18.

BRYOPHYTE AND LICHEN ECOLOGY AT SWANSON. - T.C. Chambers.

History of the Swanson Area: This is fully discussed in an article by C.B. Trevarthen in this volume. To save unnecessary repetition readers are referred to his maps. Ecological Nomenclature; R.G. Robbins was the first investigator in N.Z. to employ quantitative as well as qualitative methods in the study of our Bryophyte communities. In Europe and U.S.A. bryophytes and lichens have been included in many investigations on higher plant comm• unities but they have been seriously neglected in N.Z. Various terms have been used by overseas investigators of bryophyte communities, e.g. 'societies', 'clans', 'colonies', 'families', 'associations', 1assoc- iules' etc. Professor Lippmaa (1934-35) introduced a new approach— the unistratal association concept in which the layers (synusiae) are regarded as separate associations. At the Amsterdam Botanical Cong• ress Du Rietz and Gams proposed to name these "one-layered associations" - Unions - and Lippmaa accepted this. The term Union admirably fits the bryophyte component of a plant community. Sirgo (Estonia) first used this term and it has since been more extensively used by Cain and his associated in U.S.A. and by Robbins and Butler* in N.Z. In the present investigation a Union has been looked upon as a unistratal community dominated by one or more species having high cover and high frequency and generally being of similar or related life form. Methods; The size of the quadrat used in the analyses was 0.1 sq. metres, which is the most usual size in bryo-ecological investigations. An oblong quadrat was used 20 cms. X 50 cms., which Robbins found was slightly better than the square for some of his work at Woodhill. AS the bryophyte community at Swanson is fairly homogeneous, due largely to the vegetative reproduction of the moss plants, it is likely that the oblong quadrat would get a better sample. Probably, any shape would be efficient providing sufficient quadrats were studied. In the field work a species list for the quadrat and the coverage classes were noted as follows: Class X Species covering less than 1% of quadrat. If 1 ti ti 1 to 5% " It 2 tt ti 5 to 25% " II 3 ti H 25 to 50% " II 4 ti ti 50 to 75$ " II 5 it it 75 to100% " AS the quadrats were small accurate estimates of coverage were possible. Prom the species list for each quadrat, besides noting coverage, frequency was also calculated. The bryophytes in the first two phanerogamic communities discussed were investigated from both qualitative and quantitative aspects. The other communities mentioned have only been considered qualitatively. 1. Leptospermum Associes on eastern side of Stream: The average height of the scrub is about 18 feet and is never less than 10 feet, Leptospermum scoparium is dominant with fewer plants of L. ericoides. The most striking feature of this scrub is the almost complete terres• trial carpet of bryophytes and lichens. A series of quadrats was made in this area and the results analysed.*" Dicranoloma billardieri is the dominant moss and from both statistical results and field observations this forms a Dicranoloma billardieri Union—the major terrestrial bryo• phyte association in the area. Very often the Dicranoloma is assoc• iated with lichens of the genus Cladonia, particularly with 0. floerk- iana and this forms the Dicranoloma billardieri - Cladonia Union. In

