Emergy, environmental impact, and economic assessment of rubber–edible mushroom–vegetable intercropping in Hainan, China

Intercropping in rubber plantations has been widely recognized as an effective measure to enhance the economic benefits and mitigate the environmental impact of rubber cultivation systems. The practice of cultivating specialty edible mushrooms under rubber, followed by utilizing spent mushroom substrate to grow vegetables under the same forest canopy, has been widely adopted by rubber farmers in Hainan, China, forming a distinctive rubber–edible mushroom–vegetable intercropping (RMVI) model. However, the economic benefits and environmental impacts of the RMVI cultivation management process remain unclear. This study compared the environmental sustainability and economic benefits of monoculture systems for rubber, edible mushrooms, and vegetables (RMVM) with those of an RMVI system through the combined use of emergy evaluation (EME), life cycle assessment (LCA), and economic analysis (EA). The EME analysis indicated that the total emergy value of the RMVI system was lower than that of the RMVM system. From the perspective of the emergy index, the RMVI system exhibited lower environmental pressure and higher system sustainability than the RMVM system. The LCA suggest that transitioning from monoculture to intercropping can reduce all environmental impact categories by approximately 3.59 %–36.84 %. In terms of climate change specifically, the CO₂ emissions were reduced by 12.94 %. In both the RMVM or RMVI systems, the input of mushroom spawn sticks (MSS) and their transportation were critical factors contributing to environmental consequences, accounting for 4.95 %–55.73 % and 22.13 %–88.97 % of the total environmental impact, respectively. Therefore, optimizing the inputs in the MSS production process and decreasing the MSS transportation distance can reduce the system’s environmental impact. The EA revealed that compared with RMVM, the RMVI system reduced costs by 19.74 % and increased profits and the cost–benefit ratio by 5.93 % and 31.99 %, respectively. These findings indicate that the RMVI system is conducive to enhancing the environmental sustainability and economic viability of rubber cultivation. Policies should promote the widespread adoption and practice of the RMVI system to enhance the sustainable transformation of rubber production systems.