The promotion of afforestation and forest restoration frequently cites the benefits of woodland to water quality, carbon sequestration and biodiversity. Here our postgraduate community describe research that is delving into the complexity of whether these expected benefits can be achieved. Our final piece describes the production of a parliamentary briefing which summarises the necessity to adapt nature conservation approaches to climate change. The research encompassed here contributes to designing future landscapes that can cope with change and deliver benefits to society.
Trade-offs and synergies in ecosystem service provision of different spatial configurations of trees on farms at both a farm and a landscape scale
Sally Westaway, Postgraduate Researcher at the Royal Agricultural University and the University of Reading
To achieve ‘net zero’ greenhouse gas emissions by 2050 the Climate Change Committee recommend increasing afforestation rates to at least 30,000 hectares per year across the UK by 2025, as well as establishing agroforestry on 10% of farmland. UK agricultural holdings cover around 71% of the land mass, the remaining 29% is either mostly already wooded or is unsuitable for afforestation. Therefore, significant areas of tree planting on existing agricultural land will be necessary to achieve ‘net zero’. Since the publication of the 2011 UK National Ecosystem Assessment, the ecosystem services (ES) approach has become widely adopted and UK policy objectives for afforestation aim for ‘multiple benefits’. However, there is limited spatially-explicit evidence for the effect of afforestation on more than one ES at a time or the interactions between these services (Burton et al., 2018; Firbank et al., 2013). The current drivers and targets for woodland creation are almost exclusively focused on carbon sequestration, which sets up a conflict between tree planting for carbon benefits, land use for food production and maintenance of biodiversity. My PhD research investigates the impact of increasing farmland tree cover on these three interacting ES at both a farm and a landscape scale.
Case study farms will be used to collect field data and farm production data to give baseline of current ES provision of trees on farms. Data from the case study farms will be combined with national datasets and will feed into farm level assessments of public goods provision (e.g. Gerrard et al. 2011) and Life Cycle Analysis (LCA) to generate a series spatially explicit enhanced tree cover scenarios optimized for different outcomes. Farmer acceptability of the different tree cover scenarios will then be tested in farmer workshops with mapping used as a visual communication tool to consult on land change scenarios. Workshop results can then be used in decision making processes at a farm and a landscape scale to help to inform wider tree planting initiatives.
Farm level results from the scenario testing will be scaled up to a regional or catchment level. The spatial modelling approach will build on existing woodland opportunity maps (e.g. Terra Sulis, 2020), and habitat connectivity models (e.g. Correa Ayram et al., 2016), adding the agricultural context and data to allow the trade-offs and synergies between different ecosystem services to be included. LCAs will allow multiple comparisons and LCA outputs will feed back into the spatial model. This model will increase our understanding of the interactions between agricultural production and trees and allow comparisons of different tree cover scenarios on agricultural land at a farm and landscape scale.
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Burton et al. (2018) Forest Ecology and Management, 430(April), 366–379
Gerrard et al. (2011) OCIS Public Goods Tool Development, Report for Defra.
Correa Ayram et al. (2016) Progress in Physical Geography, 40(1), 7–37.
Firbank et al. (2013) Agriculture, Ecosystems and Environment, 166, 65–75.
Terra Sulis (2020). Opportunity Woodland Mapping in England
The legacy of former land use on nutrient cycling in forest soils
Caitlin Lewis, Postgraduate Researcher at the University of Reading
Periods of great societal change have historically driven shifts in woodland cover and management practices across Great Britain. From the Black Death to the Industrial Revolution, timber demand and subsequently forest cover has ebbed and flowed with population trends and technological advancements (Rackham, 2010). Perhaps the most influential drivers of woodland changes in modern history were the World Wars. The alarming depletion of timber supplies during WW1 triggered the formation of the Forestry Commission in 1919, which then initiated large-scale planting of non-native coniferous plantations on non-forested land. This continued after WW2, then with an interest in also replacing some native woodlands, including ancient woodlands, with forestry plantations. Today, conifers account for 51 % of the 3.24 million hectares of woodland in the UK (Forest Research, 2022).
