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.
Publication date: 2015-12-31
The location of the sample sites was determined by randomly allocated quadrats. Twenty two 1 x 1 m quadrats were randomly allocated to each mudflat and saltmarsh site using R (R Development Core Team, 2014) to specify four different spatial scales (A = 1 quadrat only, B = 3 quadrats at 1 m to 10 m apart, C = 6 quadrats at 10 m to 100 m apart, D = 12 quadrats at 100 m to 1000 m or site maximum). These quadrats are common to all CBESS quadrat data. NDVI measurements were obtained before any destructive harvesting of the quadrats.
An OceanOptics USB2000 spectrometer with a 1.5 m fibre optic was used in all measurements. OOIBase32 Version 188.8.131.52 was used to log data on a laptop. Reflectance measurements were taken at 1.5 m above the ground surface. At each quadrat: 1) the integration time of the spectrometer was adjusted such that the peak of the white reference spectra was ~75% of the spectrometers maximum level; 2) for short integration times (<100 ms) spectral averaging was used to reduce measurement noise; 3) a dark measurement was recorded; 4) a white reference measurement was recorded; and 5) the reflectance measurement was made. A note is made of the number of the OOBase files associated with the quadrat number and percentage cloud and water cover of the quadrat and any other relevant information are taken. NDVI is calculated in Matlab.