Water sensitive design features: their function and effectiveness over ten years in a botanic garden

Water sensitive design (WSD) is a nature-based solution to urban stormwater problems which involves intercepting rainfall and stormwater from impervious surfaces using a range of devices. These devices rely on soils and plants to slow water flows, reduce water volumes and improve the quality of the water reaching our rivers, streams, lakes and oceans. Common devices used in Auckland, New Zealand are rain gardens and swales. Auckland Botanic Gardens (ABG) has applied a variety of these devices, often in ‘treatment trains’ and focusing on the use of native New Zealand plants, to solve an on-site environmental problem. ABG additionally supports research, advocates for the selection and effective maintenance of the native New Zealand plants, and educates the public about WSD. Recommendations for plant selection in Auckland for rain gardens and swales are made based on ten years of observations and trials at ABG

Reclamation of aggregate mines in the Manawatu, Rangitikei and Horowhenua Districts, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of PhD in Soil Science at Massey University

Aggregate is the largest extractive industry in New Zealand, in terms of both volume and value of product. In central New Zealand unsustainable extraction of aggregate from rivers has encouraged development of alluvial terrace resources which are often overlain by valuable agricultural soils. Research at commercially reclaimed aggregate mines has shown long-term degradation of the soil resource with productivity of reclaimed land not being maintained at any reported site. Field trials were designed and implemented on three soils characteristic of major landscape units containing aggregate resources which are mined in the greater Manawatu region. Rangitikei fine sandy loam represents free draining Recent soils; Ashhurst stony silt loam represents excessively draining Yellow-brown soils; and Ohakea silt loam represents imperfectly to poorly drained Yellow-grey soils. In each of the trials a "best-case" reclaimed soil was constructed by stripping and replacing soil horizons in their natural order while minimising compaction and ensuring non-limiting nutrient levels. The productivity and soil physical characteristics of other treatments, including different depths of replaced soil and mixed soil horizons, were compared with this "best-case" treatment. Compaction and drainage treatments were also investigated. Control treatments of soils which were ploughed were also used as a reference. Soil depth and horizon mixing Spreading Rangitikei sand over compacted fill material to depths of 0, 0.4, 1.0 and 1.5 m depths resulted in incremental increases in yield of cereal of 92±21, 142±13, 169±14 and 184±7 kg ha-1 respectively. The same treatments had no consistent effect on production of clover and ryegrass for most harvests, probably because pasture roots were able to exploit the fill material as a source of moisture. Yields of pasture were reduced by removal of 0.5 m of the Ohakea upper B horizon, resulting from decreased aeration. This effect was mainly due to the closeness of th water table, which was exacerbated by the sunken surface of this treatment. In contrast, pasture yield was unaffected by removal of a 0.2 m deep Ashhurst B horizon, reflecting the lack of impediment to root extension to depth in the Ashhurst soil. Dilution of Ohakea topsoil by mixing with subsoil material resulted in an increase in soil particle density and bulk density and decrease in percentage of total soil organic carbon so that the mied soil had properties similar to unmixed subsoil. Separate stripping and replacement of topsoil significantly increased establishment of pasture in Ohakea soil but not Rangitikei soil. Dilution of topsoil had no long-term detrimental effects on soil physical properties or pasture production in any of the three soils under the management practices used. A compacted layer at 0.20 m (Ohakea soil ρb=1.64±0.11 on construction) either benefitted or did not effect pasture production over 13 of 14 harvests. The effect of compaction varied with position in the soil profile: pasture production and root length were negatively correlated with bulk density at 0.20 m depth. greater root mass was produced at 0.30 to 0.35 m depth in low compaction treatments A compacted layer at 0.20 m (Ashhurst soil ρb=1.40±0.08 on construction) had no significant effect on pasture production, although cumulative production over 9 harvests was 18% higher in the high compaction treatment. Pasture growing in a compacted Rangitikei soil (ρb= 1.61) produced less than 40% of pasture growing in the same soil with ρb= 1.21, and comprised a higher proportion of weeds. Drainage Drainage lowered the volumetric water content of Ohakea soils at four increments to 0.60 m by a mean 3% on five measurement dates. Pasture production was similar in drained and undrained treatments for 9 of 14 harvests. The Resource Management Act 1991 requires sustainable use of non-mineral resources. Sustainable use of soil resources requires reclamation of mined land. The highly competitive nature of the aggregate industry means reclamation is unlikely to occur unless it is both required and monitored by District and Regional Councils. A survey of aggregate extraction sites in the greater Manawatu region showed that, prior to the Resource Management Act, no sites were required to be reclaimed to their prior productivity. Results from the trials were used to identify basic strategies for reclamation, to pasture, of three groups of soils most commonly disturbed by extraction of alluvial aggregate. The strategies aim to ensure mining is an interim land use. Mining of alluvial aggregate should be promoted on soils which are resilient to disturbance; i.e. free-draining Recent and Yellow-brown soils. Where post-mining land use is agricultural or horticultural production, conditions of extraction must include maintenance of pre-mining productivity under a strategy of rolling reclamation. Conditions related to reclamation must be specific and monitored, preferably by the extraction company under supervision of the authorising Council. Linking specific, measureable reclamation criteria to significant bonds would provide a strong incentive to extraction companies to reclaim land adequately

