Wet Tropics Of Queensland Research Articles

A late glacial to present diatom record from Lake Euramoo, wet tropics of Queensland, Australia

A new diatom record from Lake Euramoo on the Atherton Tableland, north Queensland, Australia is used to assess regional climate change and variability and their links to forcing at a local to global scale. The major factor driving diatom composition in the approximately fifteen thousand-year record appears to be regional moisture availability. Patterns of diatom preservation and other indicators, particularly sediment organic content, suggest that permanent deep water formed at the site from ca. 15,000 cal. yr BP. However, between 13,800 and 11,500 cal. yr BP, there was a notable phase of lower lake levels and effective precipitation. The timing and duration of this phase does not correspond to large-scale climate phenomena such as the Antarctic Cold Reversal or the Younger Dryas and supports emerging evidence for a variable climate regime in the south-west Pacific during the late glacial transition. The Early to Mid Holocene record is one of remarkable stability with 5000 years of sustained dominance by the planktonic diatom Aulacoseira ambigua. Conversely, the Mid to Late Holocene record is marked by distinct diatom variability superimposed on a series of sustained shifts in composition. Accentuated Late Holocene climate variability may aid in explaining intensified land use in indigenous populations and also suggests that Europeans may have arrived in the landscape at the time it was most vulnerable to perturbation.

The Effectiveness of Agreements and Protocols to Bridge Between Indigenous and Non-Indigenous Toolboxes for Protected Area Management: A Case Study from the Wet Tropics of Queensland

In the Australian Wet Tropics World Heritage Area (WTWHA), protected areas impact on the rights and obligations of Indigenous traditional owners. This research investigated the effectiveness of two new policy instruments, a negotiated agreement, and a protocol, as mechanisms to bridge between the differing protected area management approaches of Kuku-Yalanji Aboriginal people and the WTWHA managers. The policy innovation sought from these instruments reflects a paradigm shift in protected areas globally toward a more inclusive approach, and recognition of diversity in governance types. However, the instruments' effectiveness in achieving innovation was hampered by the lack of substantive legal mechanisms to overcome the colonial legacy within protected areas. Legislative reform to properly recognize diversity in protected area governance would assist effective bridging. Internationally, rigorous criteria to measure progress toward a more inclusive approach in national systems would enhance our capacity to ensure the current paradigm shift becomes more than convenient rhetoric.

Ecology of Chytridiomycosis in Rainforest Stream Frog Assemblages of Tropical Queensland

Abstract: In the wet tropics of Queensland, Australia, eight species of stream‐dwelling frogs have experienced population declines. Some declines were associated with an emerging infectious disease of amphibians (chytridiomycosis) caused by the fungus Batrachochytrium dendrobatidis. We examined the spatial and temporal pattern of infection prevalence in a sample of frog populations. Infected adults and tadpoles of all species were found, and infections occurred at every site. Infection prevalence varied among species and was always < 10.0% in adults but ranged from 0.75 to 76.0% in tadpoles. In this system tadpoles and adults of some species may act as disease reservoirs, experiencing avirulent infections, whereas other hosts (declining species) experience virulent infections. Infection prevalence was higher during the cool, dry winter season (May to September) and at high elevations (600–800 m), suggesting regulation by environmental conditions, including temperature and precipitation. We found no relationships between infection prevalence and mean body condition, fluctuating asymmetry of hind limbs, population density, or the presence of metamorphosing tadpoles and juvenile frogs. Although it is not certain whether chytridiomycosis was responsible for past frog population declines in the wet tropics of Queensland, the pathogen is now endemic. Our data indicate that at the landscape level, environmental conditions have strong effects on host‐pathogen dynamics. These effects interact with species‐specific behavior or immune function and may be important underlying determinants of chytridiomycosis epizootics and emergence.

Kuku—Yalanji Rainforest Aboriginal People and Carbohydrate Resource Management in the Wet Tropics of Queensland, Australia

