Papers and Proceedings of the Royal Society of , Volume 123, 1989 211

PHENOLOGY AND GERMINATION IN SOME CANOPY AT MT FIELD NATIONAL PARK, TASMANIA

by Jennifer Read

(with five tables and three text-figures)

READ, J., 1989 (31 :x): Phenology and germination in some rainforest canopy species at Mt Field National Park, Tasmania. Pap. Proc. R. Soc. Tasm. 123: 211-221. ISSN 0080-4703. Botany Department, University of Adelaide, GPO Box 498, Adelaide, South 5001; formerly Botany Department, University of Tasmania.

The timing of shoot expansion, flowering, germination and fall was recorded in some rainforest canopy species at Mt Field National Park, Tasmania. Seed collected from these and two other species was germinated in Hobart under controlled conditions. Most of the variation in phenology and germination requirements was continuous and correlated broadly with distribution with respect to the temperature climate. The species which commonly occur at high altitudes ~ selaginoides, A. cupressoides, Nothofagus gunnii and N. cunninghamii ~ germinated earlier at low temperatures than the others, with provenance variation indicated in N. cunnillghamii. The cold-sensitive species Atherosperma moschatum failed to germinate at low temperatures, with a secondary dormancy indicated. Atherosperma moschatum and Phyllocladus asplelliifolius showed delayed shoot expansion during the cool growing season of 1984-85 which rendered the shoots more frost-sensitive. The periodicity of seed production is also greatest in the high altitude species, although the ecological implications are uncertain with respect to climate. Only P. aspleniifolius shows evidence of prolonged seed dormancy. This characteristic enables the populations to survive large-scale disturbance as soil-stored seed and therefore is an important feature of the regeneration ecology of this species. Key Words: germination, phenology, Atherosperma, Athrotaxis, Eucryphia, Nothofagus, Phyllocladus, Tasmania.

INTRODUCTION recorded in Athrotaxis cupressoides D. Don (Ogden 1978) and Nothofagus gunnii (Hook. f.) Oerst. Although rainforest forms one of the major (Read & Hill 1988a, unpubl. data). The occurrence vegetation types in Tasmania, relatively little of the of these species with respect to altitude and basic biology of the component species is climate, summarised in table 1, has been discussed documented, other than autecological studies of by Read & Hill (1988b) and Cullen (1987a,b). (Hook.) Oerst. (Howard Temperate trees have a limited growing season in 1973a,b,c) and a study of germination and dispersal natural conditions and there is considerable in N. cunninghamii, Eucryphia lucida (Labill.) variation among species in the timing and patterns Bail!. and Atherosperma moschatum Labill. of foliage expansion and the timing of flowering (Hickey et al. 1983). Read & Hill (1985, 1988a) and seed release (e.g. Wareing 1956, Bussell 1968). have described regeneration patterns in the major Variation may also occur within a single species at canopy species, N. cunninghamii, A. moschatum, different sites. Similarly, the importance of the E. lucida, D. Don and relationships between the physical environment and Phyllocladus aspleniijolius (Labill.) Hook. f. They seed germination in the distribution of a species in noted differences among the species in their gap space and time, and the variability of these requirement for regeneration and modes of relationships has been noted by many authors (e.g. reproduction which have a large impact on the Grubb 1977, Bazzaz 1979). These features are forest dynamics and community composition. The examined in Nothofagus cunninghamii, Eucryphia large gap requirement of P. aspleniijolius and lucida, Atherosperma moschatum, Phyllocladus A. selaginoides is of particular interest, since aspleniijolius and Athrotaxis selaginoides at Mt regeneration in closed forests by these species is Field National Park (42°4l'S, l46°40'E), with commonly insufficient to maintain their continued experimental germination studies on seed collected presence in such forests, although they may from these species, as well as from Nothofagus currently form a major component of the forest gunnii and Athrotaxis cupressoides, in order to canopy (Ogden 1978, Cullen 1987a,b, Read & Hill determine whether differences among species in 1988a). Similar population dynamics have been phenology and germination characteristics may 212 1. Read

TABLE 1

Summary of the Distribution of some Rainforest Canopy Species with Respect to Altitude in Tasmania

Species Altitudinal occurrence

Range % of records (m a.s.l.) over 800 m a.s.l.*

Atherosperma moschatum 0-1120 12 Athrotaxis cupressoides 600-1330 93 A. selaginoides 20-1300 56 Eucryphia lucida 0-1000 3 Nothojagus cunninghamii 0-1260 27 N. gunnii 550-1260 88 Phyllocladus aspleniifolius 0-1160 25

* The percentages refer to records from surveys and herbarium collections (data supplied by M.J. Brown, J.R. Busby and the Tasmanian Herbarium), and do not necessarily reflect stem frequency over these altitudes.

