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Orchids as Indicators of Ecosystem Health in Urban Bushland Fragments
Get PDFIn this thesis I investigate the utility of orchids as indicators of ecosystem health. The study areas were urban bushland fragments on the Swan Coastal Plain, a global biodiversity hotspot. The study focuses on the abundance, reproductive success, mycorrhizal abundance and seedling biomass accumulation of a suite of native terrestrial orchids common to Perth’s urban bushland fragments. A critical factor in exploring the ecological responses of these orchids to site condition and their application as indicators of ecosystem health is the assessment of the ecosystem health of each of the study sites.
I studied the vegetation condition gradient across eleven urban bushland fragments using three known ecosystem health assessment methods. Correlations were found between the perimeter to area ratio, native vegetation cover, weed cover and canopy cover in relation to site condition gradients. Floristic complexity at sites was found to mask relationships with environmental variables that were apparent following classification into plant functional groups. Of the plant functional traits only facultative sprouter, sub-shrub, barochory and perennial trait frequencies correlated with the vegetation condition gradient, all traits showing a decline with decreasing vegetation condition.
Multivariate analysis of orchid abundances and environmental parameters revealed three orchid species that could potentially be used as indicators of ecosystem health. Diuris magnifica and Microtis media correlated strongly with poor condition sites. Pterostylis sanguinea correlated strongly with very good condition sites. However, environmental parameters, floristic composition and plant functional groups provided weak correlation to orchid species presence and abundance. Reproductive response, mycorrhizal abundance and biomass accumulation across the vegetation condition gradient were then measured to determine the extent to which orchids can be used as indicators of ecosystem health.
The effects of site condition on fruit set success were not found to be significant for any of the orchid species in this study. Widespread pollen limitation across sites revealed that fruiting success was likely to be too insensitive a measure for examining ecosystem health.
Mycorrhizal distribution across the cline of condition was found to be patchy within fragments and revealed unoccupied niches capable of supporting orchid germination. Further evidence of the use of Microtis media as an indicator of poor condition sites was found in an increased abundance of the associated mycorrhizal symbiont. The abundance of mycorrhizal symbionts for Caladenia arenicola and Elythranthera brunonis at sites of very good condition indicated their potential use as indicators.
An inverse relationship was found to exist between biomass allocation to leaf or tuber in sites of good and poor condition. In sites of poor condition, Diuris magnifica and Caladenia arenicola increased allocation of biomass to shoots presumably in order to obtain photosynthates. In sites of very good condition these two species increased their allocation of biomass to the tuber. Initial findings suggest biomass allocation in Caladenia arenicola and Diuris magnifica may be a useful tool in measuring ecosystem health.
The lack of currently undisturbed urban remnants and a poor historical record of past disturbance events in the study sites make understanding the role of past disturbances on the current condition gradient difficult. The results of this study suggest that orchid presence and abundance, orchid growth and orchid symbionts can be used as indicators of ecosystem health, although work needs to be undertaken to refine the understanding of their response to specific disturbances. This study provides a baseline for investigating the utility of orchids as indicators of ecosystem health in highly fragmented systems
Ten educational slide-narrative programs on orchids
No full textThe present creative project was undertaken to prepare educational programs on orchids. The author has worked with orchids for a period of ten years during which time he has developed expertise in the taxonomy, culturing, photography and collection of this family of plants.The creative project involved the selection of 385 35 mm slides from the author's collection, and the development of narrative which illustrates basic information about the Orchidaceae. The programs were developed for audiences possessing at least a modest botanical background. Two specific groups expected to use the programs are botany students at Ball State University and members of the American Orchid Society.The material on orchids was divided into ten topics: (1) Definition of an Orchid, (2) Diversity of Orchids; (3) Pollination of Orchids, (4) Hybridization of Orchids; (5) Propagation of Orchids; (6) Culture of Orchids; (7) Culture and Problems of Orchids; (8) Species of Orchids; (9) Buying and Showing of Orchids; (10) Orchid Collecting in Paraguay. Complete sets of 35 mm slides to accompany the narrative for each program have been placed on file in the Department of Biology at Ball State University.Ball State UniversityMuncie, IN 47306Thesis (M.S.)"Complete sets of 35 mm slides to accompany the narrative ... have been placed on file in the Department of Biology at Ball State University.
