关键词: 物种分布, 最大熵模型, 气候变化, 适地适树

Abstract:

Objectve: Aim of this study was to identify potential geographic areas in China suitable for growing Eucalyptus camaldulensis and to predict changes in response to climate change through simulation using the maximum entropy model. The major ecological factors affecting the distribution of E. camaldulensis in China were also analyzed in order to provide a theoretical basis for sustainable development of E. camaldulensis plantations in China. Method: Climate, soil and topographic data from landscapes across China, and data from current locations of successful E. camaldulensis plantations in China, as well as data from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change were used to develop a MaxEnt model for predicting potentially suitable geographic areas for E. camaldulensis for different scenarios of current and future climate conditions in 2041-2060 and 2061-2080 respectively associated with low, medium, and high greenhouse gas emission. Ecological data from natural distribution of E. camaldulensis in Australia were compared to data from areas identified as being highly suited to this species in China. The dominant environmental factors affecting the distribution of E. camaldulensis were analyzed by Jackknife test to compare the ecological similarity between the natural distribution in Australia and highly suitable areas in China. Result: The model developed had a high precision, with the area under the curve (AUC) as training data and testing data being 0.939 and 0.847 respectively. The majority of the highly suitable areas (existence probability>0.66) identified for E. camaldulensis are concentrated in southeastern coastal hilly areas, Nanling mountain and western Yunnan-Guizhou Plateau. Under different climate change scenarios, the areas highly suited to E. camaldulensis are expected to increase significantly by 2070, and the largest increases occur for scenarios with lower greenhouse gases emission levels (RCP 2.6) and with the most sensitive response. The area highly suitable for the species in the southeastern coastal hilly areas fluctuate slightly in latitudinal direction, the areas highly suitable for Nanling mountain expand internally and highly suitable areas in western Yunnan-Guizhou Plateau expand to lower latitudes along the river systems. By the Jackknife test, the dominant ecological factors affecting the distribution of E. camaldulensis were found to be mean temperature of the driest quarter, seasonal temperature variance, maximum temperature of the warmest month, altitude, precipitation of the warmest quarter, the mean temperature of the warmest quarter, annual precipitation, slope, aspect and solar radiation. Collectively, these factors account for over 87.0% of the variation in suitable areas. Seasonal temperature variance, maximum temperature of the warmest month, mean temperature of the warmest quarter, altitude, and aspect range in areas identified as highly suitable for E. camaldulensis in China are similar to those in the natural distribution in Australia. Conclusion: The potentially high-suitability areas identified for E. camaldulensis are mainly concentrated in three regions in China, the southeastern coastal hilly areas, Nanling mountain, and western Yunnan-Guizhou Plateau. Under future climate change, E. camaldulensis is expected to become suited to wider areas in the three regions. The mean temperature of the driest and warmest quarter, seasonal temperature variance, maximum temperature of the warmest month, precipitation of the warmest quarter and annual precipitation, altitude, slope, aspect, and solar radiation are important environmental factors determining the distribution of E. camaldulensis. Even so, compared with the natural distribution, precipitation of the warmest quarter and annual precipitation in suitable areas of China are 2.24 and 2.10 times higher respectively, and these conditions in China favor rapid growth of E. camaldulensis.

Key words: species distribution, MaxEnt model, climatic change, species-site matching