Themeda Triandra Research Articles

Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides, Rytidosperma caespitosum, R. fulvum, R. richardsonii, R. duttonianum and R. racemosum, of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra, lower levels of <6 mg/kg are required to ensure botanical stability.

The effect of substrate compaction on plant water use and the implications for phytocap design specifications

There is little experimental evidence to guide the design of substrate compaction for the optimal plant water use performance of a landfill phytocap. A glasshouse study was undertaken to address this with aim to evaluate the effect of substrate compaction on the water use of a phytocap plant community. Four levels of relative compaction (RC), i.e. the ratio of dry bulk density over the standard maximum dry bulk density, (72%, 77%, 82%, and 87%) were considered. The native tree and grass species selected were typical of an Australian phytocap plant community: Themeda triandra, Microlaena stipoides, Eucalyptus camaldulensis, Eucalyptus cladocalyx, Acacia mearnsii and Allocasuarina verticillata. Plant water use was measured by weight as the difference between planted and unplanted cores over 5 drying periods occurring through the first 6 months of plant establishment traversing winter, spring and summer. Plant water use was optimal for all species at low-intermediate RC (72%, 77% and 82%), and all species except Themeda triandra, were most negatively impacted by the highest RC of 87%. The best linear model based on Akaike’s Information Criterion included a second-order term for the continuous fixed factor ‘RC’ and the categorical fixed factor ‘species’. This model showed plant water use to be optimum at a RC of 76.5% and highlighted a wide range of RC’s (70–83%), for which plant water use is not <90% of this optimum. It also highlighted increasing plant water use-sensitivity to RC’s beyond these ranges, with a RC > 86% and a RC < 67% leading to reductions in plant water use of 20% or more. Substrate specifications are recommended to optimize phytocap plant water use within achievable RC ranges. These can be generalized beyond application to a single species or substrate texture to inform the design and quality assurance of substrate placement for future landfill phytocaps.

Assessing germination characteristics of Australian native plant species in metal/metalloid solution.

This study investigated tolerance of Australian native grass species Astrebla lappacea, Themeda australis, and Austrostipa scabra and a tree species Acacia harpophylla to different concentrations of arsenic As(V) (13.34-667.36 μM), Cu2+ (0.5-200 μM), Zn2+ (9-500 μM), Mn2+ (8-10240 μM) and Pb2+ (240-9600 μM) in single solutions in germination experiments. Metal/loid tolerance indicators used were maximum germination percentage (Gmax), mean germination time (MGT), radicle and shoot tolerance indexes (RTI & STI). Radicle tolerance index was the most sensitive indicator of metal tolerance in germinating seeds. All native species were highly tolerant to the metal/loids tested, however, they showed different metal toxicity thresholds and levels of tolerance based on RTI as a metal tolerance indicator during germination. Overall, all four species could be classified as metallophytes, confirming their current suitability for and established use in mine site rehabilitation. This work may also serve as a basis for future studies on metal/loid tolerance of other plant species during germination.

Herbivore removal reduces influence ofarbuscular mycorrhizal fungi onplant growth and tolerance in an East African savanna.

The functional relationship between arbuscular mycorrhizal fungi (AMF) and their hosts is variable on small spatial scales. Here, we hypothesized that herbivore exclusion changes the AMF community and alters the ability of AMF to enhance plant tolerance to grazing. We grew the perennial bunchgrass, Themeda triandra Forssk in inoculum from soils collected in the Kenya Long-term Exclosure Experiment where treatments representing different levels of herbivory have been in place since 1995. We assessed AMF diversity in the field, using terminal restriction fragment length polymorphism and compared fungal diversity among treatments. We conducted clipping experiments in the greenhouse and field and assessed regrowth. Plants inoculated with AMF from areas accessed by wild herbivores and cattle had greater biomass than non-inoculated controls, while plants inoculated with AMF from where large herbivores were excluded did not benefit from AMF in terms of biomass production. However, only the inoculation with AMF from areas with wild herbivores and no cattle had a positive effect on regrowth, relative to clipped plants grown without AMF. Similarly, in the field, regrowth of plants after clipping in areas with only native herbivores was higher than other treatments. Functional differences in AMF were evident despite little difference in AMF species richness or community composition. Our findings suggest that differences in large herbivore communities over nearly two decades has resulted in localized, functional changes in AMF communities. Our results add to the accumulating evidence that mycorrhizae are locally adapted and that functional differences can evolve within small geographical areas.

