Data are presented showing change in saltmarsh extent along 25 estuaries/embayments in six regions across Great Britain, between 1846 and 2016. Data were captured from maps and aerial photographs. Marsh extent was delineated a scale of 1:7,500 by placing vertices every 5 m along the marsh edge. Error introduced from: (i) inaccuracies in the basemap used to georeference maps and aerial photographs; (ii) the georeferencing procedure itself; (iii) the interpreter when placing vertices on the marsh edge; and (iv) map and photo distortions that occurred prior to digitisation were calculated and used to estimate the root mean square error (RMSE) in areal extent of each marsh complex. Measures of marsh extent were only recorded if maps and aerial photographs were available for the entire estuary/embayment. Data was collected as part of a study on the large-scale, long-term trends and causes of lateral saltmarsh change. The data was used in the analysis for Ladd et al. (2019). C. Ladd and M.F. Duggan-Edwards carried out the collection and processing of the saltmarsh extent data. All authors contributed to the interpretation of the data. The work was carried out under the NERC programme - Carbon Storage in Intertidal Environment (C-SIDE), NERC grant reference NE/R010846/1. Full details about this dataset can be found at https://doi.org/10.5285/03b62fd0-41e2-4355-9a06-1697117f0717

Bed level data are presented from transects at the Tollesbury Managed Realignment site, after the managed breaching of the sea wall in August 1995. Twenty measurements were taken at fixed positions along transects relative to an aluminium bar placed across a pair of permanent wooden posts at either end of each transect. Measurements were made to the nearest millimetre using a ruler. All measurements were made by the data author. Data from the original transects were collected monthly from September 1995 to 1998, bimonthly up to 2000 and then in April and September to 2007. Extra transects were added in April 1999 and data collected at the same frequency. The data were collected investigate if the exposure of the agricultural land to seawater would result in the accumulation of silt. The work was funded by the Department for Environment Food & Rural Affairs (Defra) under the Centre for Ecology & Hydrology (CEH) contract C00356 Full details about this dataset can be found at https://doi.org/10.5285/f9513ece-a913-4774-8808-273dcf7ed0be

Physical and geochemical measurements of saltmarsh soils produced from 19 wide diameter gouge cores (60 mm in diameter) collected from eight sites encompassing saltmarshes with different origins (natural, historic breach, managed realignment) in 2019. The work was carried out under the NERC programme - Carbon Storage in Intertidal Environment (C-SIDE), NERC grant reference NE/R010846/1 Full details about this dataset can be found at https://doi.org/10.5285/fa3f4087-528e-4c5d-90d8-6bb4675d6317

The dataset comprises the pH of a 10 gram soil sample from the top 5 centimetre of soil taken within each 1 metre (m) x 1m quadrat. Sampling was conducted at six salt marsh sites at four spatial scales: 1 m (the minimal sampling unit) nested within a hierarchy of increasing scales of 1-10 m, 10-100 m and 100-1000 m. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England. The Morecambe Bay samples were taken during the winter and summer of 2013. The Essex samples were taken during the winter, early spring and summer of 2013. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/c726249f-c2d8-4aeb-9af2-60a40de40be2

The dataset comprises the bulk density taken from bulk density rings (3.1 centimetre (cm) height, 7.5 cm diameter) within each 1metre (m) x 1m quadrat. Samples were taken vertically at three depths within each quadrat to roughly quantify the following zones: 0 -10 cm, 10 - 20 cm and 20 - 30 cm. Sampling was conducted at six salt marsh sites at four spatial scales: 1 m (the minimal sampling unit) nested within a hierarchy of increasing scales of 1-10 m, 10-100 m and 100-1000 m. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England. The Morecambe Bay samples were taken during the winter and summer of 2013. The Essex samples were taken during the winter, early spring and summer of 2013. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/814be4cf-0ff2-46dd-b296-c4d9b913b6e4

The dataset comprises of dry weight root biomass data collected from 0 cm to 10 cm, 10 cm to 20 cm and 20 cm to 30 cm soil depths from six salt marsh sites. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England. The Morecambe Bay samples were taken during the winter and summer of 2013. The Essex samples were taken during the winter, early spring and summer of 2013. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/a84622db-842d-40d2-aad8-e3f85bd306c9

The dataset comprises of percentage plant cover by species observed by eye in a 1metre (m) x 1m quadrat. Measurements were recorded at six salt marsh sites at four spatial scales: 1 metre (m) (the minimal sampling unit) nested within a hierarchy of increasing scales of 1-10 m, 10-100 m and 100-1000 m. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England. Plant cover was measured during the winter and summer of 2013 for all six sites. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/90bdf4ff-03d9-4aa4-bcad-5139863ab188

The dataset comprises 10 direct measurements in centimetres of plant height taken within a 1metre (m) x 1m quadrat. Also presented are the mean, standard deviation, standard error and coefficient variation values. Sampling was conducted at six salt marsh sites at four spatial scales: 1 m (the minimal sampling unit) nested within a hierarchy of increasing scales of 1-10 m, 10-100 m and 100-1000 m. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England. All samples were taken during the winter and summer of 2013. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/d8d37579-83f1-4e36-a681-984a086d6b68

The dataset comprises biochemical measurements of salt marsh soil, and samples from fields on former salt marsh, taken using a soil corer. Sampling was conducted at three restored salt marshes and six accidentally breached sites on the Essex coast, UK, providing a chronosequence from 16 to 114 years since restoration of tidal flow. Natural salt marsh at all sites were also sampled, along with adjacent fields on former salt marsh (where access permitted). All salt marsh sampling took place in October 2011. Field sample sites were sampled between July 2010 and April 2017. This data was collected as part of the NERC Centre for Ecology & Hydrology's Multi-functional land-use options project (C03463) in order to determine the trajectory and timescale of habitat recovery, and provide empirically-based predictions of changes in the rate of carbon sequestration over time following saltmarsh restoration. Data is also represented for fields on former saltmarsh to give a 'before' time point to be able to calculate these changes. Full details about this dataset can be found at https://doi.org/10.5285/0b1faab4-3539-457f-9169-b0b1fbd59bc2

The Normalised Difference Vegetation Index (NDVI) dataset details surface reflectance measured as NDVI. NDVI provides a proxy for the amount and/or the relative 'greenness' of vegetation. Data collection was carried out at six intertidal sites in the winter and summer of 2013. Three of the sites were in Morecambe Bay, North West England and three of the sites were in Essex, South East England, each of these sites consisted of a saltmarsh area and adjacent mudflat area, twenty two sampling quadrats were placed on each area. A single NDVI observation was taken at each quadrat. Spectral reflectance was measured using a portable spectrometer. This data was collected as part of Coastal Biodiversity and Ecosystem Service Sustainability (CBESS): NE/J015644/1. The project was funded with support from the Biodiversity and Ecosystem Service Sustainability (BESS) programme. BESS is a six-year programme (2011-2017) funded by the UK Natural Environment Research Council (NERC) and the Biotechnology and Biological Sciences Research Council (BBSRC) as part of the UK's Living with Environmental Change (LWEC) programme. Full details about this dataset can be found at https://doi.org/10.5285/75b1f669-66b3-472b-9d31-eda908826e17