How does water move in mosses ? Liquid and vapour flow in living sphagnum mosses

泥炭地占加拿大陆地面积的14%。泥炭（一种主要的碳汇）的积累主要是由于泥炭藓的存在。泥水藓缺乏根和维管结构，无法将水分输送到植物的生长部分（顶部）。人们普遍认为，当苔藓聚集在一起形成一个群落时，水是通过相邻的苔藓之间形成的小毛细管空间从地下水位上来的。它们能保留或从地下吸取的水量是对生长速度的重要控制，也是植物材料分解速度的重要控制。虽然假设液体流过毛细管空间，但由于标准方法无法测量，以及对与植物结构相关的过程的理解不足，这一过程尚未得到很好的记录。在我的实验室里，我们刚刚开发了一种仪器来测量苔藓控制液体流动的特性。我们现在正准备进行一系列的实验，调查苔藓中水分的迁移和储存，以测试它在植物关键生长部位保持水分的能力。本提案还旨在对不同种类的泥鳅进行测试，这些泥鳅具有明显不同的群落结构，因此在湿地中占据不同的生态位。在一组相关的实验中，我们想知道蒸汽流是否对保持苔藓上部的水分很重要——尽管我们知道蒸汽中的水分相对较少。了解这些过程对于开采泥炭地的恢复非常重要，因为泥炭地的基质限制了水流向可能在那里再生的苔藓。上述实验将旨在了解这一过程，以便我们能够更好地管理受干扰的泥炭地，或者至少管理我们对泥炭地恢复的期望。因此，我研究的总体（长期）目标是利用实验室和实地测试来测量和了解泥炭苔藓内部、苔藓和开采的泥炭基质之间的水储存和通量，并对这些过程进行建模。

Peatlands comprise 14% of Canada's land area. The accumulation of peat (a major carbon sink) is largely due to the presence of Sphagnum mosses. Sphagnum mosses lack roots and a vascular structure to deliver water to the growing part of the plant (top). It has generally been assumed that water is wicked up from the water table below through the small capillary spaces that are formed between adjacent strands of moss, as they cluster together in a community. The amount of water they can retain or draw from below is an important control on the rate of growth, but also the rate of decomposition of plant material. While liquid flow through capillary spaces has been assumed, the process has not been well documented because of the inability of standard methods to measure it, and a poor understanding of the process relating to the structure of the plant. In my laboratory we have just developed instrumentation to measure the properties of the moss that control liquid flow. We are now set to perform a series of experiments to investigate the migration and storage of water through the mosses to test its ability to sustain moisture in the critical growing part of the plant. This proposal also aims to test this for various species of Sphagnum, which have distinctly different community structures, and therefore occupy different niches in the wetland. In a related set of experiments we want to find if vapour flow is important in keeping the upper part of the mosses hydrated - even though we know the amount of water in vapour is relatively small. Understanding these processes is important for the restoration of mined peatlands, where the substrate restricts water flow to mosses that could potentially regenerate there. The above experiments will be directed at understanding this process, so that we can better manage disturbed peatlands, or at least manage our expectation for their recovery. The overall (long-term) objectives of my research, therefore, are to use lab and field tests to measure and understand the water stores and fluxes within Sphagnum mosses, between mosses and mined peat substrates, and to model these processes.