Field Studies in Ecology presents outstanding papers arising from ANU undergraduate field courses in ecology and related disciplines. The articles are chosen for publication by the editorial team and peer-reviewed by leading ANU academics and other experts in the field. They showcase original research undertaken by these students and make the findings accessible for researchers and other stakeholders. They also serve as a resource for future students who undertake these courses. Established in 2019, FSE is managed by a team of student editors, with guidance from the staff from the Research School of Biology at ANU.
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Increasing dominance by a native shrub effects plant-pollinator interactions but not pollen transfer
Climate change is causing plant species to shift distributions, especially in alpine environments. These changes could potentially impact plant-pollinator interactions and pollen transfer. This study assessed how Nematolepis ovatifolia (F. Muell.) Paul G. Wilson, a mass flowering shrub in Kosciuszko National Park, New South Wales, Australia, effected the pollination ecology of co-flowering. Visitation surveys in small plots with differing abundances of N. ovatifolia were conducted to construct plant-pollinator networks. A compound light microscope was used to count conspecific (CP) and N. ovatifolia pollen grains on plant stigmas. Bipartite networks and generalized linear mixed models were used to find patterns in the data. There was evidence for N. ovatifolia effecting visitation patterns at high densities. However, N. ovatifolia abundance was found not to significantly effect CP and N. ovatifolia pollen deposition onto the stigmas of other plants. CP deposition was significantly lower in Pimelea alpina F. Muell. ex Meisn. and N. ovatifolia pollen deposition was very low across all species. Visitation was not a good predictor for pollen transfer. Further studies should include more plant species over longer time periods and analyze seed set. These findings demonstrate that the effect of range shifting native plants on plant-pollinator networks may not be analogous to that of invasive species.
Copyright (c) 2024 Field Studies in Ecology
Distribution of pollinator functional groups across elevations in Kosciusko National Park Australia
Plant-pollinator interactions are important indicators of ecosystem health and resilience. Previous studies have examined pollination networks across elevations in Europe and North America, but there has been little investigation of the distribution of pollinator functional groups across elevations in Australia. We aimed to examine the distribution of pollinator functional groups (Coleoptera, Anthophila, Lepidoptera and Diptera) across elevations in Kosciusko National Park (KNP) by collecting insect specimens and corresponding pollen samples from sites at three different elevations. The highest elevation was dominated by Coleoptera and Diptera with generalised foraging behaviours and the lowest elevation was dominated by Anthophila with specialised pollination behaviours. These findings hold significant implications for the future of pollination networks as warming temperatures may drive competitive pollination specialists such as Anthophila upwards, threatening to outcompete the generalised foragers such as Coleoptera and Diptera in higher elevations. An increase in specialised Anthophila foragers in higher elevations could lead to changes in floristic composition as their pollination services differ from other functional groups that perform incidental pollination.
Variable responses of alpine grassland plant species to drought in Kosciuszko National Park
Understanding how plant species in alpine Australia will respond to climate change is vital for the future management of these ecosystems. Plant and leaf traits can provide key insights into how an individual is responding to environmental stresses such as reduced water availability. By assessing traits across species and functional groups, a picture can begin to develop about whole community responses to drought stress. This study recorded a variety of traits for six alpine plant species across three functional groups to understand how plant stress responses may influence shifts in community composition in the Australian Alps. The results of this study varied greatly between species and functional groups, highlighting the need for further longer-term studies to provide a more comprehensive understanding of species-specific responses.
The Impact of Ski Resort Disturbance on Bird Species Distribution in Kosciuszko National Park
As alpine tourism expands, the disturbance of natural habitat creates substantial changes in the composition of vegetation communities and their dependent bird populations. This investigation was conducted to determine if ski resorts are negatively impacting bird species abundance and distribution within Kosciuszko National Park. Species presence was measured along six 2km transects from highly disturbed ski resorts out to less disturbed habitat. Birds were categorized by known species weight, feeding preferences and habitat choice simplified to Boolean classes (large > 100g < small) and generalist category; combined sum of suitable food and habitat types (generalist > 4 < specialist). The conclusions of the study found that total bird abundance and species richness was higher in close proximity to ski resorts and that both generalist and larger bird species were favoured in high disturbance locations. This could imply that small specialist species are the most susceptible to the effects of environmental disturbance caused by ski resorts. Future studies may consider the negative impact that ski resort disturbance has on small specialist bird species and may include the impacts of indirect disturbances such as dieback events and global warming induced habitat fragmentation.