Assessing the Impact of Spectral Resolution on Classification of Lowland Native Grassland Communities Based on Field Spectroscopy in Tasmania, Australia

This paper presents a case study for the analysis of endangered lowland native grassland communities in the Tasmanian Midlands region using field spectroscopy and spectral convolution techniques. The aim of the study was to determine whether there was significant improvement in classification accuracy for lowland native grasslands and other vegetation communities based on hyperspectral resolution datasets over multispectral equivalents. A spectral dataset was collected using an ASD Handheld-2 spectroradiometer at Tunbridge Township Lagoon. The study then employed a k-fold cross-validation approach for repeated classification of a full hyperspectral dataset, a reduced hyperspectral dataset, and two convoluted multispectral datasets. Classification was performed on each of the four datasets a total of 30 times, based on two different class configurations. The classes analysed were Themeda triandra grassland, Danthonia/Poa grassland, Wilsonia rotundifolia/Selliera radicans, saltpan, and a simplified C3 vegetation class. The results of the classifications were then tested for statistically significant differences using ANOVA and Tukey’s post-hoc comparisons. The results of the study indicated that hyperspectral resolution provides small but statistically significant increases in classification accuracy for Themeda and Danthonia grasslands. For other classes, differences in classification accuracy for all datasets were not statistically significant. The results obtained here indicate that there is some potential for enhanced detection of major lowland native grassland community types using hyperspectral resolution datasets, and that future analysis should prioritise good performance in these classes over others. This study presents a method for identification of optimal spectral resolution across multiple datasets, and constitutes an important case study for lowland native grassland mapping in Tasmania.

Characterizing a Poacher-Driven Fire Regime in Low-Nutrient Coastal Grasslands of Pondoland, South Africa

Understanding fire regimes in the coastal region of the Pondoland center of plant endemism, (Eastern Cape, South Africa) is of critical importance, especially in areas where anthropogenic ignitions influence the fire regime. We characterized the fire regime (2007 to 2016) of Mkambati Nature Reserve (9200 ha) in terms of fire season, seasonality of fire-prone weather conditions, fire return interval (FRI), and influence of poaching-related ignitions. Fires were concentrated in winter when monthly fire danger weather index was highest. The mean FRI at Mkambati was <3 years, but varied according to vegetation type, and whether censoring (for open-ended FRIs) was applied. Mean estimated FRIs were 2.6 yr to 3.1 yr in the majority of grassland types, 5.6 yr to 8.0 yr in forests, and 9.0 yr to 44.4 yr in Themeda triandra Forssk. grasslands. Poachers, with the intention of attracting ungulates, are an important source of ignitions at Mkambati. Accordingly, FRIs were shorter (1.99 yr to 2.08 yr) in areas within 3 km of likely poacher entry points than in areas farther away (2.56 yr to 2.88 yr). Although all fires recorded at Mkambati during the study period were of anthropogenic origin, mean FRI still fell within the natural range reported for interior grasslands in South Africa.

Does silica concentration and phytolith ultrastructure relate to phytolith hardness?

Abstract Grasses are an important part of the forage of many herbivorous mammals and their phytoliths have long been regarded as the most important agent of tooth wear. Recent work has challenged this “paradigm” in finding evidence 1. of native phytoliths to be much softer then tooth enamel and 2. indicating, that phytolith hardness is highly variable, 3. prone to methodology and 4. not easy to be related to habitat conditions. We conduct controlled silica-cultivations measuring SiO2 content in the common forage grass Themeda triandra. Phytoliths are extracted natively, and nano-indentation values are measured. Phytolith hardness in Themeda triandra is found to be independent of silicate availability in the substrate. We further investigate the phytolith ultrastructure of Hordeum vulgare phytoliths. Phytoliths are shown to be an anisotropic composite of at least 3 components, silica bodies, inter-body matrix (both mineralised) and globular inclusions (likely non-mineralised). It can be argued, that indentation will be largely influenced by the heterogeneity of the structure and thus nano-indentation measurements will largely reflect the matrix and its mechanical properties but not necessarily the silicate bodies, which make up the vast majority of a phytolith.

