H2009: 32nd Hydrology and Water Resources Symposium, Newcastle : Adapting to Change, 2009
Green roofs are an emerging stormwater management tool that have predominantly been analysed for ... more Green roofs are an emerging stormwater management tool that have predominantly been analysed for runoff volume reduction and peak flow mitigation. Little research has been completed on evapotranspiration (ET) in green roofs. Sedum mexicanum (Mexican stonecrop) and Disphyma australe (New Zealand iceplant) in a NZ designed, pumice- and zeolite-based substrate were analysed to determine daily ET rates. Water loss, and thus storage recovery of the substrate, was greatest when substrate moisture was near field capacity (in the first 9 days). Transpiration (T) contributed up to 39% of total ET (2.0 mm/day for both species). After the initial rate of rapid water loss, plants conserved water and ET was not significantly different from evaporation (E) from unplanted substrate (0.2 mm/day). The majority of ET occurred when substrate moisture content was between the field capacity (FC) and 1500 kPa tension, in the case of the substrate used 13.8-39.6% w/w. Once water content drops below 1500 kPa tension, transpiration ceases, but limited E continues ( 0.2 mm/day). S. mexicanum had a greater ability to conserve water and thus a greater longevity of life than D. australe under low substrate moisture (drought) conditions. When rehydrated every 7 days to maximise water availability and hence minimise plant stress, S. mexicanum and D. australe demonstrated daily average ET of 2.7 mm/day and 2.5 mm/day, respectively, when mean daily temperature was 20.5oC. When temperature is held relatively constant, the major influences on evapotranspiration are plant stress level (linked to moisture availability) and radiation. Water storage recovery is optimised when rainfall or irrigation enables maximum transpiration rates to be maintained and where roofs receive maximum solar radiation.
A new method of biodiversity assessment is developed to characterize the biodiversity values of r... more A new method of biodiversity assessment is developed to characterize the biodiversity values of roads across New Zealand. The methodology blends rigorous probability sampling and PNAP sampling methodology with environmental domains analyses to characterize the biodiversity attributes of highways. It demonstrates the usefulness of this methodology in allowing regional reporting and integrating biodiversity conservation with road management by applying it to a particular road segment, State Highway 3 from Hamilton to New Plymouth. The data gathered is also used to develop an overall biodiversity enhancement and restoration plan for the studied segment of road. The biodiversity attributes of the road reserve differed markedly between the environmental sectors, and showed a strong effect from the surrounding land cover. Results indicate that the road reserve is both a biodiversity asset and a liability. The road reserve is an asset, in that it provides public lands for conservation that are highly visible to the public, often in habitats that are under-represented in the reserve network, and can provide links between existing reserves. The road reserve may be a liability in that it has reduced biodiversity value in the surrounding forests and can act as corridors for the spread of weeds into agricultural areas or indigenous forests. Effective integration of biodiversity conservation and road management can increase these assets and reduce these liabilities. This can be achieved by changing policy at all levels (Transfund NZ, Transit NZ, other roading authorities), by increasing awareness of the biodiversity value of road reserves, and by providing specific guidelines for the management and protection of roadside biodiversity. (a)
New Zealand’s Resource Management Act requires avoiding, remedying or mitigating effects of human... more New Zealand’s Resource Management Act requires avoiding, remedying or mitigating effects of human activities on the environment, including taking action to maintain terrestrial indigenous biodiversity. Here, we suggest that maintaining biodiversity requires halting its current decline, and to achieve that, New Zealand must move away from deeming only significant ecosystems and biota worthy of protection. We identify effects that must be avoided in order to maintain biodiversity, and those to be avoided unless they can be fully and promptly remediated. Effects should be avoided that reduce the extent and quality of most ecosystems and the habitats of indigenous species, including many highly modified ecosystems and habitats. Effects can be remediated only for a few, usually low-diversity and recently-established indigenous ecosystems and habitats, and we suggest a human generation (25 years) should be the maximum time to full remediation. Effects on individuals from some species’ pop...