TABLE 2

Species, Site Locations and Phenological Features recorded at Mt Field National Park

Altitude Species Observations (m a.s.l.)

180 Atherosperma moschatum Leaf expansion: 1982-83, observations fortnightly Nothojagus cunninghamii

700 A. moschatum Leaf expansion: 1982-83, observations fortnightly. Eucryphia lucida F1owering*, seeding and germination: 1982, 1984 N. cunninghamii and 1985, observations monthly, but with some Phyllocladus aspleniijolius gaps in the observation period.

920 A. moschatum Leaf expansion: 1982-83, observations fortnightly. Athrotaxis selaginoides Flowering*, seeding and germination: 1982, 1984 N. cunninghamii and 1985, observations monthly with some gaps P. aspleniijolius in the observation period.

980 A. selaginoides Leaf expansion: 1982-83, observations fortnightly. N. cunninghamii

~~~~~~_._--_.~~~~~~- * The presence/absence of flowering was noted annually from 1982-88. Phenology and germination in some rainforest canopy species 213

contribute to the observed patterns of species The seed treatments for each species were as regeneration and distribution. follows: (I) incubated moist in light at 4°, 12°, 17°, 25° and 32°C; METHODS (2) incubated moist in dark conditions at 25°C; (3) incubated moist in light at 4°C for four weeks, Phenology followed by 25°C. The failure of Phyllodadus aspleniifolius to ger­ Four sites were selected at Mt Field over an minate in any of the above treatments led to the altitudinal range of 800 m, from 180 m a.s.l. to 980 following treatments for this species only: m a.s.l. The species observed at each site and the (4) seed soaked for 24 hours in HCI (pH 2) features recorded are listed in table 2. Sites 1--4 followed by incubation moist in light at 20°C; were observed from May 1982 to May 1983 at (5) seed scarified and incubated moist in light at fortnightly intervals. Sites 2 and 3 were also 20°C; observed from August 1984 to August 1985 at (6) seed coat removed and seed incubated moist in monthly intervals. At each site, five lateral light at 20°C; branches were tagged on three trees of each species (7) seed boiled for 5 minutes then incubated moist on exposed forest edges. Saplings (originated from in light at 20°C; seed) of Nothofagus cunninghamii, Eucryphia (8) seed sown in pots of sandy loam and placed lucida and Phyllodadus aspleniifolius were also outside in full sunlight, with daily watering. tagged at Site 2. No saplings of seedling origin In treatments 1 to 7, 30--40 seeds of each tree were found in Atherosperma moschatum at this site. were placed in a petri dish on a pad of Whatman's The following features were recorded: Seed Test Thick filter paper (three dishes per (I) the timing of bud-break; species for each treatment, one for each parent (2) leaf production and abscission; tree). "Thiram" fungicide was dusted on the seed (3) the time of flowering, seeding and germination pad prior to the addition of distilled water. The petri (where possible); germination is often difficult to dishes were incubated in controlled environment record directly in the field, and here is recorded growth cabinets under incandescent and fluorescent 2 I indirectly as the first appearance of cotyledonary lights (150 ~mol quanta m· s· ). The "dark" treat­ seedlings. ment was provided by cardboard boxes lined with Growth patterns were also observed fortnightly black cartridge paper and seeds placed in this from 1982 to 1985 in seedlings raised in Hobart treatment were sown and observed under green from seed or cotyledonary seedlings collected from light. Mt Field in June 1982. One group of five seedlings Results were observed every 1-2 days for the of each species was grown outside under natural first 50 days, then every 3-5 days until Day 100, daylengths, and another group of seedlings was followed by irregular observations. Observations of grown in a glasshouse under natural daylengths. treatments 1-3 were continued for 25 days after the last seed germinated. Observations of the \2°C treatment ceased after 125 days, due to fungal Germination infection of the remaining seeds. Observations of treatments 4-7 were discontinued after 90 days. Seed was collected from Mt Field in 1982, a year Treatment 8 was observed for 30 months. of exceptionally high seed production for all of these species, from three trees each of Nothofagus cunninghamii (Nc700), Eucryphia RESULTS lucida, Phyllociadus aspleniifolius and Atherosperma moschatum at 700 m a.s.l. and from N. cunninghamii (Nc980), N. gunnii, Athrotaxis Bud-break and Shoot Expansion selaginoides and A. cupressoides at 980 m a.s.l. All seeds were collected and sown in 1982 following The uppermost bud on Nothofagus cunninghamii dry storage at room temperature. Poorly developed shoots is lateral rather than apical, with the new seeds of A. moschatum and Athrotaxis spp. were branch rotating to appear apical (Howard 1973b). discarded, and therefore the final germination The overwintering buds are sheathed by bracts, percentages do not reflect the overall viability of whereas in Eucryphia lucida the buds are the seed crop. enclosed in a yellow wax. Apical buds of the other 214 I lead

