FLORA

	Notes on the Annotated Checklist of Hong Kong Lichens of Aptroot and Seaward (1999)
	Fire-breaks for Hong Kong’s Grasslands

Notes on the Annotated Checklist of Hong Kong Lichens of Aptroot and Seaward (1999)

by Zhang Li

Aptroot and Seaward (1999) published an updated checklist of Hong Kong lichens based on available references and specimens. Unfortunately, I found occasionally that the checklist clearly failed to consult an important literature source pertinent to this issue (Tuckerman 1978), which was based on the collections of Charles Wright of the United States North Pacific Expedition, from 1853 to 1856. Forty-three taxa of lichens were reported from Hong Kong in that paper.

Aptroot & Seaward (1999) confirmed that 261 species of lichens occurred in Hong Kong. Comparing the checklist of Aptroot & Seaward (1999) to the species of Tuckerman (1978), there are 38 species reported by Tuckerman (1978) which were not included in their checklist. In addition, Aptroot & Seaward (1999) superfluously reported Gyrostomum scyphuliferum (Ach.) Nyl. new to China, although it has been reported before to occur in Hong Kong.

In summary, with the exception of three uncertain taxa (Species No. 7, 40, 43 in the following list), and two species Gyrostomum scyphuliferum (Species No. 20) and Graphis rimulosa (Mont.) Trevisan (Tuckerman (1978) as G. asterizans Nyl, species No. 14) the same as in Aptroot & Seaward (1999), the remaining 38 species should be added to the lichen list of Hong Kong. In total, the lichen flora in Hong Kong increases to 299 species. However, all the species of Tuckerman (1978) should be carefully checked for confirmation or rejection by studying the authentic specimens in FH and FH-Tuck.

The following list is excerpted from Tuckerman (1978), with the arrangement in alphabetical order. In this list, I give no comments except that I give the name used by Aptroot & Seaward (1999) for reference (Graphis rimulosa for G. asterizans). Each entry includes scientific name, locality, collection date, herbaria and specimen numbers if I can find them in Tuckerman (1978).

Arthonia astroidea var. swartziana Nyl. Hong Kong. [FH-Tuck. 3706]

Arthonia biseptella Nyl. in Willey Hong Kong. [FH, FH-Tuck. 3727]

Arthonia stenographella Nyl. Hong Kong. August 14, 1854 [FH, FH-Tuck. 3688]

Biatora chlororphnia (Tuck.) Tuck. Hong Kong. March 23, 1854 [FH, FH-Tuck. 2926]

Biatora tephraea Tuck. Hong Kong. April 6, 1854 [FH, FH-Tuck. 2931]

Buellia parasema (Ach.) Koerb. var. triphragmia Th. Fr. Hong Kong. August 14, 1854 [FH, FH-Tuck. 3297, 3298]

Cladonia fimbriata (L.) Fr. [a variety]. Hong Kong.

Cladonia gracilis (L.) Fr. Hong Kong. April 4, 1854 [FH, FH-Tuck. 2621]

Cladonia mitrula Tuck. Hong Kong. March 30, 1854 [FH, FH-Tuck. 2746]

Coenogonium disjunctum Nyl. Hong Kong. [FH, FH-Tuck. 2756]

Glyphis confluens Nyl. Hong Kong. August 14, 1854 [FH]

Glyphis medusulina Nyl. Hong Kong [FH]

Graphis assimilis Nyl. Hong Kong. August 14, 1854 [FH, FH-Tuck. 3495, 3496]

Graphis asterizans Nyl. Hong Kong. ------ Aptroot & Seaward (1999) as G. rimulosa (Mont.) Trevisan

Graphis cleistoblephora Nyl. Hong Kong. [FH, FH-Tuck. 3506]

Graphis discurrens Nyl. Hong Kong. [FH-Tuck. 3505]

Graphis glyphiza Nyl. Whampoa. July, 1854 [FH] ------- I wonder whether Whampoa is belonged to Hong Kong or not. But from the itinerary, Wright should be in Hong Kong during the period when the specimen collected.

Graphis scalpturata Ach. Hong Kong. [FH-Tuck. 3447]

Gyalecta lutea (Dicks.) Tuck. Hong Kong Aug. 23, 1854 [FH, FH-Tuck. 2253]

Gyrostomum scyphuliferum (Ach.) Nyl. Hong Kong. April 5, 1854 [FH, FH-Tuck. 2346] ------ The authorities of the present species are different between Tuckerman and Aptroot & Seaward. After cross checking the lichen lists via the internet (http://www.cabi.org/bioscience/), I follow Aptroot & Seaward.

