## 3 Results and Discussion
### Annual Changes in GPP
The increase in the GPP estimation value is very high but is still less than the increase in the settlement area, where in general, there is a linear relationship between the increase in area and the total GPP in the settlement area (see Tables 3 and 5). The linear relationship between changes in settlement area and primary production is consistent with the study of [PERSON] et al. (2015). A linear relationship was also found in the agriculture and grass land use type, with decreases in area of approximately 55.29%, followed by a loss of ability to uptake total carbon of 54.19%. Although only approximately half of the agriculture and grass land use type has been converted, the area reached up to 4350.51 ha. The settlement areas increased to 4906.44 ha during the study period, which indicates that agriculture and grass have been converted to settlement areas. Consequently, the ability of cities to uptake carbon from the atmosphere is reduced, as displayed in Table 5. Settlement areas can uptake carbon due to the presence of vegetation. [PERSON] et al. (2015) have shown that not all settlement areas in Denpasar are covered by structures, but have various built-up land uses that include vegetated and non-vegetated areas such as backyards and front yards. However, this city is unique in that the majority of the population is Hindu, and the city is a \"flat city\" due to the absence of tall buildings. These characteristics are not found in other regions in Indonesia or in other regions in Southeast Asia. The city of Denpasar contains a \"holy area\" for Hindu religious activities at each residence that is characterized by the presence of vegetation with varying levels of cover and heights. However, the increase in settlement area has not impacted the average GPP estimates, unlike the results obtained by [PERSON] et al. (2019), which show an increase in the mean annual GPP at the time of an increase in the built-up area in the eastern United States. Given that the development of settlement areas in the city is difficult to control due to high demand for tourism activities, an increased settlement area accompanied by good management of \"holy areas\", backyards, and front yards should be able to increase the ability of settlement areas to uptake atmosphere carbon through vegetation. Interestingly, although the forest areas are degraded, forest restoration has been helpful in preventing a drastic decline in GPP in Denpasar city over the past two decades. A forest area of approximately 175.41 ha was lost during the study period, but the annual estimated GPP increased by approximately 27.23% from 1995 to 2014. This increase is due to the restoration of mangrove forests in the southern part of Denpasar from 1995 to the present. Reforestation is conducted by replanting mangroves in water (pond) land use areas and maintaining these areas by making them protection areas. The mangrove forest in southern Denpasar is part of a protected area established by the Indonesian government, the Ngurah Rai Grand Forest Park, through decision No. 544/Kpts-II/1993 in 1993. The current study indicated the importance of forest ( mangrove) restoration to sustain the carbon cycle in urban areas that have experienced rapid land use change due to increased tourism activity and urbanization. Ecological restoration is important to increasing the total carbon uptake by vegetation. Successful ecological restoration associated with primary production has been reported previously by [PERSON] et al. (2016), but this result was an increase in the amount of carbon sequestration due to an increased terrestrial vegetation area, not under the decline of forest area. However, [PERSON] et al. (2017) found an increase in tree productivity during forest conversion to urban areas. Forest productivity is a function of many factors such as species, age, resource availability, growing season length, and competition ([PERSON] et al., 2017; [PERSON] et al., 2017). Mangroves are among the most carbon-rich forests in the tropics ([PERSON] et al., 2017). [PERSON] et al.