Data from: The ‘plant economic spectrum’ in bryophytes, a comparative study in subalpine forest

PREMISE OF THE STUDY: Tradeoffs among functional traits of vascular plants are starting to be better understood, but it is unclear whether bryophytes possess similar tradeoffs or how trait relationships, or the ‘economic spectrum’, differ between the two groups. METHODS: We determined functional-trait values [including shoot mass per area (SMA), light-saturated assimilation rate (Amass), dark respiration rate (Rdmass), N and P concentrations (Nmass and Pmass), and photosynthetic N and P use efficiency (PNUE and PPUE)] and their bivariate relationships for 28 bryophytes growing in a subalpine old-growth fir forest on the eastern Tibetan Plateau. Trait values and scaling relationships of these bryophytes were compared with data for vascular plant leaves from the Global Plant Trait Network (GLOPNET) dataset. KEY RESULTS: We found that the Amass, Nmass, N:P, PNUE and PPUE of bryophyte shoots were lower than those of vascular plant leaves. In contrast, bryophytes possessed higher Pmass and the two groups had similar values of SMA and Rdmass. The Nmass and Pmass were closely associated with Amass and Rdmass, and these traits were all significantly negatively related to SMA. Metabolic rates increased faster with nutrient concentrations in bryophytes than in vascular plants. CONCLUSIONS: Our research indicates that bryophytes have similar trait relationships as vascular plant leaves, although the slopes of the relationships differ for most trait combinations. This study confirms a functional-trait tradeoff in bryophytes, and reveals that bryophytes allocate greater proportions of N and P into the metabolic pools.

研究背景：维管植物（vascular plants）的功能性状（functional traits）间的权衡（tradeoffs）关系已逐步得到更深入的阐释，但目前尚不清楚苔藓植物（bryophytes）是否存在类似的性状权衡，以及两类植物间的性状关系（或称‘性状经济谱（economic spectrum）’）存在何种差异。
研究方法：本研究测定了青藏高原东部亚高山原始冷杉林中生长的28种苔藓植物的功能性状值，包括单位面积枝条质量（shoot mass per area, SMA）、光饱和光合速率（light-saturated assimilation rate, Amass）、暗呼吸速率（dark respiration rate, Rdmass）、氮与磷质量比浓度（N and P concentrations, Nmass和Pmass），以及光合氮利用效率（photosynthetic N use efficiency, PNUE）与光合磷利用效率（photosynthetic P use efficiency, PPUE），并分析了这些性状间的双变量相关关系。将本研究获得的苔藓植物性状值与性状缩放关系，与全球植物性状网络（Global Plant Trait Network, GLOPNET）数据集提供的维管植物叶片相关数据进行对比。
主要结果：本研究发现，苔藓植物枝条的Amass、Nmass、N:P比、PNUE和PPUE均低于维管植物叶片；与之相对，苔藓植物的Pmass更高，而两类植物的SMA与Rdmass值并无显著差异。苔藓植物的Nmass与Pmass分别与Amass和Rdmass紧密相关，且这些性状均与SMA呈显著负相关关系。相较于维管植物，苔藓植物的代谢速率随养分浓度提升的增长幅度更快。
结论：本研究表明，尽管多数性状组合的关系斜率存在差异，但苔藓植物的性状关系模式与维管植物叶片相似。本研究证实了苔藓植物存在功能性状权衡现象，并揭示出苔藓植物会将更大比例的氮与磷分配至代谢库中。