Traditional knowledge of medicinal Orchids at different parts of India
No full textTraditional knowledge of medicines gets transferred from generation to generation among the tribal people verbally. Since recent past some ethnobotanists started scientific documentation of it. Beside other plants, orchids also kept their deep footprint in traditional medicines. India is a country of orchid richness with 1300 orchid species, out of those approximately 250 orchid species are being used in tribal, Ayurvedic and Unani system of medicine. In spite of having high medicinal potential, very often orchids are ignored as medicinal herbs, and emphasized as ornamental plants in India. Use of orchids in the field of medicine can draw a lot of economic benefits to the drug development industries and socioeconomic benefits to the orchid farmers. For that a compiled source of information about tradition knowledges on medicinal potential of orchids can be a good source of reference. The present review can serve the purpose
Orchids
No full textThe Orchidaceae is the most diverse of all plant families, and with incredible variety in floral form and function, orchids have captured the imagination of countless generations. Orchids have intricate and often obligate partnerships with other organisms above and below ground, making them the subject of considerable scientific enquiry for almost 200 years. Whilst many species are common and widespread, orchids, more than any other plant family, are over-represented on threatened species lists globally. Their complex environmental interactions together with recent anthropogenic changes have seen the extinction risk for many species increase dramatically, as well as efforts for their conservation. In this chapter, we explore the richness and diversity of orchid biology and ecology, linking the science to conservation, as some orchids within the proposed Yule Brook Regional Park are among the most endangered of all Australian plant species
More than symbioses : orchid ecology ; with examples from the Sydney Region
No full textThe Orchidaceae are one of the largest and most diverse families of flowering plants. Orchids grow as terrestrial, lithophytic, epiphytic or climbing herbs but most orchids native to the Sydney Region can be placed in one of two categories. The first consists of terrestrial, deciduous plants that live in fire-prone environments, die back seasonally to dormant underground root tubers, possess exclusively subterranean roots, which die off as the plants become dormant, and belong to the subfamily Orchidoideae. The second consists of epiphytic or lithophytic, evergreen plants that live in fire-free environments, either lack specialised storage structures or possess succulent stems or leaves that are unprotected from fire, possess aerial roots that grow over the surface of, or free of, the substrate, and which do not die off seasonally, and belong to the subfamily Epidendroideae.
Orchid seeds are numerous and tiny, lacking cotyledons and endosperm and containing minimal nutrient reserves. Although the seeds of some species can commence germination on their own, all rely on infection by mycorrhizal fungi, which may be species-specific, to grow beyond the earliest stages of development. Many epidendroid orchids are viable from an early stage without their mycorrhizal fungi but most orchidoid orchids rely, at least to some extent, on their mycorrhizal fungi throughout their lives. Some are completely parasitic on their fungi and have lost the ability to photosynthesize. Some orchids parasitize highly pathogenic mycorrhizal fungi and are thus indirectly parasitic on other plants.
Most orchids have specialised relationships with pollinating animals, with many species each pollinated by only one species of insect. Deceptive pollination systems, in which the plants provide no tangible reward to their pollinators, are common in the Orchidaceae. The most common form of deceit is food mimicry, while at least a few taxa mimic insect brood sites. At least six lineages of Australian orchids have independently evolved sexual deception. In this syndrome, a flower mimics the female of the pollinating insect species. Male insects are attracted to the flower and attempt to mate with it, and pollinate it in the process.
Little is known of most aspects of the population ecology of orchids native to the Sydney Region, especially their responses to fire. Such knowledge would be very useful in informing decisions in wildlife management
Vermiculiphily: Larvae Pollinating Orchids!
