The Science-Living Collections Continuum in Botanic Gardens

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Preparing for the worst: Utilizing stress-tolerant soil microbial communities to aid ecological restoration in the Anthropocene

1. Multiple drivers of environmental change pose a significant challenge for ecological restoration, including climate change, soil salinization and environmental pollution. Due to the important role that soil biota play in enabling plants to cope with a variety of abiotic stressors, there is growing interest in the use of microbial inoculations to facilitate native plant restoration in the face of such change. 2. Recently, novel methods have begun being explored in agriculture to harness stress-conditioned soil biota for improving abiotic stress tolerance in crop species. Similar applications in ecological restoration – where plants are inoculated with indigenous soil microbial communities that are preconditioned to various abiotic stressors – could potentially increase our capacity to restore degraded ecosystems under global change. 3. In this paper, we aim to (1) outline the ways in which soil microbial communities might be conditioned in order to confer greater stress tolerance to plants that are targets for restoration; (2) highlight successful (and unsuccessful) examples where stress-tolerant soil microbial communities were utilized to improve plant performance; (3) describe the ways in which stress-conditioned soil biota could be deployed in order to assist ecological restoration; and (4) discuss the potential risks and outstanding questions associated with such an approach. 4. If restoration practitioners are able to harness the soil microbiome to improve plant stress tolerance as is currently being explored in agriculture, this could revolutionize methods for the restoration of degraded lands in the Anthropocene

Climate and soil factors influencing seedling recruitment of plant species used for dryland restoration

Land degradation affects 10–20% of drylands globally. Intensive land use and management, largescale disturbances such as extractive operations, and global climate change, have contributed to degradation of these systems worldwide. Restoring these damaged environments is critical to improving ecosystem services and functions, conserve biodiversity, and contribute to climate resilience, food security, and landscape sustainability. Here, we present a case study on plant species of the mining intensive semi-arid Pilbara region in Western Australia that examines the effects of climate and soil factors on the restoration of drylands. We analysed the effects of a range of rainfall and temperature scenarios and the use of alternative soil materials on seedling recruitment of key native plant species from this area. Experimental studies were conducted in controlled environment facilities where conditions simulated those found in the Pilbara. Soil from topsoil (T) stockpiles and waste materials (W) from an active mine site were mixed at different proportions (100% T, 100% W, and two mixes of topsoil and waste at 50 : 50 and 25 : 75 ratios) and used as growth media. Our results showed that seedling recruitment was highly dependent on soil moisture and emergence was generally higher in the topsoil, which had the highest available water content. In general, responses to the climate scenarios differed significantly among the native species which suggest that future climate scenarios of increasing drought might affect not only seedling recruitment but also diversity and structure of native plant communities. The use of waste materials from mining operations as growth media could be an alternative to the limited topsoil. However, in the early stages of plant establishment successful seedling recruitment can be challenging in the absence of water. These limitations could be overcome by using soil amendments but the cost associated to these solutions at large landscape scales needs to be assessed and proven to be economically feasible

Plant scientists' research attention is skewed towards colourful, conspicuous and broadly distributed flowers

Despite the perception that plant science focuses on strictly scientific criteria, this analysis finds that there is an aesthetic bias in regards to which plants, based on certain traits, receive more research attention. Scientists' research interests are often skewed toward charismatic organisms, but quantifying research biases is challenging. By combining bibliometric data with trait-based approaches and using a well-studied alpine flora as a case study, we demonstrate that morphological and colour traits, as well as range size, have significantly more impact on species choice for wild flowering plants than traits related to ecology and rarity. These biases should be taken into account to inform more objective plant conservation efforts.Peer reviewe

The relative performance of sampling methods for native bees: an empirical test and review of the literature

