Ant-Seed Interaction in Dry Sclerophyll Forest on North Stradbroke Island, Queensland

Summary Occurrence and nest site use by pygmy possums were investigated in dry and wet sclerophyll forest in Tasmania. There were four silvicultural treatments in the dry sclerophyll forest (a clearfelled coupe with 17-year-old regrowth, two partially logged coupes and old-growth forest) and four in the wet sclerophyll forest (4- and 20-year-old regrowth resulting from clearfelling, 80-year-old natural regrowth and old-growth forest). Cercartetus lepidus was captured in all ages of regrowth and in both partially logged and old-growth forest. C. nanus was captured only in 20- and 80-year-old regrowth in wet sclerophyll forest. Partially decayed logs were important nest sites for C. lepidus. Fissures in live trees associated with fire scars and hollows in stumps were also used as nests. All three nests of C. nanus were located in stumps. The amount of suitable nesting substrate did not appear to be a factor limiting populations in either the dry or wet sclerophyll forest.

Seed Dispersal of a Neotropical Myrmecochore: Variation in Removal Rates and Dispersal Distance

Question: Are long-unburnt patches of eucalypt forest important for maintaining floristic diversity? Location: Eucalyptus forests of southeastern New South Wales, Australia. Methods: Data from 976 sites representing a range of fire history from three major vegetation formations – shrubby dry sclerophyll forest (SF), grassy dry SF and wet SF – were analysed. Generalized linear models were used to examine changes in species richness with increasing time since wildfire and analysis of similarities to examine changes in community composition. Chi-squared tests were conducted to examine the distribution of individual species across four time since fire categories. Results: Plant species relationships to fire varied between the three formations. Shrubby dry SF supported lower plant species richness with increasing time since wildfire and this was associated with shifts in community composition. Grassy dry SF showed significant shifts in community composition and species richness in relation to time, with a peak in plant species richness 20–30 yr post fire (either prescribed fire or wildfire). Wet SF increased in species richness until 10–20 yr post wildfire then displayed a general declining trend. Species richness in each vegetation type was not related to the fire frequencies and fire intervals observed in this study. Conclusions: Long-unburnt (30–50 yr post wildfire) forests appeared to play a minor role in the maintenance of plant species diversity in dry forest systems, although this was more significant in wet forests. Maintenance of a range of fire ages within each vegetation formation will assist in maintaining floristic diversity within regions.

The establishment of sustainable, low-intensity fire regimes is a pressing global challenge given escalating risk of wildfire driven by climate change. Globally, colonialism and industrialisation have disrupted traditional fire management, such as Indigenous patch burning and silvo-pastoral practices, leading to substantial build-up of fuel and increased fire risk. The disruption of fire regimes in southeastern Tasmania has led to dense even-aged regrowth in wet forests that are prone to crown fires, and dense Allocasuarina-dominated understoreys in dry forests that burn at high intensities.Here, we investigated the effectiveness of several fire management interventions at reducing fire risk. These interventions involved prescribed burning or mechanical understorey removal techniques. We focused on wet and dry Eucalyptus-dominated sclerophyll forests on the slopes of kunanyi/Mt. Wellington in Hobart, Tasmania, Australia. We modelled potential fire behaviour in these treated wet and dry forests using fire behaviour equations based on measurements of fuel load, vegetation structure, understorey microclimate and regional meteorological data.We found that (a) fuel treatments were effective in wet and dry forests in reducing fuel load, though each targeted different layers, (b) both mechanical treatments and prescribed burning resulted in slightly drier, and hence more fire prone understorey microclimate, and (c) all treatments reduced predicted subsequent fire severity by roughly 2–4 fold. Our results highlight the importance of reducing fuel loads, even though fuel treatments make forest microclimates drier, and hence fuel more flammable.Our finding of the effectiveness of mechanical treatments in lowering fire risk enables managers to reduce fuels without the risk of uncontrolled fires and smoke pollution that is associated with prescribed burning. Understanding the economic and ecological costs and benefits of mechanic treatment compared to prescribed burning requires further research.

