Effects of Coarse Woody Debris on Soil Temperature and Water Content in Two Reconstructed Soils in Reclaimed Boreal Forest

Coarse woody debris (CWD) and cover soils are used to expedite ecological processes in reclaimed boreal forests after oil sands mining. Soil water content and soil temperature are considered key factors for revegetation during mine reclamation as they impact soil surface and atmosphere interactions and plant growth. However, the effects of CWD and cover soils on soil water content and temperature are not well studied. This study assessed the impact of CWD size (large, small) and type (spruce: Picea mariana, aspen: Populus tremuloides) on soil water content and temperature in two soils constructed with forest floor-mineral mix (FMM) and peat-mineral mix (PMM)) at oil sands reclamation sites. Annual and summer precipitation showed year-to-year variability; mean air temperature did not. Soil cover type had a greater impact on moderating soil water content than CWD, with PMM having a stronger influence on water content and temperature than FMM. Adding CWD increased soil water content more in FMM than PMM, and the effect on soil temperature was mostly observed during the summer months. In PMM, spruce small CWD was associated with greater water content, whereas there was no distinct differentiation between CWD size and type in FFM. This study suggests application of CWD in FMM would be more beneficial than in PMM for reclamation.

Abiotic and biotic responses to woody debris additions in restored old fields in a multi-site Before-After-Control-Impact experiment

Ecological restoration of former agricultural land can improve soil conditions, recover native vegetation, and provide fauna habitat. However, restoration benefits are often associated with time lags, as many attributes, such as leaf litter and coarse woody debris, need time to accumulate. Here, we experimentally tested whether adding mulch and logs to restoration sites in semi-arid Western Australia can accelerate restoration benefits. All sites had been cropped and then planted with native trees and shrubs (i.e., Eucalyptus, Melaleuca, and Acacia spp.) 10 years prior to our experiment, to re-establish the original temperate eucalypt woodland vegetation community. We used a Multi-site Before-After-Control-Impact (MBACI) design to test the effects on 30 abiotic and biotic response variables over a period of 2 years. Of the 30 response variables, a significant effect was found for just four variables: volumetric water content, decomposition, native herbaceous species cover and species richness of disturbance specialist ants. Mulch addition had a positive effect on soil moisture when compared to controls but suppressed growth of native (but not exotic) herbaceous plants. On plots with log additions, decomposition rates decreased, and species richness of disturbance specialist ants increased. However, we found no effect on total species richness and abundance of other ant species groups. The benefit of mulch to soil moisture was offset by its disbenefit to native herbs in our study. Given time, logs may also provide habitat for ant species that prefer concealed habitats. Indeed, benefits to other soil biophysical properties, vegetation, and ant fauna may require longer time frames to be detected. Further research is needed to determine whether the type, quantity, and context of mulch and log additions may improve their utility for old field restoration and whether effects on native herbs are correlated with idiosyncratic climatic conditions.

Altered fire regimes modify lizard communities in globally endangered Araucaria forests of the southern Andes

Wildfire regimes are being altered in ecosystems worldwide. The density of reptiles responds to fires and changes to habitat structure. Some of the most vulnerable ecosystems to human-increased fire frequency are old-growth Araucaria araucana forests of the southern Andes. We investigated the effects of wildfires on the density and richness of a lizard community in these ecosystems, considering fire frequency and elapsed time since last fire. During the 2018/2019 southern summer season, we conducted 71 distance sampling transects to detect lizards in Araucaria forests of Chile in four fire "treatments": (1) unburned control, (2) long-term recovery, (3) short-term recovery, and (4) burned twice. We detected 713 lizards from 7 species. We found that the density and richness of lizards are impacted by wildfire frequency and time of recovery, mediated by the modification of habitat structure. The lizard community varied from a dominant arboreal species (L. pictus) in unburned and long-recovered stands, to a combination of ground-dwelling species (L. lemniscatus and L. araucaniensis) in areas affected by two fires. Araucaria forests provided key habitat features to forest reptiles after fires, but the persistence of these old-growth forests and associated biodiversity may be threatened given the increase in fire frequency.

