Innovation in plant and soil sciences to tackle critical global challenges

Anno 2024 we live with > 8 billion people on planet Earth, all in need of food, energy, clean water, air and a home. Despite all our technical innovations humans remain critically dependent on natural resources, yet we consuming these faster than they can regenerate and thereby cross our planetary boundaries. We urgently need to shift to sustainable consumption and production to enable conservation and regeneration of natural habitats and to ensure a habitable planet for future generations. To do so we need to (re)value biodiversity, conserve indigenous knowledge and manage our ecosystems wisely. Innovations in plant and soil science can play an important role in this, in combination with technological advances, ecological knowledge and socio-economic inclusion. In this talk I will explore traditional and high-tech innovations to promote synergies between natural resource use, biodiversity conservation and soil, plant and human health.

Studies on the ecology of urban systems tend to focus on the big cities, yet many urban areas comprise smaller towns where urbanness may influence ecosystem functions differently to larger cities. Moreover, ecosystem processes operate across very wide spatial scales, including the potential to be influenced by the landscape context, and this makes it imperative to identify mechanisms driving ecosystem processes in urban areas. These gaps make it hard to e.g. restore systems, not least because our understanding of mechanisms below ground in soil are also poorly resolved. Here I present findings from current projects seeking to understand how urbanness affects ecosystem processes, including those in soil, across multiple scales from within an individual greenspace to the UK, and where active restoration programmes have been implemented.

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Urban horticulture (UH) is increasingly recognised for its potential to sustainably increase local food security and support the delivery important environmental and socio-cultural benefits. However, unlike conventional horticultural production, UH production is small-scale and is managed by individual growers. This variation in management may impact the sustainability of growing and crop productivity. In addition, urban soils can be contaminated with high levels of heavy metals which could pose a risk to human health. Here, we use a combination of citizen science, crop and soil analysis and GIS in UH systems at a UK scale to quantify national food production, explore the potential risks of growing fruits and vegetables in cities and how growing practices at a small-scale impacts on crop nutrient concentrations. Our research demonstrates that UH currently makes a small, but important contribution to local food security with potential to greatly expand production in existing greenspaces without risk to human health from soil contamination.

Plants hold solutions to the global challenges we face. Botanic gardens unite science, conservation, and education, at a time when it has never been more important to engage people with the importance of plants to people and planet. This talk will explore the role of botanic gardens in the 21st century with a focus on the work of the University of Oxford Botanic Garden and Arboretum which spans biomimetics (applications of plant adaptations in technology), conserving under-represented plant groups, and engaging local communities with natural capital. Green spaces are fundamental to the brain health and wellbeing of a growing population. Botanic gardens, rooted historically in plant-based medicine, have a future role in human healing – and a vital one.

A major barrier to improving global food security is the availability of suitable land for horticulture. Urban areas offer potential, but their soils often accumulate pollutants like zinc due to unregulated use of manures and pesticides. The impact of zinc on soil health and soil-borne plant symbiotic microbes, such as arbuscular mycorrhizal fungi (AMF), is not well understood. Our study investigated the effect of environmentally relevant zinc concentrations on AMF's role in plant nutrient uptake. We found that while all plants were successfully colonised by the fungus, higher zinc levels significantly reduced phosphorus transfer from fungi to plants and carbon movement from plants to fungi. These findings suggest that although urban horticulture could enhance local food production and address food security, the impacts of soil contaminants such as zinc need to be considered to maximise the potential of urban soils.

Soils are dynamic systems that exist within an equilibrium influenced by their surroundings. Mycorrhizal fungi are sensitive to both above and belowground disturbances. These fungi are crucial for decomposition, nutrient cycling, and plant productivity, playing distinct roles in these landscapes. Limited methods for studying these fungi challenge our ability to understand their response to disturbance and their roles in ecosystem recovery. This talk will discuss trends in mycorrhizal fungal communities at various scales following disturbances, focusing on their implications for ecosystem restoration and their roles post-fire. By enhancing our understanding of how fungi respond to disturbances and the variables driving these responses, we can improve predictions of community assembly and structure across different environments. A fundamental understanding of the variation (or lack thereof) in fungal strategies, community composition, and their functions is essential to manage these fungi and their host plants across environments and disturbance regimes.

