We record vegetation dynamics both by manual and digital photography surveys of 1 m2 quadrats. We also measure growth increments of ling heather (Calluna vulgaris). The major vegetation types observed at the sites are: heather (Calluna) dominated shrub vegetation, sedge (Eriophorum spp.), some rush near stream areas, Sphagnum and other moss cover, the latter with a large component of Hypnum jutlandicum and Campylopus spp. In 2012, before mowing or burning, sites were characterised by similarly tall heather stands (~35 cm) with notably low plant diversity (ca. 8 or 14 species per 1 x 1 m plot areas and across the entire 5 x 5 m monitoring plots, respectively). The total cover was dominated by dense Calluna cover (~70%) with further considerable cover of about 20% by cotton-grass sedges (Eriophorum sp.) and further additional cover of 10% Sphagnum moss and 30% other moss. Overall a very typical cover for heather-dominated upland hill blanket bog. All sites are classed as NVC M19a (based on the % plant species cover on unmanaged plots). 

We did the first vegetation survey in 2012 with the help of Clare Rickerby (Edinburgh, now St Andrews: Clare the Botanist) and together with our PhD student, Phoebe Morton (York). In the latter years we also had help from Julie Smith (Caledonian Conservation). All sites showed on average >70% heather (Calluna) coverage with an average maximum height of around 35 cm. However, plant diversity is generally low and decreases in the order of: Mossdale > Whitendale > Nidderdale. Furthermore, at Whitendale there seems to have been some frost damage during the winters of 2011, 2012, particularly at the treatment site (see picture above; the larger fence posts indicate the 5 x 5 m no management plots). Treatments (mowing etc.) started early in 2013 and we have since remeasured vegetation cover and composition annually.

We repeat the vegetation surveys annually (so far 2012-2025), initially with the help of either Clare or Julie (A Heinemeyer, also a trained botanist, was always present), after the plots had either been mown, burnt or left uncut as a no-treatment "do nothing" control. We always take 1 x 1 m pictures as previously and also 5 x 5 m plot pictures using a wide angle GoPro camera on a telescopic pole (see below pictures). The arial pictures allow quick checks on the accuracy of the ground-based (side-way) estimates of the 5x5 m plots. 

       5 x 5 m pictures with a GoPro                          Field of view of a 5 x 5 m plot (uncut)                         1 x 1 m detailed quadrat work                                    Longest selfie picture (3.5 m!)

Mown plot with brash removed                             Mown plot with brash left in place                      Burnt plot with visible moss damage                    Uncut plot with intact vegetation

For National Vegetation Classification (NVC) we used the MAVIS software (CEH: Modular Analysis of Vegetation Information System (Malvis)) to derive NVC categories in order to relate our study sites and any vegetation composition change over time to other studies. We also specifically assessed heather height and regrowth over time in relation to total vegetation cover. A notable difference was the slow heather regrowth after burning (germination) compared to that on mown plots (re-sprouting from stems). However, heather beetle  damage caused reduced heather heights and cover, particularly in 2014/15 and 2017/18, mostly at the two wetter sites (Mossdale and Whitendale) and from 2020/21 again at Mossdale and even more so at Whitendale (first at burnt plots and from 2024 onwards more severly at the mown plots). Below are shown the heather heights (2012-2025) and the mean total vegetation cover (%) for the main managements comparing unmanaged (uncut) to burnt and mown (average of with and without brash removal) for the 5x5 m plots (note the periods of collapsing heather heights in some years on some sites (due to heather beetle; i.e., Whitendale burnt 2018):

Total heather height (above) was measured at five points across each plot each year. Important to note is that heather was tallest and regrew best at the wettest site (Mossdale), especially after mowing, and that Mossdale also showed showed the highest heather cover and height at the unmanaged plots (i.e., heather does like it wet but just not permanently wet). Morevoer, heather height was reduced by either management but was lowest on burnt plots (above). Heather cover in 2025 (14 years post management) was lower on burnt plots at Mossdale but lowest on Whitendale mown plots, but this was due to heather beetles causing death of most plants.

These findings are important as the claims around rewetting reducing heather cover is very context specific and largely based on low heather cover from very (and near permanently) wet topogenous "soup bowl" bogs like valley bogs (parts of the Flow Country and Border Mires), whereas ombrogenous hill blanket bogs are naturally drier "leaky slope" bogs as pointed out by Glatzel et al. (2024; see their Fig 6). For hill blanket bogs, rewetting together with overall drier and warmer future climatic conditions will most likely increase 'shrubification' and heather growth. 

