# Monitoring Changes in the Enhanced Vegetation Index to Inform the Management of Forests
## 4 Discussion
### Changes in EVI  
Of the forest pixels having breaks, most of them only had one break (74.9%). This means that most negative breaks were not followed by a detectable positive break or a second negative break. Thus, it seems that recovery from negative breaks is primarily gradual with few post-disturbance bursts of growth. Alternatively, the lack of detection of multiple breaks may be due to the \(h\) parameter value used. A smaller value of \(h\) (0.025 or six months) detected more breaks per pixel but much fewer breaks (Table 10).  
Most of the forest EVI pixels that showed a change in the AGPE were located in non-protected areas (95.6% of all breaks and 91.1% of all trends, respectively). This is in line with the findings by [PERSON] et al. [66] who found that protected forests change less compared to nearby non-protected forests mainly due to the lack of human activities taking place therein. Also, we found that there are proportionally more positive breaks in protected forest pixels compared to non-protected ones (35.3% vs. 24.2%, respectively), which implies that on average protected forest pixels show more multiple growth bursts per positive break pixel compared to non-protected forest pixels. Contrary to our predictions, there were fewer greening trends among protected forest pixels (but fewer browning trends) compared to non-protected forest pixels, occurring at half the rate of the latter (8% vs. 15.0%). This higher percentage of greening in non-protected forests is likely the result of regrowth from harvesting events or other anthropogenic activities that took place prior to 2003. On the other hand, the low percentage of greening pixels among protected forest pixels may be the result of the low levels of change experienced by these forests, which may be too low to be detected with the approach used here. Alternatively, the lower number of greening trends seen may be due to the EVI saturation effects of denser canopies [67] that are likely found in protected forests. Overall, given that natural disturbances are expected to occur in all forests regardless of protection status [68] and that non-protected forests experience higher rates of anthropogenic disturbance, protected forests in the AGPE are likely better at providing ecosystem services compared to non-protected forests.  
In terms of the geographical pattern, the northeast quadrant showed the greatest vegetation activity compared to other quadrants (both in terms of breaks and trends) (Figures 3 and 4). The northeast quadrant also showed clustering of pixels showing long-term browning, greening, and reverse (browning to greening) trends (Figure 11,b in Appendix A.4). Such results may suggest that the northeast quadrant is recovering from a drought event.  
In line with our initial predictions, the magnitudes of positive breaks were bigger in protected forests compared to non-protected ones. Furthermore, in terms of the overall proportion of positive breaks, protected forest pixels show more positive breaks per pixel than non-protected forest pixels. This could imply that on average protected forests show stronger and multiple growth bursts compared to non-protected forests. Interestingly, the difference in the magnitude of negative breaks between protected and non-protected forests was not significant. This is surprising given that most negative breaks and stand-replacing disturbance pixels were found in non-protected forests. However, this could mean that most negative breaks are the result of natural disturbances (e.g., droughts), which are likely to affect all forests within the AGPE.