## 5 Discussion
### LUCs Impact Ecosystem Services Value (ESV)  
The results revealed that Putian City's ESV increased steadily, reaching 15.403 billion CNY in 2000, 20.635 billion CNY in 2010, and 23.148 billion CNY in 2020. The average proportions of ESV across land-use types were as follows: forest land (67.63%) > water body (23.47%) > cultivated land (7.44%) > grassland (5.62%) > orchard land (0.32%) > unused land (0.18%), indicating the substantial contributions of forest land, water bodies, and cultivated land to Putian City's ecological services. The study also revealed that built-up land exhibited a negative ESV, the only land type to demonstrate such an ecological impact. Moreover, this negative trend intensified over time, while the ESV of other land types continued to grow. These findings are attributed to the rapid urbanization rate and unsustainable resource allocation in Putian during the study period, leading to low urbanization efficiency. According to the study team's analysis, Putian City possesses the lowest urbanization efficiency among the nine cities in Fujian Province. This inefficiency stems from the city's excessive resource input, inadequate expected output, and excessive unintended output. Resource waste, unreasonable resource input scale and structure, inefficient resource utilization, and excessive discharge of wastewater and exhaust gases have all contributed to the negative impact on ESs [69]. Therefore, rational planning of construction land is crucial for improving urban environmental quality, enhancing regional ecosystem ecological efficiency and service value, and bolstering ecosystem service capacity. This is a critical scientific challenge facing cities in the era of ecological civilization. An analysis of the various types of ecosystem services showed that regulatory services were the most prominent, amassing an ecological value of 17.12 billion CNY over the last twenty years. This represents a significant portion, specifically 73.95%, of the entire ESV. Supporting services followed, contributing 20.03%, while cultural services played a minor role, accounting for 4.05%. Provisioning services held the lowest value, representing a mere 1.97% of the total. This distribution can be attributed to several factors, including the shrinking of cultivated land due to urban expansion, poor agricultural conditions (e.g., saline and alkaline soils), low food production efficiency, rural labor migration, and the subsequent abandonment of cultivated land in various regions of Putian City. This abandoned land often transitioned into waseland (grassland) with weeds, resulting in limited land resource utilization. Among the SCES, hydrologic adjustment, climate regulation, and soil conservation emerged as the primary functions in Putian City, while the ecological value of food production held a smaller share. Putian City, a major grain sales area in Fujian Province, relies heavily on external food supplies. Its basic farmland primarily lies in Xiuyu District and Xianyou County. The government should prioritize addressing this issue. The study suggests that along with enhancing the planning of urban and rural settlements as well as industrial and mining zones and rehabilitating deserted areas, it is essential to boost the efficient use of land resources. This might include advancing the modernization of agriculture, bolstering its infrastructure, and putting into action initiatives that support sustainable farming methods. An examination of ESV across districts and counties revealed a consistent increase from 2000 to 2020. Xianyou County exhibited the most significant growth, reaching 4.186 billion CNY. Hanjiang District followed with 1.674 billion CNY, Chengxiang District with 1.103 billion CNY, Xiuyu District with 479 million CNY, and Licheng District with 304 million CNY. In terms of ESV intensity, Xianyou County and Hanjiang District exhibited a comparable upward trend.