factors affecting the recovery of orchids in a post-mining landscape

280 Pages·2013·13.89 MB·English

F
ACTORS AFFECTING THE RECOVERY
OF ORCHIDS
-
IN A POST MINING LANDSCAPE
Margaret Thora Collins
BSc. Honours (Science), MSc. (Science)
This Thesis is presented for the degree of Doctor of Philosophy
of
The University of Western Australia
School of Earth and Geographical Sciences
Discipline of Soil Science
2007
Photograph on title page: Prasophyllum hians Rchb.f. in flower.
Abstract
Currently, Alcoa World Alumina Australia (Alcoa) mines and undertakes procedures to
rehabilitate approximately 550 ha of jarrah forest each year at two open-cut bauxite
mines in South-West Western Australia. Alcoa aims to establish a self-sustaining jarrah
forest ecosystem that maintains the functions of the landscape prior to mining, including
biodiversity, on areas that have been mined for bauxite. Indigenous terrestrial orchids
form a significant proportion of the indigenous geophytic plant species that either fail to
colonise rehabilitated areas or do so very slowly. Terrestrial orchids are considered to
be particularly sensitive to competition from weeds and disturbance, which combined
with the obligate nature of the orchid-mycorrhizal fungus association suggests that
orchids would colonise rehabilitation areas only when both microhabitat sites and soil
microflora have established. Occurrence of certain orchids may therefore be expected to
be useful as indicators of ecosystem health, the success of vegetation establishment and
the recovery of edaphic conditions suitable for orchid mycorrhizal fungi.
Vegetation surveys were undertaken to compare orchid species richness and population
size of a chrono-sequence of rehabilitation areas with adjacent unmined forest. Total
orchid and clonal orchid population sizes of rehabilitation areas had returned to
densities not significantly different to those of the adjacent unmined forest within five
years of rehabilitation establishment. The total number of orchid species and clonal
species richness had also returned to levels that were not significantly different to those
of adjacent unmined forest within the same time frame. However, orchid populations in
rehabilitation areas often contained large numbers of species identified as disturbance
opportunists, which were absent from 25+ year old rehabilitation areas and undisturbed
jarrah forest sites. Six orchid taxa were identified as recalcitrant species; Cryptostylis
ovata R.Br., Cyrtostylis heugelii Endl. In Lehm., Eriochilus dilatatus Lindl.,
Prasophyllum parvifolia Lindl., Pyrochis nigricans (R.Br.) D.L.Jones and M.A.Clem.
and Thelymitra crinita Lindl.. These taxa were either very rare (compared to unmined
forest populations), or absent from rehabilitated areas.
The role of orchid mycorrhizal fungi (OMF) in the recruitment of orchids in the
rehabilitated landscape was investigated using a seed baiting technique in a subset of the
rehabilitation survey areas. These consisted of single transects that were 1, 10 and 26
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years old (established in 2001, 1992 and 1976) and their adjacent unmined Jarrahforest.
Fungal baits consisted of buried six chambered nylon mesh packets containing seed of
the six jarrah forest orchid taxa; Caladenia flava R.Br. subsp. flava (C. flava), Disa
bracteata Sw., Microtis media R.Br. subsp. media, Pterostylis recurva Benth.,
Pyrorchis nigricans and Thelymitra crinita. Germination of seed and development of
protocorms to stage 4 (initiation of shoot primordia) was regarded as evidence of the
presence of a particular orchid’s mycorrhizal fungus. Detection of orchid mycorrhizal
fungi was infrequent, especially in the youngest rehabilitation site examined, where
only mycorrhizal fungi associated with P. recurva were detected. Mycorrhizal fungi of
the other orchid taxa were widespread but sparsely distributed in older rehabilitation
and forest areas. Detection of mycorrhizal fungi varied between taxa and baiting sites
for the two survey years (2002 and 2004).
Caladenia flava and T. crinita mycorrhizal fungi were the most frequently detected. The
presence of C. flava mycorrhizal fungi was correlated with high levels of leafy litter
cover, and high maximum depth, and soil moisture at the vegetation type scale (50 x
5 m belt transects), as well as tree and litter cover at the microhabitat scale (1 m2
quadrats). The presence of T. crinita mycorrhizal fungi was positively correlated with
soil moisture in rehabilitation areas and low shrub cover in forest. The frequency of
detection of orchid mycorrhizal fungi in both rehabilitated sites (15 - 25% of baits) and
unmined forest (15 - 50% of baits) tended to increase with rehabilitation age as
vegetation recovered. The failure of some orchid taxa to reinvade rehabilitation areas is
unlikely to be entirely due to absence of the appropriate mycorrhizal fungi. However,
the infrequent detection of orchid mycorrhizal fungi suggests that they occur in isolated
patches of soil, so the majority of dispersed orchid seeds are likely to perish especially
in recently disturbed habitats.
