Adam's place in nature: Respect or domination?

The creation story in Genesis speaks of humankind being given dominion over nature. Does this support the view that nature has solely instrumental value, and is of worth only insofar as it serves the necessities and conveniences of the human species? Does dominion amount to unfettered domination here? An interpretation of the story is advanced employing procedures of practical criticism. Three central images are focussed on: Adam's being given dominion over the other creatures, his naming of them, and his being made in God's likeness. It is argued that these images, in their qualification and enrichment of each other, develop the idea that animals are of worth independently of their usefulness to us. Other key parts of the Bible, that at first may seem to promote unfettered domination, are shown to be more properly read as supporting an animal-benign religious ethics.     

Geostatistical analysis of soil hydrologic properties in a field plot

A 91-m transect was set up in an irrigated field near Las Cruces, New Mexico to obtain soil water tension and water content data to investigate their spatial variability. A total of 455 sampling points were monitored along a grid consisting of 91 stations placed 1 m apart by 5 depths per station (at 0.3, 0.6, 0.9, 1.2 and 1.5 m below the surface). Post-irrigation tension and wetness measurements were recorded over 45 days at 11 time periods. Soil water tension was measured with tensiometers using a hand-held pressure transducer. A neutron probe was used to obtain volumetric water content. Using the observed wetness and tension data, unsaturated hydraulic conductivity values were derived (using a cubic spline function to estimate the gradient), and an exponential model was used to fit the calculated conductivity-tension curves to obtain hydraulic conductivity parameter values. The spatial and temporal variability of wetness, tension, saturated hydraulic conductivity and pore-size distribution parameters, and texture at the 0.3-m depth were examined using geostatistical techniques.The exponential model was found to inadequately describe the hydraulic conductivity/tension relationship for the full range of tension, particularly in the tension range near saturation. The derived values of the saturated hydraulic conductivity parameter were much greater than expected and do not correspond to reasonable saturated hydraulic conductivity values.All of the soil parameters studied exhibited large spatial variability horizontally and vertically in the field. Ranges of dependence determined from semivariogram analysis over the 44-day drainage period are 3–32 m for wetness, 6–34 m for soil water tension, 5–35 m for natural log of saturated hydraulic conductivity parameters, 5–11 m for pore-size distribution parameter, and 8–24 m for percent sand, silt and clay at the 0.3 m depth. An alternate hole-effect model is suggested to describe the texture semivariograms.It was determined that the variance of volumetric water content generally increased at each depth over the measured time periods, which is consistent with certain past field studies and a stochastic analysis of unsaturated flow in heterogeneous soils. Future research is recommended relating soil texture to soil hydrologic parameters with the goal of predicting soil behavior with less extensive sampling schemes.     

Modifying native and exotic species richness correlations: the influence of fire and seed addition.

An important goal in restoration is to increase the richness of native species while reducing exotic species. However, native species richness is often positively correlated with exotic species richness. In a grassland-savanna system in Michigan (USA), we show that management that focuses on changing the nature of the exotic-native richness relationship can be used to restore native communities. Native and exotic species richnesses were positively correlated, likely due to a shared coupling with aboveground live biomass (a surrogate for productivity). The addition of native seed shifted the exotic-native richness relationship from a linear positive to a monotonic relationship: in areas of intermediate levels of exotic species richness, seed addition increased native diversity without an associated effect on exotic diversity, but in areas of high or low exotic richness, it did not affect native species richness. Prescribed burning broke the correlation between native and exotic richness with no consistent effect on the richness of either group. However, when burning was combined with native-seed addition, the relationship between native and exotic richness was maintained and was shifted upwards, enhancing native recruitment. Although aboveground productivity was strongly related to species richness across the landscape, changes in productivity did not drive these shifts.     

Plant uptake of inorganic and organic nitrogen: neighbor identity matters

The importance of interspecific competition as a cause of resource partitioning among species has been widely assumed but rarely tested. Using neighbor removals in combination with 15N tracer additions in the field, we examined variation among three alpine species in the uptake of 15N-NH4+, 15N-NO3-, and 15N-13C-[2]-glycine in intact neighborhoods, when paired with a specific neighbor, and when all neighbors were removed. Species varied in the capacity to take up 15N-labeled NH4+, NO3-, and glycine in intact neighborhoods and in interspecific pairs. When interspecific neighbor pairs were compared with no neighbor controls, neighbors reduced 15N uptake in target species by as much as 50%, indicating competition for N. Furthermore, neighbor identity influenced the capacity of species to take up different forms of N. Thus, competition within interspecific neighbor pairs often caused reduced uptake of a particular form of N, as well as shifts to uptake of an alternative form of N. Such shifts in resource use as a result of competition are an implicit assumption in studies of resource partitioning but have rarely been documented. Our study suggests that plasticity in the uptake of different forms of N may be a mechanism by which cooccurring plants reduce competition for N.     

