Department of Plant Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
Ann Bot. 2010 Feb;105(2):291-300. doi: 10.1093/aob/mcp288.
Initial release height and settling speed of diaspores are biologically controlled components which are key to modelling wind dispersal. Most Sphagnum (peat moss) species have explosive spore liberation. In this study, how capsule and spore sizes affect the height to which spores are propelled were measured, and how spore size and spore number of discharged particles relate to settling speed in the aspherical Sphagnum spores.
Spore discharge and spore cloud development were filmed in a closed chamber (nine species). Measurements were taken from snapshots at three stages of cloud development. Settling speed of spores (14 species) and clusters were timed in a glass tube.
The maximum discharge speed measured was 3.6 m s(-1). Spores reached a maximum height of 20 cm (average: 15 cm) above the capsule. The cloud dimensions at all stages were related positively to capsule size (R(2) = 0.58-0.65). Thus species with large shoots (because they have large capsules) have a dispersal advantage. Half of the spores were released as singles and the rest as clusters (usually two to four spores). Single spores settled at 0.84-1.86 cm s(-1), about 52 % slower than expected for spherical spores with the same diameters. Settling speed displayed a positive curvilinear relationship with spore size, close to predictions by Stokes' law for spherical spores with 68 % of the actual diameters. Light-coloured spores settled slower than dark spores. Settling speed of spore clusters agrees with earlier studies. Effective spore discharge and small, slowly settling spores appear particularly important for species in forested habitats.
The spore discharge heights in Sphagnum are among the greatest for small, wind-dispersed propagules. The discharge heights and the slow settling of spores affect dispersal distances positively and may help to explain the wide distribution of most boreal Sphagnum species.
孢子的初始释放高度和沉降速度是受生物控制的关键因素，它们是模拟风传播的关键。大多数泥炭藓（泥炭藓）物种具有爆炸性的孢子释放。在这项研究中，测量了胶囊和孢子大小如何影响孢子被推动的高度，以及排出颗粒的孢子大小和孢子数量与非球形泥炭藓孢子沉降速度的关系。
在封闭室（九种）中拍摄孢子释放和孢子云发展的过程。在云发展的三个阶段从快照中进行测量。在玻璃管中测量孢子（十四种）和孢子群的沉降速度。
测量的最大释放速度为 3.6 m s(-1)。孢子在胶囊上方达到 20 厘米（平均：15 厘米）的最大高度。所有阶段的云尺寸都与胶囊尺寸呈正相关（R(2) = 0.58-0.65）。因此，具有大枝条的物种（因为它们有大胶囊）具有传播优势。一半的孢子作为单个释放，其余的作为集群（通常为两个到四个孢子）。单个孢子的沉降速度为 0.84-1.86 cm s(-1)，比具有相同直径的球形孢子慢约 52%。沉降速度与孢子尺寸呈正曲线关系，接近球形孢子的斯托克斯定律预测，实际直径的 68%。浅色孢子的沉降速度比深色孢子慢。孢子群的沉降速度与早期的研究结果一致。有效的孢子释放和小而缓慢沉降的孢子对于森林生境中的物种尤其重要。
泥炭藓的孢子释放高度在小型风传播繁殖体中是最高的。释放高度和缓慢沉降的孢子对扩散距离有积极影响，这可能有助于解释大多数北方泥炭藓物种的广泛分布。