Emerging contaminants, such as pharmaceuticals, are inadvertently released into agricultural systems following the use of materials such as wastewater, biosolids and manure to meet crop nutrient and irrigation demands. Following targeted monitoring campaigns, we have identified a suite of human use pharmaceuticals and veterinary medicines in wastewater irrigated and biosolid/manure amended soils in the UK. Identified contaminants are diverse in nature (i.e. various therapeutic classes) and observed at a range of concentrations. However as monitoring campaigns typically focus on a small number of chemicals (~50) due to the availability of analytical methods, very little is known about the fate and accumulative potential of the hundreds of pharmaceuticals currently in use. A novel modelling approach was therefore developed which utilised high-resolution mass spectrometry datasets to identify pharmaceuticals in effluents and coupled this to a model framework to predict the accumulative potential of a pharmaceutical in wastewater irrigated crops based on chemical structure alone. Following this approach a prioritised list of pharmaceuticals was identified and a risk evaluation undertaken.

The application of synthetic fertilisers and pesticides has significantly enhanced the productiviy of agricultural systems, ensuring that crops receive essential nutrients and experience minimal damage from pests and diseases. However, a heavy reliance on these inputs is environmentally unsustainable. Alternative approaches are necessary to maintain agricultural productivity while fostering positive environmental outcomes. The potential benefits offered by the relationship between plants and arbuscular mycorrhizal (AM) fungi is well-known, yet so much of the ecology of this association remains poorly understood, limiting its application in agriculture. Here our work shows the crucial role of AM fungal community composition in enhancing crop benefits from this symbiosis. We explore how varying factors such as nutrient availability and crop species influence these dynamics, and that a greater focus on the community assembly of AM fungi in agricultural contexts may provide new insights.

As the impacts of climate change become more damaging, the need for ambitious mitigation strategies becomes more urgent. Enhancing the ability of the terrestrial biosphere to store carbon has great potential in terms of mitigation, but less attention has so far been given to evaluating potential unintended consequences on the Earth system. Using cutting-edge modelling and measurement techniques, the Val Martin group at Sheffield investigates the possible side-effects of forest expansion, enhanced rock weathering, and wetland restoration on processes from radiative forcing, to air quality, to water storage. I will present results from across our research programme, highlighting the need for extensive evaluation to ensure safe deployment of these strategies.

Rising atmospheric CO2 concentrations are significantly impacting the global terrestrial biosphere through indirect climate effects and direct effects on plant performance. In tree-dominated ecosystems, long-term monitoring suggests CO2 fertilization enhances tree productivity. However, in tropical savannas, which cover ~20% of the Earth’s land surface and contribute to ~30% of terrestrial net primary production, equivalent long-term analyses of CO2 responses in C4 savanna grasses are lacking, leaving net outcomes for tree-grass dynamics, fire regimes and carbon storage unclear. By combining a meta-analysis of CO2-addition experiments, 32 years of in situ field observations from Kruger National Park, South Africa, and vegetation simulations via the Community Land Model, we show a clear and consistent result: CO2-fertilization of wild C4 grasses is widespread, especially in dry conditions. The implications of C4 grass CO2 fertilization for future carbon storage and savanna ecosystem function will be discussed.

Plants exhibit a remarkable ability to modify their growth and development in response to environmental signals and stresses. This ability is particularly striking during root development where they forage in highly heterogeneous environments. I will describe how plant hormones enable roots to sense and/or respond to soil environmental signals. Examples include discovering how plants sense soil moisture availability by linking intercellular water fluxes with movement of hormones auxin and ABA, triggering changes in root branching designed to maximise capture of soil resources (Orosa et al, 2018, Science; Mehra et al, 2022, Science). Plant roots also employ volatile signals like ethylene to sense changes in soil physical properties like compaction stress using a novel gas diffusion based mechanism (Pandey et al, 2021, Science). I will conclude by describing how mechanistic insights about hormone-regulated root plasticity, combined with advances in technologies including single cell expression profiling, are helping design stress resilient crops.