Investigating the impact of soil moisture on the thermal tolerance of alpine Ranunculus species and hybrids in Kosciuszko National Park, Australia.
Escalating extreme temperature events significantly impact organisms, driving species selection and adaptation. To predict global species distributions in a warmer future, understanding differences in metabolic temperature tolerance and plasticity is crucial. Chlorophyll fluorescence can be used to measure critical temperature of photosynthetic heat tolerance (PHT) in plants. The upper (CTmax) and lower (CTmin) critical temperature, as well as the difference between these two limits, the thermal tolerance breadth (TTB), were measured for five Ranunculus species and four hybrid types, using a high-throughput chlorophyll fluorescence imaging method and apparatus. This study compares PHT between species and hybrids and analyses the correlation of PHT to soil moisture to gain insight into how local microclimatic factors and hybridisation might allow vulnerable species to leverage adaptive traits. Our results show very significant differences between the CTmax, CTmin and TTB of species, with hybrids often having intermediate values between their parent species. The correlation between soil moisture and CTmin was negative and significant, while the correlation with CTmax and TTB were both slightly positive, but not significant. Soil moisture marginally increasing thermal tolerance indicates that small pockets with higher soil moisture than the surrounding landscape (such as gullies and intermittent stream beds) may become increasingly important for the persistence of Ranunculus populations. This is concerning, given predictions of a drier climate in the future, especially for those species identified as having comparatively lower thermal tolerance. This study demonstrates how plant physiological measurements could aid in the identification of species that are more at risk of climate induced range shifts or local extinction and assist with setting conservation priorities.
Critical temperature, thermal plasticity, thermal tolerance breadth, chlorophyll fluorescence, soil moisture.
Role of Bogong moths (Agrotis infusa) in the nocturnal plant-pollinator network of Kosciuszko National Park
Nocturnal pollinators are essential for the maintenance of ecosystems because they allow for plant reproduction and play a crucial role in trophic interactions. Moths (Lepidoptera) are important nocturnal pollinators yet have been largely overlooked by researchers due to difficulties associated with field sampling at night. The endangered Bogong moth (Agrotis infusa) has recently been found to forage on local flowers during its summer aestivation period in the Australian Alps, but its role as a pollen vector is not yet well understood relative to other nocturnal moths. Understanding plant-pollinator interactions is of particular importance for species likely to be impacted by anthropogenic climate change and will help direct conservation efforts. This study examined how Bogong moths vary in their capacity as pollen vectors compared to other nocturnal moths in Kosciuszko National Park. This was achieved by comparing moth abundance, pollen grain abundance, and pollen richness between different taxa, as well as using network metrics to identify species of structural importance. Using UV light trapping, 132 individuals from 42 moth species were captured and swabbed for pollen, which was then identified and counted using light microscopy. Our findings indicated that Bogong moths were present in greater abundance and carried a more diverse range of pollen taxa than other moths. They had high among- and between-module connectivity in the network, indicating that they are playing an important pollen vector role. Bogong moths were also the only species to carry significant amounts of Eucalyptus pauciflora pollen, possibly suggesting the existence of a mutualistic relationship between two at-risk species.
Effect of elevation and plant communities on the flight behaviour of Lepidoptera in Kosciuszko National Park, Australia
Lepidoptera play a critical role in ecosystem functioning and are especially vital to the plant-pollinator network in alpine regions. Both their functional traits and broader environmental filters strongly influence their performance in the environment. This study aims to address the lack of research on the functional traits of Australian alpine diurnal Lepidoptera by examining whether their flapping rate differs across elevations and/or plant communities. Field surveys were conducted over four sites in Kosciuszko National Park, comprising heathland and woodland communities at both low and high elevations. Videos of Lepidoptera in flight were recorded and analysed to obtain flapping rates. The results indicate that elevation and plant community interacted to affect flapping rates. Within heathland communities Lepidopterans found at higher elevations exhibited a greater flapping rate than those found at lower elevations. On the other hand, there was no effect of elevation within woodland communities. These results correspond with existing literature, which indicate that elevation alone does not affect flapping rates. We suggest that differences in flapping rates between low and high elevation heathland sites may be driven by variation in food sources within heathland communities at different elevations, with resultant feeding habits imposing constraints on flight behaviour.