* N.J. Butler (Wellington) interpreted the Union as "a homogeneous unistratal community with a special habitat preference and dominated by one or more species of the same life form." * See Table I. 19. the small hollow on the northern side of the hut, milk moss (Leucobryum candidum) plays an important part in the bryophyte community, forming a Dicranoloma billardieri - Leucobryum Union. The terrestrial mosses here do not form such a complete carpet as in the previously mentioned Unions. In Great Britain a closely related species, L. glaucum, is an indicator of acid conditions. It is possible that L. candidum in N.Z. grows in a similar habitat. If this is true it might partly account for the poorer bryophyte cover in this area. Another factor which must be taken into consideration is that a number of dicot, shrubs have become established and the leaf fall from these appears to retard bryophyte growth. In the Dicranoloma - Cladonia Union the following species are locally-dominant in small patches and thus form facies of the Union: Ptychomnion aciculare, Thuidium furfurosum, Hypnum cupressiforme Leucobryum >'and:,;:11 m, Cladonia (species b).~ Ptychomnion aciculare is more abundant in the tea-tree near the stream than around the hut. It seems 'unlikely that this is caused by moisture conditions, as in other parts of the Waitakere Ranges this moss is often abundant in ridge veg• etation and probably in these parts forms a true Ptychomnion aciculare Union. There seems to be little doubt that the terrestrial bryophytes function as a seed bed for regeneration of forest trees. The sponge• like nature of the moss carpet makes it a great potential water storage organ of the forest. 'This is, no doubt, a big factor in assisting the establishment of these seedlings which later in the succession of the forest will dominate the area. The following species are common in the Dicranoloma - Cladonia Union: 1• Agathis australis 9. Knightia excelsa. 2. Dacrydium cupressinum 10. Olearia 1 furfuracea. 3. Phyllocladus trichomanoides. 11. 0. cunninghamii. 4. Podoparous_totara. 1 2. Pomaderris _e i 5. Meiicytibiss ramiflorus. 13• No^hopar^x aro^r•e um. 6. Gen 3. op torn a ligustrifolium. 14. Pseudopanax crassifolium. 7• Suttonia salicina. 1 5. Coprosma see,, 8. Suttonia australis. Besides those p .ants, ferns are quite numerous scattered^ partic- ularly BJLej3jraum B. fraseri. Gleichenia circinata, G_, cunnjng- hamii, Paesia 0 tendo is also The brans it ion from this scrub to the grassy area around the hut is interesting (see transect),* . The Dicranoloma gradually gives way to Hypnum cupressiforme and Thuidium furfurosum which in the less shaded par' gives way to Campylopus int. flexus which in turn gives way to gri

f i ! I

Campylopus- Campylopus introflexus Dicranoloma* Dicran• grass Hypnum- Thuidium. oloma . Teatree Open clearing scrub Dicranoloma 10 high. Belt transect showing billardieri. transition from Hypnum cupressiforme. Leptospermum scrub to Thuidium furfurosum. grassy clearing in front Campylopus introflexus. of hut. Grasses.

3are ground. 20.