these species at 980 m a.s.l. Bud-break occurred up AlhrolaxlS 980 · e-. to 2--4 weeks earlier in saplings of P. aspleniifolius selaglnoldes 920 0-0 and N. cunninghamii at 700 m a.s.l. than in adults. Phyllocladus 920 0-0 In 1984, bud-break was delayed in A. moschatum asplenllf"lIus 700 · 0-0.-. and P. aspleniifolius, so that at the 920 m a.s.l. Eucryphla luclda 700 :11=11 site, of these species were not fully expanded and hardened by June 1985 (Read & Hill NOlhofagus 980 · .-. e cunnlnghamll 920 · .-e e 1988b). In contrast, leaves of the other species were 700 . 0-,-11-0 "* e fully expanded and hardened by late summer--early . e-. 180 e autumn (Read & Hill 1988b). Alherosperm. 920 · e-e Nothofagus cunninghamii shoots from saplings moschalUm 700 0-0 180 ..-. and mature showed predominantly determinate growth, with a single flush of growth ASONDJFM from axillary buds during the spring, bearing Time of year 5-16 leaves. This growth pattern is similar to that described in detail by Howard (1973b) in FiG. 1 - Timing of leaf production at Mt Field N. cunninghamii in Victoria. Many terminal at each altitude, examined at two-week intervals axillary buds remained dormant for the whole in 1982--8J. observation period. Axillary buds formed during .-. The period during which bud-break the growth flush occasionally broke dormancy in occurred il1 mature plants saplings at 180 m a.s.l. and 700 m a.s.l. during the 0-0 The period during which bud-break late summer to form a second growth flush; occurred il1 saplings (of seedling origin) 1-1.5 m occasional sapling shoots produced leaves high. continuously. Determinate shoots were fully The dots (•) preceding the marked period expanded within 4-6 weeks at all sites and leaves indicate the time of the previous observation. were fully expanded within 6-8 weeks (fig. 1). Most Nothofagus cunninghamii leaves were N. cunninghamii seedlings which had germinated produced during the spring growth flush, but in Hobart in June 1982 showed continuous apical some expanded shoots of saplings continued to growth in the glasshouse during winter, and produce new leaves at the apices. axillary buds broke in August. Seedlings growing e The date at which N. cunninghamii leaves outside in August showed some apical growth were fully expanded. through winter, with axillary buds breaking in * The date at which N. cunninghamii leaves October. Subsequent growth in seedlings, both produced in the spring growth flush were fully inside and outside the glasshouse, was a combin­ expanded, with further leaf production occurring ation of growth flushes from axillary buds and at the shoot apices or in later growth flush. continuous apical growth until early autumn. .&. The date by which leaf production had Growth then ceased outside the glasshouse but ceased. continued inside the glasshouse, both by con­ tinuous apical growth and occasional flushes from species are protected to some extent by the dormant axillary buds, with a major period of infolding of older leaves, and in Phyllocladus determinate growth soon after daylength began aspleniifolius by bud scales. increasing in winter. This pattern of growth, with Bud-break occurred later with increasing slight variations in timing from year to year, was altitude in all species except in Nothofagus observed in the same seedlings until observations cunninghamii at 920 m and 980 m (fig. I). There ceased in October 1985. was no distinct pattern in the timing of bud-break All other species produced foliage indeter­ among species, other than the later bud-break of minately. Atherosperma moschatum and Eucryphia Phyl/ocladus aspleniijolius compared with other lucida usually produced 2--4 leaves on each shoot species. At 180 m a.s.l. N. cunninghamii buds during the growing season at Mt Field. broke earlier than those of Atherosperma Phyl/ocladus aspleniifolius usually produced a moschatum, but there was no difference in timing single whorl of 5-7 phylloclades (mostly deter­ between these species at 700 m a.s.l. and minate). The Athrotaxis selaginoides shoots 920 m a.s.!. Similarly, Athrotaxis selaginoides buds produced 11-23 leaves. Leaf production in mature opened earlier than those of N. cunninghamii at plants of A. selaginoides, A. moschatum, E. lucida 920 m a.s.l. but there was no difference among and P. aspleniifolius ceased during summer and Phenology and germination in some rainforest canopy species 215 did not resume until the following spring. Leaf production ceased later at the higher altitudes (fig. I). In seedlings raised in Hobart, leaf production was continuous in the glasshouse, and continued