Response of plant reflectance spectrum to simulated dust deposition and its estimation model

Abstract

To quantitatively reflect the relationship between dust and plant spectral reflectance. Dust from different sources in the city were selected to simulate the spectral characteristics of leaf dust. Taking Euonymus japonicus as the research object. Prediction model of leaf dust deposition was established based on spectral parameters. Results showed that among the three different dust pollutants, the reflection spectrum has 6 main reflection peaks and 7 main absorption valleys in 350–2500 nm. A steep reflection platform appears in the 692–763 nm band. In 760–1400 nm, the spectral reflectance gradually decreases with the increase of leaf dust coverage, and the variation range was coal dust > cement dust > pure soil dust. The spectral reflectance in 680–740 nm gradually decreases with the increase of leaf dust coverage. In the near infrared band, the fluctuation amplitude and slope of its first derivative spectrum gradually decrease with the increase of leaf dust. The biggest amplitude of variation was cement dust. With the increase of dust retention, the red edge position generally moves towards short wave direction, and the red edge slope generally decreases. The blue edge position moved to the short wave direction first and then to the long side direction, while the blue edge slope generally shows a decreasing trend. The yellow edge position moved to the long wave direction first and then to the short wave direction (coal dust, cement dust), and generally moved to the long side direction (pure soil dust). The yellow edge slope increases first and then decreases. The R2 values of the determination coefficients of the dust deposition prediction model have reached significant levels, which indicated that there was a relatively stable correlation between the spectral reflectance and dust deposition. The best prediction model of leaf dust deposition was leaf water content index model (y = 1.5019x − 1.4791, R2 = 0.7091, RMSE = 0.9725).

Effect of Dust Types on the Eco-Physiological Response of Three Tree Species Seedlings: Eucalyptus camaldulensis, Conocarpus erectus and Bombax ceiba

“…Smaller dust particles enter the leaf through stomatal openings, and the larger particles usually pile up on the stomatal pores, affecting gaseous exchange processes, which in turn affect photosynthesis, respiration, and transpiration that allow the penetration of phytotoxic gaseous pollutants and overall plant growth [36][37][38]. In our investigation, carbon dust concentration reduced photosynthetic rate, transpiration rate, and stomatal conductance despite increasing leaf temperature in all three species, which is in line with the results of [29,[39][40][41].…”

Leaf reflectance and functional traits as environmental indicators of urban dust deposition

“…In different gradients of pollution, with the increase in dust deposition on the leaf surface, the specific leaf area and chlorophyll content index gradually decreased, and reached extremely significant differences in different environments. Specific leaf area can represent the adaptability of plants to the environment and the ability to obtain resources, which is closely related to the survival strategies of plants [ 16 ]. Plants with lower leaf area have stronger adaptability to arid environment with poor resources, while plants with higher leaf area have stronger ability to maintain nutrition in vivo [ 27 , 38 , 44 , 45 ].…”

“…Our conclusion is consistent with the change of specific leaf area under high temperature and drought environment [ 46 ]. Chlorophyll content index can reflect the photosynthetic capacity of plant leaves [ 16 ]. In this study, with the increase of dust deposition, chlorophyll content index in plants decreased significantly.…”

“…The related research based on forestry hyperspectral mainly focuses on the estimation of plant yield, plant diseases and plant physical and chemical parameters, while the application of plant monitoring in dust pollution is relatively few [ 14 , 15 ]. In the past, in the process of studying the relationship between leaf dust deposition and spectral characteristics, attention was paid to the changes of spectral characteristics of plant leaves before and after dust deposition, while the comparison of plants in different urban environments was often neglected, and the universal applicability of the prediction model was not verified [ 16 ].…”

Effect of Dust Deposition on Chlorophyll Concentration Estimation in Urban Plants from Reflectance and Vegetation Indexes

“…According to studies of vegetation pigments [19,40], the pigment concentration was divided into three groups: "Level 1" is 5-10 mg/L; "Level 2" is 10-15 mg/L; "Level 3" is higher than 15 mg/L. Because the selected samples were all shrubs and refer to a large number of dust load measurement studies [10,[53][54][55] and the preliminary research foundation of the samples, the dust deposition capacity per plant species was divided into three levels: "Less dust" is 0-1.5 g/m 2 ; "Medium dust" is 1.5-4 g/m 2 ; "Heavy dust" is above 4 g/m 2 . When performing correlation analysis and establishing estimation models, the samples for each dust deposition level were composed of three tree species to reduce the difference among species.…”