Summary Mineralisation of nitrogen (N) was measured during a 60 day laboratory incubation of soils from 4 eucalypt forest sites on the south coast of NSW. While Eucalyptus maculata Hook. was a common component of the overstorey, the sites ranged from dry sclerophyll lower productivity forest to wet sclerophyll higher productivity forest. In undisturbed soils, N mineralisation increased linearly with total soil N content, the range in total N resulting from different depths sampled. Undisturbed soils mineralised N at rates ranging from 6.0 (dry sclerophyll forest) to 26.2 kg/ha.month (wet sclerophyll forest), with all depths contributing significantly. Greater mineralisation in soil from the wet sclerophyll site reflects both the greater N capital in the soil and greater mineralisation per unit of soil N. Nitrification rates varied from negligible (1.5% after 60 days) in dry sclerophyll forest, to slight (16%) in intermediate sclerophyll forest, to strong (61%) in wet sclerophyll forest. Soil disturbance had little effect on N mineralisation rates, but heating designed to simulate temperatures under hot regeneration burns released 7–11 kg/ha of NH4-N immediately, and increased mineralisation rates 2 to 6-fold over a 60 day period. Heating reduced nitrification rates, despite the opportunity for nitrifying populations to recover during the long incubation. There was a negative linear relationship between N mineralisation and the C/N ratio of the sample in disturbed plus heated soils, but no significant relationship in undisturbed soils. In forest soils where the C/N ratio is usually very wide (typically 20–30), the ratio appears unlikely to be a useful index of the small pools of more labile organic N. The results are discussed in relation to the patterns of regeneration following clearfelling of mature mixed species forest containing Eucalyptus maculata on the south coast of NSW.

The distribution of Phytophthora cinnamomi in victoria

Rainforest bird communities threatened by extreme fire

The flammability of plant leaves influences the spread of fire through vegetation. Exotic plants invading native vegetation may increase the spread of bushfires if their leaves are more flammable than native leaves. We compared fresh-leaf and dry-leaf flammability (time to ignition) between 52 native and 27 exotic plant species inhabiting dry sclerophyll forest. We found that mean time to ignition was significantly faster in dry exotic leaves than in dry native leaves. There was no significant native-exotic difference in mean time to ignition for fresh leaves. The significantly higher fresh-leaf water content that was found in exotics, lost in the conversion from a fresh to dry state, suggests that leaf water provides an important buffering effect that leads to equivalent mean time to ignition in fresh exotic and native leaves. Exotic leaves were also significantly wider, longer and broader in area with significantly higher specific leaf area–but not thicker–than native leaves. We examined scaling relationships between leaf flammability and leaf size (leaf width, length, area, specific leaf area and thickness). While exotics occupied the comparatively larger and more flammable end of the leaf size-flammability spectrum in general, leaf flammability was significantly correlated with all measures of leaf size except leaf thickness in both native and exotic species such that larger leaves were faster to ignite. Our findings for increased flammability linked with larger leaf size in exotics demonstrate that exotic plant species have the potential to increase the spread of bushfires in dry sclerophyll forest.

Leaf-litter thrips were much more common and diverse in dry sclerophyll forest than in wetter forest types in subtropical southeast Queensland, Australia. In dry sclerophyll forest, the species composition of thrips in leaf-litter was strongly differentiated from the thrips fauna associated with bark of the trees Eucalyptus major and Acacia melanoxylon (4 of 34 species in common). The species composition of bark-dwelling thrips was similar across the two tree species and also across two eucalypts with different bark types, Eucalyptus major (flaky) and Eucalyptus siderophloia (rough). The diversity of thrips from the leaf-litter was not differentiated across all of these tree species. Virtually all thrips collected were Phlaeothripidae, subfamilies Idolothripinae and Phlaeothripinae. Idolothripinae were associated almost exclusively with leaf-litter, but Phlaeothripinae were in leaf-litter and bark. The association of fungal-feeding thrips with dry sclerophyll forest raises questions about their ecological requirements and the role they play in nutrient cycling.