very slowly outside the glasshouse during the first winter after germination. In later years, growth continued until May outside the glasshouse, then did not resume until October. These growth patterns remained constant until ASONDJFMAMJJ observations ceased in October 1985, with slight Time of year variation in timing from year to year. The foliage of Phyllocladus aspleniifolius FIG. 2 - Timing offlowering at Mt Field at seedlings at Mt Field consisted entirely of leaves each altitude, examined at monthly intervals in for the first two to three years of growth, but 1983--84 (.) and 1984--85 (.). Flowering was seedlings of the same age which were grown not observed in A. selaginoides and Nothofagus outdoors in Hobart (with a faster growth rate) cunninghamii during this period. The dots (•) produced phylloclades within six months. preceding the marked period indicate the date of No leaf loss was recorded in any of these species the preceding observation. The date shown for other than due to browsing. Therefore the leaf life Phyllocladus aspleniifolius indicates only the first span was greater than 41 months. appearance of the cones. The dates shown for both P. aspleniifolius and Atherosperma moschatum refer only to the appearance of Flowering, Seeding and Germination female cones/flowers. at Mt Field

In 1984-85, flowering and seed maturation of Athrotaxls 920 e-e-e Eucryphia lucida were delayed (figs 2 & 3). Seed selaglnoldes maturation and germination were also delayed in .A.-.a.-A Eucryphla lucida 700 .-. Atherosperma moschatum in 1984-85, and .-.-e5 flowering in this species was delayed in 1985 Nothofagus 920 e-e-e-e (figs 2 & 3). These delays coincided with the cunnlnghaml/ 700 e-e-e-I slightly lower temperatures of the 1984-85 growing season. Bureau of Meteorology records at A-A Phyllocladus 920 .-.e-e-e Maydena (42°46'S, 146°36'E, 267 m a.s.!.) show asplenlifollus A-A 700 mean monthly temperatures from November to .-.e-e-e-e February averaging 20AoC in 1983-84, compared "'-"-A.-A Atherospenna 920 .-. with 19AoC in 1984-85. The timing of cone moschatum s development in Phyllocladus aspleniifolius was not 700 ._._.5"-A-A., delayed but seed maturation at 920 m a.s.!. was late (fig. 3). The flowering period of E. lucida is long F M A M A S relative to that of A. moschatum (fig. 2). However, Time of year the period may be narrowed by the behaviour of the insect pollinators. FIG. 3 - Timing of the period of seed Flowering and seeding of Nothofagus maturation and release (. 1982,. .1984,. cunninghamii and Athrotaxis selaginoides at Mt ... 1985), and the first appearance of seedlings Field were recorded only in the 1981-82 growing (s) at Mt Field at each study site, examined at season, which was a season of prolific seed two- or four-week intervals. The dots (. ) production for all the species in this study. indicate the dates of observations prior to seed Occasional empty cupules of N. cunninghamii were maturation and following the majority of seed observed in subsequent years, indicating that release. flowering was occurring in this species at a very low frequency. No viable seeds were found. However, cone development was recorded in Athrotaxis species in late September 1988, and also 216 1. I?ead heavy flovering of N. cunninghamii and N. gunnii no further germination was observed. Cotyledonary in October and November respectively, with seedlings of Phyllocladus aspleniifolius appeared indications of a year of heavy seeding for both in spring at 700 m a.s.!. The seed crop of genera_ Arherosperma moschatum and Eucryphia P. aspleniifolius at 920 m a.s.!. was small, except in lucida flowered prolifically each year and 1982, and no seedlings were observed at this site. PhylloclaJus aspleniifolius produced cones each year, but Illost prolifically in the 1981-82 growth season ani again in 1988-89. Experimental Germination Gennimtion of Nothofagus cunninghamii was recorded during autumn at 180 m a.s.!. and 700 m Phyllocladus aspleniifolius seed did not germinate a.s.!. in 1982, with seedlings not apparent until under treatments 1-3. The other species germinated spring at 920 m a.s.!. and 980 m a.s.!. (fig. 3). readily under these treatment conditions (table 3). Athrotaxis selaginoides seedlings did not appear The germination score for these species at 25DC until spring in 1982. Eucryphia lucida was only was unaffected by the light conditions (table 3). studied at 700 m a.s.!. at Mt Field, with autumn The onset of germination was most rapid and the germination recorded in 1982 and spring time taken to reach 50% of the final germination germinatiun in 1984 and 1985. E. lucida seed does score shortest at 25DC for all species, although with not mature until the autumn following the year of little difference at l7DC (tables 3 & 4). Incubation flowering, Atherosperma moschatum seedlings temperature did not affect the