Australian subalpine soil invertebrate diversity and abundance under simulated drought
The impact of climate change, notably more frequent and extreme drought, on soil invertebrate communities essential to the survival of the Australian subalpine ecosystem, remains a relatively unexplored concept. Using samples collected from the AMRF FutureClim site near Mt Perisher, we studied how a simulated drought environment influences soil invertebrate community composition, diversity and abundance, to predict what may occur in Kosciuszko National Park’s near future. The significant decrease in overall abundance of soil invertebrates observed under drought conditions, coupled with variations in the composition of orders and feeding guilds suggests possible negative impacts of decreased moisture availability on these communities. Whilst only preliminary findings, this research is beneficial in raising awareness on how every aspect of the environment, whether as big as the trees or as small as the grains of soil, is a significant contributor toward the ecosystem’s survival.
Variations in Thermal Tolerance and Leaf Morphology in Alpine Ranunculus Species in Kosciuszko National Park
As global temperatures increase under climate change, understanding the thermal tolerance of plant species and how this relates to other functional traits is becoming increasingly important. I investigated thermal tolerance and leaf morphology in six interfertile alpine Ranunculus species that occur in water-inundated and terrestrial habitats in Kosciuszko National Park, Australia. I sought to identify whether thermal tolerance and leaf morphology differed between species and between habitats, and whether leaf morphological traits were correlated with measures of thermal tolerance. The critical minimum and maximum temperatures at which photosystem II in leaves becomes irreversibly damaged; Tcrit (cold) and Tcrit (hot), respectively, were measured using chlorophyll fluorimetry techniques to represent plant thermal tolerance, and thermal tolerance breadth (TTB) calculated. Functional traits affecting plant responses to temperature change and inundation, including leaf dissection, effective leaf width, leaf area, leaf mass per unit area (LMA) and leaf thickness, were also assessed. Species differed in thermal tolerance and all leaf morphology characteristics measured. Plants from inundated habitats had lower heat tolerance and TTB than plants from drier, not inundated habitats, and exhibited more dissected leaves with lower leaf width, area, LMA and leaf thickness. Thermal tolerance characteristics were weakly related to most morphological traits, however strong positive correlations between TTB and both LMA and leaf thickness emerged in my data. These results provide insight into the ability of alpine Ranunculus species to cope with future climate extremes and how leaf morphology may contribute to thermal tolerance. Avenues for future research into predictors of thermal tolerance and drivers of leaf morphology in inundated and terrestrial alpine habitats are also identified.
Microclimatic features of Carlia rubrigularis habitats, a study at Lake Eacham
This study looked at the habitats and behavioural characteristics of the leaf litter rainbow-skink (Carlia rubrigularis) at Lake Eacham within the Australian Wet Tropics. The Australian Wet Tropics bioregion contains both complex ecosystems and a diverse range of habitats, and is therefore conducive for studying functional ecology. Here, we aimed to characterise the microclimates of lizard habitats in the forest interior and at the forest edge. We measured two aspects of the lizard microclimates: the leaf litter on the surface of the forest floor, and the topsoil covered by the leaf litter. In the end, we found that leaf litter and topsoil temperatures are similar in the forest interior but are more different at the forest edge. Moreover, leaf litter temperature was found to be more variable in forest-edge habitats. Secondly, basking behaviours in C. rubrigularis were only observed when the leaf litter temperatures were higher than the topsoil covered by the leaf litter. Together, these findings may help guiding the design and parameterisation of more accurate habitat prediction models for C. rubrigularis as well as other more endangered skink species to facilitate conservation in the face of climate change.
