ABSTRACT
Pickled mustard tuber (Brassica juncea var. tumida) belonging to Cruciferae, is a unique economic crop in China. Climate is an important factor affecting the distribution of pickled mustard tuber. Based on species presence data at 279 locations and 22 high-resolution environmental factor layers, we analyzed the potential planting area of pickled mustard tuber in Chongqing by MaxEnt model under the current conditions and the future distributions for the periods 2050s and 2070s under the climate change scenarios of RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 described in the Special Report on Emissions Scenarios (SRES) of IPCC (Intergovernmental Panel on Climate Change). The results showed that MaxEnt model was excellent in predicting its potential plan-ting area. The cumulative contributions of dominant factors reached as high as 81.7%, including precipitation of wettest month, temperature annual range, minimum temperature of coldest month, isothermality, mean diurnal range and average maximum temperature. The threshold of those factors was 173-183 mm, 27.2-28.3 â, 1.8-3.8 â, 22.5-24 â, 6.2-6.8 â and 14.8-18.0 â, respectively. Under current condition, the optimum suitable areas of pickled mustard tuber, which amounted to 4.2%, were in the northeast, west and east of Fuling, the east and south of Changshou, the south and southeast of Dianjiang, the northwest and north of Fengdu, the southeast of Zhongxian, and a small part of Wulong and Nanchuan, while the proportion of moderately suitable areas was 6.3%. Under four climate change scenarios, the optimum suitable areas would drop to 2.7%, 3.8%, 3.1%, 3.2% and 3.1%, 3.7%, 3.5%, 2.9% for the periods 2050s and 2070s, respectively, while moderately suitable areas would rise gradually.
