Biomass production was increased in the artificial substrate and deeper substrates, as was water retention in most cases. In contrast, dissolved organic carbon leaching was higher in the artificial substrates. Except for the Fabaceae species, nitrate leaching was reduced in deep, natural soils. The highest transpiration rates were associated with natural soils. All functions were modulated by plant families or species. Plant effects differed according to the observed function and the type and depth of the substrate. Fabaceae species grown on natural soils had the most noticeable patterns, allowing high biomass production and high water retention but also high nitrate leaching from deep pots. No single combination of factors enhanced simultaneously all studied ecosystem functions, highlighting that soil–plant interactions induce trade‐offs between ecosystem functions. Substrate type and depth interactions are major drivers for green roof multifunctionality.

No MeSH data available.


Average above‐ and belowground biomasses as a function of substrate depth and type (±SE). Biomasses from the different species were pooled for each family. Lowercase letters indicate differences (p < .05) between treatments within each family. Capital letters indicate differences (p < .05) in aboveground biomass between families within each type/depth treatment
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ece32691-fig-0001: Average above‐ and belowground biomasses as a function of substrate depth and type (±SE). Biomasses from the different species were pooled for each family. Lowercase letters indicate differences (p < .05) between treatments within each family. Capital letters indicate differences (p < .05) in aboveground biomass between families within each type/depth treatment

Mentions: Below, above and total biomasses were significantly affected by substrate depth and type, but only above and total biomasses showed significant differences between plant families (Table 2). Nonetheless, fixed factors explained 77% of variations for aboveground biomass, but only 36% for belowground biomass. For each family and each substrate type, plants grown on deep substrate exhibited higher aboveground biomasses (Figure 1) with more marked effects when growing on natural soil. On natural soil, biomasses from deep pots were two (Crassulaceae) to three times (Asteraceae) higher than from shallow pots, whereas biomasses from deep artificial pots were 1.4 (Fabaceae) to 1.9 times (Caryophyllaceae) higher than from shallow artificial pots. Depth effects were less obvious concerning root biomasses, without significant increase for Crassulaceae. Caryophyllaceae and Fabaceae showed an increase with depth only on natural soil, whereas only Asteraceae and Poaceae exhibited increases on both substrates.


Multifunctionality is affected by interactions between green roof plant species, substrate depth, and substrate type
Average above‐ and belowground biomasses as a function of substrate depth and type (±SE). Biomasses from the different species were pooled for each family. Lowercase letters indicate differences (p < .05) between treatments within each family. Capital letters indicate differences (p < .05) in aboveground biomass between families within each type/depth treatment
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5383477&req=5

ece32691-fig-0001: Average above‐ and belowground biomasses as a function of substrate depth and type (±SE). Biomasses from the different species were pooled for each family. Lowercase letters indicate differences (p < .05) between treatments within each family. Capital letters indicate differences (p < .05) in aboveground biomass between families within each type/depth treatment
Mentions: Below, above and total biomasses were significantly affected by substrate depth and type, but only above and total biomasses showed significant differences between plant families (Table 2). Nonetheless, fixed factors explained 77% of variations for aboveground biomass, but only 36% for belowground biomass. For each family and each substrate type, plants grown on deep substrate exhibited higher aboveground biomasses (Figure 1) with more marked effects when growing on natural soil. On natural soil, biomasses from deep pots were two (Crassulaceae) to three times (Asteraceae) higher than from shallow pots, whereas biomasses from deep artificial pots were 1.4 (Fabaceae) to 1.9 times (Caryophyllaceae) higher than from shallow artificial pots. Depth effects were less obvious concerning root biomasses, without significant increase for Crassulaceae. Caryophyllaceae and Fabaceae showed an increase with depth only on natural soil, whereas only Asteraceae and Poaceae exhibited increases on both substrates.

View Article: PubMed Central - PubMed

ABSTRACT

Green roofs provide ecosystem services through evapotranspiration and nutrient cycling that depend, among others, on plant species, substrate type, and substrate depth. However, no study has assessed thoroughly how interactions between these factors alter ecosystem functions and multifunctionality of green roofs. We simulated some green roof conditions in a pot experiment. We planted 20 plant species from 10 genera and five families (Asteraceae, Caryophyllaceae, Crassulaceae, Fabaceae, and Poaceae) on two substrate types (natural vs. artificial) and two substrate depths (10&nbsp;cm vs. 30&nbsp;cm). As indicators of major ecosystem functions, we measured aboveground and belowground biomasses, foliar nitrogen and carbon content, foliar transpiration, substrate water retention, and dissolved organic carbon and nitrates in leachates. Interactions between substrate type and depth strongly affected ecosystem functions. Biomass production was increased in the artificial substrate and deeper substrates, as was water retention in most cases. In contrast, dissolved organic carbon leaching was higher in the artificial substrates. Except for the Fabaceae species, nitrate leaching was reduced in deep, natural soils. The highest transpiration rates were associated with natural soils. All functions were modulated by plant families or species. Plant effects differed according to the observed function and the type and depth of the substrate. Fabaceae species grown on natural soils had the most noticeable patterns, allowing high biomass production and high water retention but also high nitrate leaching from deep pots. No single combination of factors enhanced simultaneously all studied ecosystem functions, highlighting that soil&ndash;plant interactions induce trade&#8208;offs between ecosystem functions. Substrate type and depth interactions are major drivers for green roof multifunctionality.

No MeSH data available.