Mitigating urban sprawl effects: a collaborative tree and shade intervention in Phoenix,Arizona, USA

Communities in Phoenix are confronted with numerous challenges that adversely affect human health and safety, with disproportionate impacts on low-income communities. While some challenges are being addressed at the city level, new alliances at the neighbourhood level are initiating community development programmes and projects. This article reports on an intervention study carried out in collaboration with community representatives, city staff, and non-profit organisations to mitigate adverse effects of urban sprawl in the Sky Harbour Neighbourhood in Phoenix. Participatory research was conducted to design and test a tree and shade intervention. Challenges associated with navigating community desires and broader principles of sustainable development are discussed. The study offers a replicable and adaptable intervention research design aimed at empowering communities to meet urban challenges.     

Modelling Temperature Trends in New Zealand

If global warming is accelerating, then one might expect temperatures for most stations to be accelerating and perhaps variability to be increasing. In this study, we examine 57 New Zealand temperature time series for evidence of non-linearity and changing variability. These correspond to time series for annual minima, annual means and annual maxima for 19 stations. Estimation is by an extended least-squares method. We find a surprising diversity of behaviour of these series – presumably reflecting their different geographic factors as well as series length. We give evidence of regions where temperatures are decreasing. For series where a linear trend is significant, it is downwards in about one third of the cases. This proportion was higher in the South Island, especially for series of minima. Where a non-linear trend is significant, temperatures are decelerating in about one half of the cases. The ratio of downward to upward trends is highest among annual maxima and South Island minima and smallest in annual means. Where a linear trend in the variability is significant, it is decreasing in 13 cases and increasing in 5 cases, although possibly this is partly due to poorer quality data last century. Where a non-linear trend in the variability is significant, variability is decelerating in about two thirds of the cases. The results are used to project upper and lower return levels of minima, means and maxima for each of the series to the year 2010.     

The application of local measures of spatial autocorrelation for describing pattern in north Australian landscapes

This paper tests the use of a spatial analysis technique, based on the calculation of local spatial autocorrelation, as a possible approach for modelling and quantifying structure in northern Australian savanna landscapes. Unlike many landscapes in the world, northern Australian savanna landscapes appear on the surface to be intact. They have not experienced the same large-scale land clearance and intensive land management as other landscapes across Australia. Despite this, natural resource managers are beginning to notice that processes are breaking down and declines in species are becoming more evident. With future declines of species looking more imminent it is particularly important that models are available that can help to assess landscape health, and quantify any structural change that takes place. GIS and landscape ecology provide a useful way of describing landscapes both spatially and temporally and have proved to be particularly useful for understanding vegetation structure or pattern in landscapes across the world. There are many measures that examine spatial structure in the landscape and most of these are now available in a GIS environment (e.g. FRAGSTATS* ARC, r.le, and Patch Analyst). All these methods depend on a landscape described in terms of patches, corridors and matrix. However, since landscapes in northern Australia appear to be relatively intact they tend to exist as surfaces of continuous variation rather than in clearly defined homogeneous units. As a result they cannot be easily described using entity-based models requiring patches and other essentially cartographic approaches. This means that more appropriate methods need to be developed and explored. The approach examined in this paper enables clustering and local pattern in the data to be identified and forms a generic method for conceptualising the landscape structure where patches are not obvious and where boundaries between landscape features are difficult to determine. Two sites are examined using this approach. They have been exposed to different degrees of disturbance by fire and grazing. The results show that savanna landscapes are very complex and that even where there is a high degree of disturbance the landscape is still relatively heterogeneous. This means that treating savanna landscapes as being made up of homogeneous units can limit analysis of pattern, as it can over simplify the structure present, and that methods such as the autocorrelation approach are useful tools for quantifying the variable nature of these landscapes.     

Tree Leaf Biomarkers for Atmospheric Nitrogen Deposition

The aim of this paper was to investigate the effects of nitrogen (N) deposition on tree N cycling and identify potential biomarkers forNdeposition. Between April and October 2002 extensive fieldwork was undertaken at Mardley Heath in Hertfordshire. This woodland, located adjacent to the A1(M) motorway, is exposed to high levels of atmospheric nitrogen oxides from the traffic. Measurements of ¹⁵N, in vivo nitrate reductase (NR) activity, tissue, xylem and surface nitrate concentrations as well as N concentration and growth were made along a 700-m transect at 90° to the motorway. The ¹⁵N data show that oxidised N from the road traffic is taken up by nearby trees and is incorporated into plant tissues. Our measurements of NR activities suggest elevated rates close to the motorway. However, xylem sap, leaf tissue and leaf surface nitrate concentrations showed no differences between the roadside location and the most distant sampling point from the motorway. Taken together the ¹⁵N and nitrate reductase data suggest uptake and assimilation of N through the foliage.We conclude that for this lowland deciduouswoodland, tissue, xylem and surface measurements of nitrate are unreliable biomarkers for N deposition whereas ¹⁵N, growth measurements and integrated seasonal NR might be useful. The results also point to the benefit of roadside tree planting to screen pollution from motor vehicles.     