2. leptospermum associes on trio ridge at the southern end cf the property. In contrast wi tia that around tae hut this veget• ation almost completely lacks a bryophyte flora. The Leptospermum can:py is very open. There is a very dense herbaceous layer made up mainly of Schoenus tendo, Gleichenia cunninghamii and G. circinata with scattered clumps of Gahnia xanthocarpa and Astelia trinervia. Beneath this few bryophytes can survive and probably the regeneration of phanerogams is retarded. The moss Sematophyllum amoenum is occasional on dead twigs, bases :f trunks and on the ground. a few small plants cf Dicranoloma are also present mainly at tae edges of tracks. a comparison of the bryophytes in the tea-tree around the hut with those on the ridge boars out the following statement by P.W. Richards : "Owing te their small size and restricted growth mosses are always at a great disadvantage in competition with vascular plants and it is roughly true to say that any factor which checks growth of herbaceous plants favours moss vegetation." It also bears cut another of his statements: "That such small and comparatively slow growing plants should te able te produce important changes in their habitats is mainly due to the fact that they are social organ• isms and only those species with well-marked social habit have per• ceptible reactions." . 3. Leptospermum-Kauri associes on the northern end cf the ridge : In complete contrast with Leptospermum at the southern end of the ridge this area has a bryophyte community in some respects very sim• ilar to that found around the hut. It possesses an almost complete carpet of bryophytes and lichens right to the bases of the tree trunks. The kauris are at the advanced ricker stage and the Leptospermum is gradually being eliminated. Phyllocladus, Olearia and Knightia are all abundant. Together with these there is a large well-established population cf the alien Hakea. Schoenus tendo, while fairly abun• dant, is not successful in crowding cut tae bryophytes as on the southern end of the ridge. The main terrestrial bryophyte community is the Dicranoloma billardieri Union. In places large cushions of Dicranoloma over 1 ft. in depth possibly mark the sits of old burnt or fallen logs and stumps but there are no traces cf rotten wood beneath the cush• ions to prove this point. In several localised patches there are large white areas where Cladonia floerkiana has become the sole dom• inant and in other areas it forms a Dicraneloma-Claicnia Union like that in the Leptospermum around the nut. (see Table II). The litter on the forest floor is mainly Kauri leaves and twigs but under low growing shrubs such as Olearia furfuracea there is more slow decaying leaf litter ana no bryophytes or lichens at all. While the extra shade may have some influence, the presence of slew decaying leaves and possibly their toxic effect as they decomposed, all helped to eliminate the bryophytes although the list point needs further investigation. There are numerous seedlings growing in the Pi crane Jorna• Cladonia Union. These include Agathis australis, Phyllocladus trichomanoides, Leucopogon fascicularis, Olearia cunninghamii, Senecio kirkii, Knightia excelsa anei Hakea acicularis. The average depth of the bryophyte carpet is. six inches - on the average 3 inches deeper than that around the hut. an investigation cf an old and now little-used track runn• ing through this area showed that the Cladonia species cannot tol• erate wear or hard trodden soil. The only species present in any quantity are reduced forms of Leucobryum candidum and Dicranoloma billardieri. 4• Mature Kauri Po rest: Here terrestrial bryophytes only occur in localised and generally pure patches often 2-3 feet across, among the mosses Mniodendron comosum, Tayloria sop, Sematophyllum Richards - "Bryophyte Ecology" in manual of Bryology, 1932. 21 . amo e mua, a o an t h o c I a I 1 urn extenuatum and Dicranoloma billardieri occur ia this manner, Growing over loose undecayed litter the epatic Metzgeria, hamata occurs in patches, while on bare soil Lepidozia often forms a close mat. Epiphytic bryophytes become more important here. Semat:phyilum amoenum is common at the bases of the trunks, also Macromitrium is occasionally present but this latter, together with Dicnemon calycinum is commoner higher up the trunk. On the Kauri bark Frullania aterina var. epida and Physananthus anguiformis are very common, as is also the algae Trentepohlia which Terms charac• teristic reddish tufts, while Buzzania adnexa together with stunted Dicranoloma billardieri are often present near the bases of the trunks 5. Podocarp-Dicotyledonous forest on the slopes: The forest on the ridge is predominantly Kauri. On leaving the ridge there is an immediate change in both the forest and the associated cryptogamic vegetation. In places podocarps like Rimu and Miro dominate but over most of the elope tae dicot. Knightia excelsa (Rewa Rewa) is the dominant tree while a number of very large Ratas (Metrosideros robusta are also present in scattered patches. Many cf the Knightia trees have clean smooth trunks but others support numerous cushions of epi• phytic bryophytes often together with the orchid Bulbophyllum pygmaeum. Where Blechnum fraseri is present terrestrial bryophytes are absent as this miniature tree-fern forms a dense canopy about 1 ft. above the soil level. The whole forest is characterised by the steep slope, heavy leaf fall, dense undergrowth, wide variety of species of shrubs, ferns and lianes and the low light intensity. Consequently bryophytes are scattered in discontinuous patches and a large number of species are epiphytic. also, on passing from the ridge down to the stream there is a noticeable general increase in the bryophytes both epiphytic and terrestrial. a number cf species in this area are growing on the tangle of roots of trees, others are v=ry common on lead trunks and fallen branches, e.g. Sematophyilum amoenum, Dicranoloma menziesii. The bases of the tree trunks often have a characteristic bryophyte flora, mainly Sematophyllum amoenum, Leucobryum candidum, Sciadocladus menziesii and Dicranoloma billardieri. Clay banks are common on this steep slope and ere usually covered with Hepatics such as Lepidozia capilligera, Balantiopsis diplophylla, Hymenophytun and Pallavicinia as well us Riccardia in the wetter gulleys. further down tae slope tree ferns - Cyatnea dealbata and 0. medullaris - are more abundant and on the old flood plain scrolls of the stream there are pure stands cf the tree fern Dicksonia squarrosa. In tae latter the low light intensity an! the numerous dead fronds exclude bryophytes with the exception cf the epiphytic Hymenodon piliferus on the tree fern trunks. In the area above the stream banks certain bryophytes are very abundant, e.g. Qamptcch ete arbuscula and Schistocnila, Hypnodendrum arcuatum, Hypo pterygium, Mniodendron and Symphogyna. 6. Stream and Stream Bank Communities; There is not space in the present paper to discuss these communities in detail. All species found are listed in the annotated species list accompanying this article. all names of vascular cryptogams and phanerogams are according to Cheeseman's 'Manual of N.Z. Flora', 1925.

