Satellite-based studies on large-scale vegetation changes in China.

Area of Science:

• Ecological monitoring
• Environmental science
• Remote sensing applications

Background:

• Remotely-sensed vegetation indices are crucial for monitoring vegetation dynamics.
• Satellite data have been extensively used to study vegetation cover, biomass, productivity, phenology, desertification, and grassland degradation.
• China's terrestrial ecosystems have undergone significant changes over the past 2-3 decades.

Purpose of the Study:

• To review satellite-based studies on vegetation dynamics in China over the past 2-3 decades.
• To analyze changes in vegetation cover, biomass, productivity, phenology, desertification, and grassland degradation.
• To assess the reliability of remote sensing for monitoring vegetation.

Main Methods:

• Review of satellite-based studies focusing on vegetation indices like the Normalized Difference Vegetation Index (NDVI).
• Analysis of vegetation cover changes, biomass, productivity, and phenological dynamics.
• Examination of desertification and grassland degradation trends.

Main Results:

• Significant increases observed in growing season NDVI and net primary productivity across major terrestrial ecosystems.
• Substantial decline in fresh lake numbers and urban vegetation coverage.
• Advancing growing season start in temperate regions until the 1990s; increased vegetation activity in arid/semi-arid grasslands and oases.
• Declining coverage of sparsely-vegetated areas.

Conclusions:

• Remote sensing data indicate widespread vegetation greening and productivity increases in China, alongside urban vegetation loss.
• Vegetation dynamics show complex spatial heterogeneity and regional variations.
• Caution is advised when interpreting remote sensing data due to dependencies on data sources, methods, and time periods.