No abstract

No abstract

No abstract

No abstract

Camptotheca acuminata is considered a natural medicinal plant with antitumor activity. The assessment of climate change impact on its suitable habitats is important for cultivation and conservation. In this study, we applied a novel approach to build ecological niche models with both climate and soil variables while the confounding effects between the variables in the two categories were avoided. We found that the degree-days below zero and mean annual precipitation were the most important climatic factors, while the basic soil saturation, soil gravel volume percentage, and clay content were the main soil factors, determining the suitable habitats of C. acuminata. We found that suitable habitats of this species would moderately increase in future climates under both the RCP4.5 and RCP8.5 climate change scenarios for the 2020s, 2050s, and 2080s. However, substantial shifts among levels of habitat suitability were projected. The dual high-suitable habitats would expand, which would be favorable for commercial plantations. Our findings contribute to a better understanding of the impact of climate change on this species and provide a scientific basis for the cultivation and conservation purposes.

Species distribution models are widely used in conservation biology and invasive biology. MaxEnt models are the most widely used models among the existing modeling tools. In the MaxEnt modeling process, the default parameters are used most often to build the model. However, these models tend to be overfit. Aiming at this problem, this study uses an optimized MaxEnt model to analyze the impact of past, present and future climate on the distributions of Codonopsis pilosula, an economic species, to provide a theoretical basis for its introduction and cultivation. Based on 264 distribution records and eight environmental variables, the potential distribution areas of C. pilosula in the last interglacial, middle Holocene and current periods and 2050 and 2070 were simulated. Combined with the percentage contribution, permutation importance, and jackknife test, the environmental factors affecting the suitable distribution area of this species were discussed. The results show that the parameters of the optimal model are: the regularization multiplier is 1.5, and the feature combination is LQHP (linear, quadratic, hinge, product). The main temperature factors affecting the distribution of C. pilosula are the annual mean temperature, mean diurnal range, and isothermality. The main precipitation factors are the precipitation seasonality, precipitation in the wettest quarter, and precipitation in the driest quarter, among which the annual average temperature contributes the most to the distribution area of this species. With climate warming, the suitable area of C. pilosula exhibits a northward expansion trend. It is estimated that in 2070, the suitable area of this species will expand to its maximum, reaching 2.5108 million square kilometers. The highly suitable areas of C. pilosula are mainly in Sichuan, Gansu, Shaanxi, Shanxi, and Henan Provinces. Our findings can be used to provide theoretical support related to avoiding the blind introduction of C. pilosula.

In the present study, concentrations of heavy metals (Cu, Zn, Pb, Cd) in soil and wheat grains of the agricultural areas around Baiyin, a non-ferrous metals mining and smelting base, were detected. Meanwhile, the potential health risk of the heavy metals to adult males, adult females and children was estimated using non-carcinogenic health risk assessment model: Hazard Quotient (HQ) and Hazard Index (HI). The results showed that only the level of Cd in all soil samples exceeded the permissible limit of the environmental quality standard for soil, and its average level surpassed the standard value by 4 times. In wheat grains, the levels of Pb and Cd were 50 times and 8 times of the limited values of hygienic standard for grain respectively, while Cu and Zn concentrations did not surpass the standard value. The potential health risk due to single heavy metal for all the three investigated populations followed the sequence of HQPb＞HQCd＞HQCu＞HQZn＞1 (assumed the local inhabitants wholly food on wheats), suggesting that each of the four heavy metals were making negative effect on population health, of which the situation of Pb and Cd should be paid more attention due to their significant adverse effect. The total potential health risk due to the four heavy metals followed the sequence of HIchildren＞HImales＞HIfemales＞1 (assumed that the health risk due to the four heavy metals is additive), suggesting that the heavy metals were producing adverse effect on population health, and were especially hazardous for children. According to the research results, the government is suggested to strictly control the quality of irrigation water and remove the heavy metals from agricultural soil in order to ensure the safety of foodcrop production and local inhabitants.

No abstract