Statewide Landcover And Trees Study (SLATS) Sentinel-2 - 2022 Woody Vegetation Age Since Disturbance - Queensland

The 2022 woody extent is attributed with an estimated age in years since the last significant disturbance. The method is a modification of the method used for the 2021 woody age estimation. Each woody pixel is assigned an estimated age as follows: where there was no woody clearing or regrowth mapped by SLATS in the 2021-22 monitoring period and the 2021 (previous year) woody age was valid, the 2022 woody age is assigned by incrementing the 2021 woody age, where there was 2021-22 clearing the 2022 age was reset to 0, and where there was 2021-22 regrowth /new woody additions or the 2021 age was 'indeterminate', the age was estimated using the standard model-based method. This method uses a sequential Conditional Random Fields classifier applied to 1988 - 2023 Landsat time series to predict woody cover over the 35-year period. A set of heuristic rules is used to detect and track regrowing woody vegetation in the time series of woody probabilities and record the approximate start and end dates of the most recent regrowth event. Regrowth detection is combined with the SLATS Landsat historic clearing data to provide an estimate of age. The 'last disturbance' may be due to a clearing event or other disturbance such as fire, flood, drought-related death etc. Note that not all recorded disturbances may result in complete loss of woody vegetation, so the estimated age since disturbance does not always represent the age of the ecosystem. The age since disturbance product is derived from multiple satellite image sources and derived products which represent different scales and resolutions: Landsat (30m), Sentinel-2 (10m) and Earth-i (1m).