Buxbaumia viridis leaflet - Plantlife

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Where does it grow?Buxbaumia viridis grows on damp, dead wood. Most stands are on medium tolarge logs (or logs that have been large at some point), composed of well rottedwood that is easily penetrated with a knife blade. It will persist on the fragmentsthat fall away from the log and may even continue to produce sporophytes whenthe log is no longer apparent, the moss appearing to grow on the humus of thewoodland floor. A few sites are on dead wood that is still attached to a live treeand a number of recent sites on alder still have the bark in tact with the woodunderneath dead but still hard.Many of the sites have a strong association with watercourses, usually beingclose to a river and often where this is incised, presumably giving buffering fromchanges in humidity. However some other sites are well away from watercoursesalthough all are in sites that are quite humid, either because of aspect,canopy cover or proximity to damp ground.It is absent from those dry, dead trees typical of open pine woodland in the eastof Scotland; these logs, which often look grey from a distance, have few if anybryophytes on them though they may be very important for lichens. Until a fewyears ago Buxbaumia viridis was thought to be restricted in Scotland to large,rotten logs of Scots pine. The situation is rather more complicated now as themoss has also been recorded from birch, rowan, willow and alder as well asconifer logs which are not pine.In terms of frequency, current sites suggest that it is more common on deadwood from broadleaf trees than on pine and even where it occurs on pine it isoften in quite diverse woodland. Though most sites are on fallen logs, it doesoccur on rotten cut stumps and on cut logs and one site is on old timber from abridge washed away in a spate. Buxbaumia viridis sporophytes often occur onrather open patches of rotten wood (see Fig 3) but can also occur, protrudingthrough other bryophytes making them much harder to spot. Some analysis ofthe woodland history of the sites where Buxbaumia viridis grows might proveinteresting.The largest population at Abernethy is associated with ‘ancient woodland’ andthis is also true of Rothiemurchus. A long history of cover is also probable inReelig Glen and at other sites in incised river valleys but a more thoroughinvestigation is needed for this connection to be convincing; it may just be thatolder woods tend to have more suitable habitat.Sex and dispersalTo understand some of the conservation problems posed by this moss it isnecessary to delve a little deeper into its sex life. The capsule ripens duringspring and the spores in the capsule are dispersed in early summer, the actualdate depending on the microclimate at the site. The capsule has a prodigiousnumber of spores, some six million on average, so they are very small. Even so,most will land close to the capsule with only a small percentage being blown
further away. If the spores land on a suitable substrate they will germinate andproduce microscopic filaments, called protonema, which form an open mat andeventually these filaments will bud and produce the tiny leaves which encloseeither male or female sex organs which contain the sperm and eggs.These plants with the sex organs are minute compared with most other mosses,particularly the male plant in which the antheridium (male sex organ) is claspedwithin a single modified leaf. Searching for them in the field is not really anoption. Buxbaumia viridis does not make it easy for itself as it is dioecious, withmale and female plants being produced from different spores. This means thatfor fertilisation to be possible, both male and female spores need to germinateand produce patches of protonema and eventually shoots with sex organs closeenough to each other for the sperm to swim to the egg for fertilisation to takeplace. A connecting film of water is essential for this stage. Fertilisation probablyoccurs in the late spring or early summer in the year following spore germination,as the new sporophyte is tall enough to be visible by September. So, the wholecycle from spore production to ripe sporophyte takes a minimum of two years.Fig 2. Varied habitats for Buxbaumia viridis; clockwise from top left: alder inriparian woodland; cut log in plantation woodland; birch leaning on old wall; largeold conifer.
Page 1 and 2: LOWER PLANTS AND FUNGI PROJECT - TR
Page 3 and 4: Hearag” in Strath Glass (a hill w
Page 5: Fig 1. Top left - Buxbaumia viridis
Page 10 and 11: Deadwood managementFallen trees sho
Page 12 and 13: Indicator species and other bryophy
Page 14: ReferencesDickie, G (1867a). Note o

Buxbaumia viridis leaflet - Plantlife

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