Landsat time series allow a fine-grained analysis of recent forest disturbance dynamics, highlighting differences between unmanaged and managed forest ecosystems.
Research on the remote sensing of forest disturbances has increased rapidly over the past decades, with considerable advances in identifying and mapping disturbances from space (see for instance Senf et al. 2017).
In a recent paper together with remote sensing experts from Humboldt University Berlin we have investigated the disturbance regimes of Central Europe, using Landsat data. The particular challenge in Central Europe is that natural disturbances are much finer-grained than, for instance, in North America. Furthermore, natural disturbances frequently trigger or are masked by human disturbances (such as salvage and sanitation harvesting), which makes disturbance detection and attribution from remote sensing challenging.
To address the coupled human and natural systems we focused on five landscapes in Europe which featured strictly protected areas (natural disturbances only), areas that are protected but still experience a limited amount of sanitation felling (natural disturbance and moderate level of human disturbance), as well as forests under regular management (with natural and human disturbances).
We compared the spectral signal as well as the spatio-temporal disturbance patterns across these landscapes and management categories. Disturbance patches were generally small, with 95% of the disturbances being smaller than 10 ha. Disturbance rates ranged from 0.29%/yr to 0.95%/yr, and differed substantially among management zones and study sites. Natural disturbances in strictly protected areas were longer in duration (median of 8 years) and slightly less variable in magnitude compared to human-dominated disturbances in managed forests (median duration of 1 year). However, temporal dynamics between natural and human-dominated disturbances showed strong synchrony, suggesting that disturbance peaks are driven by natural events affecting managed and unmanaged areas simultaneously.
The study was published in the ISPRS Journal of Photogrammetry and Remote Sensing and can be found here.