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Morley, Sharon E. and Gibson, Maria 2010, Successional changes in epiphytic rainforest lichens : implications for the management of rainforest communities, The Lichenologist, vol. 42, no. 3, pp. 311-321.

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Copyright : 2010, British Lichen Society The Lichenologist 42(3): 311–321 (2010) © British Lichen Society, 2010 doi:10.1017/S0024282909990570

Successional changes in epiphytic rainforest lichens: implications for the management of rainforest communities

Sharon E. MORLEY and Maria GIBSON

Abstract: We explored lichen species richness and patterns of lichen succession on rough barked Nothofagus cunninghamii trees and on smooth barked Atherosperma moschatum trees in cool temperate rainforests in Victoria, Australia. Nothofagus cunninghamii trees from the Yarra Ranges, and A. moschatum trees from Errinundra were ranked into size classes (small, medium, large and extra-large), and differences in species richness and composition were compared between size classes for each tree species. Nothofagus cunninghamii supported a rich lichen flora (108 trees, 52 lichen species), with the largest trees supporting a significantly higher number of species, including many uncommon species. This success was attributed to varying bark texture, stand characteristics and microhabitat variations as the trees age. Atherosperma moschatum supported a comparable number of species (120 trees, 54 lichen species). Indeed on average, this host supported more lichen species than N. cunninghamii. However, successional patterns with increasing girth were not as clear for A. moschatum, possibly due to the more stable microclimate that this smooth barked host provided. Victorian cool temperate rainforests exist primarily as small, often isolated pockets within a sea of Eucalypt-dominated, fire-prone forest. Many are regenerating from past disturbance. We find that protection of Victoria’s oldest rainforest pockets is crucial, as they represent sources of rare, potentially threatened lichen species, and may be acting as reservoirs for propagules for nearby ageing rainforests. Indeed, even single, large old trees have conservation importance, as they may provide exceptional microhabitats, not found elsewhere in the regenerating rainforest environment. Key words: conservation, cool temperate rainforest, island reservoir, species richness, succession