Trois toitures végétalisées extensives (TVE) ont fait l'objet d'un suivi sur des périodes de 8 mo... more Trois toitures végétalisées extensives (TVE) ont fait l'objet d'un suivi sur des périodes de 8 mois à environ 1 an afin de réaliser un bilan hydrique. Pour chaque TVE, 8 évènements pluvieux ont été échantillonnés pour évaluer la qualité de l'eau et la comparer à des données de toitures conventionnelles situées au même endroit. L'analyse de chaque évènement pluvieux a mis en évidence que les TVE, conçues avec un substrat de 100-150 mm d'épaisseur pour maximiser le stockage de l'eau, ont retenu 56 à 72 % du volume de ruissellement. Les eaux de ruissellement provenant des toitures végétalisées et conventionnelles ne contenaient pas de teneurs élevées en matière en suspension (MES) ou nitrite + nitrate (NOx). Alors que cuivre et zinc proviennent tous deux des matériaux de la toiture, le cuivre peut également provenir des substrats de TVE. L'orthophosphate et l'azote Kjeldhal sont les principaux nutriments rejetés à des concentrations élevées par les TVE. En cas d'installation dans des bassins versant sensibles aux nutriments, l'intégration des TVE dans une chaine de traitement devrait être envisagée. Des hypothèses concernant les caractéristiques en matière organique des substrats sont suggérées pour minimiser la lixiviation des polluants (i.e. rapport carbone/azote, phosphore Olsen, capacité d'échange cationique et contenu en carbone). Cependant des recherches complémentaires sont nécessaires afin d'adapter l'interprétation de ces paramètres d'un point de vue agricole pour des applications spécifiques.
Rain gardens are Water Sensitive Design devices that use bioretention to retain, and reduce pollu... more Rain gardens are Water Sensitive Design devices that use bioretention to retain, and reduce pollutants in, stormwater runoff. Resilient rain gardens consistently attenuate pollutants, volume, and peak flows from small rain events. Research projects investigated combinations of readily available materials in the Auckland region that have consistent physical and chemical properties suitable for bioretention. The mulch and filter (or fill) media used influence rain garden performance – mulches must not float and must have high permeability. Bioretention media must have permeability low enough to achieve adequate contact time (for effective pollutant removal), but high enough to minimize (untreated) overflow from water quality volume events, and avoid excessive ponding duration. Mulch and media chemistry influences effluent water quality and plant growth. Results of two studies are summarised. The studies guide development of fit-for-purpose rain garden mulches and bioretention media in...
Trois toitures végétalisées extensives (TVE) ont fait l’objet d’un suivi sur des périodes de 8 mo... more Trois toitures végétalisées extensives (TVE) ont fait l’objet d’un suivi sur des périodes de 8 mois à environ 1 an afin de réaliser un bilan hydrique. Pour chaque TVE, 8 évènements pluvieux ont été échantillonnés pour évaluer la qualité de l’eau et la comparer à des données de toitures conventionnelles situées au même endroit. L’analyse de chaque évènement pluvieux a mis en évidence que les TVE, conçues avec un substrat de 100-150 mm d’épaisseur pour maximiser le stockage de l’eau, ont retenu 56 à 72 % du volume de ruissellement. Les eaux de ruissellement provenant des toitures végétalisées et conventionnelles ne contenaient pas de teneurs élevées en matière en suspension (MES) ou nitrite + nitrate (NOx). Alors que cuivre et zinc proviennent tous deux des matériaux de la toiture, le cuivre peut également provenir des substrats de TVE. L’orthophosphate et l’azote Kjeldhal sont les principaux nutriments rejetés à des concentrations élevées par les TVE. En cas d’installation dans des b...
Large scale formal native (and adjacent conventional English) garden with totara, matai and miro ... more Large scale formal native (and adjacent conventional English) garden with totara, matai and miro hedges, kahikatea avenue, copses of different tree types and a diverse New Zealand border of trees and shrubs, Broadfi elds, near Prebbleton, Canterbury. Photo: Colin Meurk Coastal plant signature featuring sand coprosma, sea spurge, sedges, ngaio and cabbage trees, New Brighton, Christchurch. Photo: Colin Meurk Scree garden plant signatures on the Wellington Waterfront-featuring sedges, knobby clubrush, silver and other tussock grasses, rengarenga, pohuehue, NZ iris, NZ linen fl ax and reeds in swales beyond.