Carbohydrate food sources have emerged as a critical factor limiting occupation of rainforests by hunter—gatherer peoples globally. In the wet tropics bioregion of northeastern Australia, Kuku–Yalanji aboriginal people occupied the rainforests through a hunter–gatherer subsistence economy prior to European occupation. Collaborative environmental research between a researcher at the James Cook University and Kuku–Yalanji people has established that their fire management protected carbohydrate resources in the fire-sensitive rainforests and their margins, and ensured ongoing access to the critical dry season carbohydrate resource, Cycas media, growing in patches of fire-prone open forest on each clan estate. Carbohydrate resources in the wet season were obtained predominantly from seeds of rainforest tree nuts, a high proportion of which are wet tropics endemic species. Several of the genera utilized by aboriginal people in the wet tropics bioregion also occur in the rainforests of eastern Cape York Peninsula, where they were not utilized as foods. It is hypothesized that use of rainforest seeds for carbohydrate is a cultural adaptation that occurred in the wet tropics bioregion, stimulated by the unique availability of the substantial number of large-seeded rainforest trees that are wet tropics endemics. The implications of these data for concepts about the impact of aboriginal fires on Australian rainforests are considered. Aboriginal fires imposed a fine patterning on the vegetation at the local scale, with little effect on the vegetation at the regional scale, which is determined by environmental factors.

Economic Evaluation of Proposed Long-Distance Walking Tracks in the Wet Tropics of Queensland

An increasingly popular activity in the Wet Tropics of Queensland is bush walking, which can provide benefits for both the visitors and the local community. While long-distance tracks – with huts and camp sites for overnight stays – are common in some countries (notably New Zealand), this appears to be an ecotourism opportunity which has been overlooked in North Queensland. A market model can be developed in which the supply (indicated by marginal cost) and demand (community willingness to pay) and efficient pricing for a proposed long-distance walking track are estimated. Where a track does not currently exist, transfer of demand estimates from other tracks and inferences about total market size are required. This paper discusses the economic modelling and estimation issues in evaluation of long-distance walking track proposals in the Wet Tropics of Queensland. Demand estimation (with reference to a visitor survey for the Thorsbome Trail on Hinchinbrook island) and supply estimation in terms of track development and maintenance costs are examined.

Visual Disamenity in the Queensland Wet Tropics: Estimating the Economic Impacts of Overhead Transmission Lines

This paperexamines procedures and findings in estimation of the ‘visual disamenity cost’ associated with installation of high-voltage overhead power lines in the Wet Tropics of Queensland 1 . The study was performed within a short timeframe and small budget, hence the need to design a relatively simple and cost-effective approach, yet one which would yield acceptable information on environmental values. An extensive literature review and advice from a number of resource economists indicated that there was little information from previous studies to support benefit transfer methodology. It was found possible to estimate disamenity costs to ecotourism operation (using a simplified travel cost approach), agricultural operations (based on compensation payments) and residential property values (through a simplified hedonic price approach). A planned contingent valuation of the intrusive effect of the transmission lines through rainforest areas did not proceed, due at least in part to the political sensitivity of this issue.

N 2O and CO 2 emissions from three different tropical forest sites in the wet tropics of Queensland, Australia

Three different tropical rain forest sites in Northeast Queensland, Australia, two in the Coastal Lowlands (Pin Gin Hill and Bellenden Ker) and one on the Atherton Tablelands (Kauri Creek), were investigated for the magnitude of N 2O and CO 2 emissions from soils during the wet and the dry season. At all sites, mean N 2O emission rates were significantly higher during the wet season (Bellenden Ker: 242.0±7.4 μg N 2O–N m −2 h −1, Pin Gin Hill: 140.8±5.1 μg N 2O–N m −2 h −1, Kauri Creek: 80.8±3.3 μg N 2O–N m −2 h −1) as compared to the dry season when N 2O-emissions were markedly lower (<20 μg N 2O–N m −2 h −1) due to limitations in soil moisture. During the wet season, mean N 2O emission rates of the Coastal Lowland sites Bellenden Ker and Pin Gin Hill were approximately twofold higher as compared to N 2O emission rates of the Atherton Tableland site Kauri Creek. These site differences were found to be due to differences in precipitation and soil moisture, the C-to-N ratio of the organic matter, soil pH and temperature. Site and seasonal differences in CO 2-emissions were not as pronounced as for N 2O-emissions. Mean CO 2 emission rates at the different sites were in a range of 92.2±1.8 up to 137.3±4.5 mg C m −2 h −1. Correlation analysis revealed a strong dependency of N 2O and CO 2 emissions on changes in soil moisture, whereas changes in soil temperature did not significantly influence the magnitude of in situ N 2O and CO 2 emissions. N 2O emissions were positively correlated to changes in water filled pore space (WFPS) up to a threshold of 50% WFPS at the Bellenden Ker and Kauri Creek sites and up to a threshold of 60% WFPS at the Pin Gin Hill site. CO 2 emission rates were positively correlated to changes in WFPS at dry to moderate soil water contents during the dry season, but were negatively correlated to changes in WFPS during the wet season. Measurements of soil air N 2O-concentrations at the different sites revealed the following sequence in magnitude: Bellenden Ker>Pin Gin Hill>Kauri Creek, which is the same as found for the N 2O source strengths at these sites.

