Using plant water use and drought response strategies and climate of origin to select shrubs for green roofs in dry and hot climates

© 2019 Dr. Pengzhen DuGreen roofs are a novel urban ecosystem in cities which have potential to mitigate stormwater runoff, cool buildings and provide habitat for biodiversity. Plants on green roofs play an important role in providing these benefits, and therefore appropriate plant selection is critical to ensure survival and maintenance of plant cover. For stormwater retention, plants should have high water use after rainfall events to dry out substrates and maximise water retention for the next rainfall event. However, between rainfall events, green roofs are difficult environments for plants to grow due to shallow substrate depths and low water retention in the free-draining substrate. These stressful conditions are exacerbated in hot and dry climates with prolonged summer water-deficits. Therefore, it is critical to select species with both high water use when water is available and high drought resistance to balance the aims of stormwater retention and survival. Succulents have been widely used on green roofs due to their high survival, but compared with other life-forms, their ability to improve stormwater retention and evaporative cooling are limited due to their low water use. Some monocots and herbaceous species showed the combination of high water use and high drought resistance. Woody species like shrubs also have great potential to be used on green roofs as they can use more water than succulents, and many are highly drought tolerant in their natural habitats. However, shrubs are not yet widely used on green roofs and there is a need to understand what types of shrub species are better suited to green roof conditions. Climate of origin may be a useful way to select drought tolerant shrubs as rainfall distribution and aridity often relates well to plant drought response in natural habitats. Further, physiological traits including the water potential at turgor loss point (tlp), minimum water potentials (min) and the degree of iso-anisohydry are also closely related to water availability in natural ecosystems and could improve green roof plant selection. Therefore, I evaluated whether plant water use and drought response strategies and climate of origin can be used to select shrubs for green roofs in dry and hot climates. I conducted a glasshouse experiment with well-watered and water-deficit treatments to evaluate the water use and drought response strategies (degree of iso-anisohydry, min and tlp) of 20 shrubs selected across an aridity gradient (quantified by heat moisture index, HMI, calculated as (MAT+10)/ (MAP/1000)) (Chapters 2 and 3). I hypothesized that: 1) there would be higher water users with higher drought resistance; 2) species from more xeric habitats would have lower water use and higher drought tolerance (Chapter 2); and 3) shrubs with lower tlp would be more drought tolerant, more anisohydric and use less water under water-deficit (Chapter 3). I then conducted a green roof module study planted with 15 species from the glasshouse study (130 mm deep substrate) to evaluate their performance under green roof conditions for one year (Chapter 4). I assessed plant recovery after the summer by re-watering in autumn. This chapter aimed to determine whether plant water use and drought response strategies and climate of origin related with plant survival on green roofs. In the glasshouse experiment I observed a trade-off between plant water use and drought tolerance, as there were no shrubs with high water use which were also drought tolerant (Chapter 2). However, species with low drought tolerance, which avoided drought stress under water-deficit had high water use when water was available. Plant water use was closely related to morphological traits, such as total leaf area, total plant biomass, specific leaf area and leaf area ratio. However, morphological traits did not relate well with plant drought response. Plants from more arid climates were not always more drought tolerant and did not always have lower water use (Chapter 2). The tlp could be used to select drought tolerant shrubs, as species with lower tlp were more drought tolerant (lower min) and were more anisohydric (higher △MD) (Chapter 3). These species also had lower water use when water was not available. Therefore, tlp could be used to select shrubs for green roofs in hot and dry climates. However, despite relationships in natural ecosystems between tlp and climate of origin aridity, there were no such relationships in my study (Chapter 3). In the green roof module study (Chapter 4), mean gravimetric soil water content decreased to approximately 5% after a prolonged summer dry period and this resulted in increased mortality. Only two species had 100% survival, while some species only had 10% survival after this dry period, and there were no species which were completely healthy. Generally, shrubs with high drought tolerance (lower min) had higher survival after the hot and dry summer, but this was not true for all species. Plant survival was not related to plant water use or their tlp. Shrubs from more arid climates had higher drought tolerance (lower min) in response to dry substrates, but climate of origin was not related with survival and health. After re-watering, only four drought avoiding shrub species were able to resprout (Chapter 4). This suggests that when selecting shrub species for green roofs, plant drought response and water use strategies and plant climate of origin individually do not directly relate with plant survival. Plant survival on green roofs is likely to be determined by a combination of physiological traits. Overall, there was a trade-off between plant water use and drought tolerance. Drought avoiding plants (higher min), rather than drought tolerating plants, had higher water use and could optimize stormwater mitigation on green roofs. Shrubs with larger plant aboveground biomass and larger leaf areas could be higher water users and maximize rainfall retention on green roofs. The aridity of climate of species origin did not relate to water use under well-watered conditions, or plant drought response (min and tlp) under water-deficit. Therefore, climate of origin could not be used successfully to select high water users to optimize stormwater mitigation or select drought tolerant plants with more conservative water use under water-deficit. Shrubs with lower tlp had higher drought tolerance (lower min), were more anisohydric and used less water under water-deficit conditions. This indicated that tlp could be used as a screening tool to assess plant drought response and water use for green roofs. In the green roof module experiment, shrubs with higher survival and health did not always have lower water use, higher drought tolerance or originate from more xeric climates, indicating that shrubs with both higher and lower water use, or tlp, isohydric and anisohydric behaviours (drought avoiders and drought tolerators), and from any climates could all be potentially used on green roofs. This thesis showed that shrubs have potential for green roofs. However, some shrub species like Correa glabra and Calytrix tetragona, which had higher survival and health, and higher capacity for recovery, should be suggested for use on green roofs. Emergency irrigation for shrubs growing on green roofs is highly recommended during summer months to keep them alive and vigorous