The ecological specificity of mycorrhizal associations of the three orchid taxa:
Caladenia flava, Thelymitra crinita and Disa bracteata were determined. The
disturbance opportunist D. bracteata appears to be promiscuous in its mycorrhizal
associations, although the promiscuity is limited to fungi within the Tulasnallales. The
two common sympatric orchids C. flava and T. crinita used fungi from different
taxonomic groups as mycorrhizal fungi which suggests that they are not competing
directly for the same nutrient resources. Several orchid plants contained more than one
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mycorrhizal fungus, and in two individual orchids the second endophyte was a fungus
more commonly associated with an ericoid mycorrhiza or ectomycorrhiza. Phylogenetic
analysis using ITS rDNA region sequences of orchid mycorrhizal fungi (OMF) isolated
in this study were generally in agreement with previous studies: C. flava was associated
with fungi from the Sebacinales; and T. crinita and D. bracteata were associated with
fungi from the Tulasnellales.
Evidence from this study indicates that with increasing age, the vegetation of
rehabilitation areas develops structural and soil surface cover characteristics similar to
that of unmined forest. Younger rehabilitation areas (between 1 and 15 years old) are
very different to unmined forest in both vegetation structure and plant species
assemblages, while the oldest rehabilitation areas examined (26 and 27 years old) were
not significantly different to adjacent areas of unmined forest. It is evident that
vegetation of the post-mining landscape is more homogeneous than that of unmined
forest as there were fewer plant species and species assemblages present. Plant species
assemblages of 1 to 15 year old rehabilitation areas were characterised by the presence
of disturbance opportunist plant species. However, both the cover and species richness
of these disturbance opportunist species had returned to unmined forest levels in
rehabilitation areas over the chrono-sequence examined. The post-mining landscape
appears to be developing a ‘new’ jarrah forest ecosystem that is structurally similar to
unmined jarrah forest, but appears, floristically, less species rich and with fewer plant
species assemblages. This lower species richness is in part due to the lower cover and
species richness of tufted, rhizomatous and herbaceous species.
Orchid taxa present in each vegetation assemblage were generally not exclusive to these
assemblages, with the following broad exclusions: D. bracteata was found only in
species assemblages associated with rehabilitation areas; and Eriochilus sp. and T.
crinita were found only in species assemblages associated with unmined forest. No
single orchid species appears to be an indicator of ecosystem recovery. However, the
presence of populations of C. flava, P. sp. crinkled leaf (G.J.Keighery 13426) or P.
recurva in combination with the absence of the disturbance opportunist orchid taxa D.
bracteata and M. media appears to be a measure of the maturity of the rehabilitation
vegetation.
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Orchid species richness and clonal orchid population size were correlated with changes
in vegetation structure, but apart from the absence of orchids in 1 year old rehabilitation
areas, these orchid population characteristics did not show any direct relationship with
rehabilitation age or vegetation maturity. Only two orchid taxa appeared to have
potential as indicators of vegetation characteristics: T. crinita as an indicator of
undisturbed jarrah forest; and D. bracteata as an indicator of disturbed ecosystems.
The results of this study suggest that most jarrah forest orchid taxa will readily colonise
the post bauxite mining landscape, but that the unassisted colonisation by recalcitrant
orchid taxa may be a prolonged process. It is recommended that field-based
transplantation and/or seeding trials be undertaken with these recalcitrant taxa to
determine if these procedures will enhance recruitment. The results of this work have
applications not only in the management of post-mining landscapes but also in
vegetation monitoring and conservation work in Western Australia and elsewhere.
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Table of Contents
Abstract i
Table of Contents v
Acknowledgments viii
Candidates Declaration ix
Definitions and terminology used in this document x
Orchid Nomenclature xiii
Fungal Nomenclature xiii
Plant Nomenclature xiii
Papers arising from this thesis xiv
INTRODUCTION 1
CHAPTER 1 LITERATURE REVIEW 5
Introduction 5
Jarrah forest 5
Bauxite Mining 7
Orchidaceae 9
Recovery of Orchids in Disturbed Habitats 12
Mycorrhizal Associations 14
Identification of Orchid Mycorrhizal Fungi 40
Thesis Outline and Research Approach 43
CHAPTER 2 RECRUITMENT OF TERRESTRIAL ORCHIDS IN THE POST- 45
MINING LANDSCAPE
Introduction 45
Materials and Methods 47
Results 49
Discussion 55
Conclusions 60
CHAPTER 3 COLONISATION OF BAUXITE MINE REHABILITATION SITES OF 63
SOUTH-WEST WESTERN AUSTRALIA BY ORCHID
MYCORRHIZAL FUNGI
Introduction 63
Materials and Methods 66
Results 72
Discussion 81
Conclusions 86
CHAPTER 4 DIVERSITY OF ORCHID MYCORRHIZAL ENDOPHYTES 87
Introduction 87
Materials and Methods 90
Results 99
Discussion 108
Conclusions 114
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CHAPTER 5 THE RELATIONSHIP BETWEEN ORCHID DISTRIBUTION, 115
VEGETATION STRUCTURE AND PLANT SPECIES ASSEMBLAGES
OF BAUXITE MINE REHABILITATION AREAS IN SOUTH-WEST
WESTERN AUSTRALIA
Introduction 115
Materials and Methods 119
Results 125
Discussion 156
Conclusions 165
CHAPTER 6 GENERAL DISCUSSION 167
Introduction 167
Orchid colonisation of the post-mining landscape 168
Detection of orchid mycorrhizal fungi 171
OMF identification 172
Vegetation establishment 173
Limitations of study 175
Future studies 176
Management recommendations 178
REFERENCES 181
APPENDICES 201
APPENDIX 1: ORCHIDS OF THE JARRAH FOREST 201
TABLE A1.1 A complete list of the indigenous orchid taxa of the Northern 201
jarrah forest.
