JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2014, Vol. 38 ›› Issue (01): 77-82.doi: 10.3969/j.issn.1000-2006.2014.01.014

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Assessing forest disturbance patterns over the three forested areas of Nanjing using multi-temporal TM/ETM+ imagery

LYU Yingying, REN Xinyu, LI Mingshi*   

  1. College of Forest Resource and Environment, Nanjing Forestry University, Nanjing 210037, China
  • Online:2014-01-15 Published:2014-01-15

Abstract: Taking the three areas of Zijin, Mufu and Laoshan Mountains located in Nanjing as the case study, using the Landsat TM/ETM+ observations dated in 1992, 1995, 1998, 2001, 2003, 2005, 2007 and 2011, indices including brightness, greenness and wetness derived from the tasseled cap transform were obtained first, followed by the establishment of the forest disturbance index via a normalization approach. Ultimately, grading the forest disturbance severity was made and the forest disturbance analyses were in part validated by using the forest resources inventories coupled with the high spatial resolution Google Earth imagery. Results showed that the forest disturbance analysis methods developed from Landsat TM/ETM+ imagery in the current work were effective and reliable after an intensive validation. Forest disturbance intensity remained almost unchanged during the period 1992 to 2001, giving way to an increase in forest disturbance severity over the time period 2001 to 2005, connecting to a declining trend after 2005. Additionally, the average disturbance values of the three regions differed from each other, Mufu Mountains with the strongest forest disturbance and Zijin Mountains the lowest, which adequately reflects the differences in forest management purposes and approaches. Distribution of forest disturbance severity of the regions also had their own characteristics, but the patterns that higher disturbance severities were observed along the boundaries of the three regions, with lower disturbance levels located in the central portions of the regions, were same. Ultimately, the driving forces responsible for the differences in observed forest disturbances were identified as demographic expansion, mining events, forest logging and forest insects and disease and forest eco-tourism.

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