Heterothecium tuberculosum (Fee) Flot. Hong Kong. March 30, 1854 [FH]

Lecanactis premnea (Ach.) Arn. Hong Kong. [FH, FH-Tuck. 3372]

Lecanora subfusca (L.) Ach. var. cinereocarnea Tuck. Hong Kong [FH, FH-Tuck. 1970]

Leptogium tremelloides Fr. Hong Kong. June 2, 1854 [FH, FH-Tuck. 1648]

Pannaria parmelioides (Hook.) Colm. Hong Kong.

Parmelia perlata (L.) Ach. Hong Kong. April 5, 1854 [FH, FH-Tuck. 692]

Parmelia tiliacea (Hoffm.) Fr. var. flavicans Tuck. Hong Kong. [FH]

Physcia picta (SW.) Nyl. Hong Kong. Feb. 2, 1855 [FH, FH-Tuck. 952].

Physcia speciosa (Wulf.) Tuck. var. hypoleuca Ach. Hong Kong [FH, FH-Tuck. 877, 878]

Ramalina calicaris (L.) Fr. var. farinacea Schaer. Hong Kong

Ramalina scopulorum (Retz.) Ach. Hong Kong. June 4, 1854 [FH, FH-Tuck. 145]

Roccella tinctoria Ach. L’am Tong Island, Chinese Coast, May 6, 1854 [FH, FH-Tuck. 20]

Stereocaulon ramulosum (Sw.) Ach. Hong Kong. May 17, 1854 [FH, FH-Tuck. 2373]

Trypethelium sprengelii Ach. Whampoa. July, 1854 [FH, FH-Tuck. 3974] ------ The reason is same to species No.17.

Urceolaria scruposa (L.) Ach. Hong Kong. April 4, 1854 [FH] Usnea barbata Fr. var. plicata Fr. Hong Kong. August 23, 1854.

Verrucaria biformis Borr. Hong Kong

Verrucaria insulata Fee Hong Kong. April 23, 1854. [FH, FH-Tuck. 4058]

Verrucaria marginata Hook. var. diminuens Nyl. Hong Kong [FH?] Verrucaria sp. Hong Kong [FH]

Verrucaria thelena Ach. var. albidior Nyl. Hong Kong. April 21, 1854. [FH]

Verrucaria tropica Ach. Hong Kong. May 14, 1854. [FH, FH-Tuck. 3978]

[A variety based on Ramalina inflata Hook.] Hong Kong. [FH, FH-Tuck]

Acknowledgements

Thanks are extended to Dr. R. T. Corlett for correcting the manuscript, and Mr. Y.-Z. Wang for suggesting checking names via the internet.

Bibliography

Aptroot, A. & Seaward, M. R. D. (1999). Annotated checklist of Hong Kong Lichens. Trop. Bryol. 17: 57-101.

Tuckerman, E. (1978). Lichens. In Pfister, D. H. (ed.): Cryptograms of the United States North Pacific Exploring Expedition, 1853-1856. Farlow Reference Library and Herbarium of Cryptogramic Botany, Harvard University, Cambridge, Massachusetts. Pp. 65-126.

P.19

Fire-breaks for Hong Kong’ Grasslands

by R.D. Hill

Fire-breaks have long been used as a means of protecting areas of particular interest and significance though in Hong Kong they are not much used. Since about two-fifths of our land area is in Country Parks – presumably worth protecting from hill-fires – it is a little surprising that more use is not made of them. One possible reason is that the kinds of fire-breaks appropriate to what is to be protected have never been systematically investigated, though the nature and effects of hill-fires have, notably by Lawrence Chau, who studied these for his doctorate at HKU. At a recent seminar on vegetation regeneration, Richard Corlett asked that I set down some thoughts on fire-breaks since our experimental site near KARC was, we hoped, protected by them. “We” here, are Mervyn Peart and myself, more recently joined Sanjay Nagarkar. Our plot-based study, begun in 1992, was initially designed to study erosion with three treatments – vegetation protected from fire, vegetation not protected, i.e. burnt, vegetation harvested annually (in January). A fourth treatment, “kept bare” was added later. Since 1992 the site suffered two hill-fires, one of which, in December 1995, burnt out three of the four plots surrounded by fire-breaks.

