Appropriate surveying methods in the Philippines: Can modern GPS units help?

An investigation was undertaken to test the effectiveness of two procedures for recording boundaries and plot positions for scientific studies on farms on Leyte Island, the Philippines. The accuracy of a Garmin 76 Global Positioning System (GPS) unit and a compass and chain was checked under the same conditions. Tree canopies interfered with the ability of the satellite signal to reach the GPS and therefore the GPS survey was less accurate than the compass and chain survey. Where a high degree of accuracy is required, a compass and chain survey remains the most effective method of surveying land underneath tree canopies, providing operator error is minimised. For a large number of surveys and thus large amounts of data, a GPS is more appropriate than a compass and chain survey because data are easily up-loaded into a Geographic Information System (GIS). However, under dense canopies where satellite signals cannot reach the GPS, it may be necessary to revert to a compass survey or a combination of both methods.

Using the level set method to model endogenous lava dome growth

Modeling volcanic phenomena is complicated by free-surfaces often supporting large rheological gradients. Analytical solutions and analogue models provide explanations for fundamental characteristics of lava flows. But more sophisticated models are needed, incorporating improved physics and rheology to capture realistic events. To advance our understanding of the flow dynamics of highly viscous lava in Peléean lava dome formation, axi-symmetrical Finite Element Method (FEM) models of generic endogenous dome growth have been developed. We use a novel technique, the level-set method, which tracks a moving interface, leaving the mesh unaltered. The model equations are formulated in an Eulerian framework. In this paper we test the quality of this technique in our numerical scheme by considering existing analytical and experimental models of lava dome growth which assume a constant Newtonian viscosity. We then compare our model against analytical solutions for real lava domes extruded on Soufrière, St. Vincent, W.I. in 1979 and Mount St. Helens, USA in October 1980 using an effective viscosity. The level-set method is found to be computationally light and robust enough to model the free-surface of a growing lava dome. Also, by modeling the extruded lava with a constant pressure head this naturally results in a drop in extrusion rate with increasing dome height, which can explain lava dome growth observables more appropriately than when using a fixed extrusion rate. From the modeling point of view, the level-set method will ultimately provide an opportunity to capture more of the physics while benefiting from the numerical robustness of regular grids.

Compiling a GIS database of tree farms on Leyte Island

As part of ACIAR project ASEM/2003/052, Improving Financial Returns to Smallholder Tree Farmers in the Philippines, plantations of timber trees in Leyte Island, the Philippines were located using a systematic survey of the island. The survey was undertaken in order to compile a database of plantations which could be used to guide the planning of project activities. In addition to recording a range of qualitative and quantitative information for each plantation, the survey spatially referenced each site using a Global Positioning System (GPS) to electronic maps of the island which were held in a Geographical Information System (GIS). Microsoft Excel and Mapsource® software were used as the software links between GPS coordinates and the GIS. Mapping of farm positions was complicated by different datums being used for maps of Leyte Island and this caused GPS positions to be displaced from equivalent positions on the map. Photos of the sites were hyperlinked to their map positions in the GIS in order to assist staff to recall site characteristics.

Combining GIS and Expert Opinion to Model Landscapes for a Smallholder Forest Extension Program in Leyte, the Philippines

A Geographic Information System (GIS) was used to model datasets of Leyte Island, the Philippines, to identify land which was suitable for a forest extension program on the island. The datasets were modelled to provide maps of the distance of land from cities and towns, land which was a suitable elevation and slope for smallholder forestry and land of various soil types. An expert group was used to assign numeric site suitabilities to the soil types and maps of site suitability were used to assist the selection of municipalities for the provision of extension assistance to smallholders. Modelling of the datasets was facilitated by recent developments of the ArcGIS® suite of computer programs and derivation of elevation and slope was assisted by the availability of digital elevation models (DEM) produced by the Shuttle Radar Topography (SRTM) mission. The usefulness of GIS software as a decision support tool for small-scale forestry extension programs is discussed.