Object-based random forest classification of Landsat ETM+ and WorldView-2 satellite imagery for mapping lowland native grassland communities in Tasmania, Australia

This paper presents a random forest classification approach for identifying and mapping three types of lowland native grassland communities found in the Tasmanian Midlands region. Due to the high conservation priority assigned to these communities, there has been an increasing need to identify appropriate datasets that can be used to derive accurate and frequently updateable maps of community extent. Therefore, this paper proposes a method employing repeat classification and statistical significance testing as a means of identifying the most appropriate dataset for mapping these communities. Two datasets were acquired and analysed; a Landsat ETM+ scene, and a WorldView-2 scene, both from 2010. Training and validation data were randomly subset using a k-fold (k=50) approach from a pre-existing field dataset. Poa labillardierei, Themeda triandra and lowland native grassland complex communities were identified in addition to dry woodland and agriculture. For each subset of randomly allocated points, a random forest model was trained based on each dataset, and then used to classify the corresponding imagery. Validation was performed using the reciprocal points from the independent subset that had not been used to train the model. Final training and classification accuracies were reported as per class means for each satellite dataset. Analysis of Variance (ANOVA) was undertaken to determine whether classification accuracy differed between the two datasets, as well as between classifications. Results showed mean class accuracies between 54% and 87%. Class accuracy only differed significantly between datasets for the dry woodland and Themeda grassland classes, with the WorldView-2 dataset showing higher mean classification accuracies. The results of this study indicate that remote sensing is a viable method for the identification of lowland native grassland communities in the Tasmanian Midlands, and that repeat classification and statistical significant testing can be used to identify optimal datasets for vegetation community mapping.

Assessing the potential of using biochar in mine rehabilitation under elevated atmospheric CO2 concentration

Re-establishment of soil nitrogen (N) capital is a priority in mine rehabilitation. We aimed to evaluate the effects of biochar addition on improving mine spoil N pools and the influence of elevated CO2 concentration on mine rehabilitation. We assessed the effects of pinewood biochar, produced at three temperatures (650, 750 and 850 °C, referred as B650, B750 and B850, respectively), on mine spoil total N concentrations with five different plant species, including a tree species (Eucalyptus crebra), N-fixing shrubs (Acacia floribunda and Allocasuarina littoralis) and C3 and C4 grasses (Austrodanthonia tenuior and Themeda australis) incubated at ambient (400 μL L−1) and elevated (700 μL L−1) atmospheric CO2 concentrations, as well as the effects of elevated CO2 on mine rehabilitation. Soil total N significantly improved following biochar incorporation under all plant species (P < 0.05) except for T. Australis. E. crebra had the highest soil total N (0.197%, 0.198% and 0.212% for B650, B750 and B850, respectively). Different from the negligible influence of elevated CO2 on soil properties under the grasses and the N-fixing shrubs, elevated CO2 significantly increased soil water and hot water extractable organic C (WEOC and HWEOC, respectively) and decreased total C under E. crebra, indicating that the nutrient demands were not met. Biochar addition showed the potential in mine rehabilitation in terms of improving soil N pool, especially with E. crebra. However, it would be more difficulty to rehabilitate mine spoils in future with the rising atmospheric CO2 concentration.

Seasonal discrimination of C3 and C4 grasses functional types: An evaluation of the prospects of varying spectral configurations of new generation sensors

The present study assessed the potential of varying spectral configuration of Landsat 8 Operational Land Imager (OLI), Sentinel 2 MultiSpectal Instrument (MSI) and Worldview 2 sensors in the seasonal discrimination of Festuca costata (C3) and Themeda Triandra (C4) grass species in the Drakensberg, South Africa. This was achieved by resampling hyperspectral measurements to the spectral windows corresponding to the three sensors at two distinct seasonal periods (summer peak and end of winter), using the Discriminant Analysis (DA) classification ensemble. In summer, standard bands of the Worldview 2 produced the highest overall classification accuracy (98.61%), followed by Sentinel 2 (97.52%), whereas the Landsat 8 spectral configuration was the least performer, using vegetation indices (95.83%). In winter, Sentinel 2 spectral bands produced the highest accuracy (96.18%) for the two species, followed by Worldview 2 (94.44%) and Landsat 8 yielded the least (91.67%) accuracy. Results also showed that maximum separability between C3 and C4 grasses was in summer, while at the end of winter considerable overlaps were noted, especially when using the spectral settings of the Landsat 8 OLI and Sentinel 2 shortwave infrared bands. Test of significance in species reflectance further confirmed that in summer, there were significant differences (P<0.05), whereas in winter, most of the spectral windows of all sensors yielded insignificant differences (P>0.05) between the two species. In this regard, the peak summer period presents a promising opportunity for the spectral discrimination of C3 and C4 grass species functional types, than the end of winter, when using multispectral sensors. Results from this study highlight the influence of seasonality on discrimination and therefore provide the basis for the successful discrimination and mapping of C3 and C4 grass species.