Many bee species are declining globally, but to detect trends and monitor bee assemblages, robust sampling methods are required. Numerous sampling methods are used, but a critical review of their relative effectiveness is lacking. Moreover, evidence suggests the relative effectiveness of sampling methods depends on habitat, yet efficacy in urban areas has yet to be evaluated. This study compared the bee community documented using observational records, targeted netting, mobile gardens, pan traps (blue and yellow), vane traps (blue and yellow), and trap-nests. The comparative surveys of native bees and honeybees were undertaken in an urbanized region of the southwest Australian biodiversity hot spot. The outcomes of the study were then compared to a synthesis based on a comprehensive literature review of studies where two or more bee sampling methods were conducted. Observational records far exceeded all other methods in terms of abundance of bees recorded, but were unable to distinguish finer taxonomic levels. Of methods that captured individuals, thereby permitting taxonomic identification, targeted sweep netting vastly outperformed the passive sampling methods, yielding a total of 1324 individuals, representing 131 taxonomic units—even when deployed over a shorter duration. The relative effectiveness of each method differed according to taxon. From the analysis of the literature, there was high variability in relative effectiveness of methods, but targeted sweep netting and blue vane traps tended to be most effective, in accordance with results from this study. However, results from the present study differed from most previous studies in the extremely low catch rates in pan traps. Species using trap-nests represented only a subset of all potential cavity-nesters, and their relative abundances in the trap-nests differed from those in the field. Mobile gardens were relatively ineffective at attracting bees. For urbanized habitat within this biodiversity hot spot, targeted sweep netting is indispensable for obtaining a comprehensive indication of native bee assemblages; passive sampling methods alone recorded only a small fraction of the native bee community. Overall, a combination of methods should be used for sampling bee communities, as each has their own biases, and certain taxa were well represented in some methods, but poorly represented in others

Elucidating the surface geometric design of hydrophobic Australian Eucalyptus leaves: experimental and modeling studies

Three Australian native Eucalyptus species, i.e., Eucalyptus woodwardii, Eucalyptus pachyphylla and Eucalyptus dolorosa, were investigated, for the first time, with respect to the hydrophobicity of their leaves. It is well established that these leaves exhibit exceptionally high water repellency, in addition to an extraordinary ability to retain water, albeit their specific wetting mechanisms are still poorly understood. To identify the critical factors underlying this phenomenon, the surface topography of these leaves was subjected to micro-examination (SEM). Micro- and nanometer scale surface roughness was revealed, resembling that of the quintessential “lotus effect”. Surface free energy analysis was performed on two models based on the surface topographies of the study Eucalyptus species and lotus, in order to study wetting transitions on these specific microscopic surface features. The influence of surface geometrical parameters, such as edge-to-edge distance, base radius and cylindrical height, on surface free energy with different liquid penetration depths was studied with these two models. Larger energy barriers and smaller liquid-solid contact areas were more influential in the calculations for the lotus than for Eucalyptus. The information obtained from these two models may be useful for guiding the design of novel artificial surfaces in the collection and transport of micro-volume liquids. © 2019 The Author

Machine learning regression model for predicting honey harvests

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Honey yield from apiary sites varies significantly between years. This affects the beekeeper’s ability to manage hive health, as well as honey production. This also has implications for ecosystem services, such as forage availability for nectarivores or seed sets. This study investigates whether machine learning methods can develop predictive harvest models of a key nectar source for honeybees, Corymbia calophylla (marri) trees from South West Australia, using data from weather stations and remotely sensed datasets. Honey harvest data, weather and vegetation-related datasets from satellite sensors were input features for machine learning algorithms. Regression trees were able to predict the marri honey harvested per hive to a Mean Average Error (MAE) of 10.3 kg. Reducing input features based on their relative model importance achieved a MAE of 11.7 kg using the November temperature as the sole input feature, two months before marri trees typically start to produce nectar. Combining weather and satellite data and machine learning has delivered a model that quantitatively predicts harvest potential per hive. This can be used by beekeepers to adaptively manage their apiary. This approach may be readily applied to other regions or forage species, or used for the assessment of some ecosystem services

