Seed conservation is vital for restoring wild species, as seeds often mature in the dry season, while restoration happens in the rainy season. Limited seed biology knowledge hampers these efforts. Thus, this study evaluated the storability of thirteen tropical rainforest species from Sri Lanka. Effect of storage at 25, 8 and -20 °C on seed viability and vigour was determined. Seed viability retained 100
Background: Podocarpus drouynianus is an ecologically unique, taxonomically distinct range-restricted gymnosperm that occurs exclusively within Mediterranean woodlands in the south-west of Western Australia. Limited information is known about this species regarding seed dormancy, germination, and seed desiccation sensitivity. Aims: This study aimed to determine whether P. drouynianus seeds possess dormancy, quantify the responses of seeds to a range of incubation temperatures and examine seed desiccation sensitivity (i.e. recalcitrance) after exposure to different conditions to understand recruitment dynamics in a seasonally dry environment and ex situ seed storage. Methods: Fresh diaspores (seeds enclosed within an indehiscent epimatium) were collected upon maturity for experimentation. Diaspores and extracted seeds were assessed for viability, moisture content and embryo size with a subset of diaspores placed at various incubation temperatures to investigate germination response. Additional diaspores were placed under a range of storage conditions and assessed regularly for viability, moisture content and germination. Results: Upon hydration, fresh diaspore germination commenced rapidly (similar to 5 days) at several temperatures with maximum germination (0.88 germination proportion) achieved at 15 degrees C or 20 degrees C. Seeds were found to have morphological dormancy as embryos grew prior to radicle emergence. Fresh diaspores and seeds had a high moisture content ( > 56% - fresh weight basis) and viability (0.96 viability proportion) which declined to 45% MC and 0.75 viability proportion following storage for 42 days at 5 degrees C and 10% eRH. Conclusions: Podocarpus drouynianus diaspores germinate readily over a broad range of temperatures but were found to lose viability due to desiccation sensitivity when placed in either a cool (5 degrees C) dry environment (similar to 10% eRH) for 42 days or in warm (25 degrees C) ambient (similar to 40% eRH) conditions for 60 to 90 days. These findings are crucial for informing potential management strategies for P. drouynianus, particularly as the climate warms and dries across the south-west Australian biodiversity hotspot.
Soil is a huge carbon (C) reservoir, but where and how much extra C can be stored is unknown. Current methods to estimate the maximum amount of mineral-associated organic carbon (MAOC) stabilized in the fine fraction (clay + silt, < 20 μm $$ <20\;\upmu \mathrm{m} $$ ) fit through the MAOC versus clay + silt relationship, not their maxima, making their estimates more uncertain and unreliable. We need a function that 'envelopes' that relationship. Here, using 5089 observations, we estimated that the uppermost 30 cm of Australian soil holds 13 Gt (10-18 Gt) of MAOC. We then fitted frontier lines, by soil type, to the relationship between MAOC and the percentage of clay + silt to estimate the maximum amounts of MAOC that Australian soils could store in their current environments, and calculated the MAOC deficit, or C sequestration potential. We propagated the uncertainties from the frontier line fitting and mapped the estimates of these values over Australia using machine learning and kriging with external drift. The maps show regions where the soil is more in MAOC deficit and has greater sequestration potential. The modelling shows that the variation over the whole continent is determined mainly by climate, linked to vegetation and soil mineralogy. We find that the MAOC deficit in Australian soil is 40 Gt (25-60 Gt). The deficit in the vast rangelands is 20.84 Gt (13.97-29.70 Gt) and the deficit in cropping soil is 1.63 Gt (1.12-2.32 Gt). Management could increase C sequestration in these regions if the climate allowed it. Our findings provide new information on the C sequestration potential of Australian soils and highlight priority regions for soil management. Australia could benefit environmentally, socially and economically by unlocking even a tiny portion of its soil's C sequestration potential.
