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Aim: In Australia, natural grasslands largely occur on fertile clay soils and have consequently been extensively cultivated since European settlement. Other studies have demonstrated that passive restoration of subtropical grassland is possible in environments where there is substantial native remnant vegetation in the surrounding landscape. This study examined a chronosequence of abandoned fields to investigate the recovery of fragmented grassland in a matrix of cultivated land with significant exotic species that may impede succession. Location: Darling Downs, Queensland, Australia. Methods: In this study we surveyed a chronosequence of ex‐cultivated subtropical grasslands in Queensland's Darling Downs, where only 1% of the original grasslands remain. Floristic surveys were carried out in 80 fallow sites up to 51 years old, and data were compared with 16 previously surveyed remnant grasslands on the same land type. Results: Richness of native species increased with time since cultivation and approached, but did not reach, that of remnant grasslands after 51 years, whereas the richness of exotics declined with time since cultivation. Rainfall and grazing positively and negatively affected exotic plant abundance respectively and these factors had no significant direct or indirect effect on the native species richness. In terms of composition, fallow grasslands supported 54% of the native plant species from remnant grasslands after 51 years. The native perennial grasses Dichanthium sericeum and Aristida leptopoda were the only dominant species in the remnants that were present in more than 60% of the fallow grasslands. Of the species from remnants that were "missing" from fallow sites, most were native perennial forbs and grasses. Compositional dissimilarity of fallow grassland to remnant grasslands remained high after 51 years (78%). Grassland species that are uncommon in nearby hill woodlands were preferentially absent in fallow grassland and this partly explains the slow compositional recovery. Conclusion: In a highly fragmented landscape, passive restoration is only partially effective. The restoration of grassland is probably enhanced by repositories of native seeds from hill woodlands that are too rocky to cultivate. However, some species may have to be actively reintroduced to achieve complete recovery. In this landscape, where grazing is a dominant land use, exotic species do not seem to impede succession. [ABSTRACT FROM AUTHOR]

Aim: The importance of restoring ecosystem functions to native systems that have been degraded, damaged or destroyed is increasingly recognised. Yet few studies have measured the effect of restoration efforts on ecosystem functioning or the functional diversity (FD) that underpins it. Here we assessed change in FD of restored assemblages one to 25 years after the onset of post‐mine restoration. Location: Northern Jarrah (Eucalyptus marginata Donn ex Sm.) Forest bioregion of southwestern Australia. Methods: Functional richness, evenness, divergence and dispersion were derived from five plant functional traits relevant to community reassembly. Effects of three explanatory variables (i.e. age, year restoration was initiated, and time since fire) on six response variables (i.e. four FD indices, species richness, and compositional similarity to nearby reference forest) were analysed using linear mixed models for a data set with repeated measures of plots through time (n = 810 plots), and linear models for a subset of one‐time measures of different aged assemblages (i.e. space‐for‐time approach; n = 490 plots). Results: Functional evenness and functional dispersion increased with age, while functional divergence and functional richness decreased with age. Functional dispersion increased with time since fire, while functional richness decreased with time since fire. Species richness decreased with age, but at 25 years, species richness was comparable to that observed in reference forest. In contrast, similarity showed no relationship with age of restored forest, and at 25 years, similarity of restored forest to reference was low compared with similarity of reference forest to itself. Three of four FD indices had not reached those of reference jarrah forest 25 years after restoration had been initiated. Conclusions: Reassembly of FD suggests importance of environmental filtering and high functional redundancy. A longer time frame may be needed to assess FD of restored assemblages, and in the meantime, species richness is not an adequate surrogate of FD. [ABSTRACT FROM AUTHOR]