Seed quality and the true price of native seed for mine site restoration

Native seed underpins the success of most terrestrial restoration efforts globally; however, the fragility of the native seed supply chain presents a key challenge to achieving global restoration goals. With the current heightened global focus on ecological restoration, seed supply chains are under unprecedented pressure worldwide. New and practical solutions are required to help the native seed industry move toward more sustainable and reliable supply, and in turn, facilitate more cost-effective, successful, seed-based restoration. Here we focus on species used in biodiverse mine site restoration in two regions of Western Australia as a test case for evaluating two key elements of the seed supply chain: seed quality and price. The study assessed seed quality in 185 species, then combined these results with seed price to determine the actual cost of pure live seeds (PLS) used in restoration. Average seed quality, expressed as a weight percentage of PLS, is 55%. The average price for a native seed batch across 129 species is $1,093 Australian dollars (AUD)/kg, and when adjusted for viability and purity is$2,600 (AUD)/ kg of PLS. We suggest replacing the traditional approach of pricing seed per unit weight ($/kg) with a new method that would reflect seed quality and unit number; price per thousand pure live seeds ($ TPLS). We posit that this new way of pricing native seeds would increase transparency and information flow in the marketing of native seeds, which will, in turn, enable seed users to more reliably plan for, and evaluate the cost-effectiveness of seed-based restoration projects

Stockpiling disrupts the biological integrity of topsoil for ecological restoration

Purpose: Biotic and abiotic properties of soils can hinder or facilitate ecological restoration, and management practices that impact edaphic factors can strongly influence plant growth and restoration outcomes. Salvaged topsoil is an invaluable resource for mine-site restoration, and a common practice is topsoil transfer from mined areas to restoration sites. However, direct transfer is often not feasible, necessitating storage in stockpiles. We evaluated the effects of topsoil stockpiling on plant performance across diverse ecosystems impacted by mining throughout Western Australia. Methods: We conducted a bioassay experiment using a widespread native Acacia species to assess how topsoil storage might impact plant growth, physiology, and nodulation by N-fixing bacteria using soils from native reference vegetation and stockpiled soils from six mine sites across Western Australia. Results: Plant responses varied across mine sites, but overall plants performed better in soils collected from native vegetation, exhibiting greater biomass, more root nodules, and higher water-use efficiency compared to those grown in stockpiled soils. Soil physiochemistry showed few and minor differences between native soils and stockpiles. Conclusion: Results strongly suggest observed differences in plant performance were biotic in nature. This study highlights the negative effects of topsoil storage on the biological integrity of soil across diverse ecosystems, with important implications for mine-site restoration; our results show that topsoil management can strongly influence plant performance, and stockpiled soils are likely inferior to recently disturbed topsoil for restoration purposes. We also use this study to illustrate the utility of bioassays for assessing soil quality for ecological restoration

Changes in soil microbial communities in post mine ecological restoration: Implications for monitoring using high throughput DNA sequencing

The ecological restoration of ecosystem services and biodiversity is a key intervention used to reverse the impacts of anthropogenic activities such as mining. Assessment of the performance of restoration against completion criteria relies on biodiversity monitoring. However, monitoring usually overlooks soil microbial communities (SMC), despite increased awareness of their pivotal role in many ecological functions. Recent advances in cost, scalability and technology has led to DNA sequencing being considered as a cost-effective biological monitoring tool, particularly for otherwise difficult to survey groups such as microbes. However, such approaches for monitoring complex restoration sites such as post-mined landscapes have not yet been tested. Here we examine bacterial and fungal communities across chronosequences of mine site restoration at three locations in Western Australia to determine if there are consistent changes in SMC diversity, community composition and functional capacity. Although we detected directional changes in community composition indicative of microbial recovery, these were inconsistent between locations and microbial taxa (bacteria or fungi). Assessing functional diversity provided greater understanding of changes in site conditions and microbial recovery than could be determined through assessment of community composition alone. These results demonstrate that high-throughput amplicon sequencing of environmental DNA (eDNA) is an effective approach for monitoring the complex changes in SMC following restoration. Future monitoring of mine site restoration using eDNA should consider archiving samples to provide improved understanding of changes in communities over time. Expansion to include other biological groups (e.g. soil fauna) and substrates would also provide a more holistic understanding of biodiversity recovery