Sadly many of our orchids are under threat of extinction.
Fortunately, conservationists and researchers are putting in a lot of effort in an attempt to save them. Part of this work consists of caging and tagging individual plants.
Most people do the right thing and do not disturb the cages/tags. Unfortunately some, hopefully mainly through lack of knowledge, do move them. Sadly, too many of them are being moved. Sometimes they are re-positioned but not always.
There are a good reasons for the individual plants to be tagged/caged. And there are good reasons for not moving either the tags or the cages.
Tags are usually numbered. These numbered tags are reference locations from which the distance and bearing of plants are measured. If the pin is moved the record for that individual plant is invalidated. Position of pins are used to determine if plants reappear in succeeding years.
Replacing the pins can also result in inadvertently spearing, and thus destroying, the tubers.
Cages are used to protect individual plants from grazing. Moving cages, even if returned, can result in damage to the plant, as well as damage to any emerging juvenile plants.
NOSSA & Conservation
One of the main activities of NOSSA is conservation. Many of our members assist in the work of monitoring, caging and tagging of plants. They know of the time and effort required for this work. They know why it is important not to move tags or cages, not even for taking photographs.
But we are aware that there are those who do not know and so would ask that others pass this message onto friends who may be unaware of the significance of cages/tags.
So simply put, “Cages & tags are not to be moved under any circumstances”.
Over the years, we have published several blogs concerning orchids and fire. At the beginning of the year, Renate Faast spoke at the NOSSA February meeting. John Eaton wrote an extensive summary of her talk which is reprodued here as it appeared in the 2019 March edition of the Native Orchid Society of South Australia Journal, Volume 43 Number 2.
Renate’s take home message was that we cannot make sweeping statement about orchids and fire, each species responds differently and we need to take this into account when planning proscribed. This was something that Dr Michael Duncan also brought out in his 2009 report following the Victorian Black Saturday fires – see Orchids and Fire.
An interesting aside to Renate’s research was her observations of white-winged choughs – see the paragraph Not All Relationships are Friendly.
Guest Speaker Notes John Eaton
At our February 26th meeting, thirty NOSSA members were treated to a stimulating talk by Dr Renate Faast from the University of Adelaide – our first guest speaker for 2019.
Renate acknowledged the support her project received from an Australian Research Council (ARC) grant under the Linkage Program which promotes national and international research partnerships between researchers and publicly funded research agencies – in Renate’s case – support from the University of Adelaide, SA Museum, SA Water, Forestry SA, The Australian Orchid Foundation, the Nature Foundation of SA, The Environment Institute and the SA Government.
Renate had been getting mixed messages from the field observations people had made following prescribed burning or bushfires. This ARC grant enabled her to study the impacts of prescribed burning on native terrestrial orchids.
Renate found that the response of orchids to controlled burns suggests that there are winners and losers amongst orchids: Naked sun orchids responded really well to a controlled burn with 6 plants growing to 83 plants. REALLY good news for that species of orchid but the reality is more complicated than that and this study suggests that there are no generalisations that can be drawn with any confidence about regeneration following prescribed burns or bushfires! In view of the complex interactions between orchids and other plants, and between orchids and bird-and-animal grazers, orchids rely on so many things to go right in order to set seed and recruit new plants into a population. With the exception of a few self-pollinating species, most orchids rely on pollinators for seed production. For non-clonal species, releasing seed is the only way to ensure the species’ long-term survival!
Not all relationships are friendly
Over 80% of orchid flowers had been grazed at some sites. No flowers means no seeds. Renate’s film clips embedded in her PowerPoint dramatically showed the extent of orchid predation by birds such as white-winged choughs and currawongs. They picked off the flowers quite deliberately, leaving behind an intact stalk. Five flowers were grazed every 10 sec (that’s at a rate of 30 flowers/min!) And there are all the other orchid grazers such as roos, deer and rabbits as they move through a patch, often only grazing part of the stem, in a far less targeted and thorough way, compared to these birds. All of these interactions play a key role in whether seeds are released to keep the population viable.
