Abstract
After implementations of many economic and forestry policies during recent 30 years, forest cover in China has experienced significant changes. The fine scale and long-term information on forest temporary (disturbance) loss, persistent loss (deforestation), and gains (afforestation/reforestation) will provide a guide for forest management and policies at regional scale. Using Jiangxi Province as a pilot study region, here we assessed forest cover dynamics in the subtropical China during 1986–2019 by integrating time-series Landsat images, Landsat-based Detection of Trends in Disturbance and Recovery algorithm and Random Forest classifier on the Google Earth Engine Platform. The accuracy assessment indicated a high overall accuracy (>90%) and Kappa coefficient (>0.9) for both forest gain and loss detections as evaluated against various sources of plot-level sample data and the existing global forest change product. The total forest loss area was 18 697.79 km2, with persistent loss area of 3394.31 km2 due to land conversion during 1986–2019, while persistent (net) forest gain area was 45 656.96 km2, accounting for 57.70% of the forest area in 1986. Forest loss area exhibited large interannual variations, but showed a general increase trend from 1986 to 2019. The annual variation patterns of forest gain and loss area were associated with the changes in forestry policies and large disturbance events. Our assessments on the long-term and fine scale forest dynamic patterns will help evaluate the effectiveness of forest management practices and forestry polices on forest resource sustainability, and climate change and greenhouse gases mitigation in Jiangxi Province and China.
Highlights
F ORESTS play a vital role in environmental improvement, landscape aesthetics, the mitigation of climate change, and determination of energy budgets [1]
Our detected forest area in Jiangxi Province increased from 79 123.76 km2 in 1986 to 119 622.55 km2 in 2019, with a net gain of 40 498.79 km2 and an increase rate of 51.18%
Our results indicated 15 088 km2 forest losses during 2001–2019 in Jiangxi Province, but estimation from the global forest change (GFC) product was 12 744 km2, significantly lower than our results
Summary
F ORESTS play a vital role in environmental improvement, landscape aesthetics, the mitigation of climate change, and determination of energy budgets [1]. Due to increasing forest cover and relatively young forest age [2]–[5], forests in China were an important carbon sink [6]–[9] and played an important role in the global carbon budget [10], [11]. It is still uncertain about the contributions from forest disturbance and management because of the lack of a long-term and high spatial and temporal accuracy dataset for forest dynamics. Knowledge of spatiotemporally explicit forest cover dynamics is important for understanding forest carbon cycle in China
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