DOI: 10.5285/a9226e79-d4da-4d4d-bd39-3a6b4a7a327d
title: Plant physiological measurements in North Wales and Northwest England (2013, 2014 and 2016)

description: The data consists of plant physiological measurements from 15 sites located in the Conwy catchment (North Wales) and from 2 sites in North West England. Plant photosynthetic parameters for the maximum rate of carboxylation (Vcmax), the maximum rate of electron transport (Jmax) and the maximum light saturated photosynthesis (Asat) were measured on the dominant plant species as were foliar nitrogen (Foliar N) and phosphorus (Foliar P). Leaf mass area (LMA) and specific leaf area (SLA) were recorded on the same leaves. Data were collected in 2013, 2014 and 2016. The sites were chosen to represent habitat types and the terrestrial productivity gradient in Britain from intensive agriculturally managed lowland grasslands through to montane heath. Plots within the sites were located using a stratified random sampling design.

Plant parameters were tested across a land use intensification gradient to detect parameters that can predict aboveground biomass production across different land management types. Data were used to enhance the predictions of biomass production in the Joint UK Land Environment Simulator model (JULES). Measurements informed the improvement of the nitrogen cycle component in the model.

Measurements were undertaken by trained members of staff from Bangor University, the Centre for Ecology & Hydrology and Exeter University.
This data was collected for the NERC project 'The Multi-Scale Response of Water quality, Biodiversity and Carbon Sequestration to Coupled Macronutrient Cycling from Source to Sea' (NE/J011991/1). The project is also referred to as Turf2Surf.
description: Plant photosynthesis measurements, maximum rate of carboxylation (Vcmax), the maximum rate of electron transport (Jmax) and the maximum light saturated photosynthesis (Asat)  were carried out on the dominant plant species at the sites on sunny days. Asat was measured in the field over the years in 2013, 2014 and 2016. A CIRAS-I in combination with a 'Rice' Cuvette or a 'Conifer' chamber were used in 2013. After 2013, CO2 curves were measured using a Licor 6400 instead. Vcmax and Jmax were calculated using the photosynthesis package for Python.Vcmax and maximum rate of electron transport (Jmax)are calculated at 25 degrees Celsius whereas Asat was measured at 20 degrees Celsius.

The leaves used for measurements of leaf mass area were pooled together and 2 grams of oven dried leaves were ground in a ball mill and Foliar N (Vario) and Foliar P (SEAL) were measured.

For plant traits in situ measurement of specific leaf area (SLA) was carried out focussing on the dominant vascular plant species in each plot defined as the two species contributing maximum standing biomass in the year of sampling. SLA was measured by sampling 10 leaves from different plants. Leaf area was calculated based on scanned photographs analysed using the Image J software v1.46r (See Supporting Information). SLA is expressed as square millimetres per milligram of dry mass.

Leaf mass area (LMA) was determined on ten leaves that were scanned or photographed. The dry weight of these leaves was determined. The leaf area was analysed using the program Image J and LMA was calculated.

All results were entered into Excel spreadsheets. Results from all the analyses were combined into one Excel spreadsheet. Data were then exported from this combined Excel spreadsheet as .csv files for ingestion into the EIDC.