Assessment of Poplar Looper (Apocheima cinerarius Erschoff) Infestation on Euphrates (Populus euphratica) Using Time-Series MODIS NDVI Data Based on the Wavelet Transform and Discriminant Analysis

Abstract

Poplar looper (Apocheima cinerarius Erschoff) is a destructive insect infesting Euphrates or desert poplars (Populus euphratica) in Xinjiang, China. Since the late 1950s, it has been plaguing desert poplars in the Tarim Basin in Xinjiang and caused widespread damages. This paper presents an approach to the detection of poplar looper infestations on desert poplars and the assessment of the severity of the infestations using time-series MODIS NDVI data via the wavelet transform and discriminant analysis, using the middle and lower reaches of the Yerqiang River as a case study. We first applied the wavelet transform to the NDVI time series data in the period of 2009–2014 for the study area, which decomposed the data into a representation that shows detailed NDVI changes and trends as a function of time. This representation captures both intra- and inter-annual changes in the data, some of which characterise transient events. The decomposed components were then used to filter out details of the changes to create a smoothed NDVI time series that represent the phenology of healthy desert poplars. Next the subset of the original NDVI time series spanning the time period when the pest was active was extracted and added to the smoothed time series to generate a blended time series. The wavelet transform was applied again to decompose the blended time series to enhance and identify the changes in the data that may represent the signals of the pest infestations. Based on the amplitude of the enhanced pest infestation signals, a predictive model was developed via discriminant analysis to detect the pest infestation and assess its severity. The predictive model achieved a severity classification accuracy of 91.7% and 94.37% accuracy in detecting the time of the outbreak. The methodology presented in this paper provides a fast, precise, and practical method for monitoring pest outbreak in dense desert poplar forests, which can be used to support the surveillance and control of poplar looper infestations on desert poplars. It is of great significance to the conservation of the desert ecological environment.

Spatiotemporal dynamics of forest geometrid outbreaks

“…winds) and No? [46] Species for which outbreaks are known only from plantations (e.g. [32]) are excluded.…”

Climate Change Impacts on the Potential Distribution of Apocheima cinerarius (Erschoff) (Lepidoptera: Geometridae)

“…Apocheima cinerarius damages as many as 14 natural hosts [51]. Among them, Sophora japonica and Ulmus pumila are often used in the construction of protection forest in arid environments, which have huge economic and ecological benefits; P. euphratica grows on saline-alkali soils to protect oasis and maintain the stability of the oasis ecosystem [6].…”

“…In northern China, A. cinerarius can consume entire tree canopies in a matter of days when it is severe, wreaking havoc on the forest landscape and ecosystem [5]. Plantations have been constantly threatened by A. cinerarius in northern China [6].…”

“…Attacks by A. cinerarius weaken the tree. Severe attacks by this pest can kill the tree and if this occurs over large areas this can lead to reduced biodiversity [6].…”

What Is the Effect of Quantitative Inversion of Photosynthetic Pigment Content in Populus euphratica Oliv. Individual Tree Canopy Based on Multispectral UAV Images?

“…It is a rapid, accurate and practical method for detecting pest stress. It can be used to monitor and control the spring geometrid on desert Populus euphratica trees, which is of great significance to protect the desert ecological environment [35].…”