Predicting changes in the abundance of species over time is a central goal of conservation ecology. Typically, demographic data are used to parameterise models which describe population dynamics. Vital rates of plants vary across a species' distribution, yet most demographic estimates are spatially constrained. Banksia ornata (Proteaceae), a widespread serotinous obligate‐seeding shrub in southern Australia, has previously had a fire management model developed based on demographic data derived from a chronosequence in one part of the species' range. We asked: are demographic data collected from a limited geographic range robust for developing population dynamic models that are applied across the broader species' range? How much variation exists in the demography of species across their range and does this matter for estimating fire return intervals necessary for species persistence? We examine site‐to‐site variation in the pyrodemography of six populations of B. ornata encompassing its geographic range. We documented changes in population density, time to first reproduction and canopy seed bank accumulation in stands varying in age from 0.5 to 55 years. We model year of maximum seed production on demographic parameters such as population starting density and survival rate. Density, primary juvenile period, rates of mortality and seed bank accumulation varied across populations. Primary juvenile period varied across populations (from 6 to <20 years), while time to maximum seed production was estimated to take 34–39 years after fire. Hence, the fire intervals that correspond to minimising extinction risk (due to variation in primary juvenile periods) diverge moreso among populations than the fire intervals that produce (on average) the highest maximum seed production with respect to time since fire. Demographic data collected at different locations in a species' range are likely valuable for building realistic species response models to disturbance, providing underlying assumptions about key transitions, such as mortality rate, are made explicit. [ABSTRACT FROM AUTHOR]

Aims: Secondary forests are expanding rapidly in tropical regions and could play an important role in conserving native biodiversity and stabilising global climate. The recovery rate of plant communities in secondary forests varies considerably due to mechanisms associated with seed dispersal and recruitment dynamics. We explored these mechanisms along a chronosequence of tropical secondary forests in an agricultural landscape that was extensively cleared. Location: We explored these mechanisms along a chronosequence of secondary forests in tropical Australia. Methods: We used selected plant traits to characterise plant species and compared community composition between demographic stages (i.e. soil seedbank, understorey and overstorey) and forest age categories. We collected soil samples to assess seedbank composition and used quadrants and transects to assess understorey and overstorey plant community composition at each site. Results: For all demographic stages, we found that young (4‐12 years) and intermediate‐aged forests (16‐20 years) were dominated by early successional, small‐seeded species and traits associated with disturbed forests. In old secondary forest (23‐34 years) some traits associated with late successional stages were present (e.g. large seeds, trees). However, the traits and species composition of mature forests remained distinct from all secondary forests. Across the chronosequence, forest age and demographic stage were significant factors in discriminating species and trait composition between forest sites. We found clear plant community similarities within demographic stages, despite the forest age differences. This suggests stronger limitations to dispersal and recruitment between demographic stages than between forest ages. Conclusions: Our results show that secondary forests in this region assemble slowly with dispersal and recruitment limitations constraining their recovery. Although a successional transition in species and plant traits composition along the chronosequence is clear, similarities to mature forests remain low. The slow recovery of late successional and large‐seeded species in these secondary forests suggests that active restoration of such species may be necessary if we want to enhance the capacity of these forests to conserve native biodiversity. [ABSTRACT FROM AUTHOR]

Invertebrate biomonitoring can reveal crucial information about the status of restoration projects; however, it is routinely underused because of the high level of taxonomic expertise and resources required. Invertebrate DNA metabarcoding has been used to characterize invertebrate biodiversity but its application in restoration remains untested. We use DNA metabarcoding, a new approach for restoration assessment, to explore the invertebrate composition from pitfall traps at two mine site restoration chronosequences in southwestern Australia. Invertebrates were profiled using two cytochrome oxidase subunit 1 assays to investigate invertebrate biodiversity. The data revealed differences between invertebrate communities at the two mines and between the different age plots of the chronosequences. Several characteristic taxa were identified for each age within the chronosequence, including springtails within the youngest sites (Order: Collembola) and millipedes within the oldest and reference sites (Order: Julida). This study facilitates development of a molecular "toolkit" for the monitoring of ecological restoration projects. We suggest that a metabarcoding approach shows promise in complementing current monitoring practices that rely on alpha taxonomy. [ABSTRACT FROM AUTHOR]

