Context Empirical studies of intraspecific genetic diversity and population structure can inform the evolutionary and demographic history of individual species and of landscapes at the bioregional level. Aims We aimed to assess intraspecific genetic variation at macroevolutionary and microevolutionary temporal scales for Mirbelia viminalis, a key species present on the Hamersley Range in the ancient and highly diverse landscape of the Pilbara bioregion of northwest Western Australia. Methods We sampled extant populations and assessed diversity and structure using sequences (chloroplast DNA, 1759 base pairs) and microsatellite markers (nuclear DNA, 15 loci) data. Key results Significant phylogeographic structure and a lack of historical demographic signals of population contraction or expansion suggest historical population persistence. Moderate chloroplast haplotype diversity (h = 15) and moderate divergence among extant haplotypes indicates a degree of historical connectivity via seed dispersal across central populations on the Hamersley Range. Levels of nuclear genetic diversity were low to moderate (allelic richness = 3.554, expected heterozygosity = 0.489, observed heterozygosity = 0.462) and depauperate compared to another member of the Mirbelia genus present further south in the Midwest region. Nuclear diversity revealed a strong signal of isolation by distance with localised admixture among populations and some contemporary genetic clustering along a north-west to south-east transect of the Hamersley Range. Conclusions Low nuclear genetic diversity may be related to recent reductions in population size for M. viminalis. Historical population persistence with few barriers to dispersal other than geographic distance may be common for members of the Fabaceae across the Hamersley Range.

Vegetation classification systems form a base for conservation management and the ecological exploration of the patterns and drivers of species’ distributions. A standardised system crossing administrative and geographical boundaries is widely recognised as most useful for broad-scale management. The Queensland Government, recognising this, uses the Regional Ecosystem (RE) classification system and accompanying mapping as a state-wide standardised vegetation classification system. This system informs legislation and policy at local, state and national levels, underpinning decisions that have wide-ranging implications for biodiversity and people’s livelihoods. It therefore needs to be robust from a scientific and legal perspective. The current approach in the RE system for identifying vegetation communities relies on expert-based class definition procedures. This is in contrast to best practice, which is based on quantitative procedures. This paper discusses the RE system in a global context and outlines the updated approach that incorporates quantitative class definition procedures, synthesises the research behind the updated approach and discusses its implications and implementation.

This paper presents insights from long-term monitoring into the dynamics of savanna plant species composition, specifically on the ground layer. Key questions are (1) how much variation is there from year to year in plant species abundance and composition? And (2) is there evidence of directional change in community composition? Five sites were located near Mareeba, north-eastern Australia, and sampled 18 times with fixed 500-m2 plots at the annual peak of plant species richness over 23 years. The sites were located in eucalypt communities across an altitudinal range of 460 m. Sampling involved systematic searching of all plant species visible above ground. The results show variation from year to year among satellite herbaceous species, with more than 50% of grasses and forbs observed at a given site only being detected at half or fewer of the 18 samplings. Herbaceous composition did not show clear signs of directional change relative to inter-annual variability. Over the 23 years, there were three very dry periods and 4 very wet years. Rainfall variation affected total cover more than plant species composition or richness. Several fires and episodes of grazing affected ground cover but did not have a lasting impact on cover or diversity. The cover and composition of the ground layer is consistently dominated by the core perennial grasses Themeda triandra Forssk. and Heteropogon triticeus (R.Br.) Stapf, with many species collectively contributing minimally to the overall cover but significantly to richness. Many herb species are persistent long-lived perennials which do not appear above ground every year. The number of naturalised plants in the ground layer was consistently low. Overall, the ground layer communities appear to be very stable in these woodlands that have been burnt 3–5 times in 23 years. High inter-annual variability of subdominant species is consistent with other studies, and emphasises the need for replication in time in ecological sampling.