final germination appeared in autumn at 180 m a.s.!. and 700 m a.s.!. percentage, other than at 32DC, where no At 920 rr a.s.!. seeding was profuse, and seed germination occurred and seed had deteriorated collected in March 1985 was germinated in the after 28 days, and at 4DC in Atherosperma laboratory with 92% viability of well-formed seed, moschatum (table 3). At 12DC a substantial propor­ which was equivalent to 36% of the total seed tion of seeds of Nothofagus cunninghamii, collected. However, successful field germination of A. moschatum and Eucryphia lucida were infected A. moschatum was very rare at this site. Many by fungus after 125 days (tables 3 &4) and scoring hundreds uf well-formed seeds were observed close was abandoned. The final germination percentage to the parent trees, but only two cotyledonary is assumed to be the same as at 25, 17 and 4DC for seedlings were recorded, germinating in September. N. cunninghamii and E. lucida. However, since Although many seeds remained intact after winter, A. moschatum failed to germinate at 4DC, the

TABLE 3

Final Germination Percentages of each Species*

Species Site Incubation temperature (DC) (m a.s.l.) 32 25 25 17 12 4 4-25t light dark

Nothofagus cunninghamii 700 0 21 20 22 12+ 24 25 980 0 48 50 48 26+ 51 46 N. gunnii 980 0 43 40 36 39 41 40 Eucryphia lucida 700 0 93 91 93 60+ 95 93 Atherosperma moschatum§ 700 0 92 97 93 49+ 0 99 Athrotaxis selaginoides§ 980 0 61 59 63 60 67 63 A. cupressoides§ 980 0 51 52 57 57 57 51

* Each percentage value is the mean of results of seed from three trees at the same site. 4DC for 4 weeks, then incubated at 25 DC. The final count was at 125 days, with remaining seeds infected by fungus. Poorly formed seeds (small, shrivelled or discoloured) were not included. Ph"n,o/r,','" and germination in some rainjines/ canopy species 217 reduced germination score of A. moschatum at A. cupressoides stored dry at room temperature 12°C may be due to factors other than fungal germinated with 50--80% viability after 32 months. infection. Differences among trees in germination Seed of Atherosperma moschatum could not be rate were small. Variation in viability ranged from germinated at 20°C under a 24-hour photoperiod 3% of the mean value in A. moschatum to 19% in after two months dry storage at room temperature. N. cunninghamii. Seed of A, moschatum stored dry at 4°C was The 4°C pre-treatment increased the rate of successfully germinated at its original level of germination for Eucryphia lucida, Nothofagus viability after four months, but with only 3% gunnii and Athrotaxis selaginoides (table 4) but had germination after five months storage. However, no effect on the final germination percentage of the embryo appeared healthy in both cases of any species (table 3). N. gunnii, A. selaginoides germination failure and seed stored in these and A. cupressoides germinated earlier at 4°C than conditions germinated (96%) after incubation in the other species (table 5), including Nc980, and darkness at 20°e. germination of these species was complete within 125 days at 12°C (tables 3 & 4). N. cunninghamii seed collected at 980 m a s.l. germinated more DISCUSSION rapidly at 12°C and 4°C than seed collected from 700 m a s.l. (tables 4 & 5). Phenology Phyliociadus aspleniifolius failed to germinate in Treatments 1-7, although seeds had fully imbibed The patterns of shoot growth III Nothofagus water within 24 hours. Observations on Treatment cunninghamii are identical to those recorded in 3 ceased on Day 151 due to fungal attack, and on Victoria by Howard (l973b), although the Day 125 for the other treatments. However, seeds appearance of a second growth flush in germinated in soil placed in the open air with daily N. cunninghamii appears to be more frequent in watering (Treatment 8) in the spring of 1983, i.e. Victoria than at Mt Field. Howard noted that the after two winters. Seedlings appeared in September incidence of a second flush decreased with increas­ and there were no later germinations, with a final ing altitude at Mt Donna Buang, and therefore the germination percentage of 62%. occasional occurrence of a second growth flush at Seed of Nothofagus cunninghamii, N. gunnii, low altitudes at Mt Field and the absence of this Eucryphia lucida, Athrotaxis selaginoides and feature at high altitudes probably reflects the cooler

TABLE 4

The Number of Days to the Onset of Germination and to reach 50% of the Final Germination Percentage, expressed as a Range 218 J Read

TABLES

Cumulative Percentages of Laboratory Germination at 4°C

-_._-~~~- SJlecies Site Days from sowing m a.s.1. 129 136 140 151 223

NothoJagus cunninghamii 700 0 0 0 1 24 980 0 0 0 19 51 N. gunnii 980 24 40 E~cryphia lucida 700 0 0 0 0 95 Atherosperma moschatum 700 0 0 0 0 Athrotaxis selaginoides 980 0 9 17 67 A cupressoides 980 0 7 16 50 54

