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Keywords:

  • canopy cover;
  • change detection;
  • remote sensing;
  • tropical cyclone;
  • windthrow

Abstract  Severe tropical Cyclone Monica impacted the coast of northern Australia in April 2006 with estimated maximum wind gusts of 360 km h−1. It rapidly moved inland losing intensity and passed over the town of Jabiru as a category 2 system, with maximum wind gusts recorded at 135 km h−1. The cyclone had a significant impact on the landscapes within the Alligator Rivers Region and significant windthrow of trees occurred. This paper describes the level of impact that category 2 level winds had on tree canopy loss 10 days after cyclone and then again 1 year later. Recovery was assessed using multispectral satellite imagery in sub-catchments of the Magela Creek catchments. A non-linear relationship was fitted between a modified vegetation index (derived from Landsat TM5 satellite data) and percentage tree canopy cover (measured from very high resolution QuickBird satellite data). The results of the non-linear relationship, used to estimate percentage canopy cover, indicate that 10 days after cyclone, there was significant disturbance to tree canopy. However, data 1 year after cyclone show that recovery of canopy across the studied catchments varied between 8% and 19% of the percentage canopy cover that remained after the initial impact of the cyclone. Further analysis in the three sub-catchments using Geographical Information System showed that proportionally, riparian zones and inundated areas in each of the sub-catchments suffered greater loss of tree canopy cover compared with upland areas.