Get PDFOrchids are truly extraordinary organisms exhibiting a wide range of pollination mechanism, many of which awaits discovery. Epipactis veratrifolia is a terrestrial orchid that has been reported to be pollinated by various species of hoverflies in Israel1,2. This orchid is known to emit the smell of aphid pheromone that attracts hoverflies, which lay eggs inside the flower and in the process pollinate them. Recently, we observed a species of hoverfly (Ischiodon scutellaris) pollinate the same orchid species in the Western Himalaya while laying eggs inside the flowers. Ischiodon scutellaris is being reported for the first time as pollinator of this orchid. However, all flowers don’t get pollinated, even though insects visit them and lay eggs inside. In this communication we reveal the fate of those orchid flowers which are visited by the flies but are left unpollinated
DYNAMIC SPECIATION PROCESSES IN THE MEDITERRANEAN ORCHID GENUS OPHRYS L. (ORCHIDACEAE)
No full textGENERAL INTRODUCTION
CHAPTER 1: MULTI-LOCUS NUCLEAR GENE PHYLOGENY OF THE SEXUALLY DECEPTIVE ORCHID GENUS OPHRYS L. (ORCHIDACEAE)
CHAPTER 2: ANALYSIS OF VARIATION AND SPECIATION IN THE OPHRYS SPHEGODES SPECIES COMPLEX
CHAPTER 3: FLORAL ISOLATION IS THE MAIN REPRODUCTIVE BARRIER AMONG CLOSELY RELATED SEXUALLY DECEPTIVE ORCHIDS
CHAPTER 4: SPECIATION BY DISTURBANCE: A POPULATION STUDY OF CENTRAL ITALIAN OPHRYS SPHEGODES LINEAGE
Mycorrhizal specificity in endemic Western Australian terrestrial orchids (tribe Diurideae): implications for conservation
Get PDFThe specificity of fungal isolates from endemic Western Australian orchid species and hybrids in the tribe Diurideae was investigated using symbiotic seed germination and analysis of the fungal DNA by amplified fragment length polymorphism (AFLP). The distribution of the fungal isolates in the field was also assessed using two different seed baiting techniques. The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species.
Two groups of orchids in the tribe Diurideae were studied. Firstly, a number of Caladenia species, their natural hybrids and close relatives from the southwest of Western Australia were selected because orchid species from the genus Caladenia are considered to have among the most specific mycorrhizal relationships known in the orchid family ? an ideal situation for the investigation of mycorrhizal specificity. Secondly, species of Drakaea and close relatives, from the southwest of Western Australia and elsewhere in Australia, which are never common in nature and occur in highly specialised habitats, were selected to investigate the influence of habitat on specificity.
Seed from the common species Caladenia arenicola germinated on fungal isolates from adult plants of both C. arenicola and its rare and endangered relative C. huegelii, while seed from C. huegelii only germinated on its own fungal isolates. The AFLP analysis grouped the fungal isolates into three categories: nonefficaceous fungi, C. huegelii type fungi, and C. arenicola type fungi. The group of C. huegelii type fungi included some fungal isolates from C. arenicola. An analysis of the AFLP fingerprints of C. arenicola fungal isolates from different collection locations showed that some, but not all, populations were genetically distinct, and that one population in particular was very variable.
Despite being thought to have very specific mycorrhizal relationships, Caladenia species hybridise frequently and prolifically in nature, often forming self-perpetuating hybrid lineages. Five natural hybrids within Caladenia and its closest relatives were investigated. Symbiotic cross-germination studies of parental and hybrid seed on fungi from the species and the naturally occurring hybrids were compared with AFLP analyses of the fungal isolates to answer the question of which fungi the hybrids use. The germination study found that, while hybrid seeds can utilise the fungi from either parental species under laboratory conditions, it is likely that the natural hybrids in situ utilise the fungus of only one parental species. Supporting these observations, the AFLP analyses indicated that while the parental species always possessed genetically distinct fungal strains, the hybrids may share the mycorrhizal fungus of one parental species or possess a genetically distinct fungal strain which is more closely related to the fungus of one parental species than the other.
