Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： To construct shelter forests in arid areas, selecting plant species with strong stress tolerance andadaptability is key. By simulating a pot water control experiment with different drought gradients, the ecologicaladaptability of the introduced plant Atriplex canescens and the native plant Tamarix ramosissima willow todrought stress were compared. The results showed that (1) With an increase in drought degree, the water contentin the A. canescens and T. ramosissima leaves reduced gradually, and the water retention capacity, prolinecontent, and relative conductivity gradually increased. The soluble sugar and malondialdehyde contents of A.canescens and T. ramosissima were the maximum in mild and severe drought, respectively, and the increase ratewas greater in T. ramosissima. (2) The POD activity of A. canescens and T. ramosissima increased gradually, andunder severe drought, the percentage increase of T. ramosissima compared with the control wasapproximatelythree times that of A. canescens; SOD activity was greatest under moderate drought, and thepercentage increase in T. ramosissima compared with the control was approximatelyfive times that of A.canescens. The changes in the activity of both enzymes of T. ramosissima were greater than those of A.canescens. (3) The chlorophyll content of A. canescens and T. ramosissima were mildly dry > control > moderatedrought > severe drought, the net photosynthetic rate, transpiration rate, stomatal conductance, and intercellularcarbon dioxide concentration of T. ramosissima gradually decreased, and mild drought slightly promotedchlorophyll and photosynthetic capacity of A. canescens. (4) The correlation and principal component analysisresults indicated that the relationship between the T. ramosissima traits was closer under drought stress, and therelationship between traits and traits was difficult to change in A. canescens, which was relatively conservative.Conclusion: A. canescens is less affected by drought stress, and its drought adaptability is slightly stronger thanthat of T. ramosissima.
Subjects: Geosciences >> Geography submitted time 2024-03-01 Cooperative journals: 《干旱区研究》
Abstract： Forest surface combustibles are one of the important factors in forest fire propagation, and theircalorific values are an important index by which to assess combustibility. This study has aimed to assess thesurface fuels available in four typical vegetation types in the eastern Tianshan Mountains of Xinjiang, China. Thecharacteristics of the surface fuel calorific values and relationship with ignition point and absolute moisturecontent were analyzed. The results show that in coniferous and broad- leaved forests, there were significantdifferences between herb and litter components, while in shrub forest, there were significant differences betweenshrub and litter components. Within the same forest the calorific values were litter > herb > shrub > humus. Thecalorific values in the coniferous forests were the highest among the herbaceous fuel components (19.38 ± 0.08kJ·g−1), while those in the coniferous forests were highest among the litter fuel components (19.55 ± 0.05 kJ·g−1).Differences were identified in the relationship between the calorific value and the ignition point of the surfacecombustibles for the different components. There was a significant correlation between the burning point of theshrub fuel components and the calorific value (R2 = 0.81, P < 0.01), and between the burning point of litter fuelcomponents and the calorific value (R2 = 0.38, P < 0.05). However, there was no significant correlation betweenthe burning point and calorific value of the herbs and humus (P > 0.05). In addition, there was no significantcorrelation between the calorific values of the surface fuel and the absolute moisture content of all forest types.Forest type, tree species, physical and chemical properties, and other conditions were thus found to have acomprehensive effect on the calorific values of the different fuels. The results of this study provide a theoreticalbasis for forest fire management in the eastern Tianshan Mountains as they will help to accurately predict thecalorific energy and potential forest fire risks and provide data support for in-depth research on regional surfacefuels.
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