Effect of fertilizer placement on nitrogen loss from sugarcane in tropical Queensland

This paper reports on the fate of nitrogen (N) in a first ratoon sugarcane (Saccharum officinarum L.) crop in the wet tropics of Queensland when urea was either surface applied or drilled into the soil 3–4 days after harvesting the plant cane. Ammonia volatilization was measured with a micrometeorological method, and fertilizer N recovery in plants and soil, to a depth of 140 cm, was determined by mass balance in macroplots with 15N labelled urea 166 and 334 days after fertilizer application. The bulk of the fertilizer and soil N uptake by the sugarcane occurred between fertilizing and the first sampling on day 166. Nitrogen use efficiency measured as the recovery of labelled N in the plant was very low. At the time of the final sampling (day 334), the efficiencies for the surface and subsurface treatments were 18.9% and 28.8%, respectively. The tops, leaves, stalks and roots in the subsurface treatment contained significantly more fertilizer N than the corresponding parts in the surface treatment. The total recoveries of fertilizer N for the plant-trash-soil system on day 334 indicate significant losses of N in both treatments (59.1% and 45.6% of the applied N in the surface and subsurface treatments, respectively). Drilling the urea into the soil instead of applying it to the trash surface reduced ammonia loss from 37.3% to 5.5% of the applied N. Subtracting the data for ammonia loss from total loss suggests that losses by leaching and denitrification combined increased from 21.8% and 40.1% of the applied N as a result of the change in method of application. While the treatment resulted in increased denitrification and/or leaching loss, total N loss was reduced from 59.1% to 45.6%, (a saving of 13.5% of the applied N), which resulted in an extra 9.9%of the applied N being assimilated by the crop.

Fate of urea nitrogen applied to a banana crop in the wet tropics of Queensland

This paper reports a study in the wet tropics of Queensland on the fate of urea applied to a dry or wet soil surface under banana plants. The transformations of urea were followed in cylindrical microplots (10.3 cm diameter × 23 cm long), a nitrogen (N) balance was conducted in macroplots (3.85 m × 2.0 m) with 15N labelled urea, and ammonia volatilization was determined with a mass balance micrometeorological method. Most of the urea was hydrolysed within 4 days irrespective of whether the urea was applied onto dry or wet soil. The nitrification rate was slow at the beginning when the soil was dry, but increased greatly after small amounts of rain; in the 9 days after rain 20% of the N applied was converted to nitrate. In the 40 days between urea application and harvesting, the macroplots the banana plants absorbed only 15% of the applied N; at harvest the largest amounts were found in the leaves (3.4%), pseudostem (3.3%) and fruit (2.8%). Only 1% of the applied N was present in the roots. Sixty percent of the applied N was recovered in the soil and 25% was lost from the plant-soil system by either ammonia volatilization, leaching or denitrification. Direct measurements of ammonia volatilization showed that when urea was applied to dry soil, and only small amounts of rain were received, little ammonia was lost (3.2% of applied N). In contrast, when urea was applied onto wet soil, urea hydrolysis occurred immediately, ammonia was volatilized on day zero, and 17.2% of the applied N was lost by the ninth day after that application. In the latter study, although rain fell every day, the extensive canopy of banana plants reduced the rainfall reaching the fertilized area under the bananas to less than half. Thus even though 90 mm of rain fell during the volatilization study, the fertilized area did not receive sufficient water to wash the urea into the soil and prevent ammonia loss. Losses by leaching and denitrification combined amounted to 5% of the applied N.

Significance of gaseous nitrogen loss from a tropical dairy pasture fertilised with urea

This paper reports a study in the wet tropics of Queensland on the fate of urea applied to a dairy pasture in the absence of grazing animals. A nitrogen balance was conducted in cylindrical plots with 15N-labelled urea, and ammonia volatilisation was determined using a mass balance micrometeorological method. The pasture plants took up 42% of the applied nitrogen in the 98 days between fertiliser application and harvest. At harvest 18% of the applied nitrogen was found in the soil, and 40% was lost from the plant–soil system. The micrometeorological study showed that 20% of the unrecovered nitrogen was lost by ammonia volatilisation. As there was no evidence for leaching or runoff losses it was concluded that the remaining 20% of the applied nitrogen was lost by denitrification. It is evident from these results that fertiliser nitrogen is not being used efficiently on dairy pastures, and that practices need to be changed to conserve fertiliser nitrogen and reduce contamination of the environment.