The work on Caladenia hybrids revealed that C. falcata has a broadly compatible fungus that germinated seeds of C. falcata, the hybrid C. falcata x longicauda, and species with different degrees of taxonomic affinity to C. falcata. In general, germination was greater from species that were more closely related to C. falcata: seeds from Caladenia species generally germinated well on most C. falcata isolates; species from same subtribe (Caladeniinae) germinated well to the stage of trichome development on only some of the fungal isolates and rarely developed further; and seeds from species from different subtribes (Diuridinae, Prasophyllinae, Thelymitrinae) or tribes (Orchideae, Cranichideae) either germinated well to the stage of trichome development but did not develop further, or did not germinate at all. The AFLP analysis of the fungal isolates revealed that the fungi from each location were genetically distinct.
In situ seed baiting was used to study the introduction, growth and persistence of orchid mycorrhizal fungi. A mycorrhizal fungus from Caladenia arenicola was introduced to sites within an area from which the orchid and fungus were absent, adjacent to a natural population of C. arenicola. In the first growing season, the fungus grew up to 50 cm from its introduction point, usually persisted over the summer drought into the second season and even into the third season, stimulating germination and growth to tuber formation of the seeds in the baits. Watering the inoculated areas significantly increased seed germination.
Mycorrhizal relationships in Drakaeinae were less specific than in Caladeniinae. A study of the species Spiculaea ciliata revealed that this species, when germinated symbiotically, develops very rapidly and has photosynthetic protocorms, unlike all other members of the Drakaeinae. An AFLP analysis of the fungal isolates of this species grouped the isolates according to whether they had been isolated from adult plants or reisolated from protocorms produced in vitro. Isolates were genetically distinct when compared before germination and after reisolation. A cross-species symbiotic germination study of seeds of three Drakaea species and one Paracaleana species against fungal isolates from the same species and several other Drakaeinae species revealed lower specificity in this group than previously thought. A number of fungal isolates from Drakaea and Paracaleana species germinated two or more seed types, while all seed types germinated on fungal isolates from other species and the seed of Drakaea thynniphila germinated to some extent on every fungal isolate tested. An AFLP analysis of the Drakaeinae fungal isolates supported this information, revealing little genetic differentiation between the fungi of different orchid species.
An ex situ seed baiting technique was used to examine the role of mycorrhizal fungi in microniche specialisation in the narrow endemic Drakaea. Soil samples from within and outside two Drakaea populations were tested for germination of the relevant seed types. In both cases, germination was significantly higher on soil samples from within than outside the populations, suggesting that the relevant mycorrhizal fungi may be restricted to the same microniches as the Drakaea species. The presence of similar fungi at distant, disjunct locations may be related to the extreme age and geological stability of the Western Australian landscape.
The information from these investigations is essential for developing protocols for reintroduction and translocation of orchid species. It appears that the mycorrhizal relationships in these groups of orchids are not as specific as was previously thought. For reintroduction work, a broad sampling strategy is necessary, as it cannot be assumed that the same orchid species has the same fungus at different locations. A broadly compatible fungus may be of considerable utility in conservation work, such as in situations where a specific fungus appears to have poor saprophytic competence or where soil conditions have been altered. Seed baiting studies provide additional data on fungal distribution in situ. In general, molecular data do not provide information about efficacy or fungal distribution, so research programs that combine symbiotic germination studies with seed baiting investigations and genetic analyses of the fungi will provide the maximum benefit for designing more effective conservation programs
Endophytic fungi associated with Australian orchids
Get PDFAustralia is rich in orchid flora with over 1000 native species currently recorded. A
significant proportion of Australia’s terrestrial orchids are critically endangered, endangered
or threatened. Threats to many orchid species include habitat destruction, degradation and
fragmentation from increased urbanisation, overgrazing, altered fire regimes and
unfortunately, excessive collecting by orchid fanciers. Conservation efforts for Australian
orchids include both ex situ and in situ approaches. Ex situ efforts involve the growth of
orchid species under horticultural conditions and long term storage of plant and associated
fungal material in laboratories and herbaria. In situ approaches include re-establishing plants
in the wild and protection of current populations through management initiatives
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