## 4 Discussion
Recent advances in the supervised classification of land cover from annual time-series of Sentinel 2 data provide an excellent starting point for experimentation [47; 48]. An alternate approach is to compare remotely sensed vegetation activity to expectations for natural vegetation derived from models accounting for the complex natural dynamics of open ecosystems [27]. All the vegetation types monitored in this study are listed as critically endangered or endangered ecosystems in term of the South Africa's NEMBA legislation. The legislation stipulates that the removal of vegetation in these ecosystems requires prior authorization and a basic environmental assessment. Very few such authorizations were granted in this region over the period studied and therefore it is likely that most of the change reported here can be considered unlawful. Furthermore, it was confirmed that changes affected virgin soil that had remained undisturbed for at least 10 years (but in most cases far longer) as per the CARA legislation. This precludes the invocation of the common defense that old fields rather than intact natural vegetation are being targeted. The information obtained here is being used to aid ongoing investigations and has assisted in the application of administrative penalties for NEMBA contraventions. However, as demonstrated by the rate of change reported here, Renosterveld loss is ongoing. Corrective action to restore lost habitat cannot compensate for the loss of primary natural vegetation to agriculture in this ecosystem [33; 34; 35]. The only effective mitigation measures are intervention while habitat destruction is ongoing or the deterrence of future damage. The implementation of real-time monitoring as described above could allow officials to detect habitat loss soon enough after its initiation that intervention may occur before vegetation removal is completed. Even if this is not possible, reducing the time between the occurrence of an event and expert ground-truthing would aid in the collection of evidence for use in prosecution. The realization that remote sensing technology is in use to monitor threatened ecosystems may itself serve as a deterrent of potential infringements [49]. The nature of Renosterveld loss observed in this study was limited to acute vegetation change within a period of a few days to a few years. Though it is not possible to diagnose exactly the cause of change for each event, the principle factor was ploughing for cultivation. Only a few instance of overgrazing combined with fire were observed to completely transform Renosterveld in this timeframe. The intra-annual patterns of Renosterveld loss reflect patterns of agricultural activity in the region, with the peaks of loss occurring in the months prior to the planting of grains in April and May and before harvesting in October and November. Inter-annual variability may be related to high variability in yields in this region of predominantly dryland agriculture [50]. Poor rainfall over this region over certain years in the study period (2017 and 2019) and macroeconomic factors such as fluctuations in land value may explain some of the patterns seen over the study period, but a longer time series of change would be required to examine these drivers in detail [11; 51]. Given that 41% of the area lost occurs through a few incidences of 5 ha and larger, and the concentration of loss within certain sub-regions of the Overberg region, it is likely that a few actors are responsible for much of the loss observed. This may impede interpreting regional patterns of change though time, as influential individuals may respond to idiosyncratic drivers. The efficiency of the painstaking work of accurately digitizing areas of potential loss and dating individual change events could be improved through the application of improved algorithms and a larger, more diverse training data set [47; 48; 52]. However, image interpretation will continue to require the expertise of an individual with familiarly of the ecosystem under consideration.