Survey of threatened plant species in South East Queensland biogeographical region queensland cra/rfa steering committee survey of threatened plant species in
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3.18 Macrozamia lomandroides D.L. Jones3.18.1 SummaryThe natural distribution of M. lomandroides is restricted to an area south of Bundaberg between Elliot and Isis Rivers. It covers a range of approximately 35 km and encompasses an area of occurrence of approximately 1000 km2. It has been recorded from State Forest and National Parks areas. A total population of M. lomandroides was estimated to be between 28, 000 and 39, 000 individuals. The state forest sites are important to the conservation of the species because they represent a large proportion of the presently known populations. Current or perceived threats to the continued survival of M. lomandroides are considered to be loss of habitat, illegal removal of seeds, seedlings and mature plants from the wild and inappropriate fire regimes. 3.18.2 Species description and identificationThe genus Macrozamia is placed in the family Zamiaceae. Macrozamia is an Australian endemic genus and consists of approximately 25 species (Jones 1993). It occurs in subtropical and temperate regions with the majority of species in south-eastern Queensland and eastern New South Wales. Macrozamia lomandroides belongs to the section Parazamia. These are generally recognised by their subterranean trunk which have only a few leaves in the crown. The leaves are usually spirally twisted and the leaflets are all similar (ie. the lower leaflets are not reduced to spine-like structures). The leaflets lack mucilage canals. Macrozamia lomandroides has a nonbranching subterranean stem up to 25 cm diameter with 2 to 6 leaves protruding aboveground forming a sparse, erect to spreading crown. The dull green, mature leaves are 0.3-0.8 m long and hairless except for the woolly base. Each leaf consists of 50-90 leaflets arranged spirally along a central stalk. The stalk is dull, pale green with pale green to cream marginal bands between the bases of the leaflets towards the top of the stalk. The dark green leaflets are thick, leathery, broadly linear to slightly obovate, up to 35 cm long by 9-14 mm wide, shallowly concave in cross-section and with 2-8 small teeth near the tip. The leaflet bases are pale green to cream and slightly thickened. The plants reproduce by cones which are somewhat pineapple-like in appearance. Male and female cones develop on separate plants. Male cones are cylindrical, 12-15 cm long and 4-5 cm diameter. Female cones are ovoid, 12-18 cm long and 7-9 cm in diameter. Seeds are ovoid to oblong, 2.2-2.6 cm long, 1.8-2.2 cm in diameter and orange to red when ripe. For a more detailed description and illustration of this species refer to Jones (1991) and Jones (1993). (see Plate 10). M. lomandroides is related to M. parcifolia and M. pauli-guilielmi but can be distinguished from them by having generally broader leaflets which are stiff, leathery and held stiffly erect and by the many (usually 2 to 6) sharp teeth on the apex of the leaflets. 3.18.3 Current conservation statusMacrozamia lomandroides is presently listed on the schedule of the Queensland Nature Conservation Act 1992 as “Endangered”. The species has been assigned a national conservation status of E (endangered) by ANZECC (1993). It is also listed on Schedule 1 Part 1 (endangered) of the Commonwealth Endangered Species Protection Act 1992. 3.18.4 Distribution and abundanceDetails from Queensland Herbarium specimens of M. lomandroides are listed in Appendix 1.17. Altogether 13 specimens of M. lomandroides have been collected from approximately 7 localities in an area south of Bundaberg between Elliot and Isis Rivers. One other unvouchered locality record has come from the CORVEG database. The distribution of M. lomandroides has a range of approximately 35 km and encompasses an area of occurrence of approximately 1000 km2. As far as can be ascertained, the range of this species is natural and is not related to recent human activity. M. lomandroides was noted at 21 sites during the current survey within the previously recorded range. Twelve are within State Forest lands, another eight within National Parks and one site is on vacant crown land. Fifteen of the sites were examined in some detail including 6 of the 8 previously known localities. Appendix 2.5 lists the sites examined in the present survey with habitat data recorded for those sites. Detailed locality information is not given. This information is available on request from the Queensland Herbarium. Table 3.18.1 gives estimates of the area of sites and abundance of M. lomandroides at each site examined in detail. One of the previous records had imprecise locality information and the other location was not searched for due to time constraints. Another 6 new sites were vouchered but not recorded in detail due to insufficient time available. Five of these sites were within National Parks and one within State Forest. The total population of M. lomandroides was estimated to be between 