The Mount Bold Fire prompt
While engaged in her PhD research into reproductive ecology of spider orchids, Renate heard that a fire at Mt Bold had led to a “profusion” of Caladenia rigida flowers! The Victorian bushfires had also prompted changes to prescribed burning practises in South Australia. The combination of these two events led Renate to explore the effect of fire on the interactions orchids have with other plants and animals – leading her to ask such questions as:
Does fire promote the flowering of spider orchids (e.g. Caladenia rigida, C. behrii, C. tentaculata) and Glossodia major?
If there are more flowers following fire, will they be pollinated and will they set seed?
How does burn timing influence this response?
Do all species respond in the same way?
These are all critical issues to consider if we are to ensure a self-sustaining orchid population in the future.
There are seasonal influences on the effects of a burn. The response to a summer bushfire could be quite different from cooler season burns in autumn and spring. And even if some orchids are stimulated to flower, it doesn’t necessarily mean that they will end up producing and releasing more seed – which is what really matters for the long-term survival of the orchid population.
Orchid monitoring was carried out in several sites and included 1 autumn, 3 spring burns and 4 adjacent unburnt control sites across the Mt Lofty Ranges (NE of Adelaide). Renate followed the fate of 4 species by tagging up to 150 plants for each species. Renate’s presentation focused on the Millbrook sites where she studied C. rigida and G. major before and after a prescribed burn conducted in Autumn 2013. Unfortunately and fortuitously, her control site also became a bushfire site following the Sampson Flat Fire in January 2015. Fortunately, the Autumn burn site was not affected by the Sampson Flat Fire, so became something of a control site! Renate found that 97% of C. rigida did not emerge after the Autumn prescribed burn compared with 8% at the unburnt control affected site. Flowering was not promoted and no tagged plants flowered. A similar but less severe effect was recorded for Glossodia major.
Will these orchids recover in subsequent years?
Annual monitoring up until 2017, revealed that over one third of C. rigida plants did not re-emerge for 5 consecutive years after the autumn burn. Unfortunately, these plants are likely to have been killed by this burn, probably because the fire was conducted as the orchids were about to emerge. Interestingly, spring burns did not have a detrimental impact on the orchids studied, however, a proportion (18 – 28%) of C. rigida plants may also have been killed by the summer bushfires.
One of the more striking findings out of this research was the large increase in pollination for C. rigida following the bushfires – up to 65% of flowers (protected from grazing) produced a seed pod – an unprecedented rate for Renate’s research. It seems that in the sparse blackened landscape with very few other plants in flower, C. rigida had most of the attention for pollinators. However, the removal of understorey cover also meant that grazing rates were higher after the fires, and most of the flowers that were not protected inside cages were eaten. This meant that there was no actual benefit to the orchids, as there was no increase in seed release. All of these responses were short-lived, and by spring 2016, pollination, grazing and seed release rates were much the same as before the fires.
All species are not equal – fires may benefit some species others don’t fare so well; All fires are not equal; Autumn burning may be detrimental to SOME species; Bushfire may benefit seed release, only if grazing pressure is low – and Flowering was not promoted by any fire. More research is needed on other species, and in different habitats.
Therefore, Renate pointed out that no generalisations can be made about her observations!
Some good news that has come out of this research:
Burn practices are changing, with land managers taking into account the timing of prescribed burns, and bestattempts are made to avoid late autumn burns in areas containing threatened (early-emerging) orchids;
Impacts of fire on reproductive success appear to be short-term
Renate’s hope is that one day, the message will get out there that while some orchids can respond well to burning, this isn’t the case for all species – and that we still have a long way to go before we will really understand the complexities that underlie these different responses with any degree of predictability. Renate also warned that over a third of SA’s orchids are threatened with habitat loss, weed invasion, pollinator loss, grazing and fire regimes.