Copyright (c) 2023 Field Studies in Ecology
Effect of drought on plant physiology, disease susceptibility and insect herbivory in rainforest saplings
Two rainforest canopy tree species were sampled as saplings in June of 2022 in a cross-sectional study to compare the effect of drought on physiological performance, insect herbivory and leaf disease damage. Throughfall infrastructure was utilised to simulate drought in field conditions. A strong effect of drought was found across all physiological measures, with drought being correlated with lower leaf chlorophyll content, stomatal conductance, and photosystem 2 efficiency. Plant health was assessed at the leaf-level using a 0-5 visual scale. No significant effect of drought on insect herbivory of disease damage was found, except for in Argyrodendron peralatum. Correlation of physiological performance and individual health assessments revealed several trends in susceptibility. Chlorophyll content was found to be more steeply correlated to insect damage severity in drought treatments than in control treatments, the effect of stomatal water conductance was investigated, and reduction in efficiency of photosystem 2 was correlated to higher severity of affliction. Mechanisms behind trends in susceptibility were investigated but the inference power of this study was limited by the cross-sectional nature. A longitudinal study tracking the progression of plant health metrics, physiological performance, and development was suggested for future research in conjunction with studies that analyse drought impact on invertebrate communities.
Do dieback-affected Eucalyptus pauciflora subsp. niphophila have fewer roots colonised by ectomycorrhizae than healthy trees?
Eucalyptus dieback is a severe phenomenon impacting the health of Eucalyptus pauciflora subsp. niphophila (snow gum) in Kosciuszko National Park. Ectomycorrhizal (ECM) colonies within the feeder roots of species such as E. pauciflora subsp. niphophila can greatly improve tree health in light of dieback stress. We investigated if there was greater ECM presence in healthy E. pauciflora subsp. niphophila than in those suffering from severe dieback. Feeder root samples were compared between healthy E. pauciflora subsp. niphophila stands in Perisher Valley and dieback-affected E. pauciflora subsp. niphophila stands 500 m from Perisher Valley. Across the sites, 42.92% of healthy feeder roots from 13 trees were colonised by ECM, compared to 32.77% of dieback-affected feeder roots in 13 trees. However, this difference was not statistically significant. Interestingly, a post hoc observation noted dieback trees had fewer available feeder roots. Although this study was unable to demonstrate if fewer available feeder roots were a cause or effect of dieback, it was unsurprising that fewer roots sustain trees in poorer health condition, such as those affected by dieback. These novel findings stress the need for further research into the causes of widespread dieback in E. pauciflora subsp. niphophila, including a microbiome study to classify ECM samples as a function of fungal diversity and a more robust analysis of root counts to better understand the dieback phenomena.
Variation in stem hydraulic capacitance in two Eucalyptus pauciflora subspecies across an elevational gradient
Vegetation dieback is a concerning environmental phenomenon whose frequency appears to be increasing globally. The rate of dieback has recently intensified throughout subalpine snow gum woodlands in Kosciuszko National Park for reasons that are not well understood. There is a lack of research focused on the changes in stand hydraulics across elevation and how this may influence snow-gum susceptibility to woodborer-associated dieback. This study examined the relationship between stem hydraulic capacitance and elevation in two subspecies of Eucalyptus pauciflora (Sieber ex Spreng.) which appear to be differentially affected by dieback: Eucalyptus pauciflora subspecies niphophila (Maiden and Blakely) and Eucalyptus pauciflora subspecies pauciflora (Sieber ex Spreng.). Stem hydraulic capacitance and saturated water content was measured in 100 trees, ten from each of ten sites evenly spaced across a 1,000m elevation gradient. Across subspecies, we observed a significant decrease in stem hydraulic capacitance with elevation. The response of stem hydraulic capacitance to elevational change was species-specific. Further research should focus on other drought traits across snow gum subspecies and elevation to create a broader understanding of stand hydraulics and other physiological traits influencing woodborer-associated dieback susceptibility.
Eucalyptus pauciflora subspecies niphophila
Eucalyptus pauciflora subspecies pauciflora
The effects of drought on the leaf-litter invertebrates of an Australian Wet Tropics ecosystem: the Daintree Rainforest
Climate change is impacting ecosystems worldwide, and tropical rainforests, in particular, are extremely vulnerable. Tropical rainforests are predicted to experience drought events with increasing frequency, duration and severity. Understanding how drought will impact these ecosystems is critical to management strategies. In particular, understanding how drought will impact tropical leaf-litter invertebrates will provide insight into broader impacts across the entire ecosystem. We investigated the impacts of drought on leaf-litter invertebrate abundance and diversity in the Daintree Rainforest of Far North Queensland, Australia. Additionally, we investigated the ways in which litter depth, soil moisture and substrate type impact leaf-litter invertebrate abundance. We found that neither number of functional groups nor number of orders was different in drought-treated sites compared to control sites, but that invertebrate abundance was significantly lower in drought-treated sites. We found that neither soil moisture nor litter depth had any significant effect on leaf-litter invertebrate abundance or diversity. Substrate type did not affect the number of functional groups or orders present, but we found significantly higher leaf-litter invertebrate abundance in sites with rock substrate, compared to soil substrates.