28, 000 and 39, 000 individuals. Individual populations varied in size from 13 to at least 8300 individuals. Areas of occupancy varied from 1 m2 to 2.3 hectares. Twenty of the twenty one sites recorded were in relatively undisturbed habitat, although firebreaks or forestry tracks may dissect most of the populations. At site 12 the population extended through an area of remnant native vegetation into the exotic pine plantation and out onto a 50 m fire break surrounding the plantation (Plates 14 &15). Only a small proportion of the total population examined are within lands set aside for conservation of natural habitat. However, the 5 sites within the National Park lands that were not examined in detail contain a significant number of individuals. From the brief visit to these sites it is “guesstimated” that there are possibly another 10000-20000 individuals within land set aside for conservation than indicated by the data in Table 3.18.1. However, this information does not reduce the importance of those populations within the State Forest areas in terms of value for the conservation of this species. All populations examined consisted of individuals that generally appear healthy. There was evidence of illegal removal of plants at two sites within the State Forest (sites 2 & 9) (Plate 11). 3.18.5 HabitatThe sites are on the gently undulating coastal plain on flats and very gently inclined hillslopes with variable aspects and at elevations between 10-50 m above sea level. The soils are well drained, dark greyish yellow, greyish yellow brown to dark reddish brown, clayey sands to sandy clay loams with a pH 4.8-5.6. The geology is mostly deeply weathered sedimentary rocks of quartzose to sublabile sandstone, conglomerate, siltstone, mudstone and shale and with some Quaternary alluviums. The vegetation community is a layered tall open forest (Plate 13). The common canopy species are Corymbia trachyphloia, C. intermedia, Eucalyptus hallii and E. umbra. Other tree species present included E. racemosa, Angophora leiocarpa and Syncarpia glomulifera. The most frequent mid stratum species included: E. umbra, Xylomelum salicinum, Acacia leiocalyx, Allocasuarina littoralis, Banksia integrifolia subsp. compar, Acacia aulacocarpa and A. flavescens. Common shrub and ground cover species included: Xanthorrhoea latifolia, Acrotriche aggregata, Hibbertia stricta, Acacia complanata, Entolasia stricta, Themeda triandra, Acacia leiocalyx, Daviesia filipes and Lepidosperma laterale. Other shrub and ground cover species frequently observed were: Acacia flavescens, Gompholobium pinnatum, Imperata cylindrica, Jacksonia scoparia, Persoonia virgata, Acacia aulacocarpa, Alloteropsis semialata, Dianella revoluta, Grevillea sp., Pimelea linifolia and Syncarpia glomulifera subsp. glomulifera. Table 3.18.1. Estimated abundance, area of occupancy and Land tenure for Macrozamia lomandroides sites. Where abundance was estimated by random transect sampling a mean value and lower and upper 95% confidence limits are given. Populations obtained by direct counts or those visually estimated have no estimate of error associated with them
3.18.6 Life history and ecologyThere have been no studies into the biology or autecology of M. lomandroides. The majority of the following information is extrapolated from our understanding of other cycads. However, it is also becoming increasingly clear that the reproductive processes and behaviour of different species within the same genus may differ considerably, so that information collected from one species cannot necessarily be extrapolated to another. M. lomandroides is a dioecious, perennial plant that reproduces by sexually produced seeds. The longevity of the plants is unknown. Estimates of life span of other Macrozamia species range from 120 to 1500 years (Benson and McDougall 1993, Pate 1993). Coning has been recorded occurring in M. lomandroides from October to November (Jones 1993). From the present survey work undertaken in October and November 1997 the percentage of plants coning in the samples range from 2 to 25 % with a mean of 10 % over all samples (Table 3.18.2). 1.4 times more plants were observed with male cones than female cones. Similar levels of male-biased coning events and low levels of participation in given reproductive episodes have been reported in other species of Macrozamia (Ornduff 1993). The level of reproduction varies greatly from year to year. The factors controlling the level of reproduction are unknown. There are reports suggesting a cyclical nature in the level of reproductive episodes (Jones 1993, Vorster 1995). It is suggested that variable rates of coning will also lead to variable rates of seedling recruitment. The level of survivorship from seed to adult is unknown. Survivorship of M. riedlei and M. communis has been reported by Connell and Ladd (1993). They observed that only 3-4 % of the seed produced survived to become adults with the greatest mortality occurring from seed germination to seedling stage. Table 3.18.2. demographic and coning data for selected sample sites of Macrozamia lomandroides.
