@article {bnh-7484, title = {Plasticity of leaf respiratory and photosynthetic traits in Eucalyptus grandis and E. regnans grown under variable light and nitrogen availability}, journal = {Frontiers in Forests and Global Change}, year = {2020}, month = {02/2020}, abstract = {

Plant growth strategies are adapted to resource availability in native habitat(s), and thus reflected in traits such as photosynthetic and respiratory capacities of leaves. We explored acclimation of such traits to contrasting light and nitrogen supply for Flooded Gum (Eucalyptus grandis) and Mountain Ash (E. regnans) saplings growing under warm-temperate conditions. We focused on respiration parameters that are not routinely measured, but could expand our mechanistic understanding of trait correlation networks [interdependencies between leaf mass per area (LMA), foliar nitrogen concentration (Nmass), photosynthetic capacity (mass- based Amax) and respiration (R)]. We measured temperature responses of leaf R via calorimetric methods, in order to derive three respiration parameters that are useful to characterize capacity and flux mode of respiratory oxygen reduction in mature source leaves and young sink leaves. Subtropical\ E. grandis\ saplings produced 3-fold more biomass than\ E. regnans, and responded more strongly to enhanced supplies of nitrogen, in particular under semi-shade conditions. Acclimation of LMA to growth irradiance was more plastic in\ E. grandis, but light treatment had no effect on Nmass\ and mass-based Amax\ in this species. In\ E. regnans, growth under abundant nitrogen and full sunlight caused significant increases in foliar Nmass{\textendash}albeit not matched by relatively modest increases in mass-based Amax. Cool-temperate\ E. regnans\ saplings appeared to allocate a substantial share of leaf-N to protective functions upon exposure to full sunlight. Foliar nitrogen was used more effectively for the production of new foliage in\ E. grandis, owing to better coordination with foliar capacity and flux mode of mitochondrial oxygen reduction. Most of the variation in three respiration parameters can be explained by a few physiological/anatomical variables, responding to variation in absolute and relative demand for ATP, reducing power and anabolic intermediates. These demands strongly depended on leaf developmental stage and also varied between species and treatments. Our approach opens a path to improved process- based understanding of respiratory flux control, which could facilitate predictions of plant respiration in a changing environment.

}, keywords = {Eucalyptus forest, forest}, doi = { https://doi.org/10.3389/ffgc.2020.00005}, url = {https://www.frontiersin.org/articles/10.3389/ffgc.2020.00005/full}, author = {Jorg Kruse and Turnbull, Tarryn L. and Heinz Rennenberg and Adams, Mark A.} } @article {bnh-6321, title = {Geographic Patterns of Fire Severity Following an Extreme Eucalyptus Forest Fire in Southern Australia: 2013 Forcett-Dunalley Fire }, journal = {Fire}, volume = {1}, year = {2018}, month = {10/2018}, abstract = {

Fire severity is an important characteristic of fire regimes; however, global assessments of fire regimes typically focus more on fire frequency and burnt area. Our objective in this case study is to use multiple lines of evidence to understand fire severity and intensity patterns and their environmental correlates in the extreme 2013 Forcett-Dunalley fire in southeast Tasmania, Australia. We use maximum likelihood classification of aerial photography, and fire behavior equations, to report on fire severity and intensity patterns, and compare the performance of multiple thresholds of the normalised burn ratio (dNBR) and normalized difference vegetation index (dNDVI) (from pre- and post-fire Landsat 7 images) against classified aerial photography. We investigate how vegetation, topography, and fire weather, and therefore intensity, influenced fire severity patterns. According to the aerial photographic classification, the fire burnt 25,950 ha of which 5\% burnt at low severities, 17\% at medium severity, 32\% at high severity, 23\% at very high severities, while 22\% contained unburnt patches. Generalized linear modelling revealed that fire severity was strongly influenced by slope angle, aspect, and interactions between vegetation type and fire weather (FFDI) ranging from moderate (12) to catastrophic (\>100). Extreme fire weather, which occurred in 2\% of the total fire duration of the fire (16 days), caused the fire to burn nearly half (46\%) of the total area of the fireground and resulted in modelled extreme fireline intensities among all vegetation types, including an inferred peak of 68,000 kW{\textperiodcentered}m-1 in dry forest. The best satellite-based severity map was the site-specific dNBR (45\% congruence with aerial photography) showing dNBR potential in Eucalyptus forests, but the reliability of this approach must be assessed using aerial photography, and/or ground assessment.

}, keywords = {aerial photography, Eucalyptus forest, fire intensity, fire severity mapping, generalized linear modelling, geospatial validation, normalized burn ratio, Tasmania}, doi = {https://doi.org/10.3390/fire1030040}, url = {https://www.mdpi.com/2571-6255/1/3/40}, author = {Mercy Ndalila and Grant Williamson and David Bowman} } @article {BF-4289, title = {Testing existing models for predicting hourly variation in fine fuel moisture in eucalypt forests}, journal = {Forest Ecology and Management}, volume = {306}, year = {2013}, month = {10/2013}, pages = {202-215}, chapter = {202}, abstract = {Several days of hourly fuel moisture sampling were carried out in Southern Tasmania in dry and damp eucalyptus forest to test fuel moisture prediction models used in Australia, and to provide information on equilibrium moisture content and response time for use in more complex models. Moisture contents of near surface, surface, profile litter and bark fuels were measured, along with standard weather variables. On one set of four consecutive days fuel temperatures were also measured with thermocouples. One of the simple empirical fuel moisture prediction models worked well on the litter fuels for which it was intended, but another of the simple models in common use, predicted poorly, particularly on the damp site. One of the simple models was modified, and gave acceptable predictions for profile litter. Another simple model was calibrated to give good predictions for near surface, bark and litter fuels in the middle of the day. A more physically-based {\textquoteleft}bookkeeping{\textquoteright} model for estimating response time and EMC worked very well on all strata but the litter profile. Response times of all fuel strata were of the order of 1 h. A process based model worked slightly better than the EMC estimation model for near surface, litter and bark fuel and considerably better for profile litter, especially on the damp site. On the whole these models performed better than the simple empirical models, but they were tuned to various degrees by site information.}, keywords = {Bookkeeping model, Eucalyptus forest, Fine fuel moisture, Process-based model}, doi = {http://dx.doi.org/10.1016/j.foreco.2013.06.033}, url = {http://www.sciencedirect.com/science/article/pii/S0378112713004015}, author = {Slijepcevic, A. and Wendy R. Anderson and Stuart Matthews} }