Table 4 Carbon storage and carbon density of different age groups in the Zijin Mountain National Forest Park from 1987 to 2019
year | 1987 | 2002 | 2019 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Age groups | Area (ha) | Carbon storage | Carbon density (tC/ha) | Area (ha) | Carbon storage | Carbon density (tC/ha) | Area (ha) | Carbon storage | Carbon density (tC/ha) | |||
tC | % | tC | % | tC | % | |||||||
Young | 98.4 | 1,744.8 | 2.8 | 17.7 | 197.1 | 4,439.6 | 5.5 | 22.5 | 51.1 | 1582.6 | 1.5 | 31.0 |
Middle-aged | 675.9 | 25,807.3 | 41.9 | 38.2 | 557.6 | 22,081.1 | 27.4 | 39.6 | 479.0 | 21,205.1 | 20.2 | 44.3 |
Near-mature | 311.9 | 12,666.9 | 20.6 | 40.6 | 353.1 | 14,080.4 | 17.5 | 39.9 | 360.2 | 16411.7 | 15.7 | 45.6 |
Mature | 678.7 | 21,207.4 | 34.5 | 31.3 | 644.9 | 26,541.1 | 33.0 | 41.2 | 709.9 | 34118.6 | 32.6 | 48.1 |
Over-mature | 2.1 | 109.0 | 0.2 | 51.1 | 320.2 | 13,303.7 | 16.5 | 41.5 | 674.2 | 31463.8 | 30.0 | 46.7 |
total | 1,767.0 | 61,535.4 | 100.0 | 34.8 | 2,072.9 | 80,445.9 | 100.0 | 38.8 | 2,274.4 | 104,781.8 | 100.0 | 46.1 |