Reflections of stress: Ozone damage in broadleaf saplings can be identified from hyperspectral leaf reflectance

Tropospheric ozone causes widespread damage to vegetation, however, monitoring of ozone-induced damage is usually reliant on manual leaf inspection. Reflectance spectroscopy of vegetation can identify and detect unique spectral signatures of different abiotic and biotic stressors. In this study, we tested the use of hyperspectral leaf reflectance to detect ozone stress in alder, beech, birch, crab apple, and oak saplings exposed to five different ozone regimes (ranging from daily target maxima of 30ppb ozone to 110ppb). Hyperspectral reflectance varied significantly between ozone treatments, both in whole spectra analysis and when simplified to representative components. Ozone damage had a multivariate impact on leaf reflectance, underpinned by changes in pigment balance, water content, and structural composition. Vegetation indices derived from reflectance which characterised the visible green peak were able to differentiate between ozone treatments. Iterative normalised difference spe..., This experiment took place at the UK Centre for Ecology & Hydrology's air pollution facility at Abergwyngregyn, North Wales (53.2◦N, 4.0◦W). Ozone treatment was delivered in solardomes, dome-shaped glasshouses of 3 m diameter and 2.1 m height. From June to October 2022, alder, beech, birch, oak, and crab apple saplings were grown within the ozone treatment solardomes. Each month hyperspectral leaf reflectance measurements were taken.  Reflectance spectra of the adaxial leaf surface from 350-2500nm were collected using an HR-1024i with leaf clip, Spectra Vista Corp, USA including an active light source. 
The spectrometer was referenced using the incorporated leaf clip reflective standard every 5 minutes during measurements. Dark signal baseline correction was applied by the HR-1024i automatically, a dark spectrum was taken before each reflectance measurement. Once per month during ozone treatment, reflectance spectra were taken of three leaves from three replicates of each species pe..., , # Hyperspectral Leaf Reflectance Library of Ozone Exposed Saplings

Hyperspectral leaf reflectance spectral library recorded from broadleaf saplings grown under varying ozone concentrations from June-October 2022.

## Description of the data and file structure

The hyperspectral library is stored in CSV file format. Each column is an individual reflectance spectra, labelled in row 1 according to the species, month of measurement, ozone treatment and sapling number. Each row corresponds the intensity values for a particular wavelength, labelled in column 1, ranging from 350-2500nm.

The spectra are labelled according to the following protocol:

[[MONTH]_[SPECIES]_[TREATMENT]_[SAPLING NUMBER].[REPEAT NUMBER]

Where:
A = Alder
B = Birch
C = Crab apple
F = Beech
Q = Oak

OZ_1 = Ozone treatment with daily target maximum 30ppb
OZ_2 = Ozone treatment with daily target maximum 50ppb
OZ_3 = Ozone treatment with daily target maximum 65ppb
OZ_4 = Ozone treatment with daily target maximum 80ppb
O...