This report presents the results and findings of the first phase of the Forestry Commission’s Tree Roots and Archaeology project. The project phase was a collaboration between Oxford Archaeology (OA) and the Forestry Commission, funded...
moreThis report presents the results and findings of the first phase of the
Forestry Commission’s Tree Roots and Archaeology project. The project
phase was a collaboration between Oxford Archaeology (OA) and the
Forestry Commission, funded by the Nature for Climate Fund.
The Phase 1 study aimed to investigate heritage and forestry professionals’
preconceptions and practical experiences of the relationship between
tree roots and archaeological remains. It coincides with the UK
government’s commitment to significantly increase woodland cover
across England to meet the net zero target and biodiversity goals
(Environment Act 2021), which will raise the incidence of tree planting in
areas of archaeological significance. In this context, and bearing in mind
the urgency of tackling the global environmental emergency, it is
essential that archaeologists and forestry professionals scrutinise their
current practices and priorities and build a strong evidence base to guide
new tree planting policies relating to the historic environment.
A range of sources were consulted in building this report, including
published research, online reports, data held in the Archaeology Data
Service (ADS) Library, and heritage and forestry practitioners themselves
(via questionnaires and interviews). The findings are summarised in the
main report chapters and illustrated with case studies.
The key findings are:
The current approaches to tree planting in areas of archaeological interest
are largely built on anecdotal evidence that derives from ‘worst case
scenarios’ where tree roots have damaged archaeology. This view has only
been reinforced by the lack of specific detailed field-based research.
Direct investigations of the relationship between tree roots and
archaeology are rare. Where these have been undertaken, the findings are
complex. The character of the relationship between tree roots and
archaeology, including the degree of damage caused, depends on a
range of context specific factors and the type of archaeological remains.
There is clear evidence that tree roots do sometimes damage archaeology
by displacing and diminishing the preservation of artefacts and ecofacts,
blurring stratigraphic relationships, altering the soil matrix and burial
environment and making areas inaccessible for further archaeological
study. These impacts are primarily localised and unlikely to negatively
affect the overall archaeological interpretation of the site.
The level of impact of new tree planting on archaeology needs to be
assessed on a case-by-case basis. Afforestation will not be appropriate on
all archaeological sites. However, it is likely that past approaches to tree
planting in areas of known archaeological interest have overplayed and
oversimplified the detrimental impacts of tree roots on archaeology.
Trees also contribute positively to archaeology by enhancing peoples’
experiences of archaeological sites, by facilitating the conservation of
upstanding earthworks (helping to stabilise slopes, prevent soil erosion,
and discourage anti-social behaviour), by curbing other more damaging
forms of land use (e.g. ploughing) and by preventing shrub/fern
establishment. In the past, woodland creation has incorporated many
archaeological sites and monuments within programmes of long-term
land management and these have often been shown to be better
preserved than archaeological remains under different land uses or
management schemes.
Approaches to tree planting in areas of known archaeological interest are
already changing. New ‘sensitivity mapping’ methods incorporating
Historic Environment Record (HER) and LiDAR data are being developed,
which will help practitioners to identify the location of archaeological
features and to determine their broad significance (Last and Kidd 2023).
The concept of ‘adaptive release’ – the idea that, in undertaking urgent
nature restoration measures, it is sometimes necessary to manage
positively the dynamic transformation of heritage assets rather than to
stick fixedly to outdated conservation measures built on a thin evidence
base (DeSilvey et al. 2021) – presents a useful working framework for
developing future policies for tree planting in areas of archaeological
interest.
Overall, the presence of archaeology should not be seen as a prohibitive
block to new tree planting schemes. In the right areas, and with the right
planting regimes, it can be seen as a positive step in helping to protect
archaeological sites, whilst contributing to valuable biodiversity, carbon
capture and environmental goals. However, archaeology should be
considered and balanced alongside other ecological and environmental
factors, ideally on a site-by-site basis.