摘要:选取5年生川西云杉（Picea balfouriana）幼苗作为试验材料，于生长季模拟土壤温度和水分变化，研究不同土壤温度和水分处理对幼苗各器官生物量和非结构性碳水化合物（NSC）浓度的影响，以期加深对高海拔树木碳水化合物生理的理解，并为全球气候变化下植物的生理生态响应和动态变迁研究提供基础数据。于人工气候室内采用嵌套设计，设置5个土壤温度梯度（2、7、12、17、22℃），每个温度处理下3个土壤水分处理（干旱处理、正常水分含量处理、饱和水分含量处理）。每9株幼苗为同一个处理，共135株幼苗。试验处理4个月后，测定幼苗各器官生物量、可溶性糖、淀粉和NSC浓度。土壤温度对幼苗总生物量无显著影响，但土壤低温显著降低了根生物量和根冠比；干旱和饱和水分胁迫在较高的土壤温度处理下显著降低了根生物量和根冠比。随着土壤温度降低，各器官可溶性糖、淀粉和NSC浓度并未降低，反而呈现出升高或不变的趋势。。在土壤低温处理下（2和7℃）干旱显著降低了当年生叶的淀粉和NSC浓度以及当年生枝的淀粉浓度；在2和7℃时，干旱和饱和水分胁迫显著降低了根中淀粉和NSC浓度。土壤低温和水分胁迫对幼苗地上地下生物量分配影响显著，分配给光合器官的生物量相对增多。土壤低温并没有导致碳受限，甚至各器官NSC浓度随着土壤温度降低有升高的趋势，因此，土壤低温下非结构性碳水化合物的不足不是限制川西云杉幼苗存活和生长的原因，从侧面支持了林线形成的"生长抑制"假说。此外，干旱胁迫在土壤低温下很可能会导致川西云杉的"碳饥饿"。



Abstract:To better understand the carbohydrates of timberline trees, and to obtain basic data to study the physiological and ecological responses, and dynamic changes of trees under global climate change, five-year-old Picea balfouriana seedlings were selected as experimental materials to study the effects of different soil temperatures and moisture treatments on their biomass and non-structural carbohydrate (NSC) concentrations. A nested design was used in a walk-in artificial climate chamber to set five treatments for soil temperature at (2, 7, 12, 17, and 22 ℃ and three for soil moisture conditions (drought, normal moisture, and saturated moisture), respectively. Each of the nine seedlings were given the same treatment; totaling 135 seedlings. After four months, their biomass, and concentrations of soluble sugar, starch, and NSC were measured. Results showed no significant effect of soil temperature on the total biomass, but low soil temperatures significantly reduced root biomass and root to shoot ratio. Drought and saturated water stress significantly reduced root biomass and root to shoot ratio under higher soil temperatures. The concentrations of soluble sugar, starch, and NSC in different organs increased or remained unchanged with decreasing soil temperature. At soil temperatures of 2 ℃ and 7 ℃, drought significantly reduced starch and NSC concentrations in annual needles and starch concentration in annual branches, while drought and saturated water stress significantly reduced starch and NSC concentrations in the roots. Low temperatures and water stress significantly affected the distribution of aboveground and underground biomass, that allocated to photosynthetic organs increased significantly. Low temperatures did not lead to carbon limitation, and even the NSC concentrations tended to increase with decreasing soil temperatures. The results supported the "growth limit" hypothesis of the timberline in some cases. Drought stress could lead to carbon starvation of Picea balfouriana seedlings at low soil temperatures.





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