Introduction munities as extremely complex, entailing not Patterns of succession in lichen communities only ageing of the lichen vegetation itself, but have been observed in many non-Australian also that of its tree substratum and the sur- forest communities, with certain lichen rounding forest. Each successional stage was species being characteristic of younger and therefore characterized by a different suite of of older forests (Rose 1976; Lesica, et al. lichens in response to the particular light, 1991; Kuusinen 1996; Boudreault et al. substratum and moisture conditions prevail- 2000; Campbell & Fredeen 2004; Radies & ing at that time (Kantvilas 1990). Coxson 2004;). Within Australia, studies in The trunk of a tree represents a complex Tasmania have also alluded to such patterns assortment of integrated microhabitat types and been able to suggest distinctive species which influence the epiphytic community assemblages for young and old habitats (Kenkel & Bradfield 1986), and a number of (Kantvilas 1988, 1990). Kantvilas (1990) authors (Adams & Risser 1971; James et al. described succession between lichen com- 1977; Eversman et al. 1987; Kantvilas and Minchin 1989) have implied that the micro- climate was more important than macro- S. E. Morley: Department of Primary Industries, climate in determining lichen distribution. Knoxfield Centre, PB 15 Ferntree Gully Delivery Factors such as light, bark texture, bark pH, Centre, VIC, 3156, Australia. Email: sharon.morley availability of water, humidity, aspect, incli- @dpi.vic.gov.au S. E. Morley and M. Gibson: Deakin University, Plant nation of trunks, age of forest and stand Ecology Research Unit, Life and Environmental heterogeneity have been suggested as im- Sciences, Burwood, Victoria, 3125, Australia. portant in determining distribution of lichens 312 THE LICHENOLOGIST Vol. 42 at the local level (Adams & Risser 1971; Buang, Victoria. In Tasmania, smooth barked Brodo 1973; Gough 1975; Kantvilas et al. trees such as A. moschatum often retained pio- 1985; Eversman et al. 1987; Kenkel & neer lichen species throughout their life as bark, Bradfield 1986; Lesica et al. 1991; Pirintsos and lichen, are not shed periodically (Kantvilas et al. 1995). However, Kantvilas et al. (1985) et al. 1985). In eastern Victoria, A. moschatum indicated that most of these factors can be forms the dominant component of the rain- interpreted almost entirely in terms of light forest canopy. The Atherosperma-Elaeocarpus and substratum characteristics. For example, rainforests of the Errinundra Plateau are the temperature is affected by the amount of southern extremity of this type of cool temper- sunlight, and forest age is related to differing ate rainforest which extends north through the substrata characteristics, such as fissured tablelands of New South Wales (Ladd 1991; bark (Kantvilas et al. 1985; Kantvilas 1990). Peel 1999). The lichen communities in these Nothofagus cunninghamii (Hook.) Oerst., rainforests have not been studied until the a dominant cool temperate rainforest species present survey. in Victoria and Tasmania, has been shown to In this study, we explore lichen species be a very successful host for many lichen richness and patterns of lichen succession on species (Kantvilas et al. 1985; Kantvilas rough barked N. cunninghamii trees and on 1988, 1990; Kantvilas & Jarman 1993; smooth barked A. moschatum trees in cool Jarman & Kantvilas 1995; Louwhoff, 1995; temperate rainforests in Victoria, Australia. Ford 1996). This is thought to be due to these We hypothesize that lichen community com- bark characteristics and inclination of trunks position will change as the host tree ages. forming distinct wet and dry sides (Mark Furthermore, we believe that these changes et al. 1964; Kalgutker & Bird 1969; Pike will be less distinct on A. moschatum than on et al. 1975; Kantvilas et al. 1985; Kenkel & N. cunninghamii as smooth barked trees are Bradfield 1986; Kantvilas 1990; Louwhoff difficult for lichen propagules to colonize. 1995). Fissuring produces a continual cycle Victorian rainforests exist primarily in of decortication and recolonization of bark narrow, fire protected gullies. They are in ageing trees that has been linked to an limited in extent, and often exist as small overall increase in the number of lichen pockets within a sea of eucalypt-dominated species supported by N. cunninghamii in forest. They often suffer from edge-effects Tasmania (Kantvilas 1990), Quercus in and disturbance, especially the effects of fire Britain (Rose 1974), Pinus albicaulis Engelm. (Busby & Brown 1994). Our final aim was to in Canada (Kalgutker & Bird 1969) and establish whether older trees support lichen Pseudotsuga menziesii (Mirb.) Franco and assemblages not represented on younger Abies lasiocarpa (Hook.) Nutt. in Colorado, trees, and therefore, whether these trees may USA (Gough 1975). Conversely, some be acting as ‘island reservoirs’. authors have suggested fissuring and flaki- ness as causing a decline in species richness for other tree species (Adams & Risser Methods 1971; Yarranton 1972; Griffin & Conran This investigation represents a portion of a much larger 1994; Kuusinen 1996; Radies & Coxson research endeavour examining lichens in rainforests 2004). across Victoria. We have used a subsample of this larger Some rainforest trees do not shed their bark dataset to examine patterns of succession on N. cunning- periodically, for example species of Acacia and hamii (Yarra Ranges) and A. moschatum (Errinundra). However, due to differences already established in Atherosperma moschatum Labill. These species lichen community composition between rainforests in generally have lichen communities that differ the Yarra Ranges, where N. cunninghamii is dominant from those of N. cunninghamii (Louwhoff 1995; and those from the Errinundra region where A. moscha- Ford 1996, 2001; Ford et al. 2000). Louwhoff tum is dominant (Morley & Gibson 2004), we will not be directly comparing the two tree species with each other (1995) suggested that bark stability and some in a single statistical analysis. Rather, we will be looking degree of fissuring accounted for the higher at patterns of species richness and succession on each lichen diversity on Acacia found at Mt. Donna host, as inferred by a snapshot (a single sample in time) 2010 Succession in epiphytic rainforest lichens—Morley & Gibson 313

T 1. Number of trees sampled from each size class of Nothofagus cunninghamii and Atherosperma moschatum in rainforests at Yarra Ranges and Errinundra.