The effects of harvest frequency on coarse woody debris and its use by fauna

Abstract Context Forest harvest practices have the potential to alter habitat available to forest fauna. One aspect of harvesting practice that has received little research attention is the effect of multiple rotations on available habitat, and its use by fauna. Aims We examined one component of habitat that is critical to many taxa, coarse woody debris (CWD). In forests of north-eastern New South Wales, Australia, we aimed to assess whether harvest (moderate intensity for saw-logs) frequency influences CWD levels, and whether fauna activity on CWD varies with harvest frequency and with CWD attributes. MethodsUsing habitat surveys and camera trapping, we compared CWD quantity and quality in unharvested sites with those that had been harvested once, twice and three times, and assessed fauna use of CWD. Key results We found significantly greater volume of non-hollow CWD, and of medium-sized pieces (15–30cm diameter), in sites harvested three times versus unharvested sites. Camera trapping showed that the activity and composition of fauna were similar across these harvest treatments. Our results also found that a broad range of fauna used a variety of logs, including large and small logs in various states of decay. Conclusions Consistent with other Australian studies, our results suggested that there are no detectable impacts of harvesting on hollow or large CWD. Further studies using radio-tracking or similar methods are needed to more comprehensively assess how CWD is used by fauna. Implications CWD was used broadly by a range of species and should be targeted for retention under ecologically sustainable forest management practices to ensure that it continues to be present in harvested landscapes. This is particularly important in places where an intensification of practices is being considered.

Comparison of microhabitat use in young regrowth and unlogged forest by the eastern pygmy-possum (Cercartetus nanus)

We describe microhabitat use and response to disturbance by the eastern pygmy-possum (Cercartetus nanus) in heathy dry sclerophyll forest using spool-and-line-tracking. We compared unlogged forest with forest regenerating four years after selective logging. Structural and floristic attributes were scored along spool lines and compared with a random line for each possum. We found that possums (n = 23) selected areas based on both structural and floristic attributes. Possums selected dense understorey, especially that comprising flowering hairpin banksia (Banksia spinulosa) and Gymea lily (Doryanthes excelsa). Fallen logs were not selected by nocturnally active possums. Spool lines in regrowth forest had less eucalypt cover and more understorey cover (e.g. D. excelsa and B. spinulosa) than unlogged forest. Conversely, cover of Banksia serrata was less in regrowth than unlogged forest. Spool lines were commonly found both at ground level (mean = 52–57% of lengths) and above the ground (43–48% of lengths). There was no difference in the mean spool height between the logging treatments (regrowth: 0.47 ± 0.14 m; unlogged: 0.49 ± 0.10 m; ± s.e.). Overall, our results suggest that the dense, flowering understorey that regenerates after selective logging is suitable for use and is the primary attribute selected by active pygmy-possums.

Temporal Patterns in the Abundance of a Critically Endangered Marsupial Relates to Disturbance by Roads and Agriculture

The aim of this study was to investigate how landscape disturbance associated with roads, agriculture and forestry influenced temporal patterns in woylie (Bettongia penicillata) abundance before, during and after periods of rapid population change. Data were collected from an area of approximately 140,000 ha of forest within the Upper Warren region in south-western Australia. Woylie abundance was measured using cage trapping at 22 grid and five transect locations with varying degrees of landscape disturbance between 1994 and 2012. We found evidence that the distribution and abundance of woylies over time appears to be related to the degree of fragmentation by roads and proximity to agriculture. Sites furthest from agriculture supported a greater abundance of woylies and had slower rates of population decline. Sites with fewer roads had a greater abundance of woylies generally and a greater rate of increase in abundance after the implementation of invasive predator control. The results of this study suggest that landscape disturbance is less important at peak population densities, but during times of environmental and population change, sites less dissected by roads and agriculture better support woylie populations. This may be due to the role these factors play in increasing the vulnerability of woylies to introduced predators, population fragmentation, weed species invasion, mortality from road collisions or a reduction in available habitat. Strategies that reduce the impact of disturbance on woylie populations could include the rationalisation of forest tracks and consolidation of contiguous habitat through the acquisition of private property. Reducing the impact of disturbance in the Upper Warren region could improve the resilience of this critically important woylie population during future environmental change.

Response of eastern pygmy possums, Cercartetus nanus, to selective logging in New South Wales: home range, habitat selection and den use

Context Selective logging of native forests creates a mosaic of disturbance histories; however, little is known about how different taxa respond to such a mosaic. Aims We followed adaptive-management principles to test logging and burning impacts on eastern pygmy possums, Cercartetus nanus (Geoffroy and Desmarest, 1817), by undertaking a large-scale field experiment that coincided with harvesting. We predicted that home range would increase after logging because of a reduction in resources (food and/or dens) and because hollows suitable for denning would decrease, resulting in greater use of unlogged patches and alternate dens. Methods We radio-tracked C. nanus in a before-and-after logging experiment to investigate home range, habitat selection and den use. We tracked 50 possums, some individuals for a maximum of 8 months, within control, recently logged and regrowth (5 years since logging) sites. Key results Home ranges were variable (0.04–19.5 ha), with males having significantly larger home ranges. We were unable to detect a difference in home-range size between controls and the first year after logging and burning, or regrowth 5 years after logging. Home ranges comprised a mosaic of disturbed and undisturbed areas, and possums did not avoid logged habitat in their home ranges, indicating that logging did not significantly influence habitat selection. We suggest that possums were not sensitive to selective logging and burning because nectar-producing plants are adapted to fire disturbance and because a variety of den sites were used, most commonly in tree hollows and fallen logs, which were commonly left as logging residue. Indeed, possums frequently denned in logged patches, both recently after logging (63% of dens) and in regrowth 5 years after logging (76% of dens). Counts of fallen hollow logs at each site indicated that their density was not reduced by logging, with regrowth sites having the greatest abundance of logs (260 ha–1). Conclusions The mosaic of disturbance created by selective logging operations did not negatively affect home range or den selection of C. nanus. Implications Ecologically sustainable logging practices that include a range of mitigation measures to protect biodiversity can be compatible with the management of threatened species. Assessment of the effectiveness of these methods often will rely on scientific research.