Fire-breaks were two metres wide and were cleared every year in winter. Until after 1995, clearance meant cutting all vegetation, raking it up and dumping it at a distance. Following the failure of most of the breaks in the 1995 fire there was a change of practice so that all cut debris was swept off. This increased the labour requirement and, in all likelihood, erosion along the breaks as well. It is not known whether this would have succeeded in increasing the effectiveness of the fire-breaks since there has not been a fire since and in any case their maintenance has been discontinued in the hope of obtaining more data on erosion and regeneration after a fire, should one occur.

Why did the fire-breaks fail or succeed? The 1995 fire seems to have burnt very fiercely at times for woody stems 2 cm thick were burnt through in places on the hillsides, suggesting a fair amount of gusty wind. It is possible that burning embers were carried across the breaks and set new fires but as the fire occurred at night and was not seen by us we do not know. However inspection soon after the fire showed that at several points there were blackened trails, only a couple of millimetres wide, indicating that fire had found its way across the breaks from one contiguous piece of cut debris to another until it reached standing vegetation on the other side. In other words, the massive reduction in fuel load represented by cutting fire-breaks, was, on that occasion, insufficient to prevent threads of fire crossing the breaks.

An earlier fire did not burn out the whole area, approaching one plot where the break had been cut and raked but not swept. It succeeded in halting the fire. On the other hand, a fire on the north ridge of Tai Mo Shan in February 1999 crossed a fire-break five metres wide annually cut by KFBG staff in October. This break, like those at our site, is raked but not swept and was readily crossed. (It burnt out our tree-planting experiment on the ridge and also Billy Hau’s tree-planting site nearby but that is another story, yet to be told.)

Though no systematic observations on fire-break effectiveness have ever been made (to our knowledge) in HK these unsystematic ones lead to some tentative conclusions. First is that cut and raked fire-breaks are not to be relied upon, for fire may find its way across remaining debris. However, had there been anyone around (and brave enough) it is likely that “fire rails” could easily have been broken e.g. simply by baring the soil. Such fire-breaks depend upon reduction of the fuel-load to a level insufficient to support combustion, but if debris is dry enough even a tiny quantity is enough. Such fire-breaks also depend upon regenerating vegetation on them being too green and sappy to burn. Much therefore depends upon when clearance is done, the amount of residual soil moisture available during the dry season to promote new growth and the amount and frequency of rainfall. Sweeping the fire-break is likely to prevent fire from picking its way across debris but might have to be done several times during a dry season for this is when the litter falls and is blown about. It is costly and doubtless is likely to lead to increased erosion, a major consideration for any long-term fire-break maintenance.

Neither cutting and raking alone nor with sweeping offer protection against “fliers” and “fallers”. Fliers are bits of burning debris that are detached from the fire front and are carried downwind in its path. Whether they will set new fires depends – obviously – on their temperature when and where they land and the ignitability or inflammability of the surface on which they land. How far they travel depends upon the speed of the wind, their weight and volume and the height at which they form. In our grasslands the last of these variables is rarely more than two metres but many fliers are light in weight and may carry many metres, even hundreds of metres in advance of the fire-front. They are usually small, not dense and consequently go out quite quickly after landing so that unless there is something easily ignitable at the landing area ,no secondary fire ensues. Most fall close to the fire-front so that a couple of metres of fire-break will reduce the chances of a flier setting a new fire.

Fallers are different. They comprise burning debris that simply falls in place. In grass, scrub and forest fires the direction of fall is usually with the wind. Unlike fliers, fallers may be large in volume, burning for many hours, and their combustion temperatures are usually higher than for fliers. To protect against fallers, a fire-break must be at the very least as wide as the adjoining vegetation is tall – in fact a bit more for fallers which usually bounce and break up as they land. Plus 50% is the usual rule-of-thumb as a guide to width. Thus a two-metre break is enough in our grassland but not in our forests, bearing in mind that new-grown vegetation regenerating along the edges of fire-breaks, though usually lower, greener than older vegetation nearby, will still burn if neighbouring combustion temperatures are high enough. This is because some of the energy in the advancing fire-front dries out the vegetation in front of it. (You may have noticed that in grass and scrub fires the fire-front often advances in fits and starts as it pauses while it dries out nearby vegetation and then advances very quickly, sometimes almost exploding once ignition-point is reached).

Obviously there is still much to learn about fires and fire-breaks in Hong Kong. It would be nice not to have one and thus not to need the other!

Ron Hill is Honorary Professor in the Department of Ecology & Biodiversity. He admits to having been scared (almost) shitless in several of the many scrub fires he long ago helped to fight as a volunteer fire-fighter in his native New Zealand.

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