Nutritional study of local fodder species in Ahmednagar district of western Maharashtra

The locally grown forage grasses are main fodder source for maintaining the indigenous livestock breeds like Dangi cattle and Sangamneri goat in Ahmednagar district. Most commonly observed fodder grass and tree species grazed by livestock were collected from the field. The nutritional quality of these grasses and tree species was determined by undertaking proximate analysis in the laboratory. The local fodder species include Dicanthium annulatum, Setaria intermedia, Themeda triandra, Heteropogon contortus, Indigofera cordifolia, Apluda mutica, Cymbopogon martini, Tephrosia purpurea. Among the tree species Melia azedarach, Azadirachta indica, Prosopis julifera, Grewia asiatica, Clerodendrum multiflorum were the major tree species commonly available as fodder source. The nutritional analysis indicated that crude protein content ranged from 5.61 to 15.46%, crude fiber 18.09 to 34.87%, ether extract 1.00 to 3.24%, Ash 6.44 to 21.56 % and silica was less than 5.31%. The grass and tree species found in hilly regions are showing tremendous variation in nutritional composition. This study highlighted the importance of local fodder species including grasses, legumes, bushes and trees in rearing the livestock with low inputs at field conditions.

An African grassland responds similarly to long-term fertilization to the Park Grass experiment.

We compared the results of a long-term (65 years) experiment in a South African grassland with the world’s longest-running ecological experiment, the Park Grass study at Rothamsted, U.K. The climate is warm and humid in South Africa and cool and temperate in England. The African grassland has been fertilized with two forms of nitrogen applied at four levels, phosphorus and lime in a crossed design in 96 plots. In 1951, about 84% of plant cover consisted of Themeda triandra, Tristachya leucothrix and Setaria nigrirostris. Currently, the dominant species are Panicum maximum, Setaria sphacelata and Eragrostis curvula, making up 71% of total biomass. As in the Park Grass experiment, we found a significant (additive) interaction effect on ANPP of nitrogen and phosphorus, and a (marginally significant) negative correlation between ANPP and species richness. Unlike the Park Grass experiment, there was no correlation between ANPP and species richness when pH was included as a covariate. There was also a significant negative effect of nitrogen amount and nitrogen form and a positive effect of lime on species richness and species diversity. Soil pH had an important effect on species richness. Liming was insufficient to balance the negative effects on species richness of nitrogen fertilization. There was a significant effect of pH on biomass of three abundant species. There were also significant effects of light on the biomass of four species, with only Panicum maximum having a negative response to light. In all of the abundant species, adding total species richness and ANPP to the model increased the amount of variance explained. The biomass of Eragrostis curvula and P. maximum were negatively correlated with species richness while three other abundant species increased with species richness, suggesting that competition and facilitation were active. Consistent with the results from the Park Grass and other long-term fertilization experiments of grasslands, we found a positive effect of soil pH and a negative effect of nitrogen amount on species richness, a more acutely negative effect on species richness of acidic ammonium sulphate fertilizer than limestone ammonium nitrate, a negative relationship between species richness and biomass, and a positive effect on species richness of lime interacting with nitrogen.

