DOI: 10.5061/dryad.j0zpc86fx
title: Diversification of Molinia-dominated blanket bogs using Sphagnum propagules

description: This dataset contains vegetation and water table data from a trial
 described in the paper "Pilkington, M.G., Walker, J., Fry, C., Eades,
 P., Meade, R., Pollett, N., Rogers, T., Helliwell, T., Chandler, D.,
 Fawcett, E. and Keatley T. (2021). Diversification of
 Molinia-dominated blanket bogs using Sphagnum
 propagules. Ecological Solutions and Evidence. Article DOI:
 10.1002/2688-8319.12113 The trial investigates the establishment and
 growth of Sphagnum colonies arsing from planting Sphagnum
 propagules ("plugs") amongst purple moor grass, Molinia caerulea
 (‘Molinia’), a vascular plant which can dominate upland blanket bog of the
 UK. Increasing dominance by Molinia on these globally rare and
 protected bogs is a growing threat to diversity and carbon
 storage, as well as increasing the risk of wildfire. Establishment and
 growth of plug-derived Sphagnum was measured by collecting
 visually-assessed data on cover (%) within 2 m x 2 m quadrats. The cover
 of blanket bog "indicator species" was calculated according to
 the definition of this group as stated in Common
 Standards Monitoring and the concept of Favourable
 Condition. Water table data were collected manually
 from monthly campaigns. The following key results were found:
 There was an initial rapid increase in cover of plug-derived
 Sphagnum (PDS) which suggested an advantage over that of
 naturally-occurring Sphagnum colonies, the latter remaining below 1% cover
 throughout; subsequent plateauing of PDS cover in areas of moderate
 Molinia cover (&lt; 80%) was linked with drought stress, whereas
 declining cover in Molinia-dense areas (&gt; 80%) suggested additional
 competition for light. The cover of Molinia was only weakly reduced by,
 and then completely recovered from, a baseline flailing treatment.
 Increasing cover of PDS in all of the treatments had no clear effect on
 the cover of Molinia. The cover of naturally-occurring indicator species
 was strongly reduced by a baseline flailing treatment; subsequent recovery
 was not complete, even with contributions by PDS. There was a negative
 linear relationship between Molinia cover and indicator species cover,
 over all ranges of Molinia cover. Water table depths were lowered by PDS
 during the first three years of the trial, likely due to
 facilitated capillary conduction of water though the buried plug tissues.
description: Vegetation cover within each fixed quadrat was meaured by visual
 assessment of indivdual species (e.g. <em>Molinia
 caerulea</em>, <em>Sphagnum cuspidatum</em>) and groups
 (e.g. blanket bog indicator species, pleurocarpous mosses) consistent with
 UK Common Standards Monitoring and the concept of Favourable Condition,
 and expressed as a percentage of the total area of each fixed qaudrat (4
 m<sup>2</sup>). Total cover can exceed 100% due to overlapping
 layers of vegetation.  Water table depth was meaured as
 the distance between gound level and the surface of the water table in
 dipwells which were situated within the fixed vegetation
 quadrats. All vegetation data and water table data were
 shown as raw data and also as trajectories of change over time, by
 expressing the data relative to the control and normalising to a common
 zero starting point. Statisitical tests mainly involved Mann-Whitney U as
 the data did not fulfil the ANOVA criteria of a normal distribution. Trend
 lines describing the relationship between covers of
 <i>Molinia</i>, plug-derived <i>Sphagnum</i> (PDS)
 and indicator species were fitted using linear/polynomial regression
 models, with <i>Molinia</i> and plug-derived
 <i>Sphagnum/</i>indicator species cover as the predicting and
 responding variables, respectively.
description: The readme file contains an explanation of each of the variables
 and its measurement units. "Null" = values not available. More
 infomation about the collection of data can be found in the associated
 manuscript referenced above.