A GIS Based Assessment of Land Suitable for Growing Hoop Pine in the Atherton, Eacham and Herberton Shires of North Queensland

The area of private land suitable and available for growing hoop pine (Araucaria cunninghamii) on the Atherton Tablelands in North Queensland was modelled using a geographic information system (GIS). In Atherton, Eacham and Herberton shires, approximately 64,700 ha of privately owned land were identified as having a mean annual rainfall and soil type similar to Forestry Plantations Queensland (FPQ) hoop pine growth plots with an approximate growth rate of 20 m3 per annum. Land with slope of over 25° and land covered with native vegetation were excluded in the estimation. If land which is currently used for high-value agriculture is also excluded, the net area of land potentially suitable and available for expansion of hoop pine plantations is approximately 22,900 ha. Expert silvicultural advice emphasized the role of site preparation and weed control in affecting the long-term growth rate of hoop pine. Hence, sites with less than optimal fertility and rainfall may be considered as being potentially suitable for growing hoop pine at a lower growth rate. The datasets had been prepared at various scales and differing precision for their description of land attributes. Therefore, the results of this investigation have limited applicability for planning at the individual farm level but are useful at the regional level to target areas for plantation expansion.

Analysis of heat transfer and entropy generation for a thermally developing Brinkman–Brinkman forced convection problem in a rectangular duct with isoflux walls

Heat transfer and entropy generation analysis of the thermally developing forced convection in a porous-saturated duct of rectangular cross-section, with walls maintained at a constant and uniform heat flux, is investigated based on the Brinkman flow model. The classical Galerkin method is used to obtain the fully developed velocity distribution. To solve the thermal energy equation, with the effects of viscous dissipation being included, the Extended Weighted Residuals Method (EWRM) is applied. The local (three dimensional) temperature field is solved by utilizing the Green’s function solution based on the EWRM where symbolic algebra is being used for convenience in presentation. Following the computation of the temperature field, expressions are presented for the local Nusselt number and the bulk temperature as a function of the dimensionless longitudinal coordinate, the aspect ratio, the Darcy number, the viscosity ratio, and the Brinkman number. With the velocity and temperature field being determined, the Second Law (of Thermodynamics) aspect of the problem is also investigated. Approximate closed form solutions are also presented for two limiting cases of MDa values. It is observed that decreasing the aspect ratio and MDa values increases the entropy generation rate.

Using household survey data to inform policy decisions regarding the delivery of evidence-based parenting interventions.

Background: This study used household survey data on the prevalence of child, parent and family variables to establish potential targets for a population-level intervention to strengthen parenting skills in the community. The goals of the intervention include decreasing child conduct problems, increasing parental self-efficacy, use of positive parenting strategies, decreasing coercive parenting and increasing help-seeking, social support and participation in positive parenting programmes. Methods: A total of 4010 parents with a child under the age of 12 years completed a statewide telephone survey on parenting. Results: One in three parents reported that their child had a behavioural or emotional problem in the previous 6 months. Furthermore, 9% of children aged 2–12 years meet criteria for oppositional defiant disorder. Parents who reported their child's behaviour to be difficult were more likely to perceive parenting as a negative experience (i.e. demanding, stressful and depressing). Parents with greatest difficulties were mothers without partners and who had low levels of confidence in their parenting roles. About 20% of parents reported being stressed and 5% reported being depressed in the 2 weeks prior to the survey. Parents with personal adjustment problems had lower levels of parenting confidence and their child was more difficult to manage. Only one in four parents had participated in a parent education programme. Conclusions: Implications for the setting of population-level goals and targets for strengthening parenting skills are discussed.

Reducing problem behavior during care-giving in families of preschool-aged children with developmental disabilities

This study evaluated two variants of a behavioral parent training program known as Stepping Stones Triple P (SSTP) using 74 preschool-aged children with developmental disabilities. Families were randomly allocated to an enhanced parent training intervention that combined parenting skills and care-giving coping skills (SSTP-E), standard parent training intervention alone (SSTP-S) or waitlist control (WL) condition. At post-intervention, both programs were associated with lower levels of observed negative child behavior, reductions in the number of care-giving settings where children displayed problem behavior, and improved parental competence and satisfaction in the parenting role as compared with the waitlist condition. Gains attained at post-intervention were maintained at 1-year follow-up. Both interventions produced significant reductions in child problem behavior, with 67% of children in the SSTP-E and 77% of children in the SSTPS showing clinically reliable change from pre-intervention to follow-up. Parents reported a high level of satisfaction with both interventions.

