Subjects: Biology >> Botany >> Applied botany submitted time 2022-08-05 Cooperative journals: 《广西植物》
Abstract： Excentrodendron tonkinensis is a constructive species of karst seasonal rainforest and an obligate karst plant, which is also one of the national secondary key protected wild plant and an IUCN endangered plant, with high economic and ecological value. However, there is still a lack of understanding of how the potential suitable areas of Excentrodendron tonkinensis change in the context of global change and its key driving factors, which affect the scientific protection and utilization of Excentrodendron tonkinensis.To assess the impacts of climate change on the extents of the habitat of Excentrodendron tonkinensis, we used the Maximum-entropy model to analyze the potential changes in the geographical distribution in China of future climate scenarios SSP1-2.6 and SSP5-8.5), and tested the influence of the karst geological background distribution on predicting the suitable areas of karst obligate plants. The results show that: (1) in the case of adding karst geological background data, the average AUC of the prediction model for the suitable area is 0.997, which has a good prediction effect. And the model prediction results are strictly limited to the karst region, consistent with the characteristics of Excentrodendron tonkinensis which is karst obligate plant; (2) According to the fitting results of the model, the karst geological background, precipitation of warmest quarter(800-950 mm), and the min temperature of coldest month(7-11 ℃) are the key factors limiting the distribution of Excentrodendron tonkinensis; (3) with the increase of temperature in the future, the area of potential suitable areas for Excentrodendron tonkinensis would expand to higher latitudes karst areas. Large numbers of areas of stable habitats exist in parts of southwest Guangxi and southeastern Yunnan. These results suggest that the karst geological distribution is essential as predicting the potential geographic distribution of karst obligate plants such as Excentrodendron tonkinensis; if the temperature continues to rise in the future, its potential suitable areas will expand to high latitudes, and the degree of endangerment may be affected by climate, which means it is not obvious under the influence of climate changes; parts of southwestern Guangxi and southeastern Yunnan are suitable areas for the conservation and utilization of Excentrodendron tonkinensis under the climate changes in the future.
Subjects: Biology >> Botany >> Applied botany submitted time 2022-06-29 Cooperative journals: 《广西植物》
Abstract： In order to study the adaptive strategy of dominant tree species in a karst seasonal rain forest to heterogeneous habitat conditions, seven dominant tree species in a virgin forest in Nonggang, China, were taken as the research objects. The leaf micromorphological indexes of adult individuals of each tree species and the photosynthetic indexes of leaves in the growing season of these trees were measured. The ecological adaptability of these leaf structural and functional indexes to the habitat gradient in the karst peak cluster depression landform was tested. The results were as follows: (1) Along the karst habitat gradient from depression to peak, nine leaf micro-morphological indexes, such as leaf compactness, palisade tissue thickness, cuticle thickness, and upper epidermis thickness, showed a significant upward trend, while leaf looseness showed a significant downward trend. (2) Along the karst habitat gradient from depression to peak, the light compensation point, dark respiration efficiency, and maximum transpiration rate of these leaves all showed a significant upward trend. However, the maximum water use efficiency, the maximum intercellular CO2 concentration, and the apparent quantum efficiency showed a significant downward trend. (3) Leaf compactness was positively correlated with photosynthetic and transpiration ability indexes. Leaf looseness was negatively correlated with these two types of indexes. The above results show that there is a trade-off relationship between photosynthetic efficiency and drought tolerance in leaf functional traits of dominant tree species in the karst seasonal rain forest. Trees distributed in the depressions have obvious adaptive characteristics to weak light. Trees distributed on the middle slopes show extensive habitat adaptability. Due to the limitation of strong light, high temperature and exposed rock, the trees distributed on the mountain peaks show strong drought adaptability and conservative ecological adaptive strategies.
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