The impact of fire on global C cycles is considerable but complex. Nevertheless, studies on patterns of soil C accumulation following fires of differing intensity over time are lacking. Our study utilised 15 locations last burnt by prescribed fire (inferred low intensity) and 18 locations last burnt by wildfire (inferred high intensity), with time since fire (TSF) up to 43 years, in a homogenous forest type in south eastern Australia. Following a stratified approach to mineral soil sampling, the soil % total C (% C Tot ) and % recalcitrant pyrogenic C (% RPC), were estimated. Generalised additive models indicated increases in % C Tot at TSF > 30 years in sites last burnt by wildfire. Estimates in sites last subjected to prescribed fire however, remained constant across the TSF chronosequence. There was no significant difference in % C Tot between the different fire types for the first 20 years after fire. In the first 10 years after wildfires, % RPC was elevated, declining to a minimum at ca. TSF 25 years. After prescribed fires, % RPC was unaffected by TSF. Differences in response of % C Tot and % RPC to fire type may reflect the strength of stimulation of early successional processes and extent of charring. The divergent response to fire type in % C Tot was apparent at TSF longer than the landscape average fire return interval (i.e., 15 to 20 years). Thus, any attempt to increase C sequestration in soils would require long-term exclusion of fire. Conversely, increased fire frequency is likely to have negligible impact on soil C stocks in these forests. Further investigation of the effects of fire frequency, fire intensity combinations and interaction of fire with other disturbances will enhance prediction of the likely impact of imposed or climatically induced changes to fire regimes on soil C. [ABSTRACT FROM AUTHOR]

Hybrid living shorelines use a combination of engineered structures with natural ecosystems to achieve coastal protection and habitat restoration outcomes, with added co-benefits such as carbon sequestration. Rock fillets constructed along eroding estuarine banks are designed to accumulate sediment, establish mangroves, and stabilise the shoreline. There is, however, a lack of data to support whether rock fillets are achieving these goals. We used a chronosequence of rock fillets to determine their effect on mangrove development, bank stabilisation and carbon sequestration in four estuaries in New South Wales, Australia. Aboveground biomass and adult density increased with age of rock fillets, and mangrove structure was similar to a natural fringing mangrove after 15 years. The rock fillets accumulated sediment, which reduced the eroded estuary bank height, however, little effect of the fillets on bank slope was observed. Sediment carbon stocks were not different between rock fillets, eroding estuary banks and natural fringing mangroves. Rock fillet design had a significant effect on mangrove structure and coastal protection function, with greater wave transmission through lower rock fillets, suggesting design optimisation is needed. As the construction cost of the rock fillets was equal or less than traditional rock revetments, where suitable they present a more economic and environmentally sustainable solution to estuarine erosion management. • Hybrid living shorelines can provide coastal protection and habitat restoration outcomes. • Rock fillets were successful at accumulating sediment and establishing mangroves. • Mangrove structure within rock fillets was similar to natural mangroves after 15 years. • There was no effect of the rock fillets on blue carbon accumulation. • Technical guidance can inform large-scale application of rock fillets for nature-based coastal defence. [ABSTRACT FROM AUTHOR]

Reforestation has large potential for mitigating climate change through carbon sequestration. Native mixed-species plantings have a higher potential to reverse biodiversity loss than do plantations of production species, but there are few data on their capacity to store carbon. A chronosequence (5-45 years) of 36 native mixed-species plantings, paired with adjacent pastures, was measured to investigate changes to stocks among C pools following reforestation of agricultural land in the medium rainfall zone (400-800 mm yr−1) of temperate Australia. These mixed-species plantings accumulated 3.09 ± 0.85 t C ha−1 yr−1 in aboveground biomass and 0.18 ± 0.05 t C ha−1 yr−1 in plant litter, reaching amounts comparable to those measured in remnant woodlands by 20 years and 36 years after reforestation respectively. Soil C was slower to increase, with increases seen only after 45 years, at which time stocks had not reached the amounts found in remnant woodlands. The amount of trees (tree density and basal area) was positively associated with the accumulation of carbon in aboveground biomass and litter. In contrast, changes to soil C were most strongly related to the productivity of the location (a forest productivity index and soil N content in the adjacent pasture). At 30 years, native mixed-species plantings had increased the stability of soil C stocks, with higher amounts of recalcitrant C and higher C : N ratios than their adjacent pastures. Reforestation with native mixed-species plantings did not significantly change the availability of macronutrients (N, K, Ca, Mg, P, and S) or micronutrients (Fe, B, Mn, Zn, and Cu), content of plant toxins (Al, Si), acidity, or salinity (Na, electrical conductivity) in the soil. In this medium rainfall area, native mixed-species plantings provided comparable rates of C sequestration to local production species, with the probable additional benefit of providing better quality habitat for native biota. These results demonstrate that reforestation using native mixed-species plantings is an effective alternative for carbon sequestration to standard monocultures of production species in medium rainfall areas of temperate continental climates, where they can effectively store C, convert C into stable pools and provide greater benefits for biodiversity. [ABSTRACT FROM AUTHOR]

