Nitrogen ecophysiology of Heron Island, a subtropical coral cay of the Great Barrier Reef, Australia

Coral cays form part of the Australian Great Barrier Reef. Coral cays with high densities of seabirds are areas of extreme nitrogen (N) enrichment with deposition rates of up to 1000 kg N ha(-1) y(-1). The ways in which N sources are utilised by coral cay plants, N is distributed within the cay, and whether or not seabird-derived N moves from cay to surrounding marine environments were investigated. We used N metabolite analysis, N-15 labelling and N-15 natural abundance (delta(15)N) techniques. Deposited guano-derived uric acid is hydrolysed to ammonium (NH4+) and gaseous ammonia (NH3). Ammonium undergoes nitrification, and nitrate (NO3-) and NH4+ were the main forms of soluble N in the soil. Plants from seabird rookeries have a high capacity to take up and assimilate NH4+, are able to metabolise uric acid, but have low rates of NO3- uptake and assimilation. We concluded that NH4+ is the principal source of N for plants growing at seabird rookeries, and that the presence of NH4+ in soil and gaseous NH3 in the atmosphere inhibits assimilation of NO3-, although NO3- is taken up and stored. Seabird guano, Pisonia forest soil and vegetation were similarly enriched in N-15 suggesting that the isotopic enrichment of guano (delta(15)N 9.9parts per thousand) carries through the forest ecosystem. Soil and plants from woodland and beach environments had lower delta(15)N (average 6.5parts per thousand) indicating a lower contribution of bird-derived N to the N nutrition of plants at these sites. The aquifer under the cay receives seabird-derived N leached from the cay and has high concentrations of N-15-enriched NO3- (delta(15)N 7.9parts per thousand). Macroalgae from reefs with and without seabirds had similar delta(15)N values of 2.0-3.9parts per thousand suggesting that reef macroalgae do not utilise N-15-enriched seabird-derived N as a main source of N. At a site beyond the Heron Reef Crest, macroalgae had elevated delta(15)N of 5.2parts per thousand, possibly indicating that there are locations where macroalgae access isotopically enriched aquifer-derived N. Nitrogen relations of Heron Island vegetation are compared with other reef islands and a conceptual model is presented.

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.

Subantarctic Macquarie Island - a model ecosystem for studying animal-derived nitrogen sources using N-15 natural abundance

Plants collected from diverse sites on subantarctic Macquarie Island varied by up to 30 parts per thousand in their leaf delta(15)N values. N-15 natural abundance of plants, soils, animal excrement and atmospheric ammonia suggest that the majority of nitrogen utilised by plants growing in the vicinity of animal colonies or burrows is animal-derived. Plants growing near scavengers and animal higher in the food chain had highly enriched delta(15)N values (mean = 12.9 parts per thousand), reflecting the highly enriched signature of these animals' excrement, while plants growing near nesting penguins and albatross, which have an intermediate food chain position, had less enriched delta(15)N values (> 6 parts per thousand). Vegetation in areas affected by rabbits had lower delta(15)N values (mean = 1.2 parts per thousand), while the highly depleted delta(15)N values (below -5 parts per thousand) of plants at upland plateau sites inland of penguin colonies, suggested that a portion of their nitrogen is derived from ammonia (mean N-15 = -10 parts per thousand) lost during the degradation of penguin guano. Vegetation in a remote area had delta(15)N values near -2 parts per thousand. These results contrast with arctic and subarctic studies that attribute large variations in plant N-15 values to nitrogen partitioning in nitrogen-limited environments. Here, plant N-15 reflects the N-15 Of the likely nitrogen sources utilised by plants.

Estimation of body fatness from body mass index and bioelectrical impedance: comparison of New Zealand European, Maori and Pacific Island children

Objective: To compare percentage body fat (%BF) for a given body mass index (BMI) among New Zealand European, Maori and Pacific Island children. To develop prediction equations based on bioimpedance measurements for the estimation of fat-free mass (FFM) appropriate to children in these three ethnic groups. Design: Cross-sectional study. Purposive sampling of schoolchildren aimed at recruiting three children of each sex and ethnicity for each year of age. Double cross-validation of FFM prediction equations developed by multiple regression. Setting: Local schools in Auckland. Subjects: Healthy European, Maori and Pacific Island children (n = 172, 83 M, 89 F, mean age 9.4 +/- 2.8(s. d.), range 5 - 14 y). Measurements: Height, weight, age, sex and ethnicity were recorded. FFM was derived from measurements of total body water by deuterium dilution and resistance and reactance were measured by bioimpedance analysis. Results: For fixed BMI, the Maori and Pacific Island girls averaged 3.7% lower % BF than European girls. For boys a similar relation was not found since BMI did not significantly influence % BF of European boys ( P = 0.18). Based on bioimpedance measurements a single prediction equation was developed for all children: FFM (kg) = 0.622 height (cm)(2)/ resistance +0.234 weight (kg)+1.166, R-2 = 0.96, s. e. e. = 2.44 kg. Ethnicity, age and sex were not significant predictors. Conclusions: A robust equation for estimation of FFM in New Zealand European, Maori and Pacific Island children in the 5 - 14 y age range that is more suitable than BMI for the determination of body fatness in field studies has been developed. Sponsorship: Maurice and Phyllis Paykel Trust, Auckland University of Technology Contestable Grants Fund and the Ministry of Health.

