School of Ecosystem and Forest Sciences - Research Publications

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 11
  • Item
    No Preview Available
    The role of climatic variability on Eucalyptus regeneration in southeastern Australia
    Singh, A ; Baker, PJ ; Kasel, S ; Trouve, R ; Stewart, SB ; Nitschke, CR (ELSEVIER, 2021-12-01)
  • Item
  • Item
    Thumbnail Image
    Papua at the Crossroads: A Plea for Systematic Conservation Planning in One of the Largest Remaining Areas of Tropical Rainforest
    Parsch, C ; Wagner, B ; Pangau-Adam, M ; Nitschke, C ; Kreft, H ; Schrader, J (FRONTIERS MEDIA SA, 2022-02-11)
    Land-use change has progressed rapidly throughout the Indonesian archipelago and is now intruding into western New Guinea (Tanah Papua), one of the world’s last wilderness areas with extensive tracts of pristine and highly diverse tropical rainforests. Tanah Papua has reached a crossroads between accelerating environmental degradation and sustainable development policies entailing landscape-scale conservation targets, pledged in the Manokwari Declaration. We assessed the representation of ecoregions and elevational zones within Tanah Papua’s protected area network to identify its shortcomings at broad spatial scales. Lowland ecoregions are less protected than mountainous regions, with half of the western and southern lowlands designated for land-use concessions. Under the direct threat from land-use change, the political motivation in Tanah Papua toward conservation- and culture-centered land management provides a window of opportunity for scientifically guided, proactive conservation planning that integrates sustainable development for the benefit of Indigenous communities.
  • Item
    Thumbnail Image
    Predicting plant species distributions using climate-based model ensembles with corresponding measures of congruence and uncertainty
    Stewart, SB ; Fedrigo, M ; Kasel, S ; Roxburgh, SH ; Choden, K ; Tenzin, K ; Allen, K ; Nitschke, CR ; Jarvis, S ; Jarvis, S (WILEY, 2022-03-17)
    Aim The increasing availability of regional and global climate data presents an opportunity to build better ecological models; however, it is not always clear which climate dataset is most appropriate. The aim of this study was to better understand the impacts that alternative climate datasets have on the modelled distribution of plant species, and to develop systematic approaches to enhancing their use in species distribution models (SDMs). Location Victoria, southeast Australia and the Himalayan Kingdom of Bhutan. Methods We compared the statistical performance of SDMs for 38 plant species in Victoria and 12 plant species in Bhutan with multiple algorithms using globally and regionally calibrated climate datasets. Individual models were compared against one another and as SDM ensembles to explore the potential for alternative predictions to improve statistical performance. We develop two new spatially continuous metrics that support the interpretation of ensemble predictions by characterizing the per-pixel congruence and variability of contributing models. Results There was no clear consensus on which climate dataset performed best across all species in either study region. On average, multi-model ensembles (across the same species with different climate data) increased AUC/TSS/Kappa/OA by up to 0.02/0.03/0.03/0.02 in Victoria and 0.06/0.11/0.11/0.05 in Bhutan. Ensembles performed better than most single models in both Victoria (AUC = 85%; TSS = 68%) and Bhutan (AUC = 86%; TSS = 69%). SDM ensembles using models fitted with alternative algorithms and/or climate datasets each provided a significant improvement over single model runs. Main conclusions Our results demonstrate that SDM ensembles, built using alternative models of the same climate variables, can quantify model congruence and identify regions of the highest uncertainty while mitigating the risk of erroneous predictions. Algorithm selection is known to be a large source of error for SDMs, and our results demonstrate that climate dataset selection can be a comparably significant source of uncertainty.
  • Item
    Thumbnail Image
    Mapping canopy nitrogen-scapes to assess foraging habitat for a vulnerable arboreal folivore in mixed-species Eucalyptus forests
    Wagner, B ; Baker, PJ ; Moore, BD ; Nitschke, CR (WILEY, 2021-12-16)
    Herbivore foraging decisions are closely related to plant nutritional quality. For arboreal folivores with specialized diets, such as the vulnerable greater glider (Petauroides volans), the abundance of suitable forage trees can influence habitat suitability and species occurrence. The ability to model and map foliar nitrogen would therefore enhance our understanding of folivore habitat use at finer scales. We tested whether high-resolution multispectral imagery, collected by a lightweight and low-cost commercial unoccupied aerial vehicle (UAV), could be used to predict total and digestible foliar nitrogen (N and digN) at the tree canopy level and forest stand-scale from leaf-scale chemistry measurements across a gradient of mixed-species Eucalyptus forests in southeastern Australia. We surveyed temperate Eucalyptus forests across an elevational and topographic gradient from sea level to high elevation (50-1200 m a.s.l.) for forest structure, leaf chemistry, and greater glider occurrence. Using measures of multispectral leaf reflectance and spectral indices, we estimated N and digN and mapped N and favorable feeding habitat using machine learning algorithms. Our surveys covered 17 Eucalyptus species ranging in foliar N from 0.63% to 1.92% dry matter (DM) and digN from 0.45% to 1.73% DM. Both multispectral leaf reflectance and spectral indices were strong predictors for N and digN in model cross-validation. At the tree level, 79% of variability between observed and predicted measures of nitrogen was explained. A spatial supervised classification model correctly identified 80% of canopy pixels associated with high N concentrations (≥1% DM). We developed a successful method for estimating foliar nitrogen of a range of temperate Eucalyptus species using UAV multispectral imagery at the tree canopy level and stand scale. The ability to spatially quantify feeding habitat using UAV imagery allows remote assessments of greater glider habitat at a scale relevant to support ground surveys, management, and conservation for the vulnerable greater glider across southeastern Australia.
