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(一个主要的碳汇)的积累很大程度上是由于泥炭苔藓的存在。泥炭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)。通常认为，水从地下水位通过相邻苔藓之间形成的微小毛细空间向上流动，因为它们聚集在一起形成一个群落。它们能从下面保留或吸收的水量是生长速度的重要控制因素，也是植物材料分解速度的重要控制因素。虽然已经假设了液体通过毛细管空间的流动，但由于无法用标准方法测量它，以及对与工厂结构有关的过程的了解不足，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控制液体流动的苔藓的特性。我们现在准备进行一系列实验，调查水在苔藓中的迁移和储存，以测试它在植物关键生长部分保持水分的能力。这项建议还旨在对不同物种的泥炭藓进行测试，这些物种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，我们想要找出水蒸气流动是否对保持苔藓上部的水分很重要--尽管我们知道水蒸气中的水量相对较少。了解这些过程对于恢复开采的泥炭地很重要，泥炭地的底物限制了水流到苔藓，这些苔藓可能会在那里再生。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它们恢复的期望。因此，我研究的总体(长期)目标是使用实验室和田间测试来测量和了解泥炭苔藓内、苔藓和开采的泥炭基质之间的储水量和通量，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.