Species Total number Number sampled Small Medium Large Extra large

Yarra Ranges Nothofagus cunninghamii 136 37 36 27 36 Subsample 108 27 27 27 27 Errinundra Atherosperma moschatum 145 30 31 45 39 Subsample 120 30 30 30 30

of variously sized trees. While it is logical to be able to patches, and A. moschatum trees from the same number suggest successional patterns from a single sampling and size of quadrats in rainforests of the Errinundra event in time using trees of different sizes (ages), these Plateau were used in the analyses for this study. The conclusions are inferences only, as ideally, given the lichen communities up to 2 metres high on different historical differences that even small patches of rain- ranked size classes were examined on each of these two forest might undergo, a long term study will give the species. The size classes were defined as small (0–5cm most accurate picture of successional changes as radius), medium (6–10cm radius), large (11–20cm forests age. Time constraints rarely permit long term radius) and extra large (>21cm) (Ford 2001). The size investigations, and this study was no exception. classes were determined on the basis of distinct changes in the appearance of the bark of N. cunninghamii trees. Study Area The small to medium ranked trees had similar smooth textured bark; however, they were divided into two size In Australia, temperate rainforests occur in Tasmania, classes for a more detailed analysis of lichen patterns. disjunct areas in south-central Victoria and in small Large trees were determined as those where the deeper patches along the Great Dividing Range in New South fissures had begun to form in the bark, and extra-large Wales and southern Queensland (Busby & Brown 1994). trees were those with deeply dissected ‘plates’ of bark Victorian rainforests usually occur in scattered patches of that were easily dislodged from the tree. These size less than 100 hectares, and are generally confined to deeply classes were used for all tree species throughout the larger dissected country within gullies and along streams and study. Further information on the field method and study rivers (Department of Conservation, Forests & Lands areas can be found in Morley & Gibson (2004). 1987; Busby & Brown 1994; Peel 1999). Pure rainforest stands (those without a eucalypt component) occur only in Statistical Analysis the most fire protected niches where catastrophic bushfire occurs at intervals of 100–500 years (Peel 1999). Although Unequal numbers of trees representing each size class they account for less than one percent of Australia’s rain- occurred in field collected data, representing natural forest, those in Victoria are nevertheless of ecological, variation in tree sizes in forests. In order to compare size botanical, recreational and educational significance class characteristics, random sub-sampling of the two (D.C.F.L., 1987). dominant hosts was undertaken to get even sample sizes Rainforests from two regions in Victoria were used for each size class. The original number and the number in this study. Yarra Ranges cool temperate rainforests in the random subsample for each host are presented in (central Victoria) are dominated by N. cunninghamii and Table 1. These data are used in all analyses of differences have a subdominant canopy of A. moschatum. Rain- between size classes. forests of Errinundra (far east Victoria) are dominated by Non-parametric ANOVA was used to test for signifi- A. moschatum with Elaeocarpus holopetalus F. Muell. and cant differences in lichen species richness between the Telopea oreades F. Muell. occurring in some pockets. four size classes of each dominant host. The data were Annual rainfall is quite high in both regions, with Yarra square root transformed in order to improve normality. Ranges receiving 1391mm and Errinundra receiving Lichen species cover data were mostly skewed towards 1341–1725mm per annum (Bureau of Meteorology, pub- lower numbers, reflecting the low abundance and fre- lic records). The altitude range of quadrats in the Yarra quency of many lichens in Victorian rainforests. Trans- Ranges was 560–960m, and at Errinundra, 940–1080m. formations on data of this nature often fail to improve normality enough to meet the assumptions of parametric Field Method and Study Sites statistical tests, therefore, the cover of particular lichen species was compared between the four size classes of Nothofagus cunninghamii trees from 20m by 20m dominant hosts using the non-parametric equivalent of quadrats in the centre of ten Yarra Ranges rainforest ANOVA, the Kruskal-Wallis test. For this analysis, 314 THE LICHENOLOGIST Vol. 42