Soil chronosequences provide valuable model systems to investigate pedogenesis and associated effects of nutrient availability on biological communities. However, long-term chronosequences occurring under seasonally dry climates remain scarce. We assessed soil development and nutrient dynamics along the Jurien Bay chronosequence, a 2 million-year sequence of coastal dunes in southwestern Australia. The chronosequence is significant because it occurs in a Mediterranean climate and supports hyperdiverse shrublands within a global biodiversity hotspot. Young soils formed during the Holocene (<6,500 years old) are strongly alkaline and contain abundant carbonate, which is leached from the profile within a few thousand years. Middle Pleistocene soils (ca 120,000-500,000 years old) are yellow decalcified sands with residual iron oxide coatings on quartz grains over a petrocalcic horizon that occurs at increasing depth as soils age. Early Pleistocene soils (>2,000,000 years old) are completely leached of iron oxides and consist of bleached quartz sand several meters deep. Changes in soil organic matter and nutrient status along the Jurien Bay chronosequence are consistent with patterns observed along other long-term chronosequences and correspond closely to expectations of the Walker and Syers () model of biogeochemical change during pedogenesis. Organic carbon and nitrogen (N) accumulate rapidly to maximum amounts in intermediate-aged Holocene dunes and then decline as soils age. In contrast, total phosphorus (P) declines continuously along the chronosequence to extremely low levels after 2 million years of pedogenesis, eventually representing some of the lowest P soils globally. Ratios of soil organic carbon to P and N to P increase continuously along the chronosequence, consistent with a shift from N limitation on young soils to extreme P limitation on old soils. Phosphorus fractionation by sequential extraction reveals a rapid decline in primary and non-occluded phosphate and an increase in organic and occluded P as soils age. Concentrations of extractable (that is, readily bioavailable) N and P, as well as exchangeable cations, are greatest in Holocene dunes and decline to low levels in Pleistocene dunes. Extractable micronutrient concentrations were generally very low and varied little across the chronosequence. We conclude that the Jurien Bay chronosequence is an important example of changing patterns of nutrient limitation linked to long-term soil and ecosystem development under a Mediterranean climate. [ABSTRACT FROM AUTHOR]

The terminal lake systems of central Australia are key sites for the reconstruction of late Quaternary paleoenvironments. Paleoshoreline deposits around these lakes reflect repeated lake filling episodes and such landforms have enabled the establishment of a luminescence-based chronology for filling events in previous studies. Here we present a detailed documentation of the morphology and chemistry of soils developed in four well-preserved beach ridges of late Pleistocene and mid-to-late Holocene age at Lake Callabonna to assess changes in dominant pedogenic processes. All soil profiles contain evidence for the incorporation of eolian-derived material, likely via the formation of desert pavements and vesicular horizons, and limited illuviation due to generally shallow wetting fronts. Even though soil properties in the four studied profiles also provide examples of parent material influence or site-specific processes related to the geomorphic setting, there is an overall trend of increasing enrichment of eolian-derived material since at least ~ 33 ka. Compared to the Holocene profiles, the derived average accumulation rates for the late Pleistocene profiles are significantly lower and may suggest that soils record important regional changes in paleoenvironments and dust dynamics related to shifts in the Southern Hemisphere westerlies. [ABSTRACT FROM AUTHOR]