growing seasons. The only feature of the timing of Athrotaxis selaginoides, also observed in the bud-break that may be differentially limiting to congenerics N. gunnii and A. cupressoides, and to a regeneration and geographic distribution of species lesser extent in Phyllocladus aspleniifolius (J. is the delaying effect of a cool growing season on Hickey, pers. comm.), and the association of low the shoot expansion of Atherosperma moschatum seed viability with the years of low seed production and Phyllocladus aspleniiJolius, so that these leaves (Howard 1973b, Hickey et al. 1983) must have a may be susceptible to frost damage (Read & Hill detrimental effect on the colonisation by these 1988b). species of sites which are disturbed during periods The periodicity of seedfall in NothoJagus of low seed production. For example, mixed forest cunninghamii and Athrotaxis selaginoides has im­ burnt in western Tasmania in 1982 had a high plications for regeneration of these species. Hickey seedling density of N. cunninghamii by spring 1982 et al. (1983) recorded seedfall of N. cunninghamii, (Hill & Read 1984). If this fire had burnt after Atherosperma moschatum and Eucryphia lucida at 1982, the NothoJagus component of the mature two sites in northwestern Tasmania from 1975 to stand developing after the fire would probably be 1981, summarising N. cunninghamii seedfall back very much lower, due to the absence of seed during to 1963. These data, plus data from subsequent the early stage of site colonisation, with site pre­ years (1. Hickey, pers. comm.), indicate sporadic emption by other species, particularly the rapidly­ production of seed in N. cunninghamii, with heavy growing sclerophyll species. Similarly in falls in 1967, 1969, 1971, 1975, 1977, 1980, 1982 A. selaginoides, which is relatively drought and 1986 interspersed with years of low or mod­ sensitive (unpubl. data), establishment depends on erate seedfall. They did not find any clear the coincidence of a good seed year with moist relationship between seed production and the conditions. The infrequency of seeding in temperature of the preceding growing season, but A. selaginoides and the drought sensitivity of noted that the pattern of seed production was seedlings must limit its ability to colonise disturbed consistent at several sites around Tasmania. Poor sites, including canopy gaps, particularly combined seed production in 1986 at Mt Field, however, may with the faster growth rates of other rainforest be the result of climatic differences. Periodicity of species and rapid site pre-emption following the seeding is a common characteristic of NothoJagus disturbance. The greater consistency of seedfall in throughout its geographic range (Wardle 1984) and Atherosperma moschatum and Eucryphia lucida may allow a greater proportion of seeds and has been shown quantitatively by Hickey et al. seedlings to escape predation by herbivores (Ash (1983). There are no long-term data on seedfall in 1982). The time of flowering and seed release A. selaginoides, and data collected since 1983 on reported by Hickey et al. (1983) is, in general, P. aspleniijolius in northwestern Tasmania indicate 2 earlier than that recorded at Mt Field and probably some variability, with alternately poor « I g m· ) reflects the cooler climate at Mt Field. The sporadic and moderate seedfall (J. Hickey, pers. comm.). It nature of seed production of N. cunninghamii and is notable that the species with the greatest Phenology and germination in some rainforest canopy species 219 periodicity of seed production are those commonly rather than any pre-chilling requirement. This occurring at high altitudes. It is not clear whether feature has been previously reported in this is an evolutionary response to facilitate N. cunninghamii (Howard 1973b). The lack of any seedling establishment or to facilitate maximum requirement for pre-chilling treatment in high growth during the short growing seasons, with altitude species has also been recorded in a study reproduction only when there is an abundance of of alpine plants of the USA where only 3 out of assimilate. 60 species had a chilling requirement (Amen 1966). The time of field germination within a species, Sayers & Ward (1966) observed that temperatures with respect to altitude, is probably related to resulting in the best germination of alpine species differences both in the time of seed release and in in the USA (20-30°C) were similar to those for the time taken for germination to occur, each species native to lowlands. Similarly, in the present affected by climate. This appears to be particularly study germination was most rapid at 25°C for all critical in Atherosperma moschatum, since species, with seed of all species killed by observations indicate that the late seed release at incubation at 32°C. However, ecologically signi­ 920 m a.s.l. in 1985 led to a very low rate of ficant differences