T 2. Variation in lichen species richness between the four size classes of Nothofagus cunninghamii and Atherosperma moschatum at Yarra Ranges and Errinundra.

Total no. species Mean (SE) Maximum no. per tree

N. cunninghamii (n = 108) Small 22 3·30 (0·31) 7 Medium 25 3·48 (0·33) 8 Large 22 3·48 (0·29) 8 Extra large 33 5·19 (0·49) 10 Total species*: 52 Total lichen species for N. cunninghamii†:54 Total lichen species in Yarra Ranges‡:67 A. moschatum (n = 120) Small 23 4·07 (0·24) 7 Medium 35 4·90 (0·44) 10 Large 30 4·43 (0·42) 10 Extra large 31 4·53 (0·39) 8 Total species*: 54 Total lichen species for A. moschatum†:58 Total lichen species in Errinundra‡:78

*Total lichen species included on that host species in subsample. †Total lichen species for host includes all lichens recorded on that host in that region (from Ford 2001). ‡Total lichen species for each region includes all available hosts in that region, and excludes canopy species (published in Morley & Gibson 2004). lichen species occurring on three or four size classes, cunninghamii the richest trees were from the and occurring on 10% or more of trees for at least two extra large size class (Table 2). Extra large of the size classes in the sample, were examined to ensure adequate sample size. Generally, most lichen N. cunninghamii had a total of 33 lichen species were not sufficiently abundant to be included in species, and a maximum of 10 lichens on a this part of the investigation. single tree. Conversely, the medium sized When using the parametric equivalent of this test, A. moschatum trees were the richest, with ANOVA, it is possible to follow up significant findings 35 lichens. Maximums of 10 lichens on using Post Hoc tests, such as the Tukey test, to deter- mine which groups are different. No such tests are single trees were recorded for both me- available for the non-parametric tests, so, while it was dium and large A. moschatum. Small trees possible to say that significant differences existed in the of both species supported the fewest lichen cover of certain lichen species, it was not possible to species. determine which size classes were causing significant differences, except through obvious presence or absence The differences observed in species rich- of species from one of the size classes. ness between N. cunninghamii trees of differ- ent size classes was significant (4.760df3, P = 0·004) (Table 3), and Tukey tests revealed Results that the differences existed between the extra In total, 52 and 54 lichen species occurred on large size class and all other size classes N. cunninghamii and A. moschatum respect- (Table 4). On the other hand, no signifi- ively (Table 2). These totals were 77% of the cant differences were found in species rich- total lower trunk lichen flora recorded in the ness between size classes for A. moschatum Yarra Ranges, and 69% of the total for (0.299df3, P = 0·826) (Table 3). Errinundra (Morley & Gibson 2004). Sub- Differences in species composition be- sampling captured over 93% of the lichens tween the different size classes for both recorded from each host in both cases. host species occurred. For each host Species richness did not clearly increase species, a ubiquitous group of lichens was with increasing girth, although on N. noted, consisting of species for which the 2010 Succession in epiphytic rainforest lichens—Morley & Gibson 315

T 3. Results of ANOVA examining differences between number of lichen species supported by each size class of each dominant host. Data were square root transformed.

Source of variation Sum of squares df Mean square FP

N. cunninghamii Between groups 3·800 3 1·267 4·760 0·004 Within groups 27·676 104 0·266 Total 31·476 107 A. moschatum Between groups 0·326 3 0·109 0·299 0·826 Within groups 42·073 116 0·363 Total 42·399 119

T 4. Table of differences between means (Tukey’s HSD multiple comparisons) for N. cunninghamii.