This study investigates the germination requirements of 12 plant species native to the Argyle region of the east Kimberley, a biodiverse monsoonal tropical region characterized by high temperatures, high evaporation, and episodic seasonal rainfall. The research involved quality assessment of mature seeds, followed by dormancy alleviation and laboratory‐based germination to determine the responses of seeds to a range of temperatures (5–40°C) in terms of germination speed (T10), mean germination time, and maximum germination proportion. Data were then modeled to calculate the optimal temperature to support germination for each species. The results showed that germination rapidly commences in response to a wide range of temperatures typical of the wet season (November–February) in the east Kimberley, though germination for most species was still high (>50%) after exposure to temperatures as low as 15°C. Mean optimal temperature for germination across all species was 25.8 ± 1.5°C, with minimal variation between most species, the exception being Dodonaea physocarpa , which preferred cooler temperatures (Topt = 14.0°C). The speed of germination was also rapid (T10 = 1–3 days) across all species at the optimal germination temperature. The findings suggest that temperature is not a limiting factor for germination in this region and that the onset and intensity of the wet season are the most significant factors determining successful germination, emergence, and seedling establishment. The study underscores the importance of species‐specific understanding of environmental temperatures required for seed germination in seed‐based restoration efforts and informs the planning of direct seeding works, thus enhancing restoration outcomes.
Over the last 6 million years, the arid Australian Eremaean Zone (EZ) has remained as dry as it is today. A widely accepted hypothesis suggests that the flora and fauna of arid regions were more broadly distributed before aridification began. In Australia, this process started around 20 million years ago (Ma), leading to gradual speciation as the climate became increasingly arid. Here, we use genomic data to investigate the biogeography and timing of divergence of native allotetraploid tobaccos, Nicotiana section Suaveolentes (Solanaceae). The original allotetraploid migrants from South America were adapted to mesic areas of Australia and recently radiated in the EZ, including in sandy dune fields (only 1.2 Ma old), after developing drought adaptations. Coalescent and maximum likelihood analyses suggest that Nicotiana section Suaveolentes arrived on the continent around 6 Ma, with the ancestors of the Pilbara (Western Australian) lineages radiating there at the onset of extreme aridity 5 Ma by locally adapting to these various ancient, highly stable habitats. The Pilbara thus served as both a mesic refugium and cradle for adaptations to harsher conditions, due to its high topographical diversity, providing microhabitats with varying moisture levels and its proximity to the ocean, which buffers against extreme aridity. This enabled species like Nicotiana to survive in mesic refugia and subsequently adapt to more arid conditions. These results demonstrate that initially poorly adapted plant groups can develop novel adaptations in situ, permitting extensive and rapid dispersal despite the highly variable and unpredictable extreme conditions of the EZ.
The effective and efficient monitoring of revegetation outcomes is a key component of ecosystem restoration. Monitoring often involves labour intensive manual methods which can be difficult to deploy when sites are inaccessible or involve large areas of revegetation. This study aimed to identify plant species and quantify α-diversity index on a sub-meter scale at Manlailiang Mine Site in Northwestern China using unmanned aerial vehicles (UAVs) as a means to semi-automate large-scale vegetation monitoring. UAVs equipped with multispectral sensors were combined with three industry-standard supervised classification algorithms (support vector machine (SVM), maximum likelihood, and artificial neural network) to classify plant species. Spectral vegetation indices (NDVI, DVI, VDVI, SAVI, MSAVI, EXG - EXR) were used to assess vegetation diversity obtained from on-ground survey plot data (Margalef, Pielou, Simpson, Shannon indices). Our results showed that SVM outperformed other algorithms in species identification accuracy (overall accuracy 84%). Significant relationships were observed between vegetation indices and diversity indices, with DVI performing significantly better than many more commonly used indices such as NDVI. The findings highlight the potential of combining UAV multispectral data, spectral vegetation indices and ground surveys for effective and efficient fine-scale monitoring of vegetation diversity in the ecological restoration of mining areas. This has significant practical benefits for improving adaptive management of restoration through improved monitoring tools.