TABLE A1.2 Descriptions of taxa used as study species. 203
TABLE A1.3 Descriptions of orchid taxa identified within survey transects 206
at the study site during the course of the project.
TABLE A1.4 Descriptions of orchid taxa observed in forest at the study site 209
during the course of the project but not found within survey
transects.
TABLE A1.5 Source and weights of orchid seed collected for use in 211
experimental work and in confirmation of mycorrhizal capacity
of putative mycorrhizal fungi over the period of the study.
TABLE A1.6 Specimens of Disa bracteata Sw. (syn. Monadenia bracteata, 212
M. micrantha, M. australis) in the Western Australian
Herbarium, Department of Conservation and Land
Management, South Perth, W.A. (Date accessed May 2005).
APPENDIX 2: VEGETATION OF THE JARRAHDALE MINE SITE 214
TABLE A2.1 A cumulative list of Western Australian indigenous plant taxa 214
identified in forest and rehabilitation area transects during
vegetation surveys at the Jarrahdale bauxite-mine site in 2002.
TABLE A2.2 A cumulative list of alien plant taxa identified during 218
vegetation surveys of forest and rehabilitation area transects
at the Jarrahdale bauxite-mine site in 2002.
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FIGURE A2.1 Output matrix from TWINSPAN analysis of transect species 219
presence/absence data.
FIGURE A2.2 Prevalence of rare species (number/transect) in rehabilitation 220
areas and unmined forest.
FIGURE A2.3 Changes in mean percentage cover for ‘Lomandra and sedge- 220
like’ species over a chrono-sequence of rehabilitation areas
compared to the mean value for unmined forest.
APPENDIX 3 FORMULAE FOR MEDIA 223
SEED GERMINATION MEDIUM 223
Oatmeal Agar 223
ISOLATION AND GROWTH MEDIA 223
Soil Solution Equivalent Agar (SSE) 223
Fungal Isolation medium (FIM) 224
Potato Dextrose Agar (PDA) 224
Nutrient Broth 224
SSE Broth 224
Modified Melin Norkans (MMN) 225
10% V8/50% SSE Broth 225
APPENDIX 4 PUBLICATIONS 227
Collins, M. T. (2005) How do you determine when orchid seed germination 227
has been successful? The Orchadian, 15 (2) 60-71
Collins, M., Koch, J., Brundrett, M. and Sivasithamparam, K. (2005) 239
Recovery of terrestrial orchids in the post-mining landscape. Selbyana, 26,
255-264
Collins, M., Brundrett, M., Koch, J. and Sivasithamparam, K. (2007) 249
Colonisation of jarrah forest bauxite-mine rehabilitation areas by orchid
mycorrhizal fungi. Australian Journal of Botany, 55 653-664
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Acknowledgments
This PhD project was jointly funded through ARC linkage project LP0221070 by Alcoa
Worldwide Alumina – Australia, Botanic Gardens and Parks Authority and The
University of Western Australia. I gratefully acknowledge the generous support of
Alcoa Worldwide Alumina Australia in provision of both monetary and technical
assistance to the project. I also thank the Australian Federation of University Women
(WA) Inc. for provision of travel funding from the Mary and Elsie Stevens Bursary.
This funding enabled me to attend the second International Orchid Conservation
Congress in Sarasota, Florida, and visit the Jodrell Laboratories, Royal Botanic
Gardens, Kew, UK in 2004.
I thank my supervisors Professor Krishnapillai Sivasithamparam (UWA), Dr. Mark
Brundrett (UWA) and Dr. John Koch (Alcoa) for technical and academic advice.
In particular I thank my friends (and former colleagues) Krystina Haq, Benedict
Killigrew and Sato Juniper for their editorial feedback on this thesis. I also thank my
colleagues Titiek Yulanti, Nura Abdul Karim, Nicolyn Short, Ryan Hooper, Linda
Maccarone, Harsh Garg and Aravinda Mutukumarana for their friendship and good
humour during the time we shared an office. This was vital to maintaining my sanity.
Thanks also to Dr Andrew Batty of Kings Park and Botanic Garden and Andrew Brown
of the Department of Environment and Conservation for advice and discussions on
orchid biology and taxonomy and everyone who provided valuable field work
assistance. I also thank Kristian Pollock from the Department of Environment and
Conservation for providing information on planned control burns in the Jarrahdale area.
I also apologise to Lewis Carroll and John Tenniel for the repeated misuse of their work
in this thesis.
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