Small Medium Large Extra large

N. cunninghamii Small – 0·0887 0·1049 0·4878* Medium – 0·0162 0·0991* Large – 0·3829* Extra large –

*Significant at the P < 0·05 level. size of the tree did not appear to be import- large), and their presence on the small size ant (Tables 5 & 6). The number of ubiqui- class may have been incidental, as they were tous species was higher on A. moschatum reported once only. There was a large (11 species) (Table 6) than on N. cunning- number of lichen species, 15, that occurred hamii (7 species) (Table 5). Some lichen only on extra large N. cunninghamii trees. The species appeared to be confined to, or species Metus conglomeratus (F. Wilson) D. J. more prevalent on, a particular size class; Galloway & P. James, Bapalmuia buchananii however, often these species were recorded (Stirt.) Kalb & Lücking, Bunodophoron pat- only once. These data were too skewed in agonicum (C. W. Dodge) Wedin, Cladonia one direction and could not be normalized, subradiata (Vain.) Sandst., Arthonia apteropte- hence were not statistically analysed. ridis Kantvilas & Veˇzda, Lecidea sp. 4, Micarea On N. cunninghamii, Pseudocyphellaria spp. agg. and Topeliopsis decorticans (Müll. glabra (Hook.f. & Taylor) C. W. Dodge, Arg.) A. Frisch & Kalb all occurred rarely, Pertusaria novae-zelandiae Szatala, Cladonia but more than once. A further seven species ramulosa (With.) J. R. Laundon, Pannaria were reported only once on extra large trees. microphyllizans (Nyl.) P. M. Jørg., Micarea Much of the lichen flora of A. moschatum prasina Fr., Thelotrema lepadinum (Ach.) trees in the Errinundra region occurred only Ach. and Lepraria sp. occurred on all host once, and this was especially true on me- size classes with the latter two species being dium, large and extra large size classes (Table most frequent (Table 5). Pseudocyphellaria 6). Eleven species occurred on all size classes, glabra was more frequent on trees of medium with T. lepadinum, P. glabra and P. microphyl- and large size classes. Cladonia ramulosa and lizans showing the same frequency through- Pannaria microphyllizans were more abun- out each size class. This suggested that the dant on larger trees (medium, large and extra characteristics of A. moschatum trees did not 316 THE LICHENOLOGIST Vol. 42

T 5. Frequency of lichens on each size class of Nothofagus cunninghamii trees from the Yarra Ranges (n = 27 for each size class). Species have been manually ordered to reflect compositional drift as tree size increases. Species occurring on all size classes are presented first, followed by those on small, medium, large and extra large size classes.

Small Medium Large Extra large

Thelotrema lepadinum 24 21 22 19 Lepraria sp.17152019 Pseudocyphellaria glabra 810107 Pertusaria novae-zelandiae 2413 Cladonia ramulosa 1566 Pannaria microphyllizans 1254 Micarea prasina 1111 Megalaria grossa 322 Graphis tenella 83 Thelotrema sp. 2 6 5 Coccotrema cucurbitula 31 Micarea sp. 1 2 1 Opegrapha stellata 21 Pyrenula dermatodes 65 Leifidium tenerum 11 4 Parmelinopsis afrorevoluta 11 Psoroma asperellum 123 Parmelina quercina 11 Hafellia levierei*1 Mycoblastis sp. 1* 1 Opegrapha viridis 1 Loxospora solenospora 1 Cladia aggregata 51117 Trapeliopsis granulosa 42 Bunodophoron insigne 215 Coenogonium luteum 211 Dendriscocaulon dendriothamnodes 21 Pertusaria truncata 2 Cladonia rigida var. rigida 111 Coenogonium implexum 111 Sarrameana albidoplumbea 1 Micarea sp. 2 2 3 Bunodophoron australe 13 Parmelia cunninghamii 1 Parmelia tenuirima 1 Pannaria leproloma*1 Topeliopsis subdenticulata 114 Metus conglomeratus 4 Bapalmuia buchananii 3 Bunodophoron patagonicum 3 Cladonia subradiata 3 Arthonia apteropteridis 2 Lecidea sp. 4 2 Micarea spp. agg. 2 Topeliopsis decorticans 2 Cresponea plurilocularis* 1 Lecanactis abietina* 1 Micarea sp. 3* 1 Pertusaria sp. 1 1 Phlyctis subuncinata 1 Sticta stipitata* 1 Trapeliopsis congregans* 1 Total Number of Species: 52 22 25 22 33 *Species considered to be rare in Victorian rainforest (Morley & Gibson 2004). 2010 Succession in epiphytic rainforest lichens—Morley & Gibson 317