Renate’s address was followed by a flurry of burning questions and observations. It is hoped that we NOSSA members will use Renate’s conclusions to guide and inform our own anecdotal field observations and test our underlying assumptions and prejudices about the effects of burning on orchid viability – especially as we enter an unprecedented and potentially species-destroying period of human – induced global warming.
Short Paper 3 Identity of Pterostylis valida (Orchidaceae) by Rudie Kuiter was published in June 2017. In this paper, Rudie has tackled the difficult group of Rustyhoods or Oliogochaetochilus (specifically Pterostylis valida) within the genus Pterostylis. Many of the different species occur in isolated pockets over a wide geographical range. Differences can be subtle but Rudie has sought to clarify the distinction between P. valida and similar species. Click here read the complete paper.
Rudie Kuiter’s Short Paper 2 Taxonomic Status of the Mauve Leek-orchid Prasophyllum suttonii Rogers & Rees, 1912 (Orchidaceae) published in May 2017 documents how he used original source material to determine the identification of a species that was considered extinct. Prasophyllum suttonii belongs to the Prasophyllum odoratum/diversiflorum complex and is very similar to the later named Prasophyllum alpestre. It was considered to be extinct but Rudie’s view was not that it was extinct but that it had been “lost in taxonomy, and its status need to be restored”. His article documents how he used original material to help determine identification of the species he had photographed.
In his summary Rudie has some good advice about how to effectively use the material available –
Use original descriptions and illustrations
Original descriptions are preferred over type specimens
later descriptions may be based upon second hand information which may or may not be accurate.
Drawings have some value but depend
upon the skill of the artist to show the crucial details
upon whether they were drawings from fresh or preserved specimens
A good photograph will be better than a drawing
Type material is useful but may deteriorate over time
It’s Christmas and usually, despite Australia’s hot climate, we associate Christmas with snow and cold but we don’t tend to associate them with orchids. And yet, for Australia we do have not one but two Christmas flowering orchids in snow country, that is, on the isolated sub-Antarctic Macquarie Island, an island where “[r]ain and snow are frequent, with only a few days each year with no precipitation”. Admittedly at this time of the year, being summer it is warmer with an average temperature of 7.9degrees Celsius.
The first species was only discovered in 1978 and not recognised as an unique species until 1993 when it was named Corybas dienemus (syn. Nematoceras diemenum). Previously it had been linked with Corybas macranthus.
The second orchid species is Corybas sulcatus (syn. Nematoceras sulcatum) and this species, possibly the world’s rarest orchid, has gone travelling. Staff from the Royal Tasmanian Botanical Gardens have manage to collect and amazingly propagate the seed. Amazingly because orchids, particularly the terrestrial orchids, are difficult to grow. It is now flowering, this Christmas season, but under very carefully controlled conditions in Hobart.
Click here and here to see images and read about this amazing journey.
So Christmas, orchids and snow do go together in Australia, albeit in the far flung island of the south.
Certain flowers in large colonies were most popular over several days and both sexes were observed feeding on the boss, which suggests a food-related attraction. Virtually nothing was known about the Corybas pollinators and primary literature to date only offered hypotheses. Based on our findings, the persisting statement in literature that ‘Corybas species attract fungus-gnats as putative brood-sites’ is incorrect for the taxa in Victoria. No evidence of ovipositing in flowers was found. Females feeding looked gravid and were presumed to be unfertilised. All individuals looked fresh with undamaged wings and it was apparent they had recently hatched.
Is this a hypotheses that needs revising? Rudie definitely demonstrates the importance of careful and meticulous observations.
The Native Orchid Society of SA has been involved with the Threatened Orchid Project which is attempting to propagate some of our most threatened orchids. There has been some success such as Thelymitra epicaptoides (Metallic Sun Orchids) but others are proving elusive. Marc Freestone, from the Orchid Conservation Project, Royal Botanic Gardens Victoria, is a PhD student who is researching one such difficult to grow orchid genus, the Prasophyllum.