<b>Reduced root cortical tissue with increased root xylem investment is associated with high wheat yields in central China</b>-dataset.xlsx

We selected 20 genotypes that have been widely planted in Luoyang, in the major wheat producing area of China, to explore these relationships. A field study was performed to measure the yields of the genotypes. Root and leaf samples were collected at anthesis to measure anatomical traits relevant to carbon allocation and water transport.</p

Relationships between plant drought response, traits and climate of origin for green roof plant selection.xlsx

Under well-watered (WW) and water deficit (WD) conditions, we assessed morphological responses (leaf area, shoot mass, relative growth rate) to water availability; evapotranspiration rate (ET) and midday water potential (ΨMD) were used to evaluate species water use and drought response

AusTraits, a curated plant trait database for the Australian flora

We introduce the AusTraits database - a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g.&nbsp;photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g.&nbsp;leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual- and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data,&nbsp;which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge

AusTraits: a curated plant trait database for the Australian flora

INTRODUCTION AusTraits is a transformative database, containing measurements on the traits of Australia’s plant taxa, standardised from hundreds of disconnected primary sources. So far, data have been assembled from &gt; 250 distinct sources, describing &gt; 400 plant traits and &gt; 26,000 taxa. To handle the harmonising of diverse data sources, we use a reproducible workflow to implement the various changes required for each source to reformat it suitable for incorporation in AusTraits. Such changes include restructuring datasets, renaming variables, changing variable units, changing taxon names. While this repository contains the harmonised data, the raw data and code used to build the resource are also available on the project’s GitHub repository, http://traitecoevo.github.io/austraits.build/. Further information on the project is available in the associated publication and at the project website austraits.org. Falster, Gallagher et al (2021) AusTraits, a curated plant trait database for the Australian flora. Scientific Data 8: 254, https://doi.org/10.1038/s41597-021-01006-6 CONTRIBUTORS The project is jointly led by Dr Daniel Falster (UNSW Sydney), Dr Rachael Gallagher (Western Sydney University), Dr Elizabeth Wenk (UNSW Sydney), and Dr Hervé Sauquet (Royal Botanic Gardens and Domain Trust Sydney), with input from &gt; 300 contributors from over &gt; 100 institutions (see full list above). The project was initiated by Dr Rachael Gallagher and Prof Ian Wright while at Macquarie University. We are grateful to the following institutions for contributing data Australian National Botanic Garden, Brisbane Rainforest Action and Information Network, Kew Botanic Gardens, National Herbarium of NSW, Northern Territory Herbarium, Queensland Herbarium, Western Australian Herbarium, South Australian Herbarium, State Herbarium of South Australia, Tasmanian Herbarium, Department of Environment, Land, Water and Planning, Victoria. AusTraits has been supported by investment from the Australian Research Data Commons (ARDC), via their “Transformative data collections” (https://doi.org/10.47486/TD044) and “Data Partnerships” (https://doi.org/10.47486/DP720) programs; fellowship grants from Australian Research Council to Falster (FT160100113), Gallagher (DE170100208) and Wright (FT100100910), a grant from Macquarie University to Gallagher. The ARDC is enabled by National Collaborative Research Investment Strategy (NCRIS). ACCESSING AND USE OF DATA The compiled AusTraits database is released under an open source licence (CC-BY), enabling re-use by the community. A