SUMMARY. 1. Forty-one messes and twenty-five hepatics have been definitely recorded from the area with a further nineteen mosses and five hepat• ics doubtfully present. 2. Bryoecological terminology has been briefly discussed and the term Union has been used for the description cf the bryophyte comm• unities. 3. An attempt has been made to apply elementary statistical analysis te the terrestrial bryophytes in the Leptospermum and Leptospermum- Kauri associes. Table I. 25 0.1 sq. metre Quadrats - Leptospermum associes between Swanson Hut ana stream. 1 23456789 10 11 12 15 14 15 16 17 18 19 20 Z1 22 23 24 25 Frequency Coverage Dicranoloma billardieri 5 5 1 2 1 2 5 - 1 - 355512242-421 1 5 51% Leucobryum candidum 1 x x 1 16% Ptychomnion aciculare x - - 5 - 3 x - 4 4 2 - 1 - 36% 15% Hypnum cupressiforme - - 3 x - CO Thuidium furfurosum X 1 x - - - 1 X 1 - 24% ra Campylopus introflexus ra 3 o C. clavatus Sematophyllum amoenum 1 Bryum truncorum Mniodendron comosum i raLepidozi a allisonii XXX------X - X 20% Ok M L. capilligera - X Balantiopsis diplophylla ------1 X - 1 Cladonia floerkeana 2-31 1 2 X X - - 1 - - 1 48% 1 . M raCladoni a b. ----x1 XX X X -22-- 1 - X - 36% o g Lichen c. x 1 2 - 1 - 16% Hi Cladonia d. X No. of species 313364437 3 4 2 3 2 3 6 4 4 6 3 4 4 6 1 Average No. of Species per Quadrat = 3.6 Table II. 25 0.1 sq. metre Quadrats - Picker Agathis, north end of Ridge, Swanson. Dicranoloma billardieri 1 x -3553332545452X-5-441 22 54% ra Leucobryum candidum > _x__i ra Ptychomnion aciculare -3 2----1 ------ra o Hypnum cupressiforme - 3 1 1 Thuidium furfurosum Tayloria octoblepharis Lepidozia Cladonia floerkeana 2 3____1 2 4 1 x x 1 - X 40% 11% Cladonia b. 1 1 - 1 X X 20% Bare ground 2 - 1 2 No. of species. 2 4 3 1 1 1 1 2 2 1 1 1 3 2 4 2 2 4 3 3 Average No. of species per Quadrat = 2. 4. Only the important terrestrial lichens have been included in the investigation. 5. The epiphytic and stream bank bryophytes have only been briefly mentioned and further particulars of these species are included in the annotated species list. 6. The reasons for the great differences in the bryophyte component in the different areas cf Leptospermum are difficult to explain and detailed investigations in other similar areas in the Waitakere Ranges are necessary. At present it seems probable that the interference by man, particularly past fires, his introduced animals and the presence of the alien Hakea, as well as the surface configuration cf the area, are all contributing factors te the marked differences,

REFERENCES. Billings & Drew, Cain, Cain & Penfound, Cain & Sharp - 1936-38 American Midland Naturalist, Vols. 17, 19, 20. Dixon, H.W. - 1914-28. Studies in the Bryology of N.Z. Bull, of N.Z. Inst., No. 3, pis. 1-6. Hodgson, E.A, Hepaticae - Pts. I*VI, 1942-49. Trans. Rcyl. Sec. N.Z, Classification of N.Z. Hepaticae. Tuatara, Vol. III, Nos 1-2. Richards, P.W. 1928. The Bryophyte Communities cf a Killarney Oakwood. Annales Bryologici. Vol. XI. Robbins, E.G. 1949. Bryophyte Ecology at Woodhill. M.Sc, thesis, A.U.C. Library. Sirgo, V. 1935. Plant Unions of the Swamps at the mouth of the River Emajcgi. English summary. Acta Institute et Hortj. Botanica Universtatic Tartuensis. Vol. V. 1936-37. Verdoorn, P. 1932. "Manual of Bryology." All names of Vascular Cryptogams and Phanerogams are according te Cheeseman's "Manual cf the N.Z. flora" 1925. ^nalyasis- of Table- I Analysis of Table II. Leptospermum"associes. Ricker Kauri. '^1 00% ! Coverage Frequency Coverage Frequency

Dicranoloma billardieri. Cladonia 1c' Ptychomnion aciculare. Thuidium furfurosum Cladonia floerkeana. Lepidozia allisoni Cladonia 'b* Leucobryum candidum. Lichen c. Number of quadrats in which g sp. occurs Frequency Total number of Quadrate

Coverage Total coverage of a species Total possible