Understanding fire behaviour and vegetation flammability is important for predicting the consequences of fires. Visual assessments of fuel, such as those developed in Project Vesta, have been widely applied to facilitate rapid data acquisition to support fire behaviour models. However, the accuracy and potential wider application to other plant communities of Vesta visual fuel assessments has received limited attention. We conducted visual fuel assessments and detailed quantitative structural measurements in Eucalyptus salubris (gimlet) woodlands in the world's largest extant Mediterranean-climate woodland. With one exception, there was moderate to strong correlation between visual assessments of cover in vegetation layers and quantitative measurements, indicating that visual assessments adequately capture changes in fuels. This suggests that the Vesta visual fuel assessment methodology may have wide application in Australian eucalypt forests and woodlands and perhaps in similar communities around the world. However, several issues limiting the wider application of Vesta visual fuel assessments were identified, mainly associated with differences in community ecology between non-resprouter dominated E. salubris woodlands and the epicormic resprouter-dominated dry forests where the method was developed. Patterns of change in fuels suggest that flammability in E. salubris woodlands peaks at intermediate times since fire, potentially providing opportunities for fire management interventions. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim We examined the century-long post-fire responses of reptiles to (1) determine the time-scales over which fauna - fire relationships occur, (2) assess the capacity of a conceptual model to predict faunal response to fire, and (3) investigate the degree to which models of fauna - fire relationships can predict species occurrence and are transferable across space. Location A 104,000 km2 area in the semi-arid Murray Mallee region of south-eastern Australia. Methods We surveyed reptiles at 280 sites across a century-long post-fire chronosequence. We developed generalized additive mixed models (GAMMs) of the relationship between time since fire and the occurrence of 17 species in two subregions, and compared modelled responses with predictions derived from the conceptual model. The predictive capacity of GAMMs was then assessed (1) within the subregion the model was developed and (2) when transferred into a novel subregion. Results Eleven species displayed a significant relationship with time-since-fire, with changes in species probability of occurrence continuing up to 100 years post-fire. Predictions of the timing of species post-fire peak in occurrence were accurate for 9 of 13 species models for which a significant fire response was detected, but little success was achieved in predicting the shape of a species' response. GAMMs predicted species occurrence more accurately when applied within the subregion in which they were developed than when transferred into a novel subregion, primarily due to some species responding to fire more strongly in one part of their geographic range. Main conclusions Fire influences the occurrence of reptiles in semi-arid ecosystems over century-long time frames. Habitat-use conceptual models have value in predicting the peak occurrence of species following fire, particularly for species with distributions strongly shaped by fire. Species relationships with fire can differ across their geographic range, probably associated with variation in climatic influences on post-fire succession and the consequent provision of habitat resources. [ABSTRACT FROM AUTHOR]

Abstract: Biological soil crusts take a long time to recover after soil disturbance but data on the rate and trajectory of crust recovery are lacking. Using a space-for-time chronosequence of time-since-cultivation, we assessed the recovery of crust diversity and cover in semi-arid grasslands in southern Australia. Using sites that spanned from recently-cultivated to never-cultivated, we show that the recovery of soil crust cover is highly variable with time-since-cultivation; recently-cultivated sites generally had the lowest total cover of biological soil crusts and morphological type diversity relative to sites allowed to recover for ≥60 yrs. Moss, liverworts, squamulose and crustose lichens return to grasslands quickly after cultivation, but cover returned at highly variable rates; this might reflect that other factors (stock grazing, microtopography, soils) also affect crust cover recovery. Our results suggest that soil crusts are initially slow to recover after soil disturbance. However, post-cultivation recovery does occur but this is in the context of historical and spatial contingencies. The patterns of cover and diversity that we observed provide a useful way to interpret effects of disturbance on semi-arid grasslands in Australia and may be useful indicators of grassland condition where cultivation history is not known. [Copyright &y& Elsevier]