T 6. Frequency ranking of lichens on each size class of Atherosperma moschatum trees from Errinundra (n = 30 for each size class). Species have been manually ordered to reflect compositional drift as tree size increases. Species occurring on all size classes are presented first, followed by those on small, medium, large and extra large size classes.

Small Medium Large Extra large

Thelotrema lepadinum 26 27 25 23 Graphis tenella 17 17 7 5 Pseudocyphellaria glabra 13 19 18 19 Arthothelium interveniens 12856 Pannaria microphyllizans 10 16 17 16 Lecidea immarginata 7667 Coccotrema cucurbitula 6321 Pyrenula dermatodes 4 6 11 11 Pyrenula concatervans 4345 Lepraria sp.361012 Menegazzia nothofagi 1314 Crustose sp. 2 3 1 Sarrameana albidoplumbea 31 Arthothelium sp. 3 2 2 Chrysothrix candelaris 21 1 Coenogonium luteum 21 1 Pseudocyphellaria billardierei 141 Graphis librata 21 Collema subconveniens 133 Chiodecton colensoi 121 Parmelina quercine 1 Pseudocyphellaria rubella*1 Thelotrema sp. 3 1 Bunodophoron australe 22 Bunodophoron insigne 111 Leifidium tenerum 111 Parmeliella nigrocincta 111 Phlyctis subuncinata 11 Pseudocyphellaria dissimilis 11 Pannaria durietzii 11 Psoroma soccatum*11 Cladia aggregata 13 Opegrapha agelaeina 12 Bacidia sp. 4 1 1 Fuscoderma (amphibolum) 1 Metus conglomeratus 1 Mycomicrothelia sp.1 Parmelia tenuirima 1 Parmelina labrosa 1 Parmelinopsis afrorevoluta 1 Pertusaria novae-zelandiae 1 Topeliopsis subdenticulata 41 Psoroma asperellum 11 Strigula albicascens 11 Topeliopsis decorticans 11 Arthothelium sp. 2* 1 Bacidia sp. 6 1 Bunodophoron patagonicum 1 Hafellia levieri* 1 Bapalmuia buchananii 2 Coenogonium implexum 1 Dendriscocaulon dendriothamnodes 1 Peltigera dolichorrhiza 1 Phaeographis sp. 2* 1 Total Number of Species: 54 23 35 30 31 *Species considered to be rare in Victorian rainforest (Morley & Gibson 2004). 318 THE LICHENOLOGIST Vol. 42 vary with increasing size, at least for those was expected. A rich lichen flora has ubiquitous lichen species with wide ecologi- also been observed on this host in other cal tolerance within the rainforest. Indeed, Victorian studies (Ashton & McRae 1970; there were few examples of species that had Ford 1996; Louwhoff 1995) and in Tasmanian higher frequency on a particular size class studies (Kantvilas 1988, 1995; Kantvilas & (excluding species occurring once only), ex- Jarman 1991; Jarman & Kantvilas 1995) and, ceptions were Graphis tenella auct. non Ach., hence, the results of this part of our study which was more frequent on small and me- support previous survey efforts. Although A. dium trees, and Pyrenula occulta (C. Knight) moschatum has smooth bark, when compared Müll. Arg. and Lepraria sp. which were more to N. cunninghamii, it still proved to be an frequent on large and extra large trees. excellent host for lichens in Errinundra cool Few lichens had sufficient cover to allow temperate rainforest. In fact, on average, for Kruskal-Wallis comparisons. The species A. moschatum trees from the Errinundra that did meet the requirements tended to be region supported slightly more species than members of a ubiquitous group of rainforest N. cunninghamii trees in the Yarra Ranges lichens that occur frequently, and often (see Table 2). In optimum habitats in abundantly, in Victoria’s rainforests (Morley Tasmania, smooth barked communities of and Gibson 2004). On N. cunninghamii, A. moschatum and Telopea spp. supported a these species were: Bunodophoron spp. agg. community of 32 species, with the most Cladia aggregata (Sw.) Nyl., Lepraria sp., common being lush foliose forms of Pseudo- Pertusaria novae-zelandiae, Pseudocyphellaria cyphellaria billardieri (Delise) Räsänen and glabra, Pannaria microphyllizans and Thelo- Pannaria microphyllizans (Kantvilas 1988). trema lepadinum. Only Bunodophoron spp. At Errinundra, the dominant components of 2 agg. (
