JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2019, Vol. 43 ›› Issue (02): 184-190.doi: 10.3969/j.issn.1000-2006.201805001

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Assessing changes in forest coverage and forest fragmentation patterns in Yunnan Province from time series MODIS-VCF products(2000-2016)

ZHU Ruoning1, SHEN Wenjuan1, ZHANG Yali1, LI Mingshi1,2*   

  1. (1.College of Forestry, Nanjing Forestry University,Nanjing 210037,China; 2.Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037,China)
  • Online:2019-03-30 Published:2019-03-30

Abstract: 【Objective】The main objective of this study was to assess the effectiveness of existing forest management policies implemented in Yunnan Province, and to learn or summarize experiences regarding the implementation of forest-related strategies by analyzing the changes in the spatio-temporal patterns of forest coverage and fragmentation in Yunnnan Province during 2000-2006.【Method】Using MODIS-vegetation continuous fields(VCF)product and its derivatives as the basic data source, with a spatial resolution of 250 m, a linear equation was fitted for each pixel on the basis of its variations in forest coverage rate against the time duration of 2000 to 2016. By exploring the slope and intercept of the fitted equation as well as the variance in forest coverage at that particular pixel, empirical thresholds were modified to classify this pixel into four types of forest coverage change, and a 3 × 3 moving window analysis technique was used to extract two indices within the window: forest area density and forest connectivity. Based on these two measures, in conjunction with the percolation theory, the central forest pixel within the window was classified into one of the six fragmentation components, namely, interior, perforation, edge, patch, transitional and undetermined. Finally, interconnections between forest fragmentation and biodiversity dynamics in the typical areas of Yunnan Province were qualitatively depicted. 【Result】During 2000-2016, the forest area in Yunnan Province tended to unstably increase, and the area of the forest coverage constant increasing type accounted for 30.57% of the total territory of Yunnan Province. In addition, the high forest coverage change type was principally distributed in southern and western Yunnan, and the low forest coverage change type was mainly concentrated in central, northern and eastern Yunnan. During the study period, the areal share of the interior forest increased from 50.03% in 2000 to 57.32% in 2006, with a slight decrease to 56.33% in 2011 and increase to 63.32% in 2016; however, the areal share of the perforation forest decreased from 29.41% in 2000 to 27.81% in 2006, with a slight increase to 28.36% in 2011 and decrease to 24.54% in 2016. Simultaneously, other components, including edge, patch and transitional fragmentation elements, showed a change trend similar to perforation, suggesting decelerated forest fragmentation in Yunnan Province during the period. 【Conclusion】Driven by various forestry policies, such as returning cropland to forest and reformation of collective forest tenures, the forest area in Yunnan Province, overall, tends to increase gradually, and the forest fragmentation level appears to have decelerated. However, across 2006 and 2011, a slight decrease in forest coverage, accompanied by increased forest fragmentation, was observed in Yunnan, which is consistent with a decrease in wildlife quantity and a more compact distribution of wildlife in some typical regions. These findings provide a valuable reference for forest management decisions and conservation biology studies.

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