Gypsum solubility in seawater, and its application to bauxite residue amelioration

The solubilities and dissolution rates of three gypsum sources (analytical grade (AG), phosphogypsum (PG) and mined gypsum (MG)) with six MG size fractions ((mm) > 2.0, 1.0-2.0, 0.5-1.0, 0.25-0.5, 0.125-0.25, and < 0.125) were investigated in triple deionised water (TDI) and seawater to examine their suitability for bauxite residue amelioration. Gypsum solubility was greater in seawater (3.8 g L 1) than TDI (2.9 g L 1) due to the ionic strength effect, with dissolution in both TDI and seawater following first order kinetics. Dissolution rate constants varied with gypsum source (AR > PG > MG) due to reactivity and surface area differences, with 1:20 gypsum:solution suspensions reaching saturation within 15 s (AR) to 30 min (MG > 2.0). The ability of bauxite residue to adsorb Ca from solution was also examined. The quantity of the total solution Ca adsorbed was found to be small (5 %). These low rates of solution Ca adsorption combined with the comparatively rapid dissolution rates preclude the application of gypsum to the residue sand/seawater slurry as a method for residue amelioration. Instead, direct field application to the residue would ensure more efficient gypsum use. In addition, the formation of a sparingly soluble CaCO3 coating around the gypsum particles after mixing in a highly alkaline seawater/supernatant liquor (SNL) solution greatly reduced the rate of gypsum dissolution.

Effect of Mn deficiency and legume inoculation on rhizosphere pH in highly alkaline soils

Although plant growth is often limited at high pH, little is known about root-induced changes in the rhizospheres of plants growing in alkaline soils. The effect of Mn deficiency in Rhodes grass (Chloris gayana cv. Pioneer) and of legume inoculation in lucerne (Medicago sativa L. cv. Hunter River), on the rhizosphere pH of plants grown in highly alkaline bauxite residue was investigated. Rhizosphere pH was measured quantitatively, with a micro pH electrode, and qualitatively, with an agar/pH indicator solution. Manganese deficiency in Rhodes grass increased root-induced acidification of the rhizosphere in a soil profile in which N was supplied entirely as NO3-. Rhizosphere pH in the Mn deficient plants was up to 1.22 pH units lower than that of the bulk soil, while only 0.90 to 0.62 pH units lower in plants supplied with adequate Mn. When soil N was supplied entirely as NO3-, rhizosphere acidification was more efficient in inoculated lucerne (1.75 pH unit decrease) than in non-inoculated lucerne (1.16 pH unit decrease). This difference in capacity to lower rhizosphere pH is attributable to the ability of the inoculated lucerne to fix atmospheric N2 rather than relying on the soil N (NO3 ) reserves as the non-inoculated plants. Rhizosphere acidification in both Rhodes grass and lucerne was greatest in the meristematic root zone and least in the maturation root zone.

Control of nutrient solutions for studies at high pH

Little is known about factors effecting plant growth at high pH, with research often limited by the inability to separate nutritional deficiencies and HCO3- toxicity from the direct limitations imposed under high pH conditions. Various methods of controlling dilute nutrient solutions for studies at high pH were investigated. For short-term studies, it was found that a solution without Cu, Fe, Mn and Zn and aerated with CO2 depleted air, greatly reduced nutrient precipitation at high pH, thus eliminating nutritional differences between treatments. Manual pH adjustment and the use of ion exchange resins as pH buffers were unsuitable methods of pH control. However, pH control by automated titration had little effect on solution composition while maintaining constant pH. The system described is suitable for studies in which the pH of the bulk nutrient solution must be maintained. The system was used to examine OH- toxicity in mungbeans (Vigna radiata (L.) Wilczek cv. Emerald), with root length reduced at a bulk solution pH of 8.5 and greater.

