长期模拟增温对岷江冷杉幼苗生长与生物量分配的影响

Effect of long-term warming on growth and biomass allocation of Abies faxoniana seedlings

川西亚高山针叶林是青藏高原东部高寒林区的重要组成部分,也是研究全球变化对森林生态系统影响的重要组成。长期模拟增温对川西亚高山森林树木的生长、物质积累及其分配格局的影响至今鲜有报道。以川西亚高山针叶林优势种岷江冷杉(Abies faxoniana)幼苗为研究对象,采用控制环境生长室模拟增温的方法,研究了模拟增温对岷江冷杉幼苗生长、物质积累及其分配格局的影响。结果表明,模拟增温(2.2±0.2)℃处理65个月后,岷江冷杉幼苗基径、株高、单株叶面积和比叶面积(SLA)均显著增加,比叶重(LMA)显著下降。增温对岷江冷杉幼苗的茎、侧枝、叶和总生物量具有显著的促进作用,对根生物量没有显著影响。岷江冷杉幼苗的叶重比(LMR)下降、枝重比(SMR)增加、根重比(RMR)无显著变化。长期增温能显著促进岷江冷杉幼苗的生长和物质积累,改变生物量分配格局,促使叶片物质向茎转移,降低光合物质投入。

The global climate is predicted to become significantly warmer over the next century. This will affect ecosystem processes and functioning of natural ecosystems in many parts of the world. It is well known that responses of ecosystem to climate warming may be more sensitive and rapid in high latitude regions and high altitude regions. The subalpine zone in eastern Qinghai-Tibet Plateau is a sensitive area of climate change and ecological fragile zone and this region is predicted to experience much greater increase in surface temperatures in the future. Thus,it is an ideal region to study the response mechanism of terrestrial ecosystems to climate change. Previous studies have illustrated that warming directly influenced the plant phonology,physiological performance and species composition and increase growth and dry mass production. However,these studies have often focused on effects of short-term warming. Whereas short-term warming invariably increases the biomass of tree seedlings,it is far from clear whether elevated temperature will increase forest productivity in the long term. Thus,it is essential that the responses of subalpine tree species to long-term warming are studied. Abies faxoniana is a typical important plant species in the subalpine coniferous forest. Although A. faxoniana is an important forest tree species in China,its responses to elevated temperature remain largely unknown. Thus,our objective was to study the biomass responses of seedlings of A. faxoniana,to long-term experimental warming to provide insights into the growth of A. faxoniana seedlings under a future warmer climate.We use growth chamber to determine long-term effects of elevated temperature （ （ 2. 2 ± 0. 2） ℃ ） on growth,biomass and its allocation in A. faxoniana seedlings for 65 months. These results showed that warming significantly increased growth in the basal diameter,height,whole-plant biomass,total leaf area of seedlings and specific leaf area （ SLA） by 40. 02% ,33. 97% ,24. 24% ,35. 38% and 19. 02% ,respectively. But there was no significant effect on leaf mass per area （ LAM）. Moreover,the leaf-weight ratio （ LMR） of seedlings was inhibited by warming,implying that long-term warming had negatively affected on the foliage. The branch-and-stem weight ratio of seedlings （ SMR） was significantly improved by 25. 84% ,indicating that a larger biomass allocated to branch and stems under warming. However,warming had no significant effect on the root-weight ratio of seedlings （ RMR） ,demonstrating that the ratio of biomass allocated to roots kept constant. The Root-and-leaf weight raito （ RLR） was not affected by treatment while the Root-and-shoot weight ratio （ RSR） was decreased by 6. 34%. In summary,the presents study suggests that long-term air warming enhanced seedling growth and altered biomass allocation pattern. Moreover,warming drive plant reallocate biomass from leaves to shoots,thus,reduced the photosynthesis resources. We concluded that A. faxoniana could adapt to climate change through biomass reallocation.