df3 = 16·33, P = 0·001) and Cladia the A. moschatum rainforest community also 2 aggregata (
df3 = 29·29, P < 0·001) showed included P. microphyllizans, which was rea- significant differences between size classes, sonably frequent on all tree sizes. Pseudo- probably due to their absence on small trees. cyphellaria billardieri was uncommon and For A. moschatum, Arthothelium interveniens occurred mostly on medium sized trees. It (Nyl.) Zahlbr., Bunodophoron spp. agg., was apparently replaced by P. glabra as the Coccotrema cucurbitula (Mont.) Müll. Arg., dominant lush foliose form in the Victorian Graphis tenella, Lecidea immarginata R. Br. ex forest type. Otherwise the bulk of the com- Cromb., Lepraria sp., Menegazzia nothofagi mon flora on A. moschatum were crustose (Zahlbr.) P. James & D. J. Galloway, Pseudo- forms: Arthothelium interveniens, Thelotrema cyphellaria glabra, Pannaria microphyllizans, lepadinum, Graphis tenella. Overall, the status Pyrenula dermatodes (Borrer) Schaer., of N. cunninghamii as an ideal host for rain- Pyrenula concatervans (Nyl.) R. C. Harris and forest lichens was further established by the Thelotrema lepadinum had sufficient cover to results of this study and, A. moschatum, when allow for Kruskal-Wallis comparisons. Only present as a dominant component of the 2 G. tenella (
df3 = 21·17, P = 0·000) and rainforest canopy, is also an excellent host for 2 Lepraria sp. (
df3 = 8·13, P = 0·043) showed lichens. significant differences in cover between size Successional relationships of lichens were classes, which may be due to the prevalence indicated by comparing the frequency of li- of G. tenella on small and medium trees and, chen species to the size class of the host tree. conversely, the prevalence of Lepraria sp. on We found that the composition of lichen large and extra large trees (Table 6). communities changed as the host tree aged and that these changes were generally more distinct on N. cunninghamii than on A. mos- chatum. Hedenås & Ericson (2000) also Discussion found distinct changes in composition with That N. cunninghamii supported a very rich increasing age of aspen stands in Sweden, lichen flora in the Yarra Ranges rainforests with a general increase in numbers of species 2010 Succession in epiphytic rainforest lichens—Morley & Gibson 319 found in older stands. They cite a number of Forest fragmentation and isolation can studies demonstrating the importance of suc- have a detrimental effect on lichen popula- cessional stages in explaining differences in tions, however, studies have shown that relict species composition. Extra large N. cunning- stands of ancient forest can provide refugia hamii trees supported significantly more for particular lichen communities, in an species than other size classes. These differ- otherwise unsuitable, disturbed or developed ences in species richness and composition landscape (Rose 1976; Kantvilas & Jarman may be attributable to differences in the lev- 1993). Indeed, even single remnant trees els of bark fissuring, with the deeply fissured may provide a temporary link between old bark of older trees being more conducive to and young forests for some lichen species the growth of some species, compared to the (Hedenås & Hedström 2007) and provide a smooth bark of young trees. Furthermore, source from which propagules may disperse species that appeared to predominate on to nearby ageing forests. In the present study, older, rough