Large scale formal native (and adjacent conventional English) garden with totara, matai and miro ... more Large scale formal native (and adjacent conventional English) garden with totara, matai and miro hedges, kahikatea avenue, copses of different tree types and a diverse New Zealand border of trees and shrubs, Broadfi elds, near Prebbleton, Canterbury. Photo: Colin Meurk Coastal plant signature featuring sand coprosma, sea spurge, sedges, ngaio and cabbage trees, New Brighton, Christchurch. Photo: Colin Meurk Scree garden plant signatures on the Wellington Waterfront-featuring sedges, knobby clubrush, silver and other tussock grasses, rengarenga, pohuehue, NZ iris, NZ linen fl ax and reeds in swales beyond.
Sibbaldia: the International Journal of Botanic Garden Horticulture, 2022
An extensive living roof is constructed with load bearing structures with a deep layer of soil me... more An extensive living roof is constructed with load bearing structures with a deep layer of soil media that supports a range of plants. Living roofs have environmental benefits, particularly in an urban setting, such as slowing water runoff and promoting evapotranspiration. Auckland Botanic Gardens (ABG) has been trialling different native and exotic plant species on living roofs to identify top performing plants for these unique growing conditions. The living roofs at ABG were constructed and planted in 2010, so after 10 years of observations, we are able to provide plant lists of what has worked well, challenges with the type of roofs we have, and the adventive species observed.
The Landcare Research sustainable commercial building in Auckland, New Zealand, was designed to h... more The Landcare Research sustainable commercial building in Auckland, New Zealand, was designed to have a small demand for mains water and minimal discharge of stormwater and sewage, to reduce its impact on natural waters. This was a challenge given that the core business operations of Landcare Research, such as research laboratories and experimental glasshouses, require a large volume of water. Minimising the use of mains water was achieved by harvesting and reusing stormwater as well as reducing demand, primarily by using composting toilets. In line with the principles of sustainability, the composting toilets produced a useable product from a waste and reduced untreated discharge from the building. Harvesting the stormwater from the roof reduced the impact of runoff from the building. The other key discharge was stormwater running off a carpark. The carpark forms part of a stormwater treatment train including a bioretention strip and raingarden which reduced the total volume and pea...
Sibbaldia: the International Journal of Botanic Garden Horticulture, 2022
An extensive living roof is constructed with load bearing structures with a deep layer of soil me... more An extensive living roof is constructed with load bearing structures with a deep layer of soil media that supports a range of plants. Living roofs have environmental benefits, particularly in an urban setting, such as slowing water runoff and promoting evapotranspiration. Auckland Botanic Gardens (ABG) has been trialling different native and exotic plant species on living roofs to identify top performing plants for these unique growing conditions. The living roofs at ABG were constructed and planted in 2010, so after 10 years of observations, we are able to provide plant lists of what has worked well, challenges with the type of roofs we have, and the adventive species observed.
A Induced Hyperaccumulation: Metal Movement and Problems Chris Anderson, Annabelle Deram, Daniel ... more A Induced Hyperaccumulation: Metal Movement and Problems Chris Anderson, Annabelle Deram, Daniel Petit, Robert Brooks, Robert (Bob) Stewart, and Robyn Simcock ABSTRACT Induced hyperaccumulation of lead was studied in field and pot trials in northern France (over ...
Although density-specific stiffness, E/rho, (where E is Young's modulus and rho is wood densi... more Although density-specific stiffness, E/rho, (where E is Young's modulus and rho is wood density) is often assumed constant by the elastic similarity model, and in determination of critical buckling height (H(crit)), few studies have tested this assumption within species. Here this assumption is tested for Pinus radiata growing across an environmental gradient, and theory is combined with data to develop a model of Young's modulus. Analyses use an extensive series of environmental plots covering the range of climatic and edaphic conditions over which P. radiata is grown in New Zealand. Reduced major axis regression was used to determine scaling exponents between log-log plots of H(crit) vs. groundline diameter (D), and E/rho vs. D. Path analysis was used to identify significant direct and indirect (through stem slenderness) edaphic and climatic influences on E. Density-specific stiffness exhibited 3-fold variation. As E/rho scaled positively with D, the exponent of 0.95 betwe...
