Emergy-based agricultural ecosystem analysis for specialized tea planting: A case study of Anxi County, Fujian Province

In pace with sustainable growth of tea drinking habit prevalent in the world today, the scale of tea plantation which is traditional agriculture activity in China, has been rapidly expanding. Accordingly, a mainly market-driven factor is the economic benefit of tea, but the effect of planting tea on the eco-environment has been easily ignored. In this paper, the specialized tea planting region of Anxi County in Fujian Province was used as a case study to grade the specialization of tea planting among towns. A total of 5 levels of tea planting specialization (high, sub-high, middle, low and no tea planting) were graded with the integration of 3 indices (tea planting area, location quotient and coefficient of concentration) in the study. Based on emergy theory and method, emergy investment and output indices were calculated and 8 emergy evaluation indices were used to analyze agricultural ecosystems at different specialized levels of tea planting. The study showed that: (1) the operation of Anxi’s specialized tea planting agricultural ecosystem was given priority to renewable environmental resources. The environmental contribution ratio for different specialized levels of tea planting was 0.96–0.99 while the emergy investment ratio was only 0.01–0.04. (2) A positive correlation existed between the density of emergy yield and specialized levels of tea planting. Agricultural ecosystem productivity improved with increasing specialized level of tea planting. Then the density of emergy output of high specialization tea planting was 4.15E+11 sej·m^-2, which was 1.32 times that of specialized level of no tea planting. (3) Specialized tea planting agricultural ecosystem had high production efficiency and economic benefit, with a positive correlation between emergy yield ratio and specialized level of tea planting. The emergy yield ratio of tea planting and high specialization was 1.29, which was 2.86 times that of specialized level of no tea planting. The environmental load ratio of each specialized level was 0.05, indicating that its environmental friendly nature. (4) Specialized tea planting reduced agricultural ecosystem stability and there was a negative correlation between system stability index and specialized level of tea planting. The system stability index of specialized level of no tea planting was 1.12, which was 1.56 times that of high specialization level. The corresponding countermeasures and suggestions based on the results were therefore as follows: (1) there was the need for compound ecological tea garden construction to focus on improving the biodiversity and stability of tea planting agricultural ecosystems with increasing specialization. (2) It was necessary to pay more attention on the management and technical aspects of agricultural production for well-coordinated and sustainable development of tea productivity capacity in the study area.