Serrated tussock (Nassella trichotoma (Nees) Hack. ex Arechav) is an unpalatable grass species that has been expanding in its native range and invading non-native ranges. In this study in its natural environment, we aimed to describe the spatial relationship between seed density, the cover and density of standing individuals of serrated tussock, the seasonal variation in the seed density in the soil seed bank, and to compare these results with those reported in non-native ranges. We took soil samples seasonally and recorded the cover and density of standing individuals of serrated tussock at two sites in the native Pampas grasslands in central-east Argentina. Seed density was evaluated by seedling emergence and seed extraction. Seed density showed a seasonality trend, with maximum values in the end of summer and minimum values in winter and spring. Seed density was independent of the cover and density of standing individuals of serrated tussock. The values of seed density were lower than those reported in the invaded ranges. Since seeds of serrated tussock are present in the seed bank regardless of the cover and density of its standing individuals, the maintenance of a high cover of desirable species may play a key role in preventing the establishment of serrated tussock in both its natural and invaded ranges.

Mapping vegetation communities requires considerable investment in field data collection, analysis and interpretation. The methods for data collection and analysis can significantly affect field time and the accuracy of the classifications. We test the ability of field data subsets and data pre-treatments to reproduce an intuitively derived vegetation classification within the Australian tropical savanna biome. The data subsets include all strata, upper strata, ground strata, and tree basal area. A range of multivariate techniques were used to describe patterns in the datasets as they related to the a priori vegetation classification. We tested the degree of floristic correlation among the data subsets and the extent to which several data transformations (square root, fourth root, presence or absence) improved the level of agreement between the numerically and the intuitively derived mapping units. Our results implied high redundancy in sampling both basal area and upper strata species cover, and the ground stratum was poorly correlated with the upper stratum. Across all statistical tests, the groups derived from analysis of square root-transformed upper stratum cover data were closely aligned with the expert classification. We propose that a numerical approach using an optimal dataset will produce a meaningful classification for vegetation mapping in poorly known Australian tropical savanna.

The objective of this 3-year study was to investigate the relationships between soil salinity and ecophysiological responses of C3 and C4 native plant species around Lake Altham and Lake Coyrecup (both are salt lakes in Western Australia), and to evaluate their potential for use in the remediation of salt-affected soils. Three shrubs (Atriplex vesicaria, Tecticornia lepidosperma and T. indica) that grew in highly saline soil of average Na concentration greater than 300 mM had higher leaf δ13C and δ15N ratios. These species also had higher Na-to-K and Na-to-Ca ratios in both their leaves and stem xylem sap, indicating that these species accumulate high amounts of sodium in their tissues. In contrast, tree species Eucalyptus loxophleba, Casuarina obesa and Acacia acuminata grew in soil of average Na concentration of less than 100 mM and had lower values of δ15N, δ13C, Na content, and Na-to-K ratio in their leaves. These species also had lower xylem Na-to-K and Na-to-Ca ratios. Seasonal effects were observed in leaf total N content, leaf Na, xylem sap Na-to-K ratio and xylem sap Na-to-Ca ratio. Strong and significant positive correlations (r > 0.75; P < 0.01) were observed between soil Na concentration and ecophysiological responses, such as leaf Na contents, leaf δ15N, xylem sap Na, xylem Na-to-K ratio and xylem Na-to-Ca ratio. Overall, Atr. vesicaria, T. lepidosperma, T. indica and Santalum acuminatum are good candidates for remediation of highly saline soils.

For Haloxylon ammodendron – a typical succulent xerophyte that accumulates Na+ to resist drought stress– the use of a Na-compound fertiliser (NaCF) at small scales could increase drought resistance. In this study we compared the effects of NaCF, NP (with N and P contents the same as in NaCF), diammonium phosphate (DP), and a control (C) on growth of H. ammodendron in the Alashan Desert regions of China. Results indicated that NaCF significantly increased plant height (PH) by 56, 27 and 12%, main root length (MRL) by 72, 60 and 45%, dry weight (DW) of whole plant by 291, 124 and 89%over the C, NP and DP treatments respectively in the nursery. NaCF also significantly improved drought resistance of H. ammodendron in large-scale desert afforestation, where it increased PH by 4.6 and 1.8 cm plant–1, main root length (MRL) by 4.5 and 4.1 cm plant–1, and DW by 17.9 and 15.9 g plant–1 compared with the C and DP treatments respectively. Furthermore, compared with the seedlings treated with DP in the nursery and in the desert afforestation, seedlings treated with NaCF resulted in water saving potentials of 50 and 33% respectively. These findings indicate that NaCF could be beneficial if widely applied in eco-restoration of the degraded vegetations in desert regions of China.