To assist with his research Marc has the sent the following request.
CAN ANYONE GROW LEEK ORCHIDS?
South Australia has about 40 species and Victoria about 74 species of the native Leek Orchids, Prasophyllum. Some are on the brink of extinction.
A major problem hampering efforts to prevent our Leek Orchids from going extinct is that they have proven next to impossible to grow in cultivation. They have proved extremely difficult, usually not germinating at all, or germinating but then dying soon after. Occasionally some success has been had (particularly with symbiotic germination) but successful germination trials to our knowledge have so far proved un-repeatable. Working out how to grow Prasophyllum is critical for the survival of many species at risk of extinction across southern Australia.
To try and change this, I will be studying Prasophyllum and their relationships with symbiotic mycorrhizal fungi.
But I need your help!
I am wanting to hear from as many people as possible who
have tried (either successfully or unsuccessfully) to grow Leek Orchids or the closely related Midge Orchids (Corunastylis).
have observed Leek Orchids (or Midge Orchids) recruiting from seed in the wild.
Recently, 10th February 2016, Anita Marquart, PhD student, Adelaide University spoke at the Field Naturalists Society of South Australia. She is a recipient of the Society’s Lirabenda Endowment Fund Research Grant. At the meeting she gave a summary of her research – Orchids, Insects and Fire: Investigating the impacts of prescribe burning on orchid pollinators in Southern Australia. Though she has not finished collating the data she has kindly supplied a summary of her talk with her preliminary findings.
It is always encouraging to see research on our native orchids. They are the Barometer of the Bush, so the more we can discover about them, hopefully the more we will better understand how to manage our native bushland.
Orchids, Insects and Fire: Investigating the impacts of prescribed burning on orchid pollinators in Southern Australia
Anita Marquart, Renate Faast, José M. Facelli, Andrew Austin
School of Earth and Environmental Sciences,
The University of Adelaide, Adelaide 5005 Australia
Fire is an important ecological factor in Australian ecosystems. Orchids that depend on specific pollinators may be more susceptible to disturbance than more generalist species. Therefore, declines or changes in pollinator communities due to prescribed burns and wild fires could lead to reduced pollination success and consequently declines in orchid populations. The project combines traditional plant and insect ecology with advanced molecular techniques to identify orchid pollinators and assess their response to prescribed burns and wild fires. Insect relevant habitat characteristics (such as floral abundance, vegetation height, presence of logs, litter and standing litter) were assessed and trapping surveys of potential orchid pollinators were conducted in spring, before and after prescribed burns. The effect of both spring burns and autumn burns is being investigated.
Study sites are located in the Adelaide hills with always one burn and one adjacent control site respectively in Kersbrook Native Forest, Millbrook Reservoir, Para Wirra Recreation Park and South Para Reservoir. Some parts of the study sites in Kersbrook and Millbrook were affected by the Sampson Flat Bushfire. Affected sites are used to compare the effects on orchid pollinators after prescribed burns in contrast to wild fires.
Potential orchid pollinators are being identified using DNA barcoding with the mitochondrial cytochrome oxidase I (COI) gene. Sequencing results will be compared with existing databanks and confirmed using morphological identification. As the data accumulates it will build up a reference library of COI barcodes for the species found in the surveys.
The outcome of this research project might help to advise the optimal management of orchid species under fire-managed regimes in the Mount Lofty region of South Australia, as well as more generally in south eastern Australia.