• Fire risk in Tasmanian tall wet Eucalyptus forest decreases as they mature. • Older stand have a moister understorey and less dense ladder fuels. • Extreme fires in older forests are unlikely unless the moist understorey ignites. • Tasmanian tall wet Eucalyptus forests are vulnerable to a 'landscape trap' effect. Forest fire risk, and how it changes over time, has important influences on forest dynamics. Two common models describing how fire risk changes with stand development, known as flammability functions, are (a) the 'moisture model', where fire risk initially increases, then decreases, as a stand develops after a fire, and (b) the 'Olson model', where fire risk increases asymptotically as a function of time since previous fire. These two flammability functions have both been used to describe the world's tallest angiosperm forest, the Australian tall wet Eucalyptus forest (TWEF). It is unclear, however, which function is more appropriate for TWEF, as there are little empirical data describing fuels and microclimate, two important influences on fire risk and potential severity, across the long lifespan of these forests. Accordingly, we use a chronosequence of TWEF stands in southeast Tasmania, Australia, to see how fuels, microclimate, and resulting fire risk and potential fire severity changed amongst four stand-development stages ranging from regrowth to old forests. We measured fuel loads, understorey microclimate, and forest physiognomy. We then used these data with historical fire weather data and fire behaviour models to estimate how often low- and high-severity fire was possible historically. We also investigated if the severity of the previous disturbance influenced the likelihood of a subsequent high-severity fire. We found that, while fuel loads remained unchanged across the chronosequence, later development stages had a significantly moister understorey, an increased abundance of rainforest trees, and more vertically discontinuous fuels. These factors resulted in a significantly reduced fire risk, with high-severity fire much more likely in the early stages. Further, we found that stands that had been initiated by stand-replacing fire were more susceptible to subsequent high-severity fire than those that experienced non stand-replacing fire, due to a lack of a remaining mature canopy. We concluded that, unlike most other fire-dependent ecosystems where the Olson curve is an appropriate model, the flammability function in TWEF is best described by the moisture model. Our results indicate that TWEF is vulnerable to a 'landscape trap' effect, where intensive disturbance creates large areas of regrowth stands with increased risk of high-severity fire, which increases the likelihood of landscape-wide, demographic collapse. We suggest that fire and forest management incorporate techniques mimicking low-severity disturbances to create more resilient landscapes. [ABSTRACT FROM AUTHOR]

The structural and floristic changes occurring with time since fire in Taxandria linearifolia swamps were investigated using chronosequence analysis. Sixty-six swamps in the northern jarrah forest of south-western Australia were investigated and the effect of fire on them was quantified. Habitat units were mapped from aerial photographs that were imported into a geographic information system. Field surveys were then conducted at each site to ground-truth mapped habitat units. Habitat units were differentiated using factor analysis. The vegetation within the swamps remained relatively open for the first five years following a fire while being largely dominated by three or four species. Thereafter, vegetation density increased to a peak between 20 and 24 years (>90%) and species richness from 10 to 14 (mean = 5.7 ± 0.4). Long unburnt Taxandria swamp shrubland habitat returned to intermediate vegetation density levels, although becoming increasingly woody, as relatively few species dominated. Such a response to fire probably reflects adaptations to the frequent, low intensity fire regimes utilised by Aborigines prior to European colonisation. [ABSTRACT FROM AUTHOR]

A number of indices of soil carbon (total C, Walkley–Black organic C, water-soluble C, K2SO4-extractable C and microbial biomass C) were measured to assess the stability of soil carbon in two managed forest types in Australia. Carbon concentrations generally decreased, and soil density increased, with soil depth to 50 cm, and were an order of magnitude greater in clay loam soils under native forests of Eucalyptus regnans than in sandy soils under plantations of Pinus radiata.In E. regnans stands, concentrations of soil carbon increased with stand age, but due to a corresponding decrease in soil density there was no trend in carbon content with stand age, with the exception of microbial biomass C, which increased. In P. radiata stands, concentrations of water-soluble C and K2SO4-extractable C increased with stand age, whereas there was no trend in concentrations of the other carbon indices, and for none of the indices of soil C was there a significant trend in carbon content with stand age.Microbial C was less than 4% of total C, and water-soluble C and K2SO4-extractable C less than 1%. There was no significant trend in the ratio of microbial C to total C (microbial quotient) with stand age for either species.These results show that soil carbon in these contrasting temperate forest ecosystems is relatively stable, particularly where regeneration occurs soon after disturbance. The impact of management on the net carbon balance of these forests will therefore depend largely on carbon storage in vegetation. [Copyright &y& Elsevier]