Analysis of sampling methods for coarse woody debris

The birds of retained vegetation corridors: A pre- and post-logging comparison in dry sclerophyll forest in Tasmania

Above‐ground biomass and its nutrient content were measured in a 15.5 year old rehabilitated bauxite mine in the jarrah forest of southwest Australia. The litterfall and its nutrient content was also measured on the same site, 4–6 years and 8–10 years after rehabilitation. The total mass of the vegetation and litter was 103t ha−1, 25% of that in a nearby jarrah forest. The mass of the trees was 58t ha−1, approximately 22% of that in the jarrah forest. The amount of nitrogen in the soil, in the litter and in the understorey, and in the total system, exceeded that in the nearby jarrah forest. Annual litterfall in the rehabilitated area was comparable to that measured in the jarrah forest and other dry sclerophyll forests. The nitrogen content of the litterfall in the rehabilitated area was around three to four times that in other dry sclerophyll forests.

Aspects of the ecology of Rattus lutreolus velutinus (Thomas) were studied in dry sclerophyll forest, buttongrass and heathland communities in north-eastern Tasmania. In each habitat environmental parameters which might influence the species' microhabitat selection (e.g, soil moisture, vegetation structure and floristics) and diet (e.g. monocotyledon food), were assessed. R. I, velutinus began to breed during late August. Sexually active males were captured between September and February, inclusive. Pregnant females were captured between September and November, and the number of lactating females peaked during November in all habitats. Juveniles were captured between December and February. R. I. velutinus was predominantly herbivorous, preferring stem and leaf tissue but also eating seeds, insects, roots and fungus. Captures of rats were positively correlated with vegetation cover less than 50 cm high and with a monocotyledonous food index. Population density was substantially higher in heathland than in buttongrass and dry sclerophyll forest. Animals had similar body condition in each habitat.

Tawny frogmouth (Podargus strigoides) nests were surveyed in grassy woodland, dry sclerophyll forest and suburbia in the Australian Capital Territory. In total, 253 tawny frogmouth nests were recorded in 145 nest sites. Nests were oriented to the north-east, which would expose them to morning sunshine and partially shelter them from the prevailing wind. Most nests were placed in rough or flaky-barked tree species, on open mid-branch sites with no foliage, where the birds’ plumage and posture resemble the colour and form of the branches. Although smooth-barked gum trees were the most abundant types in the dry sclerophyll forest they were seldom used. Nest sites in all habitats were similar; the mean nest height was 9.2 m, and most nests were set on forks in the lowest branches. By placing their nests in these positions tawny frogmouths likely maximise their potential thermoregulation, protection from wind, concealment from predators, and detection of approaching predators.

In recent years, Unoccupied Aircraft Systems (UAS) have been used to capture information on forest structure in unprecedented detail. Pioneering studies in this field have shown that high spatial resolution images and Light Detecting And Ranging (LiDAR) data captured from these platforms provide detailed information describing the dominant tree elements of canopy cover and biomass. However, to date, few studies have investigated the arrangement of vegetation elements that contribute directly to fire propagation in UAS LiDAR point clouds; that is the surface, near-surface, elevated and intermediate-canopy vegetation. This paper begins to address this gap in the literature by exploring the use of image-based and LiDAR 3D representations collected using UAS platforms, for describing forest structure properties. Airborne and terrestrial 3D datasets were captured in a dry sclerophyll forest in south-eastern Australia. Results indicate that UAS LiDAR point clouds contain information that can describe fuel properties in all strata. Similar estimates of canopy cover (TLS: 68.27% and UAS LiDAR: 64.20%) and sub-canopy cover (Elevated cover TLS: 44.94%, UAS LiDAR: 32.27%, combined surface and near-surface cover TLS: 96.10% UAS LiDAR: 93.56%) to TLS were achieved using this technology. It was also shown that the UAS SfM photogrammetric technique significantly under performed in the representation of the canopy and below canopy structure (canopy cover - 20.31%, elevated cover 10.09%). This caused errors to be propagated in the estimate of heights in the elevated fuel layer (TLS: 0.51 m, UAS LiDAR: 0.34 m, UAS SfM: 0.15 m). A method for classifying fuel hazard layers is also presented which identifies vegetation connectivity. These results indicate that information describing the below canopy vertical structure is present within the UAS LiDAR point clouds and can be exploited through this novel classification approach for fire hazard assessment. For fire prone countries, this type of information can provide important insight into forest fuels and the potential fire behaviour and impact of fire under different scenarios.