Search

• · Biomod2 and MaxEnt models was tested, and the predictions of the two models were compared. • · The optimized model was used to predict and analyze the potential suitable habitat for Z. jujuba. • · Reconstruct the history of changes in the geographical distribution pattern of Z. jujuba. • · Establish a theoretical foundation for studies on the evolution of North China flora. Ziziphus jujuba has high ecological and economic value and is widely distributed in northern China. Reconstructing the historical geographic distribution patterns of Z. jujuba and determining the environmental distribution restrictions could provide a scientific basis for its germplasm conservation and management. Here, the R packages ENMeval and Biomod2 were used assess to 121 distribution records and 18 environmental variables and model and analyze the geographic distribution changes of Z. jujuba in different periods since the last interglacial period. Environmental anomalies and factors underlying the geographical distribution changes and migration trends in distribution areas under climate change were assessed. The optimized MaxEnt model generated the best predictions, and the modern highly suitable area was located in the Yellow and Haihe river basins. Climate anomalies in the historical periods ranged in decreasing order from the last interglacial > last glacial maximum > middle Holocene. The degree of climate anomalies under RCP (Representative Concentration Pathways) 2.6-2050s was the lowest, and the degree of climate anomalies under RCP8.5-2070s was the highest. From the last interglacial period to the 2070s, the most dissimilar variable was initially precipitation but gradually changed to temperature with climate change, which was the key factor for the geographical distribution of Z. jujuba. Although extensive habitat expansion occurred during the last interglacial period, the area suitable for Z. jujuba retreated to higher latitudes during the last glacial maximum and middle Holocene. As climate warming intensifies, suitable habitats will shift to higher latitudes while habitats in lower latitudes will become scarcer. The whole suitable region in China will migrate to a higher latitude area, indicating that the Z. jujuba distribution shows a strong response to climate change. This study provides a theoretical basis for establishing conservation measures for Z. jujuba genetic resources and studying trends in plant formation and evolution in North China. [ABSTRACT FROM AUTHOR]

The continuous global climate change has affected the living habits, morphological characteristics and spatial distribution of tree species. Chinese fir (C. lanceolata (Lamb.) Hook) is one of the most important conifer tree species in China, which plays a major role in terms of timber supplies and environment protection. Predict the potential suitable habitats of Chinese fir under different climatic scenarios, can not only provide scientific theoretical basis for the planning and planting of Chinese fir, but also have great significance for maintaining the stability of the plantation ecosystem. Here, we used the maximum entropy (Maxent) model which optimized by the ENMeval package, to predicted the potential suitable habitats for Chinese fir under current climatic conditions and two climatic scenarios in 2070s. Our results showed that the complexity of the model was relative low, when the regularization multiplier (RM) was 0.5 and feature combination (FC) was linear (L) and quadratic (Q). Under this parameter setting, the high and moderate suitable habitat area of Chinese fir were 83.90 × 104 km2 and 97.62 × 104 km2, respectively, which suggested we can carry out Chinese fir planting activities with different cultivation purposes. The minimum temperature of the coldest month, annual precipitation, annual mean temperature and mean temperature of warmest quarter were identified as the essential factors shaping habitat suitability for Chinese fir. Under future climate scenarios, the high suitable habitat was reduced and the degree of fragmentation was increased, and the total potential suitable habitat of Chinese fir had the tendency to migrate to high-altitude regions. Managers should be cautious about the cultivation area selection of Chinese fir plantation as the potential suitable habitat changed under the global climate change continuously. It is therefore imperative to adjust the long-term management and protection strategy of Chinese fir plantation. • Maxent was used to predicted the potential habitat of Chinese fir. • R package ENMeval was used to optimized the Maxent model. • Potential habitat of Chinese fir were concentrated in subtropical regions. • Potential habitat had a tendency to migrate to high-altitude regions. • Temperature and precipitation were main factors affecting potential distribution. [ABSTRACT FROM AUTHOR]