Coniferous plantations were linked to negative effects on water quality via elevated levels of nitrate leaching in the late 1980s and 1990s, exacerbated by high levels of atmospheric N pollution resulting from agricultural intensification and traffic pollution during this time period (Gundersen et al., 2006). For part of my PhD, I extracted data from published literature to assess how former land use affects the ability of European coniferous and broadleaved soils to retain N entering the ecosystem. Our analysis found that forests planted on former arable, heathland and plantation soils differed in their ability to retain N-inputs, potentially due to variations in the content of other nutrients between these soils.
As interests in modern forest management broaden to incorporate the provision of ecosystem services including improved biodiversity, many plantations, especially plantations on ancient woodland sites (PAWS), are being restored to native broadleaved species. Using Thetford Forest as a case study, the second part of my PhD is investigating how converting coniferous plantations to broadleaved species affects nitrate leaching. We are testing the hypothesis that the conversion process will stimulate soil microbial activity and increase nitrate leaching within the first few decades, a legacy of the former plantation. This research quantifies the implications of changing forest management on groundwater quality and will be important to consider when planning afforestation and forest restoration in Great Britain.
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Rackham, O (2010) Chapter 3, Outline of Woodland History, In: Woodlands. 4th edn. London: William Collins.
Forest Research (2022) Chapter 1: Woodland Area and Planting, In: Forestry Statistics 2022. Available: https://www.forestresearch.gov.uk/tools-and-resources/statistics/forestry-statistics/forestry-statistics-2018/woodland-areas-and-planting/national-forest-inventory/woodland-area-by-species-broadleaves/
Gundersen, P., Schmidt, I.K., Raulund-Rasmussen (2006) Leaching of Nitrate from Temperate Forests- Effects of Air Pollution and Forest Management. Environmental Reviews, 14, 1-57.
“Climate Adaptation for Nature”: Writing a POSTnote for the Parliamentary Office for Science and Technology
Wilson Chan, Postgraduate Researcher at the University of Reading
As part of a fellowship scheme funded by the SCENARIO Doctoral Training Partnership, I was fortunate enough to work with the Parliamentary Office for Science and Technology (POST) last year to produce a parliamentary briefing on climate change and nature recovery. The POSTnote, titled “Climate Adaptation for Nature”, was co-authored with POST’s environment advisor, Dr. Jonathan Wentworth. POSTnote topics are selected based on their relevance to the parliamentary agenda, which means that PhD fellows, who commonly lead POSTnote development, are not typically assigned a topic aligned with their PhD research. As my PhD research is focused on the hydrological impacts of climate change in the UK, the ecological focus of this POSTnote required much background learning in a short period of time.
The POSTnote summarised the impacts of climate change on terrestrial, marine and freshwater species and outlined options for nature to adapt to the changing climate. The briefing was based on a review of the scientific literature and interviews with a wide range of stakeholders. Over the three-month fellowship, I interviewed around 30 stakeholders, from academic researchers to practitioners in conservation organisations and policymakers in government departments of each devolved nation. I also attended the IaleUK Postgraduate Workshop on Local Nature Recovery Strategies (LNRS) which featured excellent discussion on UK biodiversity and nature restoration policies and ways to ensure their success in the future.
The published POSTnote highlights the need for conservation strategies and targets to consider the impacts of climate change, e.g. geographic distribution shifts, if they are to achieve their stated aims. This includes the UK Government’s ambition to protect 30 % of land and sea by 2030 (30x30) and to reverse the decline in UK biodiversity. As climate change progresses, management approaches may need to shift from preserving historical or current conditions to accommodating new species and facilitating transition to a new ecosystem state. Past and current strategies for climate adaptation can include creating heterogenous ecosystems for wildlife, improving habitat connectivity, restoring degraded ecosystems, and assisted species migration.
Find out more in the published, peer reviewed POSTnote here: https://post.parliament.uk/research-briefings/post-pn-0679/