Grazing pressure impacts on two Aristida/Bothriochloa native pasture communities of central Queensland

Managing native pastures for sustainable and economic production requires a good understanding of grazing effects on pasture dynamics. The Aristida/Bothriochloa pastures of north-eastern Australia are important for cattle production but little data on grazing pressure impacts on pastures are available to guide management decisions of producers, for land management education programs, or for predictive modelling. To address this deficiency, four different continuous grazing intensities were imposed on woodland communities over 7 or 8 years at two sites: a Eucalyptus populnea (poplar box) and a E. melanophloia (silver-leaved ironbark) community. Both sites had replicated paddocks grazed at a low, medium or high grazing pressure by +/− tree killing using herbicide (12 paddocks), and 12 ungrazed (nil grazing pressure) 1-ha plots subjected to the same tree-killing contrasts. Grazed paddock areas were fixed and varied between 3.5 and 21.5 ha. Differential grazing pressures were reset each autumn, by adjusting cattle numbers to consume over the next year the equivalent of 0%, 25%, 50% or 75% of the standing pasture mass available. Pasture grasses suitable as indicators of grazing pressure were identified for both communities. Under low grazing pressure, Themeda triandra (kangaroo grass) was the only desirable grass to show a significant increase in total contribution over time at both sites, although Dichanthium sericeum (Queensland bluegrass) also increased its contribution at the poplar box site. Chloris species increased their contribution as grazing pressure increased. The proportion of less palatable Aristida spp. (wiregrasses) in the pasture was not affected by high grazing pressure, although they increased at low grazing pressure in the poplar box community. There were no consistent changes in native legumes or weedy forb species to any treatment. Increasing grazing pressure had a greater negative effect on pasture mass, ground cover and pasture crown cover area than on changing species composition. Most changes in composition due to grazing pressure were smaller than those associated with variable seasonal rainfall, and were greater in the poplar box community. In above-average rainfall years grazing up to 50% of autumn standing pasture mass had no detrimental effect on composition in treeless poplar box country in the short term. The pastures remained stable or improved in both communities when grazing pressure was set annually to utilise 25% of the standing autumn forage.

Does season and grazing influence the δ13C and δ15N of C4 native grasses in semi-arid rangelands of the Pilbara region of NW Australia?

Much of the semi-arid, native rangelands Pilbara region of NW Australia is used for cattle production with the most productive grasslands for cattle grazing dominated by the C4 perennials grasses; Astrebla pectinata, Themeda triandra, and Eragrostis xerophila. In both grazed and ungrazed plots, we quantified the seasonal variation in the natural abundance of 13C and 15N of green foliage. We assigned the C4 pathway of individual species (NAD-ME vs. NADP-ME) on the basis of δ13C. Foliage δ13C varied with seasonal conditions that in turn dictated patterns of growth (and of photosynthate production), and possibly also with the ‘leakiness’ of the bundle sheath cells. However the significant differences present in grazed and ungrazed plots for Astrebla and Themeda, indicate that grazing may result in greater water use efficiency in these semi-arid rangelands. Seasonal patterns of δ15N were highly variable and exhibited little correlation with seasonal patterns of growth and periods of inorganic N uptake. While it is possible that N obtained from sources other than the simple uptake of inorganic N contributed to observed δ15N patterns, there is little additional evidence to support this hypothesis. There was no difference in δ15N between grazed and ungrazed treatments for any of these grasses.

Complex mammal species responses to fire in a native tropical savannah invaded by non-native grader grass (Themeda quadrivalvis)

Invasive non-native grasses can greatly alter habitat structure. Land managers use fire to reduce invasive grass infestations, a strategy which is intended, at least in part, to reduce the impact of wildfires on fauna. The response of fauna to fire in invasive grass environments may be complex. To examine the responses of fauna to fire and invasive grass we compared mammal richness and abundance in a group of 24 replicated sites in north Queensland, Australia. Our sites were characterised by native kangaroo grass, native black spear grass, or invasive, non-native grader grass, and we surveyed them at three times in relation to fire. First, when they had remained unburnt for 2 years (pre-burnt), just after burning (post-burnt), and up to 15 months after burning (revegetated, i.e., the grass had naturally regrown). Therein, we monitored vegetation structure and mammal richness, abundance and assemblage composition. The lowest overall mammal abundances occurred in sites revegetated after fire (40–55 % lower abundances in revegetated compared to pre-burnt sites), but rufous bettongs (Aepyprymnus rufescens) and tropical short-tailed mice (Leggadina lakedownensis) increased in abundance following fire. Abundance of eastern chestnut mice (Pseudomys gracilicaudatus) and common planigales (Planigale maculata) decreased after fire, but returned with returning grass cover. We detected a gradual decline in northern brown bandicoots (Isoodon macrourus) over the course of the study, with no recovery. We found no evidence that mammals showed stronger responses in invasive than native grasses after fire. Mammal responses to fire were distinctive, some species were more abundant following fire, some less, and some species returned to their prior abundances. Thus, in tropical savannahs, a naturally fire-prone system, overall mammal abundance, but not richness, decreased after fires, in both native and non-native grass, but the responses of individual species varied greatly. Decisions to burn invasive grasses for biodiversity conservation should include an awareness of the likelihood of enhancing certain species while discouraging others.

