Relationships of soil phosphorus status to wood anatomical traits and to nutrient translocation in woody plants

各种适应策略使维管植物能够在全球几乎所有生态系统中生存和繁荣。除了面临缺水和缺光外，木本植物通常还必须克服营养限制，以维持光合作用和生长。在植物新陈代谢的所有必需的宏观营养中，土壤中可利用的最少的是磷(P)。由于磷的有效性低，植物必须优化其养分获取和/或减少养分损失。一些功能性状已经被确定为适应策略，如有效地从衰老的叶片中吸收养分和增加叶片寿命。然而，关于树干木材特别是树枝中的营养物质转运及其相关的解剖特征的研究仍然很少。此外，系统和环境因素对磷循环的适应性权衡和控制还不是很清楚，植物体内磷的储存和动员在整个植物养分收支中的整合到目前为止还不是很清楚。在本提案中，我想把选择的植物叶、茎和根的功能性状与生长在土壤中的磷含量不同的树种的养分转运模式、生长表现和全株营养状况联系起来。这项研究将在澳大利亚悉尼的麦格理大学进行，加入在植物功能特性领域拥有丰富经验的Mark Westoby教授和Ian Wright教授的研究小组。该提案的重点是理清土壤低磷对木材解剖特征的影响，特别是对木材薄壁组织(即负责储存的活细胞)的影响，以及了解木本植物在磷运输方面的策略。为了实现这一目标，将对生长在贫磷土壤和富磷土壤上的植物群落的功能特性进行调查。此外，将在普通花园试验中建立的磷有效性梯度中选择发生的物种作为苗木进行栽培。将分析活的和新鲜衰老的组织，如树叶、树枝、树干、树皮和根的营养含量，并与营养物质重新定位有关。为了探索养分转运对全树预算的重要性，将调查叶凋落物、细根和茎生长的年生产量。木材解剖分析将侧重于不同树种木材中的薄壁组织成分与磷和其他养分含量之间的关系，以及在磷供应增加后木材组织成分的潜在塑性反应。我相信，本提案提供的机会不仅有助于加深对与磷使用相关的复杂特征的科学知识，还将让我获得必要的专业知识、方法和知识，以成为未来的科学领导者。

A variety of adaptation strategies have enabled vascular plants to survive and prosper in nearly all ecosystems on the globe. Besides facing scarcity in water and light supply, woody plants often have to overcome nutrient limitations to sustain photosynthesis and growth. Of all essential macro nutrients for plant metabolism one of the least available in the soil is phosphorus (P). Due to the low P availability plants have to either optimize their nutrient acquisition and/or reduce nutrient losses. Several functional traits have already been identified as adaptation strategies such as effective nutrient resorption from senescent leaves and increased leaf longevity. However, research on nutrient translocation in stem wood and particularly twigs and associated anatomical features remain scarce. Moreover, adaptive trade-offs as well as the control of P cycling by systemic and environmental factors are still not well understood and the integration of plant-internal P storage and mobilization in the whole-plant nutrient budget is lacking so far.In the present proposal I want to link selected plant functional traits of leaf, stem and roots with nutrient translocation patterns, growth performance and whole-plant nutrient status in tree species growing on soils with contrasting P contents. The research will be conducted at Macquarie University in Sydney, Australia, joining the research groups of Prof. Mark Westoby and Prof. Ian Wright who have profound experience in the field of plant functional traits. The focus of the proposal is to disentangle the effects of low soil P on wood anatomical traits and in particular on wood parenchymatic tissue (i.e. living cells responsible for storage) as well as to understand strategies of woody plants with respect to phosphorus translocation. To achieve this aim the investigation of functional traits in plant communities in growing on P-poor as compared to P-rich soils will be conducted. Additionally, a selection of the occurring species will be cultivated as seedlings in a P availability gradient established in a common garden experiment. The nutrient content of living and freshly senescent tissues such as leaves, twigs, stem wood, bark and roots will be analyzed and related to nutrient relocation. To explore the importance of nutrient translocation for the whole-tree budget the annual production of leaf litter, fine roots and stem growth will be investigated. Wood anatomical analyzes will focus on the relationship between parenchyma fraction and phosphorus and other nutrient content in the wood of different species and the potentially plastic response of wood tissue composition following increased P supply.I am convinced that the opportunities provided by the present proposal will not only contribute to a deeper scientific knowledge of the complex traits associated with phosphorus use, but will also let me acquire the necessary expertise, methodology and knowledge to become a future scientific leader.