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Communication Dans Un Congrès Année : 2022

Field evaluation of the cotton-strip assay for quantifying organic matter decomposition rates on extensive green roofs

Résumé

Green roofs are increasingly popular “nature-based solutions” which may help mitigating stormwater runoff and urban heat island phenomenon in a global change context. Shallow substrate depths (below 150 mm) characterize extensive green roofs that are especially designed to be low weight and maintenance infrastructures. Moreover, they are usually less expensive than intensive green roofs that are thicker. Thus, they may offer unique opportunities to expand the greening of cities meanwhile providing numerous other ecological and social co-benefits. However, green roof multifunctionality and potentialities to maintain several ecosystem services strongly depend on their technical components including substrate physicochemical characteristics, as well as on their ecological functioning to support healthy vegetation communities. Within this context, the organic matter decomposition rate, which directly influences the local nutrient recycling appears as a key ecological process for achieving long-term sustainability of these “man-made urban ecosystems”, with no additional maintenance requirement (e.g. fertilizer application, plant replacement). Nevertheless, to our knowledge, there is no published work to date that attempted to assess this crucial ecosystem function on these green infrastructures. Therefore, the primary aim of this study was to evaluate the convenience and sensitivity of a cheap and easy-to-use standardized method, the cotton-strip assay, to compare the organic matter decomposition rate on green roofs from various construction design. For this purpose, nine green roof plots were selected, contrasting in their initial specifications in terms of substrate composition, presence/absence of a water storage layer or vegetation palette. Three metrics (tensile strength loss, mass and surface) were compared for the assessment of cotton-strip decomposition rates following 34, 91 and 110 days of burying into substrates. Data also included those obtained from arable land and a gravel roof (serving as “positive” and “negative” control groups respectively). Results allowed validating the cotton-strip assay for green roof infrastructures while providing first insights into the influence of substrate composition on both water content and organic matter decomposition. Similarly to “natural soils”, decreased C:N favoured decomposition. Finally, broader green roof monitoring regarding organic matter decomposition rate could help to better understand their ecological functioning, potentially leading to improved media formulation for enhanced ecosystem multifunctionality.
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Dates et versions

hal-04484103 , version 1 (29-02-2024)

Identifiants

  • HAL Id : hal-04484103 , version 1

Citer

Didier Técher, Delphine Aran, Mélanie de Silva, Rémy Claverie, Michel Erbrech, et al.. Field evaluation of the cotton-strip assay for quantifying organic matter decomposition rates on extensive green roofs. SFE² GfÖ EEF Joint meeting, International Conference on Ecological Sciences, 2022, Metz, France. ⟨hal-04484103⟩
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