Plant evaluations for living roofs in Auckland, New Zealand

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

Elevated enclaves – Living roof biodiversity enhancement through prosthetic habitats

Living roofs offer an opportunity to bring conservation into a contemporary context integrated within urban landscapes. Once neglected and under-utilized roof landscapes can now become biodiverse enclaves of indigenous flora and fauna. The microhabitat variables required for lizards, including temperature, humidity, refuge/shelter and prey, on New Zealand’s first fully indigenous (a plant or animal which occurs naturally in NZ) (Department of Conservation 2000) (4) extensive living roof were studied over three years. Temperature and humidity data from a known lizard site was used to assess the suitability of the living roof in conjunction with a comparison of insects monitored on the living roof and a literature review of lizard diet. This data provided a team of ecologists, landscape architects and product designers with the parameters needed to develop, prototype and field-test a prosthetic habitat that provides enhanced conditions on the living roof for lizards. Results indicate a New Zealand indigenous extensive living roof plant community can provide the basic microhabitat variables required to support lizards with the exception of humidity. Although existing vegetation will provide refuge from predators and modifies temperature and humidity, the designed prosthetic habitat creates humid micro-sites (refuges), allowing a trial translocation of native skinks

Modelling environmental variation in Young’s modulus for Pinus radiata and implications for determination of critical buckling height.

Background and Aims: Although density-specific stiffness, E/, (where E is Young's modulus and is wood density) is often assumed constant by the elastic similarity model, and in determination of critical buckling height (Hcrit), 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.Methods 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 Hcrit vs. groundline diameter (D), and E/ vs. D. Path analysis was used to identify significant direct and indirect (through stem slenderness) edaphic and climatic influences on E.Key Results: Density-specific stiffness exhibited 3-fold variation. As E/ scaled positively with D, the exponent of 0·95 between Hcrit and D exceeded the assumed value of 0·67 under constant E/. The final path analysis model included mean air temperature in early autumn (Taut) and slenderness as significant (P < 0·05) positive direct influences on E. Tree leaf area index and Taut were indirectly associated with E through their significant (P < 0·05) positive direct relationship with stem slenderness. Young's modulus was most sensitive to Taut, followed by stem slenderness then leaf area index, and the final model explained 76 % of the variance in E.Conclusions: The findings suggest that within species E/ variation may influence Hcrit and the scaling exponent between D and Hcrit so important in assumptions regarding allometric relationships. The model presented may provide a useful means of determining variation in E, E/ and Hcrit across environmental gradients

Coherence of Personal Narratives Across the Lifespan: A Multidimensional Model and Coding Method

Personal narratives are integral to autobiographical memory and to identity, with coherent personal narratives being linked to positive developmental outcomes across the lifespan. In this article, we review the theoretical and empirical literature that sets the stage for a new lifespan model of personal narrative coherence. This new model integrates context, chronology, and theme as essential dimensions of personal narrative coherence, each of which relies upon different developmental achievements and has a different developmental trajectory across the lifespan. A multidimensional method of coding narrative coherence (the Narrative Coherence Coding Scheme or NaCCS) was derived from the model and is described here. The utility of this approach is demonstrated by its application to 498 narratives that were collected in six laboratories from participants ranging in age from 3 years to adulthood. The value of the model is illustrated further by a discussion of its potential to guide future research on the developmental foundations of narrative coherence and on the benefits of personal narrative coherence for different aspects of psychological functioning