Traditionally cycads have been thought to be wind-pollinated (Chamberlain 1935), but evidence has been mounting that most cycad species are in fact pollinated by insects, specifically by beetles (Tang 1987, Norstog and Fawcett 1995). Forster et al. (1994) reported a number of Coleoptera, Hymnenoptera and Thysanoptera in association with reproductive structures of Macrozamia species including M. lomandroides. Seeds of M. lomandroides mature from March to April in the year following coning (Jones 1993). The seeds have a red to orange fleshy outer layer and fall from the cone at maturity. It has been reported that the fleshy outer layer attracts animals which feed on this fleshy tissue and secondarily disperse the seed. Possums, kangaroos, wallabies and rodents have been reported as dispersal agents of Macrozamia species (Jones 1993). However, from present field observations it would appear that most seeds are not dispersed far from the parent plant. The seeds of most cycad species will not germinate immediately on maturity, for the embryo requires an after-ripening period (Jones 1993). M. communis and M. riedlei are reported to require 10-13 months before germination will occur (Ladd and Connell 1995). The seed of M. lomandroides requires approximately 6 to 12 months before it will germinate (Forster pers. comm.). The length of time that the seeds of M. lomandroides retain their viability is unknown. It is reported that under controlled storage conditions seeds of other Macrozamia species will retain their viability for many months (Jones 1993). Under field conditions it is suspected that seed would not stay viable for more than 6-12 months. As germination occurs the micropylar end of the hard seed coat is ruptured by the emerging radicle, which turns down into the soil and grows rapidly. The greater part of the cotyledons remain inside the seed on the soil surface, absorbing all of the endosperm and transferring the food resources into the young root and developing underground stem of the seedling. Usually only one leaf appears initially at the soil surface some months after germination. The time from coning to the establishment of a juvenile with a single leaf is estimated to be 2 years. The length of time taken from seed germination to maturity is unknown. The time taken for cultivated cycads to reach maturity ranges from 2 to 30 years (Jones 1993). From field observations it is suggested that seeds and the early stages of the seedling development are fire-sensitive. The time required before the seedling can tolerate fire is unknown. Mature plants are not greatly affected by fire. The destruction of the leaves above-ground occurs but the important growing tip is protected below ground level. There are some suggestions that some cycads may benefit from periodic exposure to fire (Zunckel 1995). It was observed during the present survey that in recently burnt areas M. lomandroides was quick to recover and was usually the first species in its habitat to produce new growth after fire (Plate 12). General field observations during the present survey were that coning levels were comparable in burnt and unburnt areas. It is suggested that fire may promote coning and the production of seed but does not appear to be an essential requirement for coning to occur. 3.18.7 ThreatsIn the light of the field survey and from consultation with others, current or perceived threats to the continued survival of M. lomandroides are considered to be: Loss of habitat: There can be no doubt that past habitat alienation, for agriculture and exotic pine plantations in the species’ narrow geographical range has led to a decline in populations in the past. With a large proportion of the population occurring on State Forest lands of low commercial timber values and Vacant Crown Land there is still a potential threat of conversion of habitat to agricultural or forestry production or other uses that could be detrimental for the populations. Illegal removal of seeds, seedlings and mature plants from the wild: There was clear evidence of continuing pressure on wild populations through the illegal removal of plants from the wild. Site 2 was one the largest known populations in the past of several hundred individuals (Forster pers. comm.). During the present survey only 54 plants were recorded at the site and there was evidence of recent extractions of plants from the site (Plate 11). The proximity of all populations to tracks and roads makes them potentially threatened by the illegal removal of plants. Inappropriate fire regime: Mature Macrozamias generally cope very well with fire and as pointed out earlier may benefit from periodic exposure to fire. However, fire can certainly effect the recruitment of new individuals because the seeds and young seedlings of M. lomandroides are fire-sensitive. Too frequent a fire regime would certainly lead to a gradual decline in the population as mature plants became senescent and there was a lack of recruitment of new plants. The consequences of repeated burning over a long time on the invertebrate pollinators are also unknown. M. lomandroides grows at a number of sites with Eucalyptus hallii, another endangered species. Erskine (1992) observed a correlation between the level and extent of soil waterlogging and the distribution of E. hallii within its restricted range. It could be speculated that the soil hydrology may also be significant in the distribution of M. lomandroides in the region. If so, changes in soil hydrology through irrigation or drainage of areas may effect the capability of this species to survive. 3.18.8 Management, Research and Conservation MeasuresThe protection of the remaining natural vegetation in the state forest lands should be pursued through either declaration of a State Forest Scientific Area under the Forestry Act 1959 or by converting the land to a conservation reserve. Eight populations were observed to be within conservation reserves. Three of the populations are small with less that 50 plants in each population. The remaining five populations were visually estimated to contain several thousand individuals in each population. These populations need to be assessed. To reduce the illegal removal of plants and propagules of M. lomandroides from the wild, locality information of populations should not be supplied to persons who do not have appropriate permits from Department of Environment and Department of Primary Industries. Current legislation to prevent illegal collection of threatened species from the wild needs to be enforced. During the present survey one stand of M. lomandroides was observed within an area planted with exotic pines. It is unlikely that these individuals of M. lomandroides will survive in the long term in these areas. Investigations should be undertaken into the possibility of salvaging these individuals. There is little information available on the role of fire in the ecology and reproductive biology of M. lomandroides. This needs to be understood if successful management techniques are to be developed for the conservation of the species in the wild. Research into the effect of fire on coning and seedling survival is required. It is speculated that levels and extent of waterlogging may be significant in the survival of the species. The relationship between soil hydrology and the local distribution of M. lomandroides should be established. Macrozamia lomandroides when assessed against the IUCN (1994) criteria for threatened wildlife falls into the category of Vulnerable, ie. is facing a high risk of extinction in the wild in the near future, as defined by criteria D.2. Its population is characterised by an acute restriction in its area of occupancy (typically less than 100 km2). The present status of Endangered for M. lomandroides should be reconsidered in the light of the present data available. |