Editing Ashdown Forest (section)

====Streams and ponds====
Forest streams, often lined by [[alder]] trees such as ''[[Alnus glutinosa]]'', and [[Salix|grey sallow]] ''[[Salix cinerea]]'', birch and oak, cut through the soft sandstone forming steep-sided valleys (ghylls) that are sheltered from winter frosts and remain humid in summer, creating conditions more familiar in the Atlantic-facing western coastal regions of Britain. Uncommon [[bryophyte]]s such as the liverwort ''[[Nardia compressa]]'' and a range of ferns including the mountain fern ''[[Oreopteris limbosperma]]'' and the [[Dryopteris|hay-scented buckler fern]] ''[[Dryopteris aemula]]'' thrive in this “Atlantic” microclimate.

The damming of streams, digging for marl, and quarrying have produced several large ponds containing, particularly in former marl pits, localised rafts of [[Potamogeton natans|broad-leaved pondweed]] ''Potamogeton natans'', beds of [[Typha latifolia|bulrush (reedmace)]] ''Typha latifolia'' and [[Equisetum fluviatile|water horsetail]] ''Equisetum fluviatile''.