## 3 Results
### LAI and GPP Analysis  
LAI and GPP values for the MODIS IGBP Permanent Wetlands (PW) pixels were extracted. The classified mangrove and MODIS PW pixels of 2000 and 2019 are shown in Figure 5. There were 559 and 388 MODIS PW pixels (500 m) for years 2000 and 2019, respectively, and most of the MODIS PW pixels are located within the classified mangrove area (68% for the year 2000 and 65% for the year 2019). This means that MODIS PW pixels can be used to extract the LAI and GPP values and to analyze their changes over time due to mangrove area changes. The converted total area of MODIS PW is 13,975 ha for the year 2000 and 9700 ha for the year 2019, which was found to be close to the area based on the classification in this study (13,612.25 ha and 10,704.96 ha, in Section 3.1). Similar to the classification result (Figure 3a,b), most of the disappearance of PW pixels were noticed over the Sungai Pulai and Tanjung Piaia area (Figure 5). The mean and standard deviation of MODIS LAI and GPP at 8-day intervals for 2000 and 2019 are plotted and shown in Figures 6 and 7. Five cases are plotted and discussed namely: (1) mean LAI and mean GPP extracted over all mangrove areas--Figures 6a and 7a, (2) mean LAI and mean GPP extracted over areas where mangrove is unchanged--Figures 6b and 7b, (3) mean LAI and mean GPP extracted over areas where a mangrove gain is detected--Figures 6c and 7c, (4) mean LAI and mean GPP extracted over areas where a mangrove loss is detected--Figures 6d and 7d, and (5) mean LAI and mean GPP extracted over selected fragmented areas--Figures 6e and 7e. Table 7 summarizes the mean and standard deviation values of LAI and GPP for these cases. Note that there are some missing data in these graphs due to unsuccessful retrieval of the MODIS products on certain dates that could be due to cloud cover, failure of detectors, or failure of the main radiative transfer algorithm used to retrieve the LAI/GPP values. The analysis starts from day of year (DOY) 57 because the MODIS LAI and GPP products are only available after February 2000. Figure 5: Mangrove area overlaid with the MODIS Permanent Wetlands pixels for year (a) 2000 and (b) year 2019. Figure 6: MODIS LAI values extracted based on (**a**) all mangrove area, (**b**) mangrove no change area, (**c**) mangrove gain area, (**d**) mangrove loss area, and (**e**) fragmented mangrove area. Figure 7: MODIS GPP values extracted based on (**a**) all mangrove area, (**b**) mangrove no change area, (**c**) mangrove gain area, (**d**) mangrove loss area, and (**e**) fragmented mangrove area. Figure 6a shows the mean LAI extracted from the MODIS 8-day product overlaid with all of the PW pixels found in the classified mangrove area. The yearly mean LAI was 3.18 \(\pm\) 1.56 (mean \(\pm\) standard deviation) with minimum and maximum values of 0.10 and 6.90, respectively, for the year 2000; while it was 3.46 \(\pm\) 2.09 (mean \(\pm\) standard deviation) with minimum of 0.10 and maximum of 6.60 for the year 2019. Figure 6b shows that the values extracted from the PW pixels on the unchanged mangrove area also showed an increasing trend, increasing from 3.03 to 3.55 for the years 2000 and 2019, respectively. The increases of mean LAI for all PW and unchanged areas indicate that the mangrove leaf area has grown over the years. Previous analysis (Section 3.1 and Figure 3c) show that relatively less mangrove gain was noticed when compared to area of mangrove loss. Based on the values in Figure 6c,d, the mean LAI extracted from the mangrove gain increased from 2.81 to 3.51, while the mangrove loss area recorded mean LAI decrease from 2.99 to 2.62, respectively. The loss of native mangrove trees, which have dense leaves, to oil palm, which have a less dense canopy, may be the main reason for the reduced LAI values. The mean LAI values were found to correspond to the growth or loss of the mangrove in the study area.