Contributions of AM fungi and soil organic matter to plant productivity in tropical savanna soils under different land uses

Arbuscular mycorrhizal fungi (AM fungi) and soil organic matter (SOM) can be important factors in soil fertility, cycling of nutrients, and plant productivity. It is still unclear whether greater AM fungi abundance is advantageous for plant productivity under nutrient-poor tropical soils despite the relatively common lack of phosphorus (P) and the purported benefit of AM fungi in obtaining and exchanging P with plants for carbon. We explored whether AM fungi and/or SOM augmented plant productivity in different field soils to test the hypotheses that AM fungi were important contributors to plant productivity and that the contribution by AM fungi is higher on soils with lower organic matter and presumably lower nutrient availability compared to soils with higher organic matter. We conducted a factorial experiment in the greenhouse with potted soils of either high or low organic matter (SOM) collected from each of three different land uses; grazed by wildlife in a protected area (Serengeti National Park, Tanzania), grazed by livestock, and cropland. Half the soils were sterilized to remove soil microbes, including AM fungi. Two grass species, Zea mays and Themeda triandra, were grown for 12 weeks in 8 replicates of each soil type and sterilization treatment. About 52.4% and 62.6% of Z. mays roots grown in non-sterilized soils were colonized by AM fungi in low and high SOM, respectively, and 38.1% and 46.7% of T. triandra roots grown in non-sterilized soils were colonized by AM fungi in low and high SOM respectively. Overall, plant biomass of both plant species was significantly higher on control soils than sterilized soils, indicating that AM fungi likely contributed to productivity, and on soils with higher SOM. However, the separate contribution to productivity of SOM and soil microbes varied significantly among plant species and soils from different land uses. Z. mays productivity increased most strongly to higher SOM, and declined with sterilization in agricultural, but not livestock or wildlife grazed soils. In contrast, T triandra production was largely insensitive to SOM or sterilization except on wildlife-grazed soils, where it increased most strongly in unsterilized soils. AM fungi impacts on productivity therefore may be driven more by host plant species than by lower nutrient supply, as associated with lower SOM. Furthermore, efforts to enhance productivity in uncultivated lands should perhaps focus on altering plant species composition, while efforts to enhance productivity in agriculture soils might not depend on beneficial soil microbes or additional fertilizer but instead on effective crop rotations.

Restoration rocks: integrating abiotic and biotic habitat restoration to conserve threatened species and reduce fire fuel load

With rapid urban expansion, biodiversity conservation and human asset protection often require different regimes for managing wildfire risk. We conducted a controlled, replicated experiment to optimise habitat restoration for the threatened Australian pink-tailed worm-lizard, Aprasia parapulchella while reducing fire fuel load in a rapidly developing urban area. We used dense addition of natural rock (30 % cover) and native grass revegetation (Themeda triandra and Poa sieberiana) to restore critical habitat elements. Combinations of fire and herbicide (Glyphosate) were used to reduce fuel load and invasive exotic species. Rock restoration combined with herbicide application met the widest range of restoration goals: it reduced fire fuel load, increased ant occurrence (the primary prey of A. parapulchella) in the short-term and increased the growth and survival of native grasses. Lizards colonised the restored habitat within a year of treatment. Our study documents an innovative way by which conflicts between biodiversity conservation and human asset protection can be overcome.

Do microbial osmolytes or extracellular depolymerisation products accumulate as soil dries?