Preference and avoidance behaviour of Chrysomelid beetles using olfactory sensing of potential host-tree competitors
Chrysomelid beetles are a family of phytophagous insects which feed on nutritious young Eucalyptus leaves. Though they have been known to cause extensive damage to Eucalyptus crops, they are considered a charismatic native insect in Australia. Comparatively, the Steelblue sawfly (Perga affinis), more commonly known as “spitfires” are known to not only affect, but strip entire trees of their leaves, particularly in Eucalyptus crops. In Kosciuzsko National Park, NSW, we investigated the olfactory preferences of Chrysomelid beetles when presented with a variety of odours. We aimed to identify the attractance and avoidance behaviours of these beetles to their potential competitior, the Steelblue sawfly, using a Y-maze olfactometer. Results revealed a complex relationship between these herbivores and their host plant, whilst illuminating possible hijacking of P. affinis pheromones by Chrysomelid beetles in order to maximise their nutrition from foraging, both as adults and larvae. An increase in P. affinis population in the area could cause the Chrysomelid beetles to be outcompeted. By understanding the preference and avoidance behaviours of these beetles, we can better manage and maintain their populations into the future
The effect of elevation on the timing of the dawn chorus
Due to rising temperatures driven by climate change, the daily rhythms of the Australian Alps are undergoing profound shifts, impacting a diverse array of species and their behaviours. The ‘dawn chorus,’ a natural symphony where birds unite in melodic harmony in the early morning, is falling out of sync due to evolving environmental cues, notably temperature and light. This study addresses the question of whether the dawn chorus initiation time varies with elevation and explores the hypothesis that bird routines are tied to the availability of food resources. Our findings assessing the calls of the grey fantail, Ripidura albiscapa, derived from autonomous recordings at four sites along an elevational gradient and taking temperature into account, consistently reveal a delayed start to the dawn chorus at higher elevations, with an associated decrease in average temperature. These results not only illuminate the complex interplay between elevation, temperature and the dawn chorus, but also underscore the far-reaching implications of climate change on the delicate rhythms of nature.
Exposure to rainfall inhibits the reflectiveness of glossy buttercup petals
Ranunculus flower petals possess a multilayered structure that enhances the reflectance of ultraviolet (UV) and visible light. This study investigated how water interferes with the structural colouration in Ranunculus graniticola flowers, using spectrophotometry to compare the reflectance of petals exposed to dry versus wet weather conditions. Petals recently exposed to rainfall showed lower reflectance in the visible spectra and almost no UV reflectance; upon returning to dry conditions UV reflectance increased at a linear rate. During rainfall, water invades the air layer between the upper epidermis and the starch layer of the mesophyll, which restricts the scattering effect of the starch cells. The glossy surface of the petals was unchanged by exposure to water, indicating that the gloss is not the cause of the remarkably high UV reflectance seen in Ranunculus flowers. The significance of these results were discussed in relation to two prominent theories about the adaptive purpose of Ranunculus structural colouration.
The effects of Phoracantha-induced dieback on photosynthesis, respiration and estimated leaf nitrogen in Eucalyptus pauciflora
Eucalyptus pauciflora stands in Kosciuszko National Park are experiencing severe dieback events induced by Phoracantha beetles, threatening the habitat complexity of subalpine ecosystems. This study investigated the effects of Phoracantha-induced dieback on the maximum photosynthetic rate (Amax), average dark respiration (rdark) and nitrogen (N) concentration in E. pauciflora leaves, and the relations between Amax, rdark and estimated leaf N concentration. We collected leaf samples from a healthy stand in Charlotte Pass and a dieback-affected stand in Perisher and measured their rates of photosynthesis and dark respiration using a LI-COR 6400, and estimated leaf nitrogen using a SPAD. We found no difference in Amax and rdark between leaf categories, but epicormic leaves had significantly higher N content than healthy canopy leaves. In contrast to the literature, we found no correlation between Amax and N. Our findings suggest that E. pauciflora may exhibit a plastic response in photosynthetic rate to drought or dieback stress, but that dieback may damage vascular tissue, limiting dark respiration. The high nitrogen content in epicormic leaves does not have a corresponding increase in photosynthetic rate. These results suggest the effects of Phoracantha attack on the vascular system and source-sink flows within a tree.