Early maternal investment in male and female African elephant calves

Summary The suckling behaviour of 130 freeranging elephant calves aged between birth and 4.5 years old was examined in Amboseli National Park, Kenya. Analyses of frequencies of suckling and durations of suckling bouts showed that males attempted to suckle more often, were more successful at their attempts, and as a result were estimated to have a higher milk intake than did female calves. Mothers were equally tolerant of their sons' and daughters' demands to suckle at young ages, but were less tolerant of their older sons' demands. The growth rates of males based on hind footprint length were faster than those of females from birth onwards. During drought years with low food availability, male calf survivorship in the first year was lower than that of female calves. During wet years, there was little difference between sexes in survivorship. It appeared that during dry years mothers were unable to sustain milk production at a level that met the metabolic requirements of their sons, and as result male calves were more likely to die. Females with a surviving son tended to have a longer interbirth interval than did females with a surviving daughter. We suggest that greater early maternal investment in male calves occurs because, in the highly-competitive polygynous mating system of elephants, size in adult male elephants is an important factor in mating success.     

A bayesian network for comparing dissolved nitrogen exports from high rainfall cropping in southeastern Australia

Best management practices are often used to mitigate nutrient exports from agricultural systems. The effectiveness of these measures can vary depending on the natural attributes of the land in question (e.g., soil type, slope, and drainage class). In this paper we use a Bayesian Network to combine experiential data (expert opinion) and experimental data to compare farm-scale management for different high-rainfall cropping farms in the Hamilton region of southern Australia. In the absence of appropriate data for calibration, the network was tested against various scenarios in a predictive and in a diagnostic way. In general, the network suggests that transport factors related to total surface water (i.e., surface and near surface interflow) runoff, which are largely unrelated to Site Variables, have the biggest effect on N exports. Source factors, especially those related to fertilizer applications at planting, also appear to be important. However, the effects of fertilizer depend on when runoff occurs, and, of the major factors under management control, only the Fertilizer Rate at Sowing had a notable effect. When used in a predictive capacity, the network suggests that, compared with other scenarios, high N loads are likely when fertilizer applications at sowing and runoff coincide. In this paper we have used a Bayesian Network to describe many of the dependencies between some of the major factors affecting N exports from high rainfall cropping. This relatively simple approach has been shown to be a useful tool for comparing management practices in data-poor environments.     

Perfluorinated compounds in the Antarctic region: Ocean circulation provides prolonged protection from distant sources

In order to investigate the extent to which Perfluorinated Contaminants (PFCs) have permeated the Southern Ocean food web to date, a range of Antarctic, sub-Antarctic and Antarctic-migratory biota were analysed for key ionic PFCs.Based upon the geographical distribution pattern and ecology of biota with detectable vs. non-detectable PFC burdens, an evaluation of the potential contributory roles of alternative system input pathways is made. Our analytical findings, together with previous reports, reveal only the occasional occurrence of PFCs in migratory biota and vertebrate predators with foraging ranges extending into or north of the Antarctic Circumpolar Current (ACC).Geographical contamination patterns observed correspond most strongly with those expected from delivery via hydrospheric transport as governed by the unique oceanographic features of the Southern Ocean. We suggest that hydrospheric transport will form a slow, but primary, input pathway of PFCs to the Antarctic region.     

A review of the cost-effectiveness and suitability of mitigation strategies to prevent phosphorus loss from dairy farms in New Zealand and Australia

The loss of phosphorus (P) from land to water is detrimental to surface water quality in many parts of New Zealand and Australia. Farming, especially pasture-based dairying, can be a source of P loss, but preventing it requires a range of fully costed strategies because little or no subsidies are available and the effectiveness of mitigation strategies varies with different farm management systems, topography, stream density, and climate. This paper reviews the cost-effectiveness of mitigation strategies for New Zealand and Australian dairy farms, grouping strategies into (i) management (e.g., decreasing soil test P, fencing streams off from stock, or applying low-water-soluble P fertilizers), (ii) amendments (e.g., alum or red mud [Bauxite residue]), and (iii) edge-of-field mitigations (e.g., natural or constructed wetlands). In general, on-farm management strategies were the most cost-effective way of mitigating P exports (cost range, $0 to $200 per kg P conserved). Amendments, added to tile drains or directly to surface soil, were often constrained by supply or were labor intensive. Of the amendments examined, red mud was cost effective where cost was offset by improved soil physical properties. Edge-of-field strategies, which remove P from runoff (i.e., wetlands) or prevent runoff (i.e., irrigation runoff recycling systems), were generally the least cost effective, but their benefits in terms of improved overall resource efficiency, especially in times of drought, or their effect on other contaminants like N need to be considered. By presenting a wide range of fully costed strategies, and understanding their mechanisms, a farmer or farm advisor is able to choose those that suit their farm and maintain profitability. Further work should examine the potential for targeting strategies to areas that lose the most P in time and space to maximize the cost-effectiveness of mitigation strategies, quantify the benefits of multiple strategies, and identify changes to land use that optimize overall dairy production, but minimize catchment scale, as versus farm scale, nutrient exports.