## 3 Results
### LAI and GPP Analysis
Note that the standard deviation values of the LAI are relatively high, which might be due to the changes in LAI values but are also dependent on species composition, forest structure, and vegetative phenology, which are all intrinsically related to temperature and rainfall, and this may need to be examined further. GPP serves as one of the most important parameters in global carbon analysis, ecosystem assessment, and monitoring of environmental changes [56; 57]. To date, studies relating to mangrove ecosystem processes (including Net Primary Production) have been few, and the majority of them depend on ground-based flux data (i.e., FLUXNET), which are restricted to certain locations [21; 58; 59]. Introducing remote sensing products such as MODIS GPP could be a solution that will help in improving and extending the study of mangrove carbon processes at a larger scale. Figure 7 shows the GPP values extracted in this study based on the five cases. For all PW pixels (Figure 7a), a reduction in mean GPP from 6.82 g C m\({}^{-2}\) to 5.49 g C m\({}^{-2}\) is noticed. This reduction could be due to the lower GPP contributions by the newly gained mangroves in the PW pixels, which may have lowered the productivity of the whole area. Figure 7b shows the GPP values of the area with no change. The mean GPP of these pixels increased from 5.81 g C m\({}^{-2}\) to 6.73 g C m\({}^{-2}\). The increase of mean GPP over the no change area shows the great ability of mangrove forests to assimilate CO\({}_{2}\). Over the mangrove gain areas, the mean GPP shows an increasing trend from 1.88 g C m\({}^{-2}\) to 2.78 g C m\({}^{-2}\). Most of the mangrove gained areas were found to be mangroves regrown from abandoned aquaculture ponds. Recent studies [60; 61] confirmed that the regrowth of the _R Rhizophoreaceae_ family on the abandoned ponds is feasible, thus supporting the increase of GPP over the gained areas. For the mangrove loss area, mean GPP increased only slightly from 6.38 g C m\({}^{-2}\) to 6.68 g C m\({}^{-2}\). Based on the classification results, most of the mangrove losses are due to transformation of the mangrove areas to oil palm cultivation. The fast-growing oil palm cultivation surrounding the mangrove areas, which are mixed in the larger MODIS pixels (500m), could be the reason for increasing GPP despite the loss of mangrove. The effect of fragmentation on CO\({}_{2}\) assimilation and biomass accumulation by ecosystems is dependent on the size and location of the fragmented patches [62]. To analyze the impact of mangrove fragmentation on the LAI and GPP, we selected the patch of mangrove area with the largest loss (6883.06 ha in 2000), with a loss 1131.68 ha (16.54%) of mangroves and which had fragmented into 60 smaller patches between 2019 and 2000. The mean LAI and GPP values extracted from the MODIS products (Figures 6e and 7e) show a slight increase from 3.11 to 3.41 and a large change from 4.65 g C m\({}^{-2}\) to 6.37 g C m\({}^{-2}\), respectively. Of the fragmented patches, six are of a very large size--total of 5704.50 ha (82.88% of the total area) compared to the MPS (26.63--Table 6), one patch is 17.27 ha, and the remaining 53 patches are smaller than 9 ha. According to [PERSON] et al. [63], the interior of relatively large fragments tends to change less following fragmentation than it does at the forest margins. This may be due to the edge effects, such as altered microclimate, which do not penetrate into the core habitat of the forest interior. [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] [18] concluded that productivity is stable in fragments of more than 9 ha. Therefore, despite serious fragmentation over this selected patch, the increases of LAI and GPP may be supported by the impact of fragmentation on productivity, and the survival rate of trees/plants may be higher in relatively smaller patches because the abundance of solar radiation along the edges of the patches may increase the productivity [63].