H2009: 32nd Hydrology and Water Resources Symposium, Newcastle : Adapting to Change, 2009
Green roofs are an emerging stormwater management tool that have predominantly been analysed for ... more Green roofs are an emerging stormwater management tool that have predominantly been analysed for runoff volume reduction and peak flow mitigation. Little research has been completed on evapotranspiration (ET) in green roofs. Sedum mexicanum (Mexican stonecrop) and Disphyma australe (New Zealand iceplant) in a NZ designed, pumice- and zeolite-based substrate were analysed to determine daily ET rates. Water loss, and thus storage recovery of the substrate, was greatest when substrate moisture was near field capacity (in the first 9 days). Transpiration (T) contributed up to 39% of total ET (2.0 mm/day for both species). After the initial rate of rapid water loss, plants conserved water and ET was not significantly different from evaporation (E) from unplanted substrate (0.2 mm/day). The majority of ET occurred when substrate moisture content was between the field capacity (FC) and 1500 kPa tension, in the case of the substrate used 13.8-39.6% w/w. Once water content drops below 1500 kPa tension, transpiration ceases, but limited E continues ( 0.2 mm/day). S. mexicanum had a greater ability to conserve water and thus a greater longevity of life than D. australe under low substrate moisture (drought) conditions. When rehydrated every 7 days to maximise water availability and hence minimise plant stress, S. mexicanum and D. australe demonstrated daily average ET of 2.7 mm/day and 2.5 mm/day, respectively, when mean daily temperature was 20.5oC. When temperature is held relatively constant, the major influences on evapotranspiration are plant stress level (linked to moisture availability) and radiation. Water storage recovery is optimised when rainfall or irrigation enables maximum transpiration rates to be maintained and where roofs receive maximum solar radiation.
A new method of biodiversity assessment is developed to characterize the biodiversity values of r... more A new method of biodiversity assessment is developed to characterize the biodiversity values of roads across New Zealand. The methodology blends rigorous probability sampling and PNAP sampling methodology with environmental domains analyses to characterize the biodiversity attributes of highways. It demonstrates the usefulness of this methodology in allowing regional reporting and integrating biodiversity conservation with road management by applying it to a particular road segment, State Highway 3 from Hamilton to New Plymouth. The data gathered is also used to develop an overall biodiversity enhancement and restoration plan for the studied segment of road. The biodiversity attributes of the road reserve differed markedly between the environmental sectors, and showed a strong effect from the surrounding land cover. Results indicate that the road reserve is both a biodiversity asset and a liability. The road reserve is an asset, in that it provides public lands for conservation that are highly visible to the public, often in habitats that are under-represented in the reserve network, and can provide links between existing reserves. The road reserve may be a liability in that it has reduced biodiversity value in the surrounding forests and can act as corridors for the spread of weeds into agricultural areas or indigenous forests. Effective integration of biodiversity conservation and road management can increase these assets and reduce these liabilities. This can be achieved by changing policy at all levels (Transfund NZ, Transit NZ, other roading authorities), by increasing awareness of the biodiversity value of road reserves, and by providing specific guidelines for the management and protection of roadside biodiversity. (a)
New Zealand’s Resource Management Act requires avoiding, remedying or mitigating effects of human... more New Zealand’s Resource Management Act requires avoiding, remedying or mitigating effects of human activities on the environment, including taking action to maintain terrestrial indigenous biodiversity. Here, we suggest that maintaining biodiversity requires halting its current decline, and to achieve that, New Zealand must move away from deeming only significant ecosystems and biota worthy of protection. We identify effects that must be avoided in order to maintain biodiversity, and those to be avoided unless they can be fully and promptly remediated. Effects should be avoided that reduce the extent and quality of most ecosystems and the habitats of indigenous species, including many highly modified ecosystems and habitats. Effects can be remediated only for a few, usually low-diversity and recently-established indigenous ecosystems and habitats, and we suggest a human generation (25 years) should be the maximum time to full remediation. Effects on individuals from some species’ pop...