Orchids and their pollinators
Native bees, thyninne wasps and Syrphid flies are known orchid pollinators of South Australian orchid species. Orchids of main interest for this study were Caladenia rigida, Caladenia behrii, Caladenia tentaculata and Glossodia major. Caladenia tentaculata and C. behrii are sexually deceptive orchids and are known to be pollinated by thynnine wasps (Bates 2011). In contrast, C. rigida is food advertising and uses a broad range of bee and fly species, such as native bees and hoverflies (Faast et al. 2009). Glossodia major is a generalist in its pollination strategy and is using small native bees of several genera (Bates 2011, personal observations).
Syrphid flies were successfully separated into different species using DNA barcoding methods. Results show that we have two dominating species on our field sites in the Adelaide hills. Both species, Melangyna collatus and Symosyrphus grandicornis are common native Australian species. Both species were caught with orchid pollinia attached and were observed on Caladenia rigida flowers.
First findings suggest that hoverflies don’t seem to be much affected by prescribed burns or bushfires. Syrphid fly numbers vary greatly between the years of sampling, but we did not find a significant impact of prescribed burning or the Samson Flat bushfire.
Statistical analyses for the data on syrphids, native bees and thynnine wasps are currently underway.
Preliminary findings suggest that a range of pollinators are still present on field sites after prescribed burns and even after bushfires. Nevertheless, some specific species might be more sensitive to fires and might have disappeared from the study sites. For example, orchids relying on one species of wasp could be more affected by changes in the abundance of their pollinator after fire, than orchids that are pollinated by a number of different insects.
We will have to analyse our results in more detail to look into the specific species composition for the insect families, especially for native bees and thynnines, rather than looking at overall abundance.
Faast R, Farrington L, Facelli JM, Austin AD (2009). Bees and white spiders: unravelling the pollination syndrome of Caladenia rigida (Orchidaceae). Australian Journal of Botany57, 315–325.
Bates, R. J. (2011). South Australia’s Native Orchids. Native Orchid Society of South Australia.
This week there was a workshop South Lofty Block Orchid Recovery Project with representatives from Adelaide and Mt Lofty Ranges Natural Resource Management, SA Water, Forestry SA, Park Rangers, Threatened Plant Action Group and NOSSA. Many issues were discussed. One issue briefly discussed was the development of unofficial bike and walking tracks in parks and the negative impact that this would have on rare and endangered orchids.
The researchers studied the effects of visiting a site once a day and standing in the same spot for 10 minutes ie the effects of trampling. Their research suggested that there are possible longer term consequences as they found that the effects of compaction was still observable 18 months later. This does not seem like much but it was sufficient for them to offer some advice such as
stay on the tracks,
don’t walk on the side as even walking on the side of the track can result in unintended damage as the track is widened,
when one person walks off the track others are likely to follow
think carefully of the consequences before walking off the track
where possible step on rocks, not soil
The research was carried out in Canada and though there are differences between the two countries, there are so many similarities it is worth our while to take note of their advice.
Possibly there is scope for research here in South Australia but in the meantime their summary sentence says it all – Until we know what is happening beneath our feet, we should really watch our step
Part One – Attracting Pollinators looked at pollination strategy, but the fourth aim of the paper was to establish that Corunastylis littoralis reproduced by xenogamy or geitonogamy and that the species was not autogamous or apomictic, that is, pollinated, self pollinating or non pollinating plants.
Xenogamy or geitonogamy that is vector mediated pollination or out-crossing is when fertilization occurs by the transfer of pollen from one flower to another flower usually by the means of insect.
Autogamy or self-pollinating is when the flower is pollinated by its own pollen.
Apoximis is when reproduction occurs without pollination, that is, vegetative reproduction.
As explained in the paper, there are visual clues for determining which process is used by the plant.
Pollinia removal and pollen deposition
Pollinia not removed
Lacks pollen or it is tightly bound
Pollinia weakly attached to the viscidium
If pollinia present, then unable to be removed
Not all the ovaries are fertilized
All the ovaries are fertilized and have viable seeds
Swelling of the ovaries can occur whilst in bud
Likely to have no perfume
Flowers short lived
More detailed information was gained by dissecting the flower.