How many mature microhabitats does a slow-recolonising reptile require? Implications for restoration of bauxite minesites in south-western Australia

If we are to accelerate the recolonisation of restored areas by slow-recolonising species, we must provide suitable microhabitats at appropriate densities. Previous research in south-western Australia has shown that Napoleon’s skink (Egernia napoleonis) rarely recolonises restored areas. We trapped Napoleon’s skink in restoration and unmined forest to confirm the species was late successional. We also radio-tracked six skinks in unmined forest, to determine types and characteristics of used microhabitats, and estimated home ranges to determine required microhabitat densities, with the aim of accelerating skink recolonisation of restored areas. All tracked skinks used logs and hollow-bearing trees. Used logs were larger, and used trees were larger and taller than random samples, probably because large logs and trees were more likely to contain cracks and hollows that provide a refuge from predators. Extrapolations from home-range estimates indicated that a minimum of four logs ha–1 are required in restored areas to facilitate recolonisation by skinks, with skink densities likely to increase with log densities. Our study demonstrated that not all fauna will naturally recolonise restored areas and management of these areas is required to provide suitable habitat for late-successional species. Our approach could potentially be applied to other ecosystems or species.

Use of Xanthorrhoea semiplana (grass-trees) for refuge by Rattus fuscipes (southern bush rat)

This study investigated the use of the grass-tree, Xanthorrhoea semiplana F.Muell. (family Xanthorrhoeaceae), for shelter by Rattus fuscipes (southern bush rat) in South Australia. Eight bush rats were radio-tracked for 4–8 days each. To identify the understorey shelters available to each animal, surveys were conducted using point-intercept sampling at 2-m intervals along transect lines. Grass-tree density was calculated in each area used by the radio-tracked animals, and canopy thickness of grass-trees selected for refuge was assigned a score; the availability of other potential shelters was also calculated. The results indicated that (1) R. fuscipes preferentially selected grass-trees over other understorey shelter; (2) the grass-trees chosen had thick canopy covers; (3) areas with high grass-tree densities were preferred for cover over areas with fewer grass-trees; and (4) grass-trees provided dense cover and, therefore, concealed burrows and nest sites.

Salvage logging in the montane ash eucalypt forests of the Central Highlands of Victoria and its potential impacts on biodiversity

The two major forms of disturbance in the montane ash eucalypt forests of the Central Highlands of Victoria (southeastern Australia) are clearfell logging and unplanned wildfires. Since the 1930s wildfire has been followed by intensive and extensive salvage-logging operations, which may proceed for many years after a wildfire has occurred. Although applied widely, the potential effects of salvage logging on native flora and fauna have been poorly studied. Our data indicate that the abundance of large trees with hollows is significantly reduced in forests subject to salvage harvesting. This has implications for thepersistence of an array of such cavity-using vertebrates as the endangered arboreal marsupial, Leadbeater's possum (Gymnobelidues leadbeateri). Salvage logging also reduces the prevalence of multiaged montane ash forests--places that typically support the highest diversity of arboreal marsupials and forest birds. Limited research has been conducted on the effects of salvage logging on plants; thus, we constructed hypotheses about potential impacts for further testing based on known responses to clearfell logging and key life history attributes. We predict many species, such as vegetatively resprouting tree ferns, will decline, as they do after clearfelling. We also suggest that seed regenerators, which typically regenerate well after fire or conventional clearfelling, will decline after salvage logging because the stimulation for germination (fire) takes place prior to mechanical disturbance (logging). Understoryplant communities in salvage-logged areas will be dominated by a smaller suite of species, and those that are wind dispersed, have viable soil-stored seed remaining after salvage logging, or have deep rhizomes are likely to be advantaged. We recommend the following improvements to salvage-logging policies that may better incorporate conservation needs in Victorian montane ash forests: (1) exemption of salvage logging from some areas (e.g., old-growth stands and places subject to only partial stand damage); (2) increased retention of biological legacies on burned areas through variations in the intensity of salvage logging; and (3) reduction in the levels of physical disturbance on salvage-logged areas, especially through limited seedbed preparation and mechanical disturbance.