Aim: Dispersal and environmental filtering processes affect plant species colonisation success on islands and can be identified by functional traits. However, the lack of synthesis about the different methodological approaches in functional ecology hampers generalisation of filtering processes across island systems.LocationSeventy islands of the Houtman Abrolhos archipelago, Western Australia.Major Taxa StudiedAngiosperms.Methods: We (i) apply a simple, conceptual framework based on the mean and variability of individual functional traits in plant assemblages to identify species filters on islands, (ii) illustrate how trait distributions of island assemblages change in relation to island area and their source pool, (iii) compare distributions of individual traits to multivariate functional diversity indices and trait spaces and (iv) provide guidelines to detect a signal of trait filtering in island floras.Results: The island assemblages showed evidence for selective filters operating on seed mass and marginally on leaf area but not on plant height. Mean and variability of seed mass differed to those of the source pool indicating selective forces operating between source pool and island assemblages, especially on smaller islands. Multivariate functional diversity indices and trait spaces failed to reveal filtering processes acting on the island assemblages and insights into the putative processes.Main Conclusions: Using the mean and variability of individual traits in plant assemblages provides direct information on the trait composition of island floras and the processes involved beyond what can be inferred from multivariate functional diversity indices or trait spaces. We used islands as their distinct boundaries and relatively simple sets of species provide good research models, but joint analyses of trait means and variability should also be applicable to understand filtering processes in isolates and habitat fragments on mainlands.
For the last six million years, the arid Australian Eremaean Zone (EZ) has been as dry as today. An accepted hypothesis, applied to arid regions worldwide, suggests that flora and fauna were more broadly distributed before aridification began. In Australia, this aridification process started around 20 million years ago (Mya), leading to gradual speciation processes via vicariance as the climate became increasingly arid. Here, we use genomic data to investigate the biogeography and timing of divergence of native allotetraploid tobaccos, Nicotiana section Suaveolentes (Solanaceae), which putatively entered the EZ 5 Mya. The original allotetraploid migrants from South America were adapted to mesic areas of Australia and putatively radiated recently in the EZ, including sandy dune fields (only 1.2 My old), after developing drought adaptations. Based on coalescent and maximum likelihood analyses designed to corroborate timing of the Australian radiation independently, arrival of Nicotiana section Suaveolentes on the continent occurred approximately 6 Mya, and ancestors of the Pilbara (Western Australian) lineages radiated there at the onset of extreme aridity 5 Mya by locally adapting to these various ancient, highly stable habitats. The Pilbara thus served as both a mesic refugium and cradle for adaptations to harsher conditions. This dual role is due to its high topographical diversity, providing microhabitats with varying moisture levels, and its proximity to the ocean, which buffers against extreme aridity. Consequently, species like Nicotiana have been able to survive in mesic refugia during arid periods and subsequently adapt to more arid conditions. These results demonstrate that initially poorly adapted plant groups can develop novel adaptations in situ, permitting extensive and rapid wide dispersal despite the highly variable and unpredictable extremes of heat and drought in the EZ. ### Competing Interest Statement The authors have declared no competing interest.
The International Principles and Standars for the Ecological Restoration and Recovery of Mine Sites were used to assess the restoration quality of one of the world's largest mines, located in the world's most biodiverse temperate forest. Quantitative analysis of longitudinal data spanning 35 years scored restoration quality at 2-stars against a 5-star forest ecosystem restoration target, with little indication of improvements from adaptive management. Two-thirds of indicator plants were significantly under-represented in early-stage restoration and declined with age. Most plant species were effectively absent, including key structural species. Invasive plants and native legumes were persistently overabundant. Time required for the maturation of tree species will prevent the production of fundamental ecosystem features for well over a century (e.g. hollows and fallen logs), inhibiting functional fauna return (reptiles, bats, and conservation priority cockatoos in particular). The significantly different outcome compared with previous assessments is due to the age of restoration assessed and previous assumptions that early-stage success indicate that restoration is on the correct, prolonged trajectory toward full ecological restoration. However, previous assessment methods did not consider many key metrics of the standards, nor accurately predict future restoration trajectory. In particluar, initial plant species richness (the only measure of biodiversity in the company's restoration completion criteria) did not reflect future restoration quality. These substandard restoration outcomes may result from removing the deep, multi-layered bauxitic substrate on which the ecosystem evolved and establishing restoration on shallow topsoil over a more homogenized, impervious substrate. This study demonstrates the value of a robust, adaptable multi-factor framework and methodology to evaluate restoration outcomes.
