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.     

Diuron occurrence and distribution in soil and surface and ground water associated with grass seed production

Little is known about the occurrence and distribution of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] in soil, ground water, and surface water in areas affected by grass-seed production. A field study was designed to investigate the occurrence and distribution of diuron and its transformation products at a poorly drained field site located along an intermittent tributary of Lake Creek in the southern Willamette Valley of Oregon. The experimental sites consisted of a field under commercial grass seed production with a cultivated riparian zone and a second site that was part of the same grass seed field but with a noncultivated riparian zone. Diuron and its transformation product DCPMU [3-(3,4-dichlorophenyl)-1-methylurea] were the only significant residues detected in this study. Concentrations of diuron in surface water declined from a maximum of 28 microg/L immediately following application to low levels that persisted as long as flow was present. Diuron and DCPMU concentrations in shallow ground water (15-36 cm below ground surface) were highest (2-13 microg/L) in the zone immediately adjacent (0.5 m) to Lake Creek and indicated the influence of stream water on shallow ground water near the stream. Diuron and DCPMU detected in soil prior to the second season's application indicated the persistence of diuron and DCPMU from the previous year's application. Surface runoff during the rainy season removes only a very small percentage (<1%) of the applied herbicide. In addition, no evidence was obtained for the downward transport of diuron or its transformation products to deep ground water.     

Spatial variation of soil phosphorus within a drainage ditch network

Agricultural drainage ditches serve as P transport pathways from fields to surface waters. Little is known about the spatial variation of P at the soil-water interface within ditch networks. We quantified the spatial variation of surficial (0-5 cm) soil P within vegetated agricultural ditches on a farm in Princess Anne, MD with an approximately 30-yr history of poultry litter application. Ditch soils from 10 ditches were sampled at 10-m intervals and analyzed for acid ammonium oxalate-extractable P, Fe, Al (P(ox), Fe(ox), Al(ox)), and pH. These variables were spatially autocorrelated. Oxalate-P (min = 135 mg kg(-1), max = 6919 mg kg(-1), mean = 700 mg kg(-1)) exhibited a high standard deviation across the study area (overall 580 mg kg(-1)) and within individual ditches (maximum 1383 mg kg(-1)). Several ditches contained distinct areas of high P(ox), which were associated with either point- or nonpoint-P sources. Phosphorus was correlated with Al(ox) or Fe(ox) within specific ditches. Across all ditches, Al(ox) (r = 0.80; p < 0.001) was better correlated with P(ox) than was Fe(ox) (r = 0.44; p < 0.001). The high level of spatial variation of soil P observed in this ditch network suggests that spatially distributed sampling may be necessary to target best management practices and to model P transport and fate in ditch networks.     

Fuelwood Prices in India: Policy Implications

The price of fuelwood has been increasing at a rate higher than that of the consumer price index in most of the major urban centres of India. Today, in terms of cost per unit of energy delivered, fuelwood is more than twice as expensive as kerosene for cooking. This has immense public policy implications. A number of complementary policy interventions are needed so that forests can be saved and the stability of energy supplies can be achieved in developing countries.     

A novel framework to classify marginal land for sustainable biomass feedstock production

To achieve food and energy security, sustainable bioenergy has become an important goal for many countries. The use of marginal lands to produce energy crops is one strategy for achieving this goal, but what is marginal land? Current definitions generally focus on a single criterion, primarily agroeconomic profitability. Herein, we present a framework that incorporates multiple criteria including profitability of current land use, soil health indicators (erosion, flooding, drainage, or high slopes), and environmental degradation resulting from contamination of surface water or groundwater resources. We tested this framework for classifying marginal land in the state of Nebraska and estimated the potential for using marginal land to produce biofuel crops. Our results indicate that approximately 1.6 million ha, or 4 million acres, of land (approximately 8% of total land area) could be classified as marginal on the basis of at least two criteria. Second-generation lignocellulosic bioenergy crops such as switchgrass ( Panicum virgatum L.), miscanthus (Miscanthus giganteus), native prairie grasses, and short-rotation woody crops could be grown on this land in redesigned landscapes that meet energy and environmental needs, without significant impacts on food or feed production. Calculating tradeoffs between the economics of redesigned landscapes and current practices at the field scale is the next step for determining functional designs for integrating biofuel feedstock production into current land management practices.     

Perceptions of the security and attractiveness of urban parking lots

This study concerns design features of urban parking lots which can increase the perception of such areas as both safe and attractive. College students evaluated the attractiveness and perceived security associated with 180 scenes of parking lots adjacent to commercial and multi-family residential structures in Atlanta and Athens, Georgia, U.S.A. High intergroup correlations (r > 0·90) indicated the reliability of evaluations of both perceived features. Regressions of physical features on perceived security ratings and attractiveness ratings yielded highly predictive models (R² = 0·76 and 0·80, respectively). For both sets of ratings a Maintenance and Design factor accounted for the most variance. Although attractiveness ratings were higher as the total amount of vegetation increased in a scene, security was in general rated higher only when vegetation was well maintained and appeared to be installed as part of a landscape design. Attractiveness was generally higher for multi-family residential scenes than for commercial scenes. Perceived security was higher for frontal views of structures, especially when entrances were proximate to the viewer. Research implications are discussed in terms of the impact of natural features in urban areas for increasing attractiveness and reducing fear of crime.