Context It has been proposed that the distribution of resprouter and seeder Erica in the Cape Floristic Region (CFR) of South Africa is determined by drought rather than by fire frequency. Seedlings of Erica seeders are predicted to withstand the mild droughts of the southwest CFR better than those of Erica resprouters, which would account for the abundance of seeders in this region. Aims This study aimed to test this hypothesis using Erica coccinea (L.), which contains both a resprouter and a seeder form. Methods One-year-old seedlings of both forms were subjected to a progressively severe 50-day drought in the greenhouse. Key results Contrary to expectations, seeder seedlings had 67% higher mortality than resprouters during the initial phase of drought (30% vs 18% after 32 days). However, both forms were unable to survive as the drought progressed, resulting in 95% mortality by Day 50. There were limited differences between the forms in gas exchange and water potential, and no difference in root:shoot ratios. However, resprouters had significantly higher soluble carbohydrates than did seeders, which may have aided in delaying mortality. Conclusions Our results showed no evidence of resprouter seedlings being more vulnerable to mild drought than seeders in E. coccinea. Implications Our findings challenge the hypothesis that the distribution of this species can be explained by the vulnerability of resprouter seedlings to mild drought.

Some of the largest remaining fragments of the Atlantic rainforest are affected by acid rain. Knowing the responses of its native plant species to acidity may be crucial to use them as bioindicators in affected areas. We tested the effects of pH 3.0 simulated acid rain on the stem of Libidibia ferrea (Mart. ex Tul.) L.P. Queiroz var. leiostachya (Benth.) L.P. Queiroz (ironwood, “pau-ferro”). Visual symptomatology consisted in dark spots on the stem that initiated on and irradiated from lenticels. As they grew larger, adjacent spots coalesced, conferring a blackened aspect to a large extension of the organ. Anatomically, the damage started with hypertrophy and increased accumulation of phenolic compounds in the outermost cell layers of the young, still subepidermal cork, which is what conferred the blackened aspect to the stem. In addition, epidermal cells showed turgor loss and ultimately collapsed, resulting in alteration of cell shape and a consequent alteration of epidermal relief. The stem of L. ferrea var. leiostachya was shown to be a more sensitive organ to the impacts of acid rain than the leaf. The dark spots visualised on the stem may be a promising macroscopic marker to be used in the biomonitoring of acid rain.

The significant impacts of the introduced plant pathogen Phytophthora cinnamomi on native Australian vegetation have been well documented, but there is less knowledge of long-term effects. We assessed long-term (26 years) disease progression and impacts on vegetation floristics and structure at a heathy woodland site in the Great Otway National Park, eastern section. Disease progressed dramatically between 1989 and 2005 and by 2015 only 0.08% of the site was non-diseased. There were significant declines in plant species richness and numbers of susceptible species; and increases in percentage cover of resistant sedges and grasses overall, and in cover of Leptospermum continentale (prickly tea-tree) in post-disease areas. There were significant declines of Xanthorrhoea australis (Austral grass-tree), a keystone species that contributes greatly to vegetation structure and fauna habitat. There is an urgent need to map the distribution of P. cinnamomi affected vegetation and identify floristically important non-diseased vegetation in the national park. It is imperative that quarantine of non-infested areas, phosphite application, track closures and vehicle wash-downs be implemented to reduce disease extension and protect the significant biodiversity of the region including species rich heathlands and nationally listed threatened plant and fauna species and their habitats.