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Picea asperata, a common tree species in the subalpine areas of Li County, Sichuan Province, China, is susceptible to Lophodermium piceae. Remote sensing has the advantages of large-scale, fast information acquisition, and low cost, which can overcome the shortcomings of ground survey. Hence, we used Landsat 8 satellite multi-spectral images and fo...
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... annual rainfall is between 650 to 1000 mm, and the annual average temperature in valleys is 6.9 to 11 • C. The high altitude and humid climate are very likely to cause the outbreaks of forest pests, which seriously affects the sustainable development of the local ecological environment. The location of Li County is illustrated as below, see Figure 1. With regard to forestry resources, there are typical subalpine vegetation coverages in Li County, which are vertically stratified along altitudes and diverse in multi-level structures. ...
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... method was adopted to verify the reliability and adaptability of this model. In the light of F-test theory, if F > F(m, n-m-1, α), there is a significant linear regression relationship between x and y, where m is the number of independent variables, n is the num- In order to study quantitatively, a correlation analysis was performed between the damage degree of Picea asperata forests and the NDVI change rate from the ground survey sites to verify whether there is a significant correlation. The correlation analysis results showed that there was a significant negative correlation between the NDVI change rate and damage degree when R = −0.860 ...
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... terms of visualization, based on the remote sensing disease-investigation results and geographic information data, it is found that the occurrence regions of Lophodermium piceae is mainly distributed between 3000 to 3300 m above sea level; an example is displayed in Figure 10. It can be summarized that to some extent, the lower the altitude is, the more damaged the Picea asperata forest is, which coincides with the ranking chart for the damage degree of Picea asperata forests and impact factors. ...
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... can be summarized that to some extent, the lower the altitude is, the more damaged the Picea asperata forest is, which coincides with the ranking chart for the damage degree of Picea asperata forests and impact factors. As for slope, it is remarkable in Figure 11 that Lophodermium piceae more commonly occurs in steep terrains, mostly in steep slopes (26 to 35 • ), urgent slopes (36 to 45 • ) and dangerous slopes (≤46 • ). The steeper the slope is, the greater the damage degree is, which can also be drawn from the CCA ranking chart for ground survey sites and impact factors that damage degree is strongly negatively correlated with slope. ...
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... general, thick soil is more suitable for Picea asperata. As illustrated in Figure 12, it can be noticed that Lophodermium piceae mainly occurs at the areas where the thickness of the soil layer is 70 or 80 cm. This kind of soil layer is relatively thin and lacks water and nutrients, which is also unfavorable to the growth of Picea asperata. ...
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... primary reason is that the thicker the soil layer is, the more water and nutrients are in the soil, so the better the spruces grow and the less susceptible they are. Last but not the least, it can be observed from Figure 13 that Lophodermium piceae mostly occurs in young or over-mature forests. Some reasons can be employed to interpret this phenomenon. ...