barked N. cunninghamii were we found many rare or uncommon species rare on the smooth bark of A. moschatum on extra large N. cunninghamii trees, and a (e.g. Metus conglomeratus (F. Wilson) D. J. large proportion of species represented only Galloway & P. James, Topeliopsis subdenticu- once in this study occurred on these very old lata (Zahlbr.) A. Frisch & Kalb and C. aggre- trees. It is feasible that the combined ele- gata). No significant differences in species ments of increasing bark fissuring and flaki- richness were noted for the A. moschatum ness with age, increased canopy openness, trees of Errinundra. On A. moschatum, the which may reduce the barrier effect of the species Coccotrema cucurbitula (Mont.) Müll. closed rainforest canopy, plus the appear- Arg. and Graphis tenella (which were fre- ance of suitable specialized microhabitats on quently found on smooth barked small to older trees is contributing to this influx of medium N. cunninghamii) were frequent on rare species. These factors provide a rich and all size classes. As predicted, succession on varied microclimate with recurring opportu- A. moschatum was much less clear, possibly nities for colonization of new species, es- because obvious changes in substratum char- pecially rare lichens. Hedenås & Ericson acteristics did not occur with increasing (2000) also found that particular lichen girth. It is likely that this has led to retention species (especially those with blue-green of pioneer species in the community, perhaps photobionts) required certain habitat con- at the expense of a significantly richer com- ditions for successful establishment. As many munity developing as tree diameter in- Victorian rainforests represent sub-climax or creased. In addition, the pronounced regenerating communities (Cameron 1992), shading effect of the larger leaves of A. mos- the scarcity of specialized niches, such as the chatum (Kantvilas et al. 1985; Kantvilas & dry sides of very old N. cunninghamii trees, Minchin 1989), and the absence of obvious may have contributed to the absence of trunk inclination, may afford a more equable species usually associated with these microclimate as the rainforest matures. In- microhabitats in Tasmania, for example deed, a comparatively large number of lichen Sagenidium molle Stirt. and Chaenotheca species on A. moschatum were present on all brunneola (Ach.) Müll. Arg. (Kantvilas of the different size classes, and those species 1988), and the rarity of species such as confined to one size class only were reported Lecanactis abietina (Ach.) Korb. and Arthonia once only. Overall, patterns of succession apteropteridis Kantvilas & Ve˘zda. This has were less distinct for A. moschatum than for implications for management of rain- N. cunninghamii. We believe that the com- forests, as regenerating rainforests may not paratively stable microclimate found in A. provide the habitat niches for a wide var- moschatum rainforests, while providing excel- iety of lichens, especially rare species. lent conditions for a very rich lichen flora to Therefore, extra protection of Victoria’s develop, provided less opportunity for clear oldest rainforest pockets is considered patterns of succession to establish. critical as they represent a source of rare, 320 THE LICHENOLOGIST Vol. 42 potentially threatened, lichen species and Brodo, I. M. (1973) Substrate ecology. In The Lichens act as a reservoir of propagules for other, (V. Ahmadjian & M. E. Hale, eds): 401–441. London, New York: Academic Press. ageing rainforests. Busby, J. R. & Brown, M. J. 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Accepted for publication 15 September 2009