Katharine J. M. Dickinson

Alpine cushion plants inhibit the loss of phylogenetic diversity in severe environments

Biotic interactions can shape phylogenetic community structure (PCS). However, we do not know how the asymmetric effects of foundation species on communities extend to effects on PCS. We assessed PCS of alpine plant communities around the world, both within cushion plant foundation species and adjacent open ground, and compared the effects of foundation species and climate on alpha (within-microsite), beta (between open and cushion) and gamma (open and cushion combined) PCS. In the open, alpha PCS shifted from highly related to distantly related with increasing potential productivity. However, we found no relationship between gamma PCS and climate, due to divergence in phylogenetic composition between cushion and open sub-communities in severe environments, as demonstrated by increasing phylo-beta diversity. Thus, foundation species functioned as micro-refugia by facilitating less stress-tolerant lineages in severe environments, erasing a global productivity - phylogenetic diversity relationship that would go undetected without accounting for this important biotic interaction.

Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage

If snow cover in alpine environments were reduced through climatic warming, plants that are normally protected by snow-lie in winter would become exposed to greater extremes of temperature and solar radiation. We examined the annual course of frost resistance of species of native alpine plants from southern New Zealand that are normally buried in snowbanks over winter (Celmisia haastii and Celmisia prorepens) or in sheltered areas that may accumulate snow (Hebe odora) and other species, typical of more exposed areas, that are relatively snow-free (Celmisia viscosa, Poa colensoi, Dracophyllum muscoides). The frost resistance of these principal species was in accord with habitat: those from snowbanks or sheltered areas showed the least frost resistance, whereas species from exposed areas had greater frost resistance throughout the year. P. colensoi had the greatest frost resistance (−32.5°C). All the principal species showed a rapid increase in frost resistance from summer to early winter (February–June) and maximum frost resistance in winter (July–August). The loss of resistance in late winter to early summer (August–December) was most rapid in P. colensoi and D. muscoides. Seasonal frost resistance of the principal species was more strongly related to daylength than to temperature, although all species except C. viscosa were significantly related to temperature when the influence of daylength was accounted for. Measurements of chlorophyll fluorescence indicated that photosynthetic efficiency of the principal species declined with increasing daylength. Levels of frost resistance of the six principal alpine plant species, and others measured during the growing season, were similar to those measured in tropical alpine areas and somewhat more resistant than those recorded in alpine areas of Europe. The potential for frost damage was greatest in spring. The current relationship of frost resistance with daylength is sufficient to prevent damage at any time of year. While warmer temperatures might lower frost resistance, they would also reduce the incidence of frosts, and the incidence of frost damage is unlikely to be altered. The relationship of frost resistance with daylength and temperature potentially provides a means of predicting the responses of alpine plants in response to global warming.

Garden Size, Householder Knowledge, and Socio-Economic Status Influence Plant and Bird Diversity at the Scale of Individual Gardens

Domestic gardens collectively cover substantial areas within cities and play an important role in supporting urban biodiversity and ecosystem functioning. The extent of their contribution to urban biodiversity is ultimately determined by the attitudes, motivations, and practices of their owners. We identified variables characterizing individual householders and their properties that explained variation in perennial plant and avian species richness and plant diversity among 55 gardens in New Zealand. The size of the vegetated area was most important in explaining bird and plant diversity, independent of property size. Also important and positively associated with plant richness were socio-economic status and ability to discriminate between native and exotic species. Median housing age and neighborhood green space were less important. Contrary to expectations, better educated householders who demonstrated pro-environmental orientation (NEP) did not necessarily have gardens with greater plant diversity, however, people with higher NEP scores tended to have gardens with more structurally complex vegetation. Similar variables were important in explaining native and exotic species richness, but higher exotic plant diversity was associated with older people with smaller properties of lower value. Avian species richness increased primarily with vegetated area, but also the areas of beds and hedges. We demonstrate that although householder knowledge is an important determinant of garden biodiversity, vegetated area is most important. Promoting urban garden biodiversity requires that larger vegetated properties be supported and encouraged, and that planners should consider biodiversity when formulating policies concerning garden size, property size, and consents that may result in a progressive increase in the proportion of built over/paved areas.

