Woody Age Since Disturbance - Sentinel-2, DETSI Algorithm, QLD Coverage

The woody vegetation extent for Queensland is attributed with an estimated age in years since the last significant disturbance. The method uses a sequential Conditional Random Fields classifier applied to Landsat time series starting 1988 to predict woody cover over the time 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 Statewide Land and Trees Study (SLATS) Landsat historic clearing data to provide a preliminary estimate of age since disturbance for each woody pixel in the woody extent. 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 (30 m), Sentinel-2 (10 m) and Earth-i (1 m).

昆士兰州木本植被覆盖范围附带了自上次重大扰动以来的估算年龄（单位：年）。该方法采用序列条件随机场（Conditional Random Fields）分类器，以1988年起的陆地卫星（Landsat）时间序列为输入，预测该时段内的木本覆盖。本研究通过一组启发式规则，在木本概率时间序列中检测并追踪再生木本植被，并记录最近一次再生事件的近似起止日期。将再生检测与全州土地与树木研究（Statewide Land and Trees Study, SLATS）的陆地卫星历史植被清除数据相结合，可为木本覆盖范围内的每个木本像素提供扰动后年龄的初步估算值。此处的“上次扰动”可指代植被清除事件，或火灾、洪水、干旱相关植被死亡等其他扰动类型。需注意，并非所有记录在案的扰动都会导致木本植被完全消失，因此估算得到的扰动后年龄并不总能代表该生态系统的实际年龄。
本次扰动后年龄产品源自多种卫星影像数据源及其衍生产品，这些数据具备不同的空间尺度与分辨率：陆地卫星（Landsat，30米）、哨兵2号（Sentinel-2，10米）以及Earth-i（1米）。