## 1 Introduction  
The energy consumption, pollution, and carbon emissions generated from tourism activities have gradually become significant driving factors for environmental degradation and global climate variation [1]. The transportation mode, accommodation choices, and activities undertaken by tourists during travel are the primary sources of energy consumption and carbon emissions in the tourism industry [2, 3, 4]. In 2008, an integrated literature research using a bottom-up approach was conducted focusing on carbon emissions in China's tourism industry [5, 6]. The study revealed that tourism transportation carbon emissions accounted for 90% of China's total tourism-related carbon emissions from 2000 to 2013 [7]. Using carbon emission factors from UNWTO-UNEP-WMO, the carbon emissions from tourism transportation in China from 1980 to 2009 were calculated. The findings indicated that, in 2009, the amount of carbon emission from railway, road, waterway, and civil aviation tourism transportation was 6.722 million tons, 24.8 million tons, 0.078 million tons, and 29.92 million tons, respectively, with civil aviation having the highest amount of carbon emission [8]. The input-output method for tourism accommodation has been used to measure the energy consumption of tourism accommodation and explore low-carbonmanagement paths for China's hotel industry [9]. The outbreak and spread of COVID-19 have significantly impacted global carbon emissions [10]. In the Singapore Strait, carbon emissions from ferries, cargo ships, passenger ships, and roll-on/roll-off (Ro-Ro) vessels in 2020 decreased by 75.82%, 0.84%, 28.35%, and 0.73%, respectively, compared to 2019 [11]. France experienced a 6.6% year-on-year reduction in total carbon emissions during a 55-day lockdown in 2020 [12]. In Los Angeles, during the lockdown period in March and April 2020, carbon emissions decreased by 0.57 MtC, 0.30 MtC, 1.09 MtC, and 0.21 MtC compared to the same period in 2018 and 2019 [13]. Colombia witnessed a 28% decrease in carbon emissions during the travel lockdown in the first half of 2020 compared to the same period in 2018 [14]. Regarding vegetation carbon sink estimation, using net primary productivity (NPP) constitutes a mature approach and has become an essential indicator in global vegetation ecosystem assessments [15]. Spatiotemporal changes primarily depend on the complex interactions among vegetation, soil, and climate [16], with precipitation being the main limiting factor for the net primary productivity of vegetation in China [17]. Scholars have estimated the total carbon stock of grassland ecosystems in the Three Rivers Source Region to be 53.38 \(\times\) 10\({}^{8}\) tons, with an average carbon density of 14.94 kg/m\({}^{2}\), using MODIS GPP/NPP, MODIS NDVI, and various climatic data analyses [18]. The central part of Hainan Island is characterized by high carbon density in natural rubber forests, with an average carbon density ranging from 25 to 33 t/hm\({}^{2}\). In comparison, the northern part is a low-value area with an average carbon density below 20 t/hm\({}^{2}\)[19]. The calculation of net primary productivity (NPP) involves two main methods: NPP inversion models [20; 21; 22] and direct utilization of MODIS NPP data for measuring carbon sinks [18]. Additionally, utilizing carbon as ecological compensation is an effective strategy for facilitating regional coordination and achieving carbon neutrality [23]. Ecological compensation is called payment for ecological/environmental services (PES). It involves the restoration of ecologically damaged sites or the replacement of original ecological sites or qualities with new ones, aiming to restore the affected environmental functions and values that persist even after minimizing the impacts of intervention (mitigation) [24; 25]. In China, ecological compensation includes payment for ecological/environmental services (PES) and compensates units and individuals for the costs incurred in protecting the umbrella ecological environment and functions [26].