Abstract:

Objective: This study aims to explore the dominant environmental factors affecting the distribution of C. mollissima and simulate the potential distribution areas of C. mollissima under different climatic conditions, which would provide a theoretical basis for the conservation and introduction of C. mollissima germplasm resources. Method: Based on geographical information on 472 distribution points of existing C. mollissima populations and 21 environmental variables, an ensemble species distribution model was used to simulate the potential suitable distribution areas of C. mollissima, and the accuracy of the model was evaluated by the value of AUC and TSS. The ensemble model was used to speculate the distribution of suitable areas for C. mollissima and their change trends in the Last Glacial Maximum, Mid-Holocene, Current, 2030 and 2050. Result: 1) Among the 10 models, RF, GBM, MARES and GAM displayed the best and stable performance in prediction accuracy, and AUC and TSS values of the ensemble model were 0.974 and 0.816, respectively, indicating a high accuracy. 2) The main environmental factors affecting the geographical distribution of C. mollissima were the minimum temperature of the coldest month, altitude, precipitation of the wettest quarter, temperature annual range and precipitation of wettest month, and their cumulative contribution was 89.79%. 3) Under the current climate conditions, the potential growing areas of C. mollissima in China were widely distributed, and since the Last Glacial Maximum, the growing areas of C. mollissima have been expanding to higher latitudes, and the warmer the climate, the faster the expansion. The overall suitability of C. mollissima has been decreasing, more prominently in the south and less in the north, and the total area of high suitability zones has been gradually decreasing. Conclusion: The geographical distribution of C. mollissima is influenced by both climatic and topographic factors, among which the temperature makes the greatest contribution and altitude also plays a crucial role. Under the current climate, C. mollissima have a wide range of suitable areas in China, and it is recommended that planting and germplasm conservation should be carried out in highly suitable areas, and migration to higher latitudes should be appropriate when climate conditions are unfavorable for C. mollissima growth in the future, so as to reduce the losses caused by climate change.

Key words: Castanea mollissima, species distribution model, climate suitability, distribution prediction