Thermoregulatory behaviours and ecology of wolf spiders in the Australian alpine region
Research on temperature regulation in invertebrates has been limited, particularly in arachnids such as the alpine wolf spider Tasmanicosa musgravei. This study examined thermoregulatory activity in T. musgravei and whether this changed with temperature and spider size. The spatial distribution of this species and the relationship between burrow width and temperature/size were also explored. Spiders were filmed for at least one hour to determine frequency of thermoregulatory behaviours and compared to both temperature and size. Burrows and ground temperatures were also measured at different sites within Kosciusko National Park, Australia. From this data, there was no significant difference in the activity patterns at temperatures between 14-21°C nor with body mass. Body mass also had no significant effect on the spatial distribution of this species. Burrow dimensions were not affected by temperature but were significantly correlated with the size of the spider. This information may be useful in formulating management strategies for this species both currently and in response to changes in environment.
Copyright (c) 2021 Field Studies in Ecology
Photosynthetic capacity and water use efficiency of Argyrodendron peralatum leaves across a vertical gradient
A simple model of rainforest resource allocation is the Big Leaf Theory model. Rainforest ecosystems distribute resources to the canopy in order to maximise the benefits of increased irradiance exposure. Argyrodendron peralatum is an Australian tree species, endemic to Far North Queensland. Through analysis of photosynthetic capacity and stomatal capacity, which also allows analysis of water use efficiency, across understory, mid canopy, and top canopy levels, it was shown that A. peralatum follows the Big Leaf Theory model; performing these functions at higher rates at the top canopy level.
A preliminary investigation into the relationship between petiole and water-related traits in tropical flowering trees
Water deficit impacts photosynthetic productivity and whole plant energy budgets, and generally leads to stress and decreased growth. The petiole plays a key role in mitigating against water stress, as the petiole is the terminal region of water transport before the leaf. This study investigated the relationship between petiole traits, leaf traits and plant lifespan. We studied petiole and petiole xylem dimensions in 10 species of tropical rainforest tree species, and compared this to the relative growth rates (RGR) and leaf areas (LA) of those same species. First, we found that petiole volume accurately predicts potential petiole conduit hydraulic conductance (R2= 0.992; n= 7). Second, we found petiole volume and LA to be correlated across families (R2=0.859; n=48). Lastly, we found weak intra-family correlation between petiole volume and RGR, but this did not hold across families. Improved knowledge about the role of the petiole in water relations will inform future study into physiological responses to water stress. This is especially pertinent given the concerns about increasing drought conditions in the tropics under predicted climate change scenarios.
Thermostability of Rubisco and Rubisco activase in five tropical plant species
Rubisco activase (RCA) plays a regulatory role in photosynthetic function, by facilitating removal of inhibitors from the Rubisco active site. The RCA variants in most plant species thus far surveyed lose function between 35°C and 40°C, which is significantly lower than the putative thermostability of Rubisco itself. As such, RCA may be a ‘weak link’ in photosynthesis at moderate temperatures, and so may prove a fruitful target for crop fortification to improve crop yields. This study surveyed five tropical species chosen for their potential to possess highly thermostable RCA variants. We found one unusually thermostable RCA variant in the South American native Caesalpinia pulcherrima, and found two distinct RCA isoforms which exhibited differing thermostabilities. We also found that Rubisco was much less thermostable than previous literature suggests, becoming decreasingly functional in three of the five species studied between 25°C and 50°C. We suggest that these findings 1) provide support for RCA as a potential crop improvement target in a warming world, 2) suggest thermostable RCA variants may occur in a wide variety of locations and taxonomic groups, and 3) may have important implications for our understanding of temperature limitations to photosynthesis.