Transaction costs for carbon sequestration projects in the tropical forest sector

There is general consensus that carbon (C) sequestration projects in forests are a relatively low cost option for mitigating climate change, but most studies on the subject have assumed that transaction costs are negligible. The objectives of the study were to examine transaction costs for forest C sequestration projects and to determine the significance of the costs based on economic analyses. Here we examine four case studies of active C sequestration projects being implemented in tropical countries and developed for the C market. The results from the case studies were then used with a dynamic forest and land use economic model to investigate how transaction costs affect the efficiency and cost of forest C projects globally. In the case studies transaction costs ranged from 0.38 to 27 million US dollars ($0.09 to $7.71/t CO₂) or 0.3 to 270 % of anticipated income depending principally on the price of C and project size. The three largest cost categories were insurance (under the voluntary market; 41–89 % of total costs), monitoring (3–42 %) and regulatory approval (8–50 %). The global analysis indicated that most existing estimates of marginal costs of C sequestration are underestimated by up to 30 % because transaction costs were not included.     

The contingent effect of constructive confrontation on the relationship between shared mental models and decision quality

Work teams are being utilized more frequently to give organizations access to the broader knowledge and skill base of employees, as well as to provide for adaptive, efficient decision‐making. In teams, we argue that constructive confrontation norms are an important contingency variable in the relationship between mental model similarity and decision quality. Mental model similarity helps team members understand one another's perspectives and reduces the likelihood of conflict. Accordingly, mental model similarity improves decision quality. When strong norms of constructive confrontation are in place, however, teams are in a better position to reap the benefits of conflict (greater diversity of inputs) without experiencing its negative consequences. Thus, when constructive confrontation norms are strong, less mental model similarity (i.e., more diversity of perspectives) is likely to improve decision quality. Copyright © 2007 John Wiley & Sons, Ltd.     

Sulfur Concentrations in Plant Foliage and Related Effects

Sulfur Is an essential element for plants and is normally taken up from soil In the sulfate form. S0₂ absorbed from the air also can supply S for plant nutrition. Plants are therefore dependent on an optimum S content, but deficiencies or excesses can result in deleterious effects. The Phytotoxicology Section has conducted numerous assessment surveys in rural, urban, or industrial locations in Ontario to determine the concentrations of S in plants and related effects. During the ten year period, 1968 to 1977, about 50,000 samples of vegetation and soil were collected and analyzed for S concentrations. The results of these analyses were examined with respect to natural background concentrations of S in foliage of 33 different species, and effects observed on plant life associated with excess concentrations of S. For example, in one situation 0.35% sulfur in foliage of trembling aspen trees was found to be the threshold level for injury to occur. Some of the industries surveyed for the degree and extent of S effects in their vicinity included pulp mills, power plants, iron concentrators, and gold, nickel, and copper smelters. In interpreting the results of S analyses in plant foliage for diagnostic purposes, consideration should be given also to the geographical location, the stage of growth of the plant, the relation of visible injuries to pollutant or biological causes, the S content of the soil, and S0₂ emission data for the area.     

Assisting Australian indigenous resource management and sustainable utilization of species through the use of GIS and environmental modeling techniques

Information on distribution and relative abundance of species is integral to sustainable management, especially if they are to be harvested for subsistence or commerce. In northern Australia, natural landscapes are vast, centers of population few, access is difficult, and Aboriginal resource centers and communities have limited funds and infrastructure. Consequently defining distribution and relative abundance by comprehensive ground survey is difficult and expensive. This highlights the need for simple, cheap, automated methodologies to predict the distribution of species in use, or having potential for use, in commercial enterprise. The technique applied here uses a Geographic Information System (GIS) to make predictions of probability of occurrence using an inductive modeling technique based on Bayes' theorem. The study area is in the Maningrida region, central Arnhem Land, in the Northern Territory, Australia. The species examined, Cycas arnhemica and Brachychiton diversifolius, are currently being 'wild harvested' in commercial trials, involving sale of decorative plants and use as carving wood, respectively. This study involved limited and relatively simple ground surveys requiring approximately 7 days of effort for each species. The overall model performance was evaluated using Cohen's kappa statistics. The predictive ability of the model for C. arnhemica was classified as moderate and for B. diversifolius as fair. The difference in model performance can be attributed to the pattern of distribution of these species. C. arnhemica tends to occur in a clumped distribution due to relatively short distance dispersal of its large seeds and vegetative growth from long-lived rhizomes, while B. diversifolius seeds are smaller and more widely dispersed across the landscape. The output from analysis predicts trends in species distribution that are consistent with independent on-site sampling for each species and therefore should prove useful in gauging the extent of resource availability. However, some caution needs to be applied as the models tend to over predict presence which is a function of distribution patterns and of other variables operating in the landscape such as fire histories which were not included in the model due to limited availability of data.