may occur at a finer scale of successful field germination, although this seed temperatures than those tested here. was successfully germinated in the laboratory soon Germination failure at 30-35°C has been reported after its release. Since observations were made only previously in Atherosperma moschatum by Read at monthly intervals, fine-scale differences which (1981) and in Nothofagus cunninghamii by Howard have not been detected may exist in the onset of (l973b), although seed of A. moschatum, germination among species. Eucryphia lucida and N. cunninghamii was successfully germinated by Hickey et al. (1983) in a 30o/20°C regime. The importance of high tem­ Germination Requirements peratures in limiting establishment from seed in the field is uncertain. Prolonged high temperatures in The early germination of Nothofagus gunnii, the range 30-35°C are unusual in the current Athrotaxis selaginoides and A. cupressoides that distribution of forests containing these species, was observed experimentally at low temperatures both in Victoria and Tasmania, but this feature may correlates with the predominantly high altitude be relevant to the absence of these species from distribution of these species. The earlier onset of warmer sites. germination at l2°C and 4°C of seed collected from A suitable combination of moisture and N. cunninghamii at 980 m a.s.l. than of seed temperature is probably the most important factor collected at 700 m a.s.l. is consistent with this determining seed germination under natural trend. Cotyledonary seedlings of A. selaginoides, conditions (Mayer & Poljakoff-Mayber 1982). A. cupressoides, N. gunnii and N. cunninghamii Howard (1973b) noted that suitable conditions for were observed in September 1982 at 980 m a.s.l. at germination of Nothofagus cunninghamii occur Mt Field (4-5 months after seed release) (tables 4 within 8-9 months of seedfall and therefore & 5), but the precise timing of seed release and reduction of viability with seed age is unlikely to germination is unknown. A high mortality, due to be a limiting factor for regeneration. The same is desiccation, occurred during the following summer, true for Eucryphia lucida, Atherosperma particularly on the more exposed microsites. Early moschatum, N. gunnii, Athrotaxis selaginoides and germination may therefore be important in allowing A. cupressoides. At low altitudes N. cunninghamii, early growth and establishment during a period of A. moschatum and E. lucida germinate in autumn, low evaporative loss, although early germination within 1-2 months of seed release (fig. 3) and it is may also place the seedlings at risk from frost unlikely that the lack of germination recorded in damage. Howard (1973b) noted that seed of dry-stored A. moschatum seed (also noted by N. cunninghamii of lowland populations in Victoria Hickey et al. 1983» would be a significant germinated soon after release in autumn, but did occurrence in the natural lowland environment. The not germinate until spring at high altitudes. This greatly reduced germination score in apparently pattern would be expected to show some annual viable seed of A. moschatum at 900 m a.s.l. at Mt variation, according to the timing of seed release as Field in 1985 is consistent with the secondary well as the climatic conditions following seed dormancy induced experimentally by cold moist or release. The data obtained in the present study cold dry storage. However, in the field, cessation of indicate that the timing of germination in the field dormancy was not observed to any significant is due to the slow germination at low temperatures degree, and it is not certain that light is the only 220 J. Read factor initiating release from this secondary densities on sites where it was failing to regenerate. dormancy. The environmental feature which is Therefore it is unlikely that dormancy initiati ng the secondary dormancy observed at high characteristics are directly limiting its regeneration altitudes is uncertain, since it is induced experi­ within undisturbed rainforest, even though the mentally at both moderate and low temperatures percentage of its annual seed crop which and in both dry and moist conditions (except in the germinates may possibly be small relative to that combination of moist, moderate temperatures). Any which remains dormant. delay in germination will also result in greater mortality due to fungal attack (e.g. table 3) and insect attack. These characteristics may limit the ACKNOWLEDGEMENTS ability of A. moschalum to colonise sites/microsites in which conditions suited to germination are I gratefully acknowledge the Department of Lands, consistently absent soon after seed release, e.g. at Parks and Wildlife for allowing me to conduct this high altitudes. study at Mt Field National Park. I thank M.J. The only species which may have soil-stored seed Brown, J.E. Hickey