When dry soil is re-wet there is a pulse of C mineralization. It is likely that the pulse of mineralization is fuelled by soluble C that accumulates as soil is drying. When soil is drying soluble C could accumulate as products of exo-enzyme mediated depolymerisation (i.e. protein amino acids and small carbohydrates) in the extracellular fraction of the soil (i.e. adsorbed and in free solution). Alternatively there could be an accumulation of osmolytes within the microbial biomass. To test whether extracellular depolymerisation products and/or microbial osmolytes accumulate as soil dries, soil from a Themeda triandra grassland was dehydrated and then depolymerisation products and osmolytes were quantified by capillary electrophoresis-mass spectrometry and gas chromatography–mass spectrometry. A secondary aim of this experiment was to determine if the response of soil to drying is the same when soil is dehydrated rapidly in the laboratory as when an intact soil containing plants is slowly dehydrated by withholding water from large (200 L) mesocosms.The responses of soil to dehydration differed between lab incubations and mesocosms, despite involving the same soil being dehydrated to the same final water content. When soil was dehydrated slowly in 200-L mesocosms the accumulation of osmolytes was more quantitatively significant than accumulation of depolymerisation products, whereas when soil was dehydrated more rapidly in lab incubations there was negligible accumulation of osmolytes but large accumulation of depolymerisation products. This study has highlighted that when soil dries the accumulation of osmolytes within microbial biomass and depolymerisation products within the extracellular fraction of soil are both quantitatively important and likely underpin the flush of soil CO2 efflux when dried soil is re-wet.

Short-term responses of reptile assemblages to fire in native and weedy tropical savannah

Fire is frequently used as a management tool to reduce the cover of weeds, to reduce the amount of fuel available for future fires, and to create succession mosaics that may enhance biodiversity. We determined the influence of fire on wildlife, by quantifying reptile assemblage composition in response to fire in a weedy environment characterised by very short-term fire return intervals (<2 years). We used reptiles because they are often understudied, and are only moderately vagile compared to other vertebrates, and they respond strongly to changes in vegetation structure. We repeatedly sampled 24 replicate sampling sites after they had been unburned for two years, just prior to burning (pre-burnt), just after burning (post-burnt), and up to 15 months after burning (revegetated) and monitored vegetation structure and reptile richness, abundance and assemblage composition. Our sites were not spatially auto-correlated, and were covered by native kangaroo grass (Themeda triandra), black spear grass (Heteropogon contortus), or an invasive weed (grader grass, Themeda quadrivalvis). Reptile abundance and richness were highest when sites had been unburned for 2 years, and greatly reduced in all areas post burning. The lowest reptile abundances occurred in sites dominated by the weed. Reptile abundance and richness had recovered in all grass types 15 months after burning, but assemblage composition changed. Some species were present only in before our focus fire in native grass, and their populations did not recover even 15 months post-burning. Even in fire-prone, often-burnt habitats such as our study sites, in which faunal richness and abundance were not strongly influenced by fire, reptile assemblage composition was altered. To maintain faunal biodiversity in fire-prone systems, we suggest reducing the frequency of prescribed fires, and (if possible) excluding fire from weedy invasions if it allows native grasses to return.

A plant traits approach to managing legacy species during restoration transitions in temperate eucalypt woodlands

Degraded communities often contain a subset of the species that comprised the predisturbance community. These represent an important legacy of the predisturbance state, yet restoration treatments may be detrimental to them. This study examined the potential of leaf traits and life form to predict whether restoration treatments can maintain legacy swards of Austrostipa bigeniculata (hereafter Austrostipa) while controlling exotic annuals in temperate eucalypt woodlands. Treatments included carbon addition to reduce soil nitrate, both with and without burning or pulse grazing to deplete exotic seed pools. We compared leaf traits of Austrostipa with a native grass (Themeda triandra) known to be advantaged, and 8 exotic annual species known to be disadvantaged by these treatments. Leaf traits indicated potentially greater negative impacts of carbon addition on exotic annuals compared to Austrostipa, and on Austrostipa compared to Themeda, suggesting a net restoration benefit. Similarly, burning or pulse grazing is expected to have little negative impact on perennial resprouting grasses (hemicryptophytes; Austrostipa and Themeda) compared with annual exotics (therophytes) with short-lived seed banks. Treatment responses were largely consistent with predictions: treatments that significantly reduced exotic annuals had no net disadvantage to Austrostipa swards despite significant reductions in Austrostipa seedling growth with carbon addition. Indeed by Year 3, Austrostipa mortality in untreated plots led to 46% lower Austrostipa abundance than in treated plots at one site, potentially due to litter build-up or other mechanisms. We conclude that plant traits provide a useful framework for designing restoration transitions that retain native legacy species while controlling exotics.