BEIJING, Dec. 25 (Xinhua) -- A research team from Nanjing University has developed a high-precision remote sensing inversion framework and, for the first time, mapped the spatiotemporal distribution of maximum non-photosynthetic vegetation cover across China's terrestrial areas, the Science and Technology Daily reported Wednesday.
The team also proposed an innovative terrestrial ecosystem carbon exchange flux index, revealing how non-photosynthetic vegetation responds to climatic gradients and highlighting its central role in the carbon cycle.
Non-photosynthetic vegetation, which includes dead branches, fallen leaves, stems and other plant residues, is a highly active and critical component of the terrestrial carbon pool.
"However, due to spectral coverage limitations in traditional multispectral satellite remote sensing, non-photosynthetic vegetation is often indistinguishable from bare soil in imagery. This has made it difficult to accurately quantify its contribution to carbon sink estimates at large scales," said Tian Qingjiu, a researcher from the university.
Thus, precisely identifying non-photosynthetic vegetation over broad areas and assessing its impact on carbon flux has remained a major challenge in global carbon cycle monitoring, Tian added.
In this research, the team conducted estimations of the annual maximum non-photosynthetic vegetation coverage across the country from 2016 to 2024, at a resolution of 300 meters.
"We found that within the 750-900 nanometer spectral range, non-photosynthetic vegetation and bare soil exhibit distinct reflective spectral signatures," Tian said.
The results show that the peak annual average non-photosynthetic vegetation coverage accounts for about 37 percent of China's total land area and is increasing significantly at a rate of 0.14 percent per year, largely due to conversion from bare soil.
Semi-arid to semi-humid regions show both the highest non-photosynthetic vegetation coverage and the most rapid growth, with an annual increase of 0.75 percent. Seasonal temperature and precipitation were identified as the dominant drivers of non-photosynthetic vegetation spatial variation.
"This research underscores the growing importance of non-photosynthetic vegetation in regulating surface energy balance and soil carbon sequestration," Tian said.
The study fills a gap in large-scale dynamic monitoring and estimation of non-photosynthetic vegetation in China, providing valuable insights for accurately assessing ecosystem resilience and carbon cycle feedback mechanisms across different climate zones.
The findings have been published in the journal Science China: Earth Sciences. ■
