The question asks to identify the incorrect statement regarding the Normalized Difference Vegetation Index (NDVI).

NDVI Fundamentals

NDVI is a widely used indicator in remote sensing to assess vegetation health and density. It is calculated using the reflectance values in the near-infrared (NIR) and red (Red) portions of the electromagnetic spectrum.

The formula for NDVI is:

$ \text{NDVI} = \frac{(\text{NIR} - \text{Red})}{(\text{NIR} + \text{Red})} $

Healthy vegetation strongly reflects NIR light and absorbs Red light during photosynthesis. This characteristic difference is key to interpreting NDVI values.

Statement Analysis

• Statement 1: "NDVI is directly related to the percent of ground cover and amount of biomass."

  This statement is correct. As vegetation cover increases, both biomass and NDVI values generally increase.

• Statement 2: "Greater difference between near-infrared and red reflectance indicates less vegetation."

  This statement is incorrect. Healthy, dense vegetation reflects NIR light strongly and absorbs Red light. Therefore, a greater difference, specifically (NIR - Red) being a large positive number, indicates *more* vegetation, not less. Bare soil or sparse vegetation typically shows smaller differences.

• Statement 3: "NDVI values close to zero represent bare soil."

  This statement is correct. Bare soil generally has similar reflectance in both the NIR and Red bands. This results in the numerator (NIR - Red) being close to zero, leading to an NDVI value near 0.

• Statement 4: "Higher values of NDVI represent dense green vegetation."

  This statement is correct. The highest NDVI values (typically ranging from 0.6 to 0.9) correspond to areas with dense, healthy green vegetation, due to the strong contrast between high NIR reflectance and low Red reflectance.

Conclusion

Based on the analysis, the statement claiming that a greater difference between near-infrared and red reflectance indicates less vegetation is factually incorrect according to NDVI principles.