and R.S. Hill for commenting is Phyllocladus aspleniifolius; however, there are on the manuscript and J.E. Hickey for phenology no data to indicate storage times of this species. data collected by the Forestry Commission from P. aspleniifolius commonly appears on rainforest northwestern Tasmania. This project was supported sites after fire (Kirkpatrick 1977, Hill & Read by a Commonwealth Forestry Post-Graduate 1984); this may be the result either of soil storage Research Award. and release from dormancy, whether "natural" or precipitated by the disturbance, or of efficient spatial dispersal. Kirkpatrick (1977) suggested that REFERENCES the early appearance of P. aspleniifolius on disturbed sites is due to bird dispersal. Seed of AMEN, R.D., 1966: The extent and role of seed dormancy P. aspleniifolius has been recorded in pellets that in alpine plants. Quart. Rev. Bioi. 41: 271-281. have passed through the gut of birds, but the ASH, J., 1982: The Nothofagus Blume (Fagaceae) of New frequency of dispersal by animals and its effect on Guinea. In Gressitt, J.L. (Ed.): BIOGEOGRAPHY AND seed germination is uncertain for this species. The ECOLOGY OF NEW GUINEA. Dr W. Junk Publishers, pattern of seed dormancy of P. aspleniifolius is The Hague: 355-380. similar to that of Tasmannia lanceolala, a species BAZZAZ, F.A., 1979: The physiological ecology of that commonly invades forest disturbances and has succession. Ann. Rev. Ecol. Syst. 10: 351-371. seeds that are commonly bird-dispersed (Read & BUSSELL, W.T., 1968: The growth of some New Zealand Hill 1983). Howard (1974) noted that most trees. I. Growth in natural conditions. N.2. J. Bot. 6: 63-75. T. lanceolala seedlings appeared 12 months after CULLEN, PJ., 1987a: The Ecology and Biogeography of soil containing the seeds was collected from the Athrotaxis D. Don. Unpub!. M.A. thesis, Univ. Tasm. field (18 months after the latest seedfall). She CULLEN, P.1., 1987b: Regeneration patterns in suggested that this was due to leaching of a populations of Athrotaxis selaginoides D. Don from germination inhibitor from the seed. It is likely that Tasmania. J. Biog. 14: 39-51. some dormancy mechanism is necessary to survive GRUBB, PJ., 1977: The maintenance of species richness bird-dispersal. in plant communities: the importance of the Studies of the dynamics of populations of regeneration niche. Bioi. Rev. 52: 107-145. PhyUocladus aspleniifolius suggest that large-scale HICKEY, J.E., BLAKESLEY, A.J. & TURNER, B., 1983: Seedfall and germination of Nothofagus cunninghamii disturbance is an important feature of its (Hook.) Gerst., Eucryphia lucida (Labil!.) Baill. and regeneration (Read & Hill 1988a). Dormancy Atherosperma moschatum Labil!. Implications for mechanisms, permitting a large soil store of seed regeneration practice. Aust. For. Res. 13: 21-28. which can survive a large-scale disturbance such as HILL, R.S. & READ, 1., 1984: Post-fire regeneration of fire or severe frost, would facilitate rapid rainforest and mixed forest in western Tasmania. Aust. establishment, especially if the disturbance factor 1. 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HOWARD, T.M., 1973c: Studies in the ecology of READ,J. & HILL, R.S., 1985: Dynamics of Nothofagus­ Nothofagus cunninghamii Oerst. Ill. Two limiting dominated rainforest on mainland Australia and factors: light intensity and water stress. Aust. 1. Bot. lowland Tasmania. Vegetatio 63: 67-78. 2!: 93-102. READ, J. & HILL, R.S., 1988a: The dynamics of some HOWARD, T.M., 1974: Nothofagus cunninghamii ecotonal rainforest associations in Tasmania. J. Ecol. 76: stages. Buried viable seed in north-west Tasmania. 558-584. Proc. R. Soc. Viet. 86: 137-142. READ, J. & HILL, R.S., 1988b: Comparative responses to KIRKPATRICK, J.B., 1977: Native vegetation of the west temperature of the major canopy species of Tasmanian eoast region of Tasmania. In Banks, M.R. & cool temperate rainforest and their ecological Kirkpatrick, LB. (Eds): LANDSCAPE AND MAN. significance. I. Foliar frost resistance. Aust. 1. Bot. 36: Royal Society of Tasmania, Hobart: 55-80. 131-143. MAYER, A.M. & POLJAKOFF-MAYBER, A., 1982: THE SAYERS, R.L. & WARD, R.T., 1966: Germination GERMINATION OF SEEDS. 3rd edition, Pergamon responses in alpine species. Bot. Gaz. 127: 11-16. Press, Oxford. WARDLE, LA., 1984: THE NEW ZEALAND BEECHES: OGDEN, J., 1978: Investigations of the dendrochronology ECOLOGY, UTILISATION AND MANAGEMENT. of the Athrotaxis D. Don () in New Zealand Forest Service, Wellington. Tasmania. Tree-Ring Bull. 38: 1-13. WAREING, P.F., 1956: Photoperiodism in woody plants. READ, J., 1981: Patterns and processes in the A. Rev. Pl. Physiol. 7: 191-214. regeneration of cool temperate rainforest in old-fields. Unpub!. Hons. thesis, Univ. Tasm. READ, J. & HILL, R.S., 1983: Rainforest invasion onto Tasmanian old-fields. Aust. 1. Ecol. 8: 149·-161. (accepted 18 August 1989)