Speleothem master chronologies: combined Holocene O-18 and C-13 records from the North Island of New Zealand and their palaeoenvironmental interpretation

The stable isotope records of four stalagmites dated by 19 TIMS uranium series ages are combined to produce master chronologies for delta(18)O and delta(13)C The delta(18)O records display good overall coherence, but considerable variation in detail. Variability in the delta(13)C records is greater, but general trends can still be discerned. This implies that too fine an interpretation of the structure of individual isotopic records can be unreliable. Speleothem delta(18)O values are demonstrated to show a positive relationship with temperature by comparing trends with other proxy records, but also to respond negatively to rainfall amount. Speleothem delta(13)C is considered to be most influenced by rainfall. The postglacial thermal optimum occur-red around 10.8 ka BP, which is similar in timing to Antarctica but up to 2000 years earlier than most Northern Hemisphere sites. Increasingly negative delta(18)O values after 7.5 ka BP indicate that temperatures declined to a late mid-Holocene minimum centred around 3 ka BP, but more positive values followed to mark a warm peak about 750 years ago which coincided with the 'Mediaeval Warm Period' of Europe. Low 5110 values at 325 years BP suggest cooling coincident with the 'Little Ice Age'. A marked feature of the delta(13)C record is an asymmetric periodicity averaging c. 2250 years and amplitude of c. 1.9parts per thousand. It is concluded that this is mainly driven by waterbalance variations with negative swings representing particularly wet intervals. The 5110 record shows a higher-frequency cyclicity with a period of c. 500 years and an amplitude of c. 0.25 parts per thousand. This is most likely to be temperature-driven, but some swings may have been amplified by precipitation.

Late pleistocene to holocene composite speleothem O-18 and C-13 chronologies from south island, new Zealand-did a global younger dryas really exist?

Oxygen and carbon data from eight stalagmites from northwest South Island are combined to produce composite records of delta(18)O and delta(13)C from 23.4 ka to the present. The chronology is anchored by 43 thermal ionization mass spectrometry (TIMS) uranium series ages. Delta O-18 values are interpreted as having a first order positive relationship to temperature, but also to be influenced by precipitation in a complex manner. Delta C-13 is interpreted as responding negatively to increases in atmospheric CO, concentration, biological activity and precipitation amount. Six climatic phases are recognized. After adjustment of 1.2parts per thousand for the ice volume effect, the delta(18)O record between 23 and 18 ka varies around -3.72parts per thousand compared to the Holocene average of -3.17parts per thousand. Late-glacial warming commenced between 18.2 and 17.8 ka and accelerated after 16.7 ka, culminating in a positive excursion between 14.70 and 13.53 ka. This was followed by a significant negative excursion between 13.53 and 11.14 ka of up to 0.55parts per thousand depth that overlapped the Antarctic Cold Reversal (ACR) and spanned the Younger Dryas (YD). Positive delta(18)O excursions at 11.14 ka and 6.91-6.47 ka represent the warmest parts of the Holocene. The mid-Holocene from 6 to 2 ka was marked by negative excursions that coincide with increased glacial activity in the South Island. A short positive excursion from 0.71 to 0.57 ka was slightly later than the Medieval Warm Period of Europe. Delta C-13 values were high until 17.79 ka after which there was an abrupt decrease to 17.19 ka followed by a steady decline to a minimum at 10.97 ka. Then followed a general increase, suggesting a drying trend, to 3.23 ka followed by a further general decline. The abrupt decrease in delta-values after 17.79 ka probably corresponds to an increase in atmospheric CO2 concentration, biological activity and wetness at the end of the Last Glaciation, but the reversal identified in the delta(18)O record from 13.53 to 11.14 ka was not reflected in delta(13)C changes. The lowest delta(13)C values coincided with the early Holocene climatic suboptimum when conditions were relatively wet as well as mild. Major trends in the delta(18)O(c) record are similar to the Northern Hemisphere, but second order detail is often distinctly different. Consequently, at the millennial scale, a more convincing case can be made for asymmetric climatic response between the two hemispheres rather than synchronicity. (C) 2004 Elsevier B.V. All rights reserved.

Co-opting conservation: Migrant resource control and access to national park management in the Philippine uplands

The history of political and economic inequality in forest villages can shape how and why resource use conflicts arise during the evolution of national parks management. In the Philippine uplands, indigenous peoples and migrant settlers co-exist, compete over land and forest resources, and shape how managers preserve forests through national parks. This article examines how migrants have claimed lands and changed production and exchange relations among the indigenous Tagbanua to build on and benefit from otherwise coercive park management on Palawan Island, the Philippines. Migrant control over productive resources has influenced who, within each group, could sustain agriculture in the face of the state's dominant conservation narrative - valorizing migrant paddy rice and criminalizing Tagbanua swiddens. Upon settling, migrant farmers used new political and economic strengths to tap into provincial political networks in order to be hired at a national park. As a result, they were able to steer management to support paddy rice at the expense of swidden cultivation. While state conservation policy shapes how national parks impact upon local resource access and use, older political economic inequalities in forest villages build on such policies to influence how management affects the livelihoods of poor households.