Plant-soil feedbacks as drivers of seedling establishment in tropical and sub-tropical forests

Lead Research Organisation: University of Manchester
Department Name: Earth Atmospheric and Env Sciences


This Pump-Priming proposal builds specifically on our NERC research in tropical forests, as well as other NERC and RCUK funding, to develop a new collaboration with a leading Chinese research group (led by Prof Yu at Sun Yat-sen University, Guangzhou) to generate outstanding research on how plant-soil feedbacks mediate seedling establishment and tree diversity in sub-tropical forests. Our proposal takes advantage of Prof Yu's high-impact research findings on tree seedling recruitment with our own mechanistic approaches used to understand the ecology of mycorrhizal fungi, which are globally prevalent and key symbionts in these forests. The proposal will enable PI-researcher exchanges to design field experiments, first, to interrogate existing datasets on plant community composition and soil properties, and second, to devise field experiments to test in situ ideas developed previously either in pot-based experiments, or in grassland. Specifically, we will use unique field experimental facilities and data made available by Prof Yu to test how mycorrhizal type and mycorrhizal fungal hyphal networks facilitate seedling establishment. Moreover, integration of field experiments with existing unique datasets on soil and plant properties (led by Prof Yu), together with application of cutting-edge isotope tracers (led by Prof Johnson) will make a step-change in understanding how soil biota influences seedling establishment in realistic conditions. The Pump Priming proposal will provide the ground-work for development of new collaborative research proposals, as well as generating exciting new synthetic datasets and outputs. The durability of the collaboration will be aided immediately by significant investment from our partners, including allocation of Chinese-funded research studentships to further develop our findings and ensure continuity beyond the lifetime of the proposal.

Planned Impact

This proposal concerns gaining a greater understanding of how seedlings are recruited in sub-tropical and tropical forests. The focus is on the interactions between plants, root symbionts and soil properties. Our work will generate new knowledge that will inform new ecological theory and provide important insights to help conservationists. We will extend the impact plan of the current NERC project that this IOF is affiliated with. Specifically, our project will build on the activities of the related NERC Discovery grant, but include more focus on Chinese forest systems, which are globally hugely important. We will help understand the mechanisms that maintain the remarkable richness of tree species found in pristine tropical forests, and also encourage conservation organisations to have broad perspectives on how to conserve these keystone ecosystems by appreciating plant-soil feedbacks. Because it impacts on several aspects of tropical forest ecology and sustainability it will be of interest to a broad range of end-users and stakeholders.

1. Politicians in China and the UK who seek to find a balance between timber production and forest sustainability

We will interact with key provincial Chinese agencies, notably the Guangdong Province Forestry Department, who are charged with conserving and managing forest services, see
They have an active afforestation policy and our work will be of direct relevance to this aim. We will use our local collaborators to influence conservation and management programmes through invitation of key staff to the Heishiding Nature Reserve including during our research exchange visits to China. We will organise presentations and round-table discussions to illustrate the key findings from our work, and how these can be translated to management practices.

2. Private sector companies who seek to exploit tropical forests for commercial reasons

Examples: Sustainable timber production from forests is dependent on maintenance of functioning biogeochemical cycles that are themselves heavily reliant on plant-microbial interactions. Although the role and importance of mycorrhizal interactions will not be well-known to timber producers, they will be understood by technical staff in forest nurseries who generate seedlings for re-planting programmes. To reach this audience we will target training in mycorrhizal inoculation techniques for staff of the nurseries that supply seedlings for large-scale rehabilitation of degraded logged forests.

3. National and international organisations who have remits for conservation of tropical diversity, e.g. WWF, International Mycological Association, International Union for Conservation of Nature.

Examples: We are already active in the IUCN's Species Survival Commission, and our research will therefore inform the development of conservation assesments and advice that feeds into the international conservation policy agenda. Data on the identity, role and conservation status of tropical fungi are currently very limited, therefore the new data from our project will achieve a high profile in discussions around conservation policy for tropical fungi. Indirectly, our work will also be relevant to the needs of those with interests in understanding the causes and importance of plant diversity more generally, including the UK Biodiversity Research Advisory Group (UK BRAG) who highlight the urgent need to understand the link between plant and microbial functional diversity.

4. The general public through educational activities associated with the project (see Pathways to Impact)


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Description We have forged strong collaboration with The Ecology group at Guangzhu University that has initiatated 2 visits already, and 3 month research stay for three visiting Chinese PhD students. Through our collaboration, we have co-written two papers relating to seedling establishment in subtropical forests. These findings show two general outcomes: 1) that the mycelium of underground mycorrhizal fungi promotes the establishment of trees that typically dominate the canopy, but not for trees that are mainly found in the understorey. 2) that soil pathogens negtaively affect seedling growth but these effects are counteracted when communities had high phylogenetric diversity (that is, how related the seedlings were relative to each other).

We have also analysed how tree root traits respond to phosphorus limitation and availability in ectomycorrhizal and arbuscular mycorrhizal systems.

• Soil phosphorus availability regulates the growth and survival of plants in many subtropical and tropical forests, but the mechanisms under-pinning these effects are unclear, which limits our ability to adequately understand plant community dynamics in these systems.
• Here, we conducted a field survey and manipulative experiment in a subtropical forest to investigate how root functional traits, mycorrhizal colonization and putative pathogenic fungal infection of arbuscular and ectomycorrhizal tree seedlings respond to gradients of soil phosphorus (P).
• In the field, arbuscular mycorrhizal seedling roots were more heavily infected by pathogenic fungi compared to ectomycorrhizal seedling roots, while the opposite was seen for mycorrhizal colonisation. In the manipulative experiment, colonisation of seedlings by mycorrhizal fungi was enhanced, and infection by pathogenic fungi was reduced, when P availability in soil was low. Root functional traits, including root-to-shoot ratio and root branching intensity, of arbuscular and ectomycorrhizal plants showed opposite trends in their response to P availability.
• Our findings suggest arbuscular and ectomycorrhizal seedlings have contrasting strategies to deal with P limitation: arbuscular mycorrhizal plants produce more fine roots, while ectomycorrhizal plants invest in mycorrhizal colonisation to deal with soil P limitation whilst also reducing the likelihood of pathogen infection. These contrasting strategies may regulate interspecific competition and contribute to the stable coexistence of different types of mycorrhizal plants within communities.

We made a major discovery that common mycorrhizal networks have key roles in shaping seedling establishment grwoth and fitness. Our findings show that ectomyccorhizal networks from surrounding adult trees have significant posiitve effects on compatible seedlings but thi sis not seen in arbuscular mycorrhizal networks. Our findings provide critical mechanistic insight explaining coexistence in forests and plant soil feedback. There is a battle going on betweeen mutualistic fungi and pathogenic fungi, and for ectomycorrhizal fungi, the battle is being won.
Exploitation Route The work has potential importance for conservation efforts. For example, the importance of both underground fungal networks and phylogenetic diversity need to be considered when promting seedling establishment (for exampe for forest restoration projects and conservation efforts)
Sectors Environment

Description Public Talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Public/other audiences
Results and Impact Talk to the Cheshire Wildlife Trust on mycorrhizal fungi
Year(s) Of Engagement Activity 2018