Aborigines and Fire in the Wet Tropics of Queensland, Australia: Ecosystem Management Across Cultures

Australian indigenous people may retain common law native title rights in lands that have been reserved for nature conservation purposes . They are seeking greater equity in management of these places , and recognition of their cultural practices , such as "fire-stick farming." This article examines the approach to fire management of one group of Australian Aborigines , the Kuku-Yalanji , and that of the government managers of the Wet Tropics of Queensland World Heritage Area . The comparative ecosystem management framework used to analyze the cultural interface highlights potential conflicts over the control of management and information, while identifying common interests in maintaining species and communities . Kuku-Yalanji use fire to protect fire-sensitive rainforests as well as to promote fire-prone open forests. The study suggests a Fire Protocol to mediate the different goals of the two groups, and supports the view that implementation of ecosystem management requires a social decision process.

Population Ecology and Reproductive Seasonality in Three Species of Antechinus (Marsupialia : Dasyuridae) in the Wet Tropics of Queensland

The population and reproductive ecologies of three sympatric species of antechinus were examined in upland rainforests in the wet tropics of Queensland. The three species, Antechinus stuartii adustus, A. flavipes rubeculus and A. godmani, exhibited unusually low trapping success compared with that of sites in temperate regions of Australia. Spatial distributions were extremely patchy both between and within study sites. Comparison with trapping data for temperate populations of A. stuartii and A. flavipes suggests that densities in the wet tropics are among the lowest in Australia. The reproductive season was similar for the three species, commencing during the mid-dry season with juveniles weaned by the early to mid-wet season. The phenomenon of male die-off was observed in the three species. However, the highly synchronous two- week breeding season observed in temperate populations of A. stuartii and A. flavipes was not observed in the tropical populations. The breeding season of the tropical species extended over a six- week period. Timing of reproduction in A. s. adustus and A. f. rubeculus was more similar to temperate than to subtropical populations of A. s. stuartii and A. f. flavipes.

Predicting the potential distribution of rain‐forest structural characteristics

Abstract. Models are reviewed that predict the potential distribution of classes of rain‐forest structural characteristics in relation to indices of climate and soil parent material. A description is given of the field survey undertaken to examine these relations in the Wet Tropics of Queensland, Australia. The predicted probabilities are compared with the observed values and the extent of correspondence between the two data sets examined. Environmental relations based on finer‐scaled landscape processes are proposed to explain the mismatches. An index of catchment hydrology is described that represents the most feasible additional independent variable for spatial extension purposes.

Special Paper: A Spatial Analysis of the Environmental Relations of Rainforest Structural Types

The environmental relations of rainforest struc- tural and physiognomic characteristics (in the Wet Tropics of Queensland, Australia) were quantified using the Monomax algorithms. The probabilities of occurrence for these characteristics were predicted in relation to indices of soil parent material and long-term mean monthly climate estimated at the point of survey for a set of 256 sites. A relatively small number of indices proved the best predic- tors (minimum temperature of coldest month; maximum temperature of hottest month; precipitation seasonality; precipitation of driest quarter; nutrient supply index). Spatial predictions of potential distributions were generat- ed by coupling the predictive functions to gridded esti- mates of the indices used as independent variables. Landsat MSS data were used to restrict the analysis to forested land. Numerical classification and ordination tech- niques were also employed to gain further insight into the spatial relationships. The assumptions of monotonicity required by the Monomax algorithms drew upon hypothe- ses of plant-environmental relations. The results supported the notion that as long as moisture is not limiting, the like- lihood of both larger leaf size and complex structure increases with increasing values of temperature and nutri- ent supply. The potential distributions of structural types were suggested as useful biological units for ecological comparison and conservation evaluation.

Factors affecting the growth of Pennisetum purpureum in the wet tropics. II. Uninterrupted growth

Six plantings of elephant grass (Pennisetum purpureum) were made at 2-monthly intervals in the wet tropics of Queensland and grown for 6 months, ratooned and grown for a further 6 months. Yields of crop fractions were taken at monthly intervals. Dry matter yield attributes were all positively and significantly correlated with each other, and negatively correlated with nitrogen and phosphorus percentages. Stem height was strongly associated with total and stem dry matter yields. Time trends in dry matter yields could be well described by logistic growth curves. It was found that dry matter yields were linearly and significantly related to crop age, degree days, radiation receipt, energy-degree days, cumulative evapotranspiration and moisture stress-free days. The crop was well adapted to the environment and could be grown and harvested year-round for agro-industrial purposes.