Trois toitures végétalisées extensives (TVE) ont fait l'objet d'un suivi sur des périodes de 8 mo... more Trois toitures végétalisées extensives (TVE) ont fait l'objet d'un suivi sur des périodes de 8 mois à environ 1 an afin de réaliser un bilan hydrique. Pour chaque TVE, 8 évènements pluvieux ont été échantillonnés pour évaluer la qualité de l'eau et la comparer à des données de toitures conventionnelles situées au même endroit. L'analyse de chaque évènement pluvieux a mis en évidence que les TVE, conçues avec un substrat de 100-150 mm d'épaisseur pour maximiser le stockage de l'eau, ont retenu 56 à 72 % du volume de ruissellement. Les eaux de ruissellement provenant des toitures végétalisées et conventionnelles ne contenaient pas de teneurs élevées en matière en suspension (MES) ou nitrite + nitrate (NOx). Alors que cuivre et zinc proviennent tous deux des matériaux de la toiture, le cuivre peut également provenir des substrats de TVE. L'orthophosphate et l'azote Kjeldhal sont les principaux nutriments rejetés à des concentrations élevées par les TVE. En cas d'installation dans des bassins versant sensibles aux nutriments, l'intégration des TVE dans une chaine de traitement devrait être envisagée. Des hypothèses concernant les caractéristiques en matière organique des substrats sont suggérées pour minimiser la lixiviation des polluants (i.e. rapport carbone/azote, phosphore Olsen, capacité d'échange cationique et contenu en carbone). Cependant des recherches complémentaires sont nécessaires afin d'adapter l'interprétation de ces paramètres d'un point de vue agricole pour des applications spécifiques.
Rain gardens are Water Sensitive Design devices that use bioretention to retain, and reduce pollu... more Rain gardens are Water Sensitive Design devices that use bioretention to retain, and reduce pollutants in, stormwater runoff. Resilient rain gardens consistently attenuate pollutants, volume, and peak flows from small rain events. Research projects investigated combinations of readily available materials in the Auckland region that have consistent physical and chemical properties suitable for bioretention. The mulch and filter (or fill) media used influence rain garden performance – mulches must not float and must have high permeability. Bioretention media must have permeability low enough to achieve adequate contact time (for effective pollutant removal), but high enough to minimize (untreated) overflow from water quality volume events, and avoid excessive ponding duration. Mulch and media chemistry influences effluent water quality and plant growth. Results of two studies are summarised. The studies guide development of fit-for-purpose rain garden mulches and bioretention media in...
Trois toitures végétalisées extensives (TVE) ont fait l’objet d’un suivi sur des périodes de 8 mo... more Trois toitures végétalisées extensives (TVE) ont fait l’objet d’un suivi sur des périodes de 8 mois à environ 1 an afin de réaliser un bilan hydrique. Pour chaque TVE, 8 évènements pluvieux ont été échantillonnés pour évaluer la qualité de l’eau et la comparer à des données de toitures conventionnelles situées au même endroit. L’analyse de chaque évènement pluvieux a mis en évidence que les TVE, conçues avec un substrat de 100-150 mm d’épaisseur pour maximiser le stockage de l’eau, ont retenu 56 à 72 % du volume de ruissellement. Les eaux de ruissellement provenant des toitures végétalisées et conventionnelles ne contenaient pas de teneurs élevées en matière en suspension (MES) ou nitrite + nitrate (NOx). Alors que cuivre et zinc proviennent tous deux des matériaux de la toiture, le cuivre peut également provenir des substrats de TVE. L’orthophosphate et l’azote Kjeldhal sont les principaux nutriments rejetés à des concentrations élevées par les TVE. En cas d’installation dans des b...
Large scale formal native (and adjacent conventional English) garden with totara, matai and miro ... more Large scale formal native (and adjacent conventional English) garden with totara, matai and miro hedges, kahikatea avenue, copses of different tree types and a diverse New Zealand border of trees and shrubs, Broadfi elds, near Prebbleton, Canterbury. Photo: Colin Meurk Coastal plant signature featuring sand coprosma, sea spurge, sedges, ngaio and cabbage trees, New Brighton, Christchurch. Photo: Colin Meurk Scree garden plant signatures on the Wellington Waterfront-featuring sedges, knobby clubrush, silver and other tussock grasses, rengarenga, pohuehue, NZ iris, NZ linen fl ax and reeds in swales beyond.