Plasticity in photosynthesis of bat laurel (Prunus polystachya) in tropical rainforest of Singapore
Rainforests are one of the most important habitats that contain an extraordinary amount of our global biodiversity. However, due to human disturbance we have lost a great portion of primary forests. Thankfully due to the rising awareness of the importance of rainforests, secondary rainforests are regenerating, providing a new environmental condition for different species as it is a much higher light environment than primary forests. Plants are then forced to adjust their traits in order to adapt to the new lighting conditions. This study investigates the plasticity in photosynthesis characteristics of Prunus polystachya, we predicted that understory leaves will have a higher chlorophyll content, higher overall carbon fixed during photosynthesis and higher photosynthetic induction. These predictions were made since understory leaves receive very little light, they rely heavily on sun flecks for photosynthesis, therefore they should have photosynthetic traits that will maximise all the sunlight they receive. We found that understory leaves do indeed have a higher chlorophyll density and carbon fix amount, but the hypothesis of understory leaves have a higher photosynthetic induction was not supported. The findings of this study could assist in determining how different species excel under different conditions, leading to the prediction of floristic composition of primary and secondary forests. In the field of conservation of forests, it will assist in predicting the species turnover rate between primary and secondary rainforests by having knowledge of which species will need protection and which we should focus on the regeneration of secondary forests.
The effects of environmental filtering on Kuhlia rupestris distribution in the Daintree rainforest region of the Australian Wet Tropics
The effects of flow velocity in freshwater streams on biodiversity are well documented and reveal a role as a potential environmental filter. For the Kuhlia rupestris, one of the most abundant fish in the Australian Wet Tropics Bioregion, understanding distribution is integral to anticipating the impacts that any change to the environment may have on the species’ diversity. Due to the linear relation between body size and top speed we expect to see high flow rates restricting the habitat of smaller K. rupestris. Through underwater visual censuses and flow rate measurements in two coastal streams it was found that smaller fish comprise a lesser proportion of the population in pools preceded by higher flow velocity. Similarly, smaller K. rupestris are restricted from the high flow microhabitats farther from the streambed. Changes to these aquatic environments may affect the distribution of K. rupestris and the resulting impact they have on the surrounding biome.
Metabolism and allometric scaling of the infraorder Acrididea, including four grasshopper species of the Australian Wet Tropics (suborder Caelifera)
The metabolic rate of various grasshopper species, in particular Valanga irregularis and Austacris guttulosa, collected from around the Daintree Rainforest Observatory, was measured. This was done to investigate the relationship between mass and metabolic rate in grasshoppers, and how closely it followed Kleiber’s law. The difference in metabolic rates between Valanga irregularis and Austacris guttulosa was also investigated. Grasshoppers are an abundant and important part of ecosystems. Additionally, Austacris guttulosa is a pest species, and information about its metabolism may be useful in controlling it. The metabolic efficiency of grasshoppers and their mass had a power relationship, but did not exactly follow the equation of Kleiber’s law. Austacris guttulosa had a significantly lower metabolic rate than Valanga irregularis.
Drivers of floristic composition in Bukit Timah Nature Reserve: an investigation of leaf functional traits
Forest fragmentation and associated edge effects can lead to considerable ecosystem degradation resulting in high mortality and loss of biodiversity. Bukit Timah Nature Reserve is a forest fragment that has been closely monitored for nearly 20 years. Though fragmentation is typically associated with negative consequences, Bukit Timah showed unexpected resilience to fragmentation effects. Interestingly, alterations in community structure were observed, though significant changes in stem density and basal area did not occur. The aim of this study was to explore the drivers of said compositional change, through examining four species of tropical rainforest trees. Two of these species are currently increasing in abundance (Shorea curtisii and Streblus elongatus) and two are decreasing in abundance (Gynotroches axillaris and Santiria apiculata). The study examined leaf mass per area, chlorophyll content, leaf thickness, and stomatal density. The results showed significant differences between species in trait values for all four functional traits, but no overarching trends to explain alteration in species composition were found. The results indicate that the four functional traits assessed are not critical in shaping community composition. Potential other drivers are explored, such as correlation with water transport systems. This is timely and important research in the face of dwindling primary forest in South-East Asia, and represents a global shift in priorities towards protecting ecological biodiversity.