Animal pollinators are vital for the reproduction of ~90% of flowering plants. However, many of these pollinating species are experiencing declines globally, making effective pollinator monitoring methods more important than ever before. Pollinators can leave DNA on the flowers they visit, and metabarcoding of these environmental DNA (eDNA) traces provides an opportunity to detect the presence of flower visitors. Our study, collecting flowers from seven plant species with diverse floral morphologies, for eDNA metabarcoding analysis, illustrated the value of this novel survey tool. eDNA metabarcoding using three assays, including one developed in this study to target common bush birds, recorded more animal species visiting flowers than visual surveys conducted concurrently, including birds, bees, and other species. We also recorded the presence of a flower visit from a western pygmy possum; to our knowledge this is the first eDNA metabarcoding study to simultaneously identify the interaction of insect, mammal, and bird species with flowers. The highest diversity of taxa was detected on large inflorescence flower types found on Banksia arborea and Grevillea georgeana. The study demonstrates that the ease of sample collection and the robustness of the metabarcoding methodology has profound implications for future management of biodiversity, allowing us to monitor both plants and their attendant cohort of potential pollinators. This opens avenues for rapid and efficient comparison of biodiversity and ecosystem health between different sites and may provide insights into surrogate pollinators in the event of pollinator declines.
The submerged aquatic carnivorous plant Aldrovanda vesiculosa (Droseraceae) is threatened by rapid deterioration of wetlands and oligotrophic lake habitats. Its native distribution spans four continents, but many historic populations are now extinct. Previous genetic studies found distinction between populations from Australia and those from the rest of the world, but due to limited genetic markers, neither detailed phylogenetic relationships nor the migration routes of A. vesiculosa populations were revealed. We used a de novo assembly of the A. vesiculosa mitochondrial genome and a previously published plastid genome as references for mapping short DNA sequence reads from 17 globally distributed populations. Phylogenetic trees were constructed based on detected polymorphisms. Genetic diversity of both the mitochondrial and plastid genome was low (Pi 0.55 x 10(-4) and 0.7 x 10(-4), respectively). Greater polymorphisms were found in the mitochondrial compared with the plastid genome, owing to its larger size (1.27 Mb). Australian populations formed a monophyletic clade in both plastid and mitochondrial trees, while the mitochondrial tree also distinguished populations from southern and northern Europe. Aldrovanda vesiculosa likely migrated to Australia and Africa from a southern European refuge during the last interglacial period similar to 100,000 years ago. When the last glaciation started, some populations could have survived in eastern Europe and moved north, when the continental glacier retreated. Aldrovanda vesiculosa experienced repeated population bottlenecks that reduced its genetic diversity.
Context In ecosystems where rainfall is episodic or highly seasonal, plant recruitment from a soil-stored seed bank occurs during periods of elevated soil moisture conducive to germination and seedling establishment. The release of seed dormancy in response to environmental conditions has significant consequences for the temperature window over which germination occurs, and as such the timing of germination can vary between years. Aims We aimed to understand in seeds of two species of Rutaceae, Diplolaena dampieri and Rhadinothamnus anceps, how dormancy loss and germination timing is influenced by warm stratification. Methods We tested the germination response to temperatures between 5 and 30°C following increasing durations (1–12 and 4–12 weeks) of warm stratification at 20, 25, or 30°C. Key results Warm stratification for 1–8 weeks at 30°C progressively alleviated seed dormancy in D. dampieri and R. anceps, increasing germination proportion from ~0.1 to ~0.5 in both species. Stratification duration was optimal at 30°C for between 4 and 8 weeks depending on species. Warm stratification was not affected by water stress down to −0.8 Mpa. Application of aerosol smoke did not significantly improve germination, and heat treatments had a negative effect on final germination proportion. Conclusions As dormancy was progressively alleviated, the range of temperatures that support germination increased for D. dampieri and decreased for R. anceps, allowing for confirmation of type 1 and type 2 non-deep physiological dormancy (PD), respectively. Implications Arising from this conclusion, we suggest that in Mediterranean climates, type 1 and 2 PD dictate risk-taking and risk-avoiding ecological strategies by shifting the thermal requirements for germination towards that characteristic of the early- or mid-germination season. Classification of non-deep PD may offer a structured approach to predict how temperature requirements shift during dormancy loss, which will provide insight into seed germination response to year-to-year variation in seasonal environmental conditions.
