This PhD will examine how woodland creation influences below-ground biodiversity, soil stabilisation, long term carbon sequestration, nutrient cycling, and the time-scales required for the development of these processes. In addition, it will enable us to understand how the below-ground soil function and biodiversity relates to overall forest biodiversity, ecosystem services and resilience.
Background and project aims: Approximately a quarter of all living species are found in soils. The soil biota (microbes, fungi and fauna) underpin functions which provide essential ecosystem services such as carbon and nutrient cycling, critical for primary production and human food security. The ectomycorrhizas, the symbiotic organs at the interface between tree roots and fungi, are the main sites of nutrient and water exchange and link between soils and trees, thus a vital part of the belowground diversity and tree resilience. Intensive farming practices often impact negatively on soil biodiversity leading to concerns over agricultural sustainability.
Agri-environment schemes provide financial support to farmers to implement measures that will benefit wildlife and agricultural sustainability. However, currently, little is known about the development of soils functions and biodiversity following restoration efforts such as the creation of woodlands and agroforestry systems.
In this project, the student will examine changes in soil properties and below-ground biodiversity of mesofauna and ectomycorrhizal fungi (ECM) in particular resulting from woodland creation over the last 160 years. Sampling will take advantage of sites that are part of an existing long-term natural experiment to assess the impact of historic land use change on current aboveground biodiversity (The WrEN project; http://www.wren-project.com
). A three-way comparison of farmed land, secondary woodlands (10-150 years from establishment on the former farmed land) and ancient woodlands will be made to test the following hypotheses:
1. Taxonomic and functional diversity of soil biota (mesofauna and ECM) increase from actively farmed land to those under woodlands of increasing age and size.
2. The soil physical structure and its biogeochemical properties and functions change significantly from actively farmed land to those under woodlands of varying characteristics.
3. There are strong linkages between ECM fungal communities, diversity and functions with soil function and above-ground biodiversity.
Methods: Site selection: Over the last five years, data on woodland characteristics, the surrounding landscape, and aboveground biodiversity has been collated from over 130 secondary and ancient broadleaf woodland sites in Scotland and England as part of the WrEN project. Sites for this PhD will be selected based on soil type, age and size to a chronosequence of secondary woodlands alongside farmed land and ancient woodland sites for comparison.
Pilot data has been collected by Forest Research comparing soil chemical properties and earthworm communities in 21 secondary and ancient woodlands and adjacent farmland in England; these data will be used to guide the sampling design for the studentship. Samples will then be analysed for key soil chemicals, physical and biological properties (e.g. soil mesofauna, ECM). Soil mesofauna will be identified using taxonomic keys. ECM fungi will be analysed by Genomic DNA methods using Sanger DNA sequencing of the full internal transcribed spacer (ITS) amplicon from individual ectomycorrhizas to maximize resolution of identifications, obtain relative abundance data and link DNA sequences directly to morphology, following previously published standardized sampling/analyses protocols. Existing WrEN data will be used to enable the relationships between soil properties, and below and above-ground biota to be quantified.
Application of results: This is a very timely project given the current UK policy focus on woodland expansion. Findings from this work will provide critical scientific evidence to inform policy, relating to woodland creation targets, biodiversity, GHG mitigation policies and soil conservation.
Student training: It is anticipated that the student will spend approximately one month per year working with researchers based at Forest Research, the research agency and the main research provider for the Forestry Commission. In addition to project-specific skills in taxonomic ID, molecular methods, sampling and laboratory analyses, the student will gain insights into understanding and formulating policy relevant research questions, skills for interdisciplinary research and the process of translating research into guidance and advice.