Rhizotoxicity of aluminate and polycationic aluminium at high pH

Although monomeric Al species are often toxic in acidic soils, the effects of the aluminate ion (Al(OH)4-) on roots grown in alkaline media are still unclear. Dilute, alkaline (pH 9.5) nutrient solutions were used to investigate the effects of Al(OH)4- on root growth of mungbean (Vigna radiata L.). Root growth was reduced by 13 % after 3 d growth in solutions with an Al(OH)4- activity of 16 μM and no detectable polycationic Al (Al13). This decrease in root growth was associated with the formation of lesions on the root tips (due to the rupturing of the epidermal and outer cortical cells) and a slight limitation to root hair growth (particularly on the lateral roots). When roots displaying these symptoms were transferred to fresh Al(OH)4- solutions for a further 12 h, no root tip lesions were observed and root hair growth on the lateral roots improved. The symptoms were similar to those induced by Al13 at concentrations as low as 0.50 μM Al which are below the detection limit of the ferron method. Thus, Al(OH)4- is considered to be non-toxic, with the observed reduction in root growth in solutions containing Al(OH)4- due to the gradual formation of toxic Al13 in the bulk nutrient solution resulting from the acidification of the alkaline nutrient solution by the plant roots.

Mg induced Ca deficiency under alkaline conditions

Little is known about Mg induced Ca deficiency in alkaline conditions, and the relationship between Mg induced Ca deficiency and Na induced Ca deficiency. Dilute nutrient solutions (dominated by Mg) were used to investigate the effect of Ca activity ratio (CAR) on the growth of mungbeans (Vigna radiata (L.) Wilczek cv. Emerald). At pH 9.0, root growth was reduced below a critical CAR of 0.050 (corresponding to 90 % relative root length). Root growth was found to be limited more in Mg solutions than had been previously observed for Na solutions. Using a CAR equation modified with plasma membrane binding constants (to incorporate the differing antagonistic effects of Mg and Na), new critical CAR values were calculated for both Na (0.56) and Mg (0.44) dominated solutions. This modified CAR equation permits the calculation of CAR irrespective of the dominant salt present.

Examination into the accuracy of exchangeable cation measurement in saline soils

Despite the increasing prevalence of salinity world-wide, the measurement of exchangeable cation concentrations in saline soils remains problematic. Two soil types (Mollisol and Vertisol) were equilibrated with a range of sodium adsorption ratio (SAR) solutions at various ionic strengths. The concentrations of exchangeable cations were then determined using several different types of methods, and the measured exchangeable cation concentrations compared to reference values. At low ionic strength (low salinity), the concentration of exchangeable cations can be accurately estimated from the total soil extractable cations. In saline soils, however, the presence of soluble salts in the soil solution precludes the use of this method. Leaching of the soil with a pre-wash solution (such as alcohol) was found to effectively remove the soluble salts from the soil, thus allowing the accurate measurement of the effective cation exchange capacity (ECEC). However, the dilution associated with this pre-washing increased the exchangeable Ca concentrations while simultaneously decreasing exchangeable Na. In contrast, when calculated as the difference between the total extractable cations and the soil solution cations, good correlations were found between the calculated exchangeable cation concentrations and the reference values for both Na (Mollisol: y=0.873x and Vertisol: y=0.960x) and Ca (Mollisol: y=0.901x and Vertisol: y=1.05x). Therefore, for soils with a soil solution ionic strength greater than 50 mM (electrical conductivity of 4 dS/m) (in which exchangeable cation concentrations are overestimated by the assumption they can be estimated as the total extractable cations), concentrations can be calculated as the difference between total extractable cations and soluble cations.

Effect of Cu Toxicity on Growth of Cowpea (Vigna unguiculata)

Accurate determination of the rhizotoxicity of Cu in dilute nutrient solutions is hindered by the difficulty of maintaining constant, pre-determined concentrations of Cu (micromolar) in solution. The critical Cu2+ activity associated with a reduction in the growth of solution-grown cowpea (Vigna unguiculata (L.) Walp. cv Caloona) was determined in a system in which Cu was maintained constant through the use of a cation exchange resin. The growth of roots and shoots was found to be reduced at solution Cu2+ activities ≥ 1.7 µM (corresponding to 90 % maximum growth). Although root growth was most likely reduced due to a direct Cu2+ toxicity, it is considered that the shoot growth reduction is attributable to a decrease in tissue concentrations of K, Ca, Mg, and Fe and the formation of interveinal chlorosis. At high Cu2+ activities, roots were brown in color, short and thick, had bent root tips with cracking of the epidermis and outer cortex, and had local swellings behind the roots tips due to a reduction in cell elongation. Root hair growth was reduced at concentrations lower than that which caused a significant reduction in overall root fresh weight.