# Monitoring Changes in the Enhanced Vegetation Index to Inform the Management of Forests
## 3 Results
### EVI Changes Throughout the Study Area  
Most forest pixels that showed breaks only had one break (74.9%) over the two decades while some showed more than one break. Of the latter pixels (\(>\)1 break, 25.1%), most had only one type of break (negative or positive) while a few (3.3%) showed both negative and positive breaks over the two decades analyzed. After collapsing multiple temporal breaks by pixel, we found that 5.3% (\(n=12\),348) of all forest pixels experienced EVI breaks (abrupt changes) over the 20-year study period (Table 2). On average, in any given year there was a 0.34% chance that a forest pixel would experience a break in the study area. Most forest EVI breaks (both negative and positive pixels) occurred in the eastern region of the AGPE (Figure 3). There were more negative break clusters in the northeast quadrant compared to other quadrants. Comparing breaks by forest protection status, 95.4% of all breaks occurred across non-protected areas, which represent 84.1% of the study area, and 4.6% of breaks occurred \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Group**} & \multicolumn{2}{c}{**\# of**} & \multicolumn{2}{c}{**\# of**} & \multicolumn{2}{c}{**\# of**} & \multicolumn{2}{c}{**Trend Types**} & \multicolumn{2}{c}{} \\  & \multicolumn{2}{c}{**Forest**} & \multicolumn{2}{c}{**Trend**} & \multicolumn{2}{c}{} & \multicolumn{2}{c}{} & \multicolumn{2}{c}{} & \multicolumn{2}{c}{} \\  & \multicolumn{2}{c}{**Pixels**} & \multicolumn{2}{c}{**Pixels**} & & & & & & & \\ \hline  & & & MIG & MDB & MIGpb & MDBnb & IInb & IDpb & RGB & RBG \\ \hline AGPE & 230,806 & 64,188 & 33,683 & 4981 & 73 & 17 & 11,637 & 1674 & 469 & 11,654 \\ \% of forest pixels & & 27.8 & 14.6 & 2.2 & 0.0 & 0.0 & 5.0 & 0.7 & 0.2 & 5.0 \\ \% of all trends & & & 52.5 & 7.8 & 0.1 & 0.0 & 18.1 & 2.6 & 0.7 & 18.2 \\ \hline Non-protected forests & 194,046 & 58,457 & 30,370 & 4366 & 69 & 15 & 10,691 & 1445 & 404 & 11,097 \\ \% of forest pixels & & & 28.9 & 15.0 & 2.2 & 0.0 & 0.0 & 5.3 & 0.7 & 0.2 & 5.5 \\ \% of all trends & & & 52.0 & 7.5 & 0.1 & 0.0 & 18.3 & 2.5 & 0.7 & 19.0 \\ \hline Protected forests & 36,760 & 5731 & 3313 & 615 & 4 & 2 & 946 & 229 & 65 & 557 \\ \% of forest pixels & & 14.6 & 8.4 & 1.6 & 0.0 & 0.0 & 2.4 & 0.6 & 0.2 & 1.4 \\ \% of all trends & & & 57.8 & 10.7 & 0.1 & 0.0 & 16.5 & 4.0 & 1.1 & 9.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary of EVI trend (gradual change) pixels from 2003 to 2022 broken down by trend type and forest protection status. The values were derived from the output of the bfastclassify algorithm. Percent of forest pixels is the number of forest pixels in each trend type divided by the overall number of forest pixels. The percentage of all trends is the number of trend pixels in each trend type divided by the overall number of trend pixels. Trend types are those proposed by [PERSON] et al. [57]. Abbreviations—MIG: monotonic increasing, greening trend (without breaks); MDB: monotonic decreasing, browning trend (without breaks); MIGpb: monotonic increasing, greening trend with a positive break; MDBnb: monotonic decreasing, browning trend with a negative break; IDb: interruption, increasing trend with a negative break; IDpb: interruption, decreasing trend with a positive break; RGB: reversal, greening to browning trend; RBG: reversal, browning to greening trend. across protected areas, which represent 15.9% of the study area. Negative break pixels amount to 4.8% of all non-protected forest pixels and only 1.0% of all protected forest pixels (Table 2). Positive breaks amount to 1.5% of all non-protected forest pixels and 0.5% of all protected ones. Positive breaks were bigger in protected areas (median = 794.5, mean = 819.6, \(n\) = 256) compared to non-protected forests (median = 719.4, mean = 801.5, \(n\) = 3679, Wilcoxon test = 510,702, \(p\)-value = 0.0236).