requirement of use is that users cite the AusTraits resource paper, which includes all contributors as co-authors: Falster, Gallagher et al (2021) AusTraits, a curated plant trait database for the Australian flora. Scientific Data 8: 254, https://doi.org/10.1038/s41597-021-01006-6 In addition, we encourage users you to cite the original data sources, wherever possible. Note that under the license data may be redistributed, provided the attribution is maintained. The downloads below provide the data in two formats: austraits-3.0.2.zip: data in plain text format (.csv, .bib, .yml files). Suitable for anyone, including those using Python. austraits-3.0.2.rds: data as compressed R object. Suitable for users of R (see below). Both objects contain all the data and relevant meta-data. AUSTRAITS R PACKAGE For R users, access and manipulation of data is assisted with the austraits R package. The package can both download data and provides examples and functions for running queries. STRUCTURE OF AUSTRAITS The compiled AusTraits database has the following main components: austraits ├── traits ├── sites ├── contexts ├── methods ├── excluded_data ├── taxanomic_updates ├── taxa ├── definitions ├── contributors ├── sources └── build_info These elements include all the data and contextual information submitted with each contributed datasets. A schema and definitions for the database are given in the file/component definitions, available within the download. The file dictionary.html provides the same information in textual format. Full details on each of these components and columns are contained within the definition. Similar information is available at http://traitecoevo.github.io/austraits.build/articles/Trait_definitions.html and http://traitecoevo.github.io/austraits.build/articles/austraits_database_structure.html. CONTRIBUTING We envision AusTraits as an on-going collaborative community resource that: Increases our collective understanding the Australian flora; and Facilitates accumulation and sharing of trait data; Builds a sense of community among contributors and users; and Aspires to fully transparent and reproducible research of the highest standard. As a community resource, we are very keen for people to contribute. Assembly of the database is managed on GitHub at traitecoevo/austraits.build. Here are some of the ways you can contribute: Reporting Errors: If you notice a possible error in AusTraits, please post an issue on GitHub. Refining documentation: We welcome additions and edits that make using the existing data or adding new data easier for the community. Contributing new data: We gladly accept new data contributions to AusTraits. See full instructions on how to contribute at http://traitecoevo.github.io/austraits.build/articles/contributing_data.html

AusTraits, a curated plant trait database for the Australian flora

International audienceWe introduce the austraits database-a compilation of values of plant traits for taxa in the Australian flora (hereafter AusTraits). AusTraits synthesises data on 448 traits across 28,640 taxa from field campaigns, published literature, taxonomic monographs, and individual taxon descriptions. Traits vary in scope from physiological measures of performance (e.g. photosynthetic gas exchange, water-use efficiency) to morphological attributes (e.g. leaf area, seed mass, plant height) which link to aspects of ecological variation. AusTraits contains curated and harmonised individual-and species-level measurements coupled to, where available, contextual information on site properties and experimental conditions. This article provides information on version 3.0.2 of AusTraits which contains data for 997,808 trait-by-taxon combinations. We envision AusTraits as an ongoing collaborative initiative for easily archiving and sharing trait data, which also provides a template for other national or regional initiatives globally to fill persistent gaps in trait knowledge