In this study, we focused on understanding key storage traits of seeds from Macrozamia fraseri, an unusual though important species that is impacted by mining. To support current restoration activities, large amounts of seed from M. fraseri have been regularly collected and stored for up to 8 years under standard seed banking conditions (5 degrees C and 20% relative humidity), though in situ recruitment from directly sown seed is poor. To investigate the underlying constraints to germination on demand, we set out to assess the viability of M. fraseri seeds that had been stored in a restoration seed bank from 6 to 66 months. Seed moisture content (MC) (fresh weight basis) was also determined for seeds with different storage histories to ascertain whether M. fraseri seeds display traits (i.e. high MC) that might suggest non-orthodox seed storage behaviour. The youngest seed accession (6 months old) was found to have a high MC (45.8 +/- 5.4%-fresh weight basis), and >50% viability. In comparison, older (>30 months old) accessions were observed to have a marked reduction in both seed MC (10-35% MC) and viability (0-29.4%). While preliminary, we conclude that M. fraseri seeds appear to lose viability during conventional storage with younger accessions displaying both a higher seed MC and viability, compared to accessions stored for longer. Given the significance of these results, future research activities are recommended to better understand the interplay between seed MC and storage environment and how this relates to the seasonally dry Mediterranean climate where this species naturally occurs. As well, storage and propagation approaches are proposed to increase success when using M. fraseri for conservation and restorative activities.
Open science is vital to the interdisciplinary field of ecology due to its integrative nature and use of longitudinal datasets that build upon earlier data collections. To highlight the importance of open science in the rapidly growing discipline of restoration ecology, we conducted a “computational reproducibility” assessment of a publication on a mining restoration program spanning several decades and over 250 km 2 in a global biodiversity hotspot. Open data and code provided alongside the original publication were assessed for consistency with the results and conclusions of the original publication, as were potential limitations in findings due to the methodology. The impacts of inconsistencies and limitations were qualitatively assessed against the key findings from the publication and data were reanalyzed where impacts were potentially significant. Of the six inconsistencies and limitations identified, two had a significant impact on 5 of the 11 key findings of the original publication and one new key finding was made. The impact of this is of high ecological significance as the findings related to key restoration parameters: species richness (similarity of species richness between forest and 25‐year‐old restoration), functional diversity (correlation of species richness and functional diversity), and the restoration trajectory (long‐term trends and restored areas' resilience to disturbance). These outcomes highlight the importance of open data and the value of detailed third‐party data reviews, particularly in restoration ecology which relies on research findings to inform decision‐making and policy and drive adaptive management.
Cochlospermum fraseri ('Kapok', Bixaceae) is a deciduous tree widely distributed throughout semi-arid and monsoon tropical northern Australia, and an important species for ecological restoration in the region. We aimed to better understand the seed biology and ecology of C. fraseri to determine the mechanisms by which seed dormancy might be alleviated, and the conditions that support germination to inform the use of this species in restoration. Dormancy breaking treatments (wet heat, dry heat, scarification) commonly applied to species with physical seed dormancy (PY) were tested along with stratification at 5-35 degrees C (nine treatments). Following dormancy alleviation, seeds were germinated at nine temperatures (5 to 40 degrees C) and five water potentials (0 to -0.8 MPa) to understand environmental thresholds that regulate germination physiology in non-dormant seeds. A proportion of seeds (<0.3) lose dormancy naturally in response to warm (25 to 35 degrees C) moist conditions, which dislodges the hypostase plug that prevents water uptake, whilst neither dry (>= 100 degrees C) nor wet (similar to 100 degrees C) heat were effective. Dormancy loss was also achieved by exposing seeds to concentrated (95-98% v/v) sulphuric acid for 3-7 hours, after which high proportions (>0.75) of germination were observed. Cochlospermum fraseri seeds possess PY, which is alleviated by seasonal temperatures that occur when soil moisture is high, allowing seeds to employ a risk-adverse strategy and maximize establishment success in episodic environments with stochastic rainfall events. The understanding of dormancy alleviation requirements gained here adds to our knowledge of PY worldwide and recruitment dynamics in the Australian monsoonal tropics and will aid land managers and restoration practitioners by informing both seeding sites and optimal time for in situ sowing as well as the potential capacity of this species to form a persistent soil seed bank.