Pollen thieves: Reproductive interference in Australian alpine angiosperm communities by invasive Taraxacum officinale
Flowering plants must vie with their peers to attract and reward animal pollinators in order to maximise the amount of conspecific pollen transferred to their ovules, and thus the number of their future offspring. When a flowering plant is introduced into a stable community, it can engage in reproductive interference by limiting the amount of conspecific pollen received by native plants, leading to potential shifts in native plant abundance and diversity. In the Australian Snowy Mountains, invasive Taraxacum officinale (L.) Weber ex F.H. Wigg has been found to be limiting pollen transferred to native species by competing for pollinators and creating a potential pollen cross-contamination risk. T. officinale pollen was found on 31% of pollinators carrying native pollen, and on a further 12% of pollinators exclusively. It was particularly attractive to Coleoptera, 75% of which were found to be carrying T. officinale pollen, putting native plants that rely on the order’s services at risk of pollen limitation. Furthermore, T. officinale produced proportionally more florets than any other native or invasive plant species across four transects. With climate change likely to boost abundance of the already formidable weed, more research into the scale of its impact on the vulnerable Australian alpine flora communities is needed.
Jump distance of Monistria concinna in relation to metabolic rate and femur length:mass ratio
Monistria concinna is an abundant grasshopper species from Kosciuszko National Park (KNP). Monistria concinna’s performance levels can be influenced by both morphology and physiology, which can in turn influence KNP’s ecosystem. We studied the effects of femur length:mass ratio (morphology) and metabolic rate (physiology) of M. concinna on jump distances. Jump distance was used as a proxy for performance levels, and there were two treatments used to compare temperatures – ambient temperature and cold temperature. Femur length:mass ratio was not correlated with jump performance, irrespective of temperature. However, the difference in the metabolic rate of the grasshoppers in these treatments approached statistical significance, and grasshoppers in the ambient temperature treatment jumped further than in the cold treatment. Sexual dimorphism was observed. Males had greater femur length:mass ratios and higher mass-specific jumping abilities, but males and females had equivalent jumping abilities. At the time of the experiment, there had been no previous studies on the factors which affect jump distance in M. concinna, though our results indicate that M. concinna may perform better in warming climates.
Copyright (c) 2019 Field Studies in Ecology https://creativecommons.org/licenses/by-nc-nd/3.0/au/
The effect of UV light intensity on anthocyanin content of Richea continentis leaves
The aim of this study was to determine the effect of UV light intensity on anthocyanin content in Richea continentis leaves. Anthocyanins play an important role in protecting plants from environmental stresses such as high UV exposure and freezing temperatures. This study was conducted because in the context of climate change it is important to understand how increased UV exposure will affect alpine plants. It was hypothesised that anthocyanin content in R. continentis leaves would increase as UV light intensity increases. Three samples of R. continentis were collected from each of four different elevations at Charlotte Pass, NSW, and UV light intensity at these sites was recorded. The leaves’ anthocyanin content was determined using thin layer chromatography and chlorophyll fluorescence (Fv/Fm) was measured as an indicator of leaf stress using a Plant Efficiency Analyser. There was a significant positive correlation between UV light intensity and anthocyanin content, and a significant negative correlation between Fv/Fm and anthocyanin content. No significant correlation was found between light intensity and Fv/Fm, suggesting that anthocyanins act to reduce UV damage in R. continentis leaves.
Morphological and physiological determinants of performance and associations to thermoregulatory preferences in an alpine skink, Eulamprus kosciuskoi
Performance is dependent on a combination of morphological and physiological features in the context of present environmental factors. Sprint speed is important in the fitness of many animals and is used to represent performance. This study explored the effects of temperature and features of body condition on performance of an Australian alpine skink, Eulamprus kosciuskoi, along with reproductive costs, using sprint speed to represent performance. Further, the effect of size on preferred body temperature was analysed to investigate the determinants of behavioural thermoregulatory responses that are associated with performance. A sample of 21 lizards consisting of juveniles, males and gravid and non-gravid females were caught in December in the Kosciuszko National Park, Australia. Lizards were raced at cold and hot temperature treatments, temperature preference tests were conducted and morphological features measured. Performance was significantly greater at higher temperature and correlated positively with body mass but not with relative tail length. Gravidity incurred no significant performance cost, and no significant correlation was found between preferred body temperature and size. Understanding the determinants of performance, along with temperature regulation effects, has conservation implications in the context of rising temperatures associated with climate change.