Numerical modelling of wind flow over a complex topography

Numerical modelling of wind flow over complex dune topography is an ambitious prospect. There is an increasing need to understand wind flow over complex topography for land planning purposes to enable prediction of sediment transport at a particular site. New surveying techniques permit the rapid development of digital terrain models, however a stumbling block is the ability of Computational Fluid Dynamics (CFD) to emulate the wind flow over such a landscape. To overcome these difficulties, it is important to establish the parameters within which such simulations can operate. This paper details an initial two-dimensional numerical model developed in order to test various modelling assumptions against experimental field wind data. Mason Bay, Stewart Island, New Zealand was chosen as an undisturbed but accessible experimental site with a prevalent on-shore wind perpendicular to a simple foredune and a complex down-wind parabolic dune system. A complex topographical two-dimensional model with vegetation represented as a roughness was compared against field data along a transect dissecting a dune system. This paper establishes that:*Replicating the roughness patterns at the surface is important *The inlet profile should be duplicated with care *Modelling only a portion of the domain can have an effect on the flow patterns due to outflow effects *There is a modelling decision to be made between the complexity of the topography and the sophistication of the turbulence model and degree to which vegetation and sand transportation are modelled. The long-term aim is to instil confidence in numerical techniques so that such technology can be used for predictive purposes.

Maximizing water yield with indigenous non‐forest vegetation: a New Zealand perspective

Provision of clean freshwater is an essential ecosystem service that is under increasing pressure worldwide from a variety of conflicting demands. Water yields differ in relation to land-cover type. Successful resource management therefore requires accurate information on yields from alternative vegetation types to adequately address concerns regarding water production. Of particular importance are upper watersheds/catchments, regardless of where water is extracted. Research in New Zealand has shown that, when in good condition, indigenous tall tussock grasslands can maximize water yield relative to other vegetation cover types. A long-term hydrological paired-catchment study revealed reductions (up to 41% after 22 years) in water yielded annually from an afforested catchment relative to adjacent indigenous grassland. Furthermore, a stable isotope assessment showed that water from fog may substantially contribute to yield in upland tussock grasslands. The tall tussock life-form and its leaf anatomy and ph...

Closing the Gap: Communicating to Change Gardening Practices in Support of Native Biodiversity in Urban Private Gardens

Private gardens collectively comprise the largest green space in most cities and the greatest potential for increasing the extent of wildlife-friendly and native-dominated habitat, improving the quality of ecosystem services, and providing opportunities for urban dwellers to reconnect with nature. Because attitudes and values driving landscape preferences in gardens are complex and often not conducive to biodiversity, and a gap exists between the possession of knowledge or values and the expression of pro-environmental behavior, facilitating change in gardening behavior is challenging. We attempted to improve knowledge and influence values, attitudes, and gardening behavior of 55 householders in favor of native biodiversity and environmentally friendly practices, through a two-way communication process, or interactive dialog, during a process of biodiversity documentation of their gardens. Informative feedback on their garden with a normative component was also provided. Despite being well educated and knowledgeable about common species at the start of the study, an increase in knowledge and shift in attitude was detected in 64% of householders: 40% reported a greater understanding of wildlife, and 26% made changes in their gardens, 13% to support native biodiversity. The normative component of our feedback information was of particular interest to 20% of householders. Because neighborhood norms influence gardening practices, changes adopted by a proportion of householders should be perpetuated across neighborhoods. The process of biodiversity assessment, dialog, and feedback was effective in improving knowledge of wildlife and native species, and stimulated a shift in attitude that resulted in native-friendly gardening practices. These changes were detected primarily through open self-report questions, rather than quantitative measures.

Alpine vegetation, plant distribution, life forms, and environments in a perhumid New Zealand region: oceanic and tropical high mountain affinities.

Macro- and mesoscale patterns of the full altitudinal range (1200–2200 m) of alpine vegetation and vascular flora on Mount Armstrong, on New Zealands perhumid Southern Alps, are deduced from 41 ve...