Large scale formal native (and adjacent conventional English) garden with totara, matai and miro ... more Large scale formal native (and adjacent conventional English) garden with totara, matai and miro hedges, kahikatea avenue, copses of different tree types and a diverse New Zealand border of trees and shrubs, Broadfi elds, near Prebbleton, Canterbury. Photo: Colin Meurk Coastal plant signature featuring sand coprosma, sea spurge, sedges, ngaio and cabbage trees, New Brighton, Christchurch. Photo: Colin Meurk Scree garden plant signatures on the Wellington Waterfront-featuring sedges, knobby clubrush, silver and other tussock grasses, rengarenga, pohuehue, NZ iris, NZ linen fl ax and reeds in swales beyond.
Sibbaldia: the International Journal of Botanic Garden Horticulture, 2022
An extensive living roof is constructed with load bearing structures with a deep layer of soil me... more An extensive living roof is constructed with load bearing structures with a deep layer of soil media that supports a range of plants. Living roofs have environmental benefits, particularly in an urban setting, such as slowing water runoff and promoting evapotranspiration. Auckland Botanic Gardens (ABG) has been trialling different native and exotic plant species on living roofs to identify top performing plants for these unique growing conditions. The living roofs at ABG were constructed and planted in 2010, so after 10 years of observations, we are able to provide plant lists of what has worked well, challenges with the type of roofs we have, and the adventive species observed.
The Landcare Research sustainable commercial building in Auckland, New Zealand, was designed to h... more The Landcare Research sustainable commercial building in Auckland, New Zealand, was designed to have a small demand for mains water and minimal discharge of stormwater and sewage, to reduce its impact on natural waters. This was a challenge given that the core business operations of Landcare Research, such as research laboratories and experimental glasshouses, require a large volume of water. Minimising the use of mains water was achieved by harvesting and reusing stormwater as well as reducing demand, primarily by using composting toilets. In line with the principles of sustainability, the composting toilets produced a useable product from a waste and reduced untreated discharge from the building. Harvesting the stormwater from the roof reduced the impact of runoff from the building. The other key discharge was stormwater running off a carpark. The carpark forms part of a stormwater treatment train including a bioretention strip and raingarden which reduced the total volume and pea...
Sibbaldia: the International Journal of Botanic Garden Horticulture, 2022
An extensive living roof is constructed with load bearing structures with a deep layer of soil me... more An extensive living roof is constructed with load bearing structures with a deep layer of soil media that supports a range of plants. Living roofs have environmental benefits, particularly in an urban setting, such as slowing water runoff and promoting evapotranspiration. Auckland Botanic Gardens (ABG) has been trialling different native and exotic plant species on living roofs to identify top performing plants for these unique growing conditions. The living roofs at ABG were constructed and planted in 2010, so after 10 years of observations, we are able to provide plant lists of what has worked well, challenges with the type of roofs we have, and the adventive species observed.
A Induced Hyperaccumulation: Metal Movement and Problems Chris Anderson, Annabelle Deram, Daniel ... more A Induced Hyperaccumulation: Metal Movement and Problems Chris Anderson, Annabelle Deram, Daniel Petit, Robert Brooks, Robert (Bob) Stewart, and Robyn Simcock ABSTRACT Induced hyperaccumulation of lead was studied in field and pot trials in northern France (over ...
Although density-specific stiffness, E/rho, (where E is Young's modulus and rho is wood densi... more Although density-specific stiffness, E/rho, (where E is Young's modulus and rho is wood density) is often assumed constant by the elastic similarity model, and in determination of critical buckling height (H(crit)), few studies have tested this assumption within species. Here this assumption is tested for Pinus radiata growing across an environmental gradient, and theory is combined with data to develop a model of Young's modulus. Analyses use an extensive series of environmental plots covering the range of climatic and edaphic conditions over which P. radiata is grown in New Zealand. Reduced major axis regression was used to determine scaling exponents between log-log plots of H(crit) vs. groundline diameter (D), and E/rho vs. D. Path analysis was used to identify significant direct and indirect (through stem slenderness) edaphic and climatic influences on E. Density-specific stiffness exhibited 3-fold variation. As E/rho scaled positively with D, the exponent of 0.95 betwe...
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Papers by Robyn Simcock