Total vegetation cover (below) was assessed either as exposed (i.e. top layer view; 100%) or as total (all layers; >=100%) cover. Important to note is that there were already differences in vegetation cover between treatments BEFORE any management changes in 2012; purely by chance, on burnt plots heather and non-Sphagnum moss cover was highest and cotton grass and Sphagnum cover lowest (see figure for total cover below), which the experimental Before-After Control-Intervention (BACI) design allows to be considered in the statistical models (not possible in a Space for Time design; Ashby & Heinemeyer, 2020). Moreoever, there were clear differences in the exposed vs total cover, relating to management exposing surface moss cover and regrowing taller vegetation covering those layers over subsequent years (so far 2013-2025). Most notably, either management clearly reduced heather cover over a long time compared to unmanaged lots (very stable cover at two sites and increasing at the wettest site, Mossdale (see above bar chart) and burning was at least as affective as mowing (see below plot for total cover over time). Moreover, Sphagnum cover was overall increasing over time, however, whilst it remained fairly stable on mown and unmanaged plots since 2019, it steadily increased and became largest by 2025; cotton-grass (sedge) increased similarly post management but overall more post mowing during 2015-2019 (see below plot for total cover over time). Clearly management and especially burning benefitted peat-forming Sphagnum moss cover. Notably, there were only very small initial reductions of total Sphagnum cover after either management (but more so after mowing) with an intermitted short peak increase on mown plots (2016-2018). Finally, it is to be noted that short-term impacts cannot reliably inform long-term outcomes; vegetation cover and composition clearly shows short-term management (disturbance) responses, but these are very different from long-term trajectories. These management benefits and time scale observations align nicely with a recent publication by Whitehead et al. (2026), who also call for a reassessment of reviews on heather management and claims made in relation to burning impacts on peatland vegetation - like reduced Sphagnum cover - many claims are misleading or even false (often based on inadequate and short-term studies) as pointed out in our 10-claims paper (Heinemeyer et al., 2025). 

Exposed cover (left) versus       Total cover (right)

Below is shown the Shannon Diversity index comparison between managements  (no management (DN); mown with either brash left (LB) or removed (BR)) and burnt (FI) management) over time as pre- vs overall post-management period (left) and split into short-term (2013-2016) and long-term (2017-2021) post-periods, (right). Further data until 2025 is still to be analysed. Notably, species richness increased most for burnt plots and less so on mown plots, whereas unmanaged plots showed only an transient change over time (slight increase in the short-term post-period.

Below is shown the species richness (the total number of different species present within a defined community) over time (2012-2021). All three alternative managements (no management (DN); mown with either brash left (LB) or removed (BR)) had either no or a much less steep increase in species richness than the burnt (FI) management. Further data until 2025 is still to be analysed.

Total Sphagnum cover per site differed considerably as did the Sphagnum species and their cover. Below is shown the mean total Sphagnum cover per species as a mean across all treatments (uncut, burn, mown) for each site (Nidderdale, Mossdale, Whitendale) for the pre-management change period (2012) versus the three post-management periods (so far 2013-2016; 2017-2021; 2022-2025). Mossdale, the wettest site, has by far the highest Sphagnum cover. There are substantial changes in species composition/cover over time, which is mostly related to changes over time for the individual managements (too complex to show) but the total Sphagnum cover per management is shown in the graphs above (i.e., line and bar charts).

Notably, as for vegetation cover, there were important pre-management differences between plots BEFORE any management changes took place. Such differences can be very important for interpreting management impacts. However, whilst Before-After Control-Intervention (BACI) studies such as ours can account for such differences (in the statistical model), space-for-time (SfT) studies do not allow capturing or considering such differences as there are no pre-management change data; as such SfT studies often compare 'apples vs oranges' as locations and often even plots within a location can differ considerably in environmental and vegetation aspects unrelated to recent management. For our plots, Sphagnum species and their cover was very different between sites (reflecting overall wetness differences) but also between plots BEFORE management changed (pre-management) as shown in the below pie charts.

Pre-management Sphagnum cover  (per species and total %) across the three sites (Nidderdale, Mossdale, Whitendale) BEFORE any management took place (2012) for (from left to right) the combined plots across all 'treatments' (ALL) and for the individual treatments of unmanaged "do nothing" (DN), burnt (FI), mown either with brash left (LB) or brash removed (BR):

ALL DN FI LB BR