Design principles for social‐ecological transformation toward sustainability: lessons from New Zealand sense of place

As society seeks to meet the needs of a growing human population and rising aspirations for consumption, many of the ecosystem services on which society depends have declined in the global aggregate. Although some local societies sustainably manage their natural resources for long time periods, the more frequent pattern is overuse of renewable resources and a trajectory toward degradation. How can this degradation be reversed? In this paper we draw on four New Zealand examples and the literature to posit a set of design principles and recommendations to foster transformation from social-ecological degradation toward more sustainable pathways. These include a strong sense of place, prioritizing long-term solutions over short-term benefits, collective engagement of all key stakeholders and willingness to compromise, right to organize and manage, negotiated consensus on sustainability goals, formal and informal monitoring, flexibility to renegotiate goals and adapt, and guidance by a skilled facilitator. We also identify guidelines that foster consensus-building in the face of contested solutions. Examples from New Zealand and the literature suggest that local social-ecological systems can self-organize to shift toward more sustainable trajectories and that society can foster conditions that increase the likelihood of favorable transformations.

Morphospecies and taxonomic species comparison for Hymenoptera

Abstract The use of morphospecies as surrogates for taxonomic species has been proposed as an alternative to overcome the identification difficulties associated with many invertebrate studies, such as biodiversity surveys. Hymenoptera specimens were collected by beating and pitfall traps, and were separated into morphospecies by a non-specialist with no prior training, and later identified by an expert taxonomist. The number of Hymenoptera morphospecies and taxonomic species was 37 and 42, respectively, representing an underestimation error of 12%. Different families presented varying levels of difficulty, and although the species estimation provided by the use of morphospecies initially appeared to have a relatively minor error rate, this was actually an artefact. Splitting and lumping errors balanced each other out, wrongly suggesting that morphospecies were reasonable surrogates for taxonomic species in the Hymenoptera. The use of morphospecies should be adopted only for selected target groups, which have been assessed as reliable surrogates for taxonomic species beforehand, and some prior training to the non-specialist is likely to be of primary importance.

Temporal responses over 30 years to removal of grazing from a mid‐altitude snow tussock grassland reserve, Lammerlaw Ecological Region, New Zealand

Abstract Monitoring of five representative sites in the 144‐ha Black Rock Scientific Reserve of mid‐altitude (690–770 m) narrow‐leaved snow tussock (Chionochloa rigida) grassland over the 30 years since its establishment has revealed, contrary to an early prediction, significant increases in both cover and height of snow tussock. By contrast, co‐dominant shrubs have shown only a slight, generally nonsignificant gain, with Dracophyllum longifolium rather than the predicted Hebe odora as the only significant increaser. Several sub‐dominant shrubs (Coprosma cheesemanii, Leucopogon colensoi, Gaultheria macro stigma) plus some mosses (Hypnum cupressiforme) and lichens (Cladia retipora, Stereocaulon ramulosum) have increased significantly while some rosette herbs (Brachyglottis bellidioides, Oreomyrrhis colensoi, Plantago novae‐zelandiae, and the adventive Hypochoeris radicata) have declined. The generally aggressive exotic flatweed Hieracium pilosella remains as yet a minor component. These changes in subcanopy cover probably reflect the obvious increase in shade and dampness of the micro‐habitat. The height‐frequency sampling indicates an overall decline in vascular species diversity since losses have significantly exceeded gains over the 30‐year period of monitoring. Our results confirm that low‐ to mid‐altitude snow tussock grassland ecosystems can be sustained for at least several decades, for their conservation, landscape, and water yield values. We question the interpretation of a general lack of tussock grassland below treeline in immediate pre‐human times, and its widespread downslope replacement of forest following Polynesian fires, since it is at variance with the known ecology of the dominant grass species, evidence from relevant pollen records, and results from the present study. Rather, we interpret the available evidence as indicative of succession to a vegetation mosaic of non‐woody and woody dominants related to physiography and disturbance, as currently being debated for north‐western Europe. We hypothesise that such a mosaic would more closely reflect the pre‐human situation below treeline which would have been moulded by periodic fire and avian and invertebrate herbivory, in the absence of land mammals.