  • Item
    Thumbnail Image
    Structural diversity underpins carbon storage in Australian temperate forests
    Aponte, C ; Kasel, S ; Nitschke, CR ; Tanase, MA ; Vickers, H ; Parker, L ; Fedrigo, M ; Kohout, M ; Ruiz-Benito, P ; Zavala, MA ; Bennett, LT ; Hickler, T (WILEY, 2020-02-11)
  • Item
    Thumbnail Image
    Climate extreme variables generated using monthly time-series data improve predicted distributions of plant species
    Stewart, SB ; Elith, J ; Fedrigo, M ; Kasel, S ; Roxburgh, SH ; Bennett, LT ; Chick, M ; Fairman, T ; Leonard, S ; Kohout, M ; Cripps, JK ; Durkin, L ; Nitschke, CR (WILEY, 2021-02-02)
  • Item
    Thumbnail Image
    Climate Change Drives Habitat Contraction of a Nocturnal Arboreal Marsupial at Its Physiological Limits
    Wagner, B ; Baker, PJ ; Stewart, SB ; Lumsden, LF ; Nelson, JL ; Cripps, JK ; Durkin, LK ; Scroggie, MP ; Nitschke, CR (Wiley, 2021-01)
  • Item
    Thumbnail Image
    The Influence of Atmosphere-Ocean Phenomenon on Water Availability Across Temperate Australia
    Khaledi, J ; Nitschke, C ; Lane, PNJ ; Penman, T ; Nyman, P (AMER GEOPHYSICAL UNION, 2022-01-01)
  • Item
    Thumbnail Image
    Climate change drives habitat contraction of a nocturnal arboreal marsupial at its physiological limits
    Wagner, B ; Baker, PJ ; Stewart, SB ; Lumsden, LF ; Nelson, JL ; Cripps, JK ; Durkin, LK ; Scroggie, MP ; Nitschke, CR (WILEY, 2020-10-01)
    Increasing impacts of climatic change and anthropogenic disturbances on natural ecosystems are leading to population declines or extinctions of many species worldwide. In Australia, recent climatic change has caused population declines in some native fauna. The projected increase in mean annual temperature by up to 4°C by the end of the 21st century is expected to exacerbate these trends. The greater glider (Petauroides volans), Australia’s largest gliding marsupial, is widely distributed along the eastern coast, but has recently experienced drastic declines in population numbers. Its association with hollow‐bearing trees, used for nesting, has made it an important species for the conservation of old‐growth forest ecosystems. Fires and timber harvesting have been identified as threats to the species. Greater gliders have disappeared however from areas that have experienced neither raising questions about the role of other factors in their decline. A unique physiology and strict Eucalyptus diet make them vulnerable to high temperatures and low water availability. As such, climatic conditions may drive habitat selection and recent climatic trends may be contributing to observed population declines. Using presence:absence data from across its distribution in Victoria, coupled with high spatial and temporal resolution climatic data and machine‐learning modeling, we tested the influence of climatic, topographic, edaphic, biotic, and disturbance variables on greater glider occupancy and habitat suitability. We found that climatic variables, particularly those related to aridity and extreme weather conditions, such as number of nights warmer than 20°C, were highly significant predictors of greater glider occurrence. Climatic conditions associated with habitat suitability have changed over time, with increasing aridity across much of its southeastern distribution. These changes in climate are closely aligned with observed population declines across this region. At higher elevation, some areas where the greater glider is observed at high densities, conditions have become wetter, which is improving habitat quality. These areas are of growing significance to greater glider conservation as they will become increasingly important as climatic refugia in the coming decades. Protecting these areas of habitat will be critical for facilitating the conservation of greater gliders as the broader landscape becomes less hospitable under future climatic change.