An Investigation of the Prerequisite Conditions Which Enable Invasion of Moist
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1 An Investigation of the Prerequisite Conditions which Enable Invasion of Moist 2 Grasslands by Dalbergia obovata 3 4 By 5 Terry Stewart 6 7 Submitted in fulfilment of the academic requirements 8 of Master of Science 9 10 in Biology 11 School of Life Sciences, 12 College of Agriculture, Engineering and Science 13 University of KwaZulu-Natal, 14 Durban 15 South Africa. 16 17 18 9th January 2019 19 . 20 21As the candidate’s supervisors we have approved this dissertation for submission. 22 23 24Signed: ___________________ Name: ___Peter Frank Scogings__ Date: ___2019.03.08____ 25 26 27Signed: ___________________ Name: ___Himansu Baijnath_____ Date: ___2019.03.08____ 1 I 2 1 PREFACE 2The research contained in this dissertation was completed by the candidate while based in the 3Discipline of Biology, School of Life Sciences of the College of Agriculture, Engineering and Science, 4University of KwaZulu-Natal, Westville, South Africa. 5 6The contents of this work have not been submitted in any form to another university and, except 7where the work of others is acknowledged in the text, the results reported are due to investigations by 8the candidate under the supervision of Professors Peter Scogings and Himansu Baijnath. 9 10The structure of the dissertation is in the form of papers for publication and therefore necessitates 11some repetition as well as some variation among the chapters. 12 13 14 15____________________________ 16Signed : Terry Stewart 17Date : ______08/03/2019_______ 18 19 20 3 1 II 2 1 DECLARATION 1: PLAGIARISM 2I, Terry Stewart, declare that: 3 (i) the research reported in this dissertation, except where otherwise indicated or 4 acknowledged, is my original work; 5 (ii) this dissertation has not been submitted in full or in part for any degree or 6 examination to any other university; 7 (iii) this dissertation does not contain other persons’ data, pictures, graphs or other 8 information, unless specifically acknowledged as being sourced from other 9 persons; 10 (iv) this dissertation does not contain other persons’ writing, unless specifically 11 acknowledged as being sourced from other researchers. Where other written 12 sources have been quoted, then: 13 a) their words have been re-written but the general information attributed 14 to them has been referenced; 15 b) where their exact words have been used, their writing has been placed 16 inside quotation marks, and referenced; 17 (v) where I have used material for which publications followed, I have 18 indicated in detail my role in the work; 19 (vi) this dissertation is primarily a collection of material, prepared by myself, 20 published as journal articles or presented as a poster and oral presentations at 21 conferences. In some cases, additional material has been included; 22 (vii) this dissertation does not contain text, graphics or tables copied and pasted 23 from the Internet, unless specifically acknowledged, and the source being 24 detailed in the dissertation and in the References sections. 3 1 III 2 1 2 3 4___________________________ 5Signed : Terry Stewart 6Date : ____08/03/2019_________ 7 3 1 IV 2 1DECLARATION 2: PUBLICATIONS 2My role in each paper and presentation is indicated. The * indicates corresponding author. For each 3paper, I conceived the idea, developed the methods, collected and analysed the data, and led most of 4the writing. My co-authors guided the overall conceptualisation of the work and contributed 5editorially to the writing. 6 7Chapter 2 8Stewart T*, Scogings PF and Baijnath H., An investigation of the encroachment of sub-tropical moist 9coast grasslands within the urban nature reserves of Ethekwini Municipality by Dalbergia obovata, an 10indigenous forest liana. Submitted to Bothalia: African Biodiversity and Conservation on 2nd 11December 2018. The paper presents the results of the analysis of reserve management records and 12field mapping surveys for the distribution of D. obovata in the grasslands of nature reserves within 13Ethekwini Municipality and concludes that D. obovata has encroached into the moist coast grasslands. 14 15Chapter 3 16Stewart T*, Scogings PF and Baijnath H. An assessment of the distribution of Dalbergia obovata 17diaspores from forest margins and post establishment vegetative propagation within adjacent 18grasslands. Submitted to Bothalia: African Biodiversity and Conservation on 16th December 2018. 19Using a simplified wind dispersal model and analysis of historical changes in distinct stands in 20grasslands it was concluded that successful establishments were infrequent and that clonal propagation 21was the primary mechanism for expansion of plants. 22 23 24Signed: Terry Stewart Date: ___08/03/2019_________ 3 1 V 2 1ABSTRACT 2Encroachment by Dalbergia obovata into moist coastal grasslands within eThekwini Municipality was 3identified as a potential threat to the conservation of this threatened habitat type. An investigation was 4undertaken to confirmation whether or not D. obovata was in fact encroaching into the city's 5grasslands and to identify the probable underlying drivers and local factors that contributed to 6encroachment. The investigation comprised four areas of focus. The first was an assessment of the 7management practices and records of D. obovata encroachment extracted from the available reserve 8management records of seventeen nature reserves and conservation areas. The summarised data from 9the records was then processed using a Chi-square test and Principal Components Analysis. The 10second phase focussed on the application of field surveys to record the distribution patterns of D. 11obovata within four selected management areas. The results were then captured in a GIS map against 12which the results of the Chi-square and PCA tests were compared. In phase three a simple theoretical 13ballistics model was developed from experimental data to predict the anomochoric distribution of D. 14obovata diaspores from the forest into adjacent grasslands and the critical positioning of parent plants 15in the host trees in relation to the edge of the canopy. The final focal area involved the mapping of 16individual plants within stands of D. obovata and comparison against sixteen years of historical 17orthophoto records in order to determine the historic patterns and rates at which D. obovata became 18established and propagated within the grasslands. During this part of the investigation the vegetative 19propagation of D. obovata by clonal propagation from lateral branches and roots was identified and 20which provided an explanation of how D. obovata was able to form large dense stands with no 21evidence of canopy contact mortality. The final conclusions were that D. obovata parent plants had to 22be positioned on the edge of the forest canopy for diaspores to successfully escape the canopy, that 23successful establishment of D. obovata in grasslands from any particular parent plant was infrequent 24and that D. obovata did not become established in the presence of large mixed feeder herbivores. 25However once established in the grasslands, the ability to spread via clonal propagation enabled D. 26obovata to both outcompete grass species for available resources and be resilient to conventional 27bush encroachment management practices which relied on controlled burning programs. 3 1 VI 2 1ACKNOWLEDGEMENTS 2The author wishes to acknowledge the following people for their continual encouragement and 3support. My brother Clive Stewart, my mother Mrs Yvonne Stewart and Mark Hodgetts my life long 4friend 5 6Gratitude is also extended to the following members of my work colleagues and staff of the Natural 7Resources management Division of the eThekwini Municipality Parks, Liesure and Cemeteries 8Department for their assistance with the collection of field data and the provision of management 9records, Kenneth L Mabila, Philip J Zuma, Nicholas Liebenberg, Thami Kunene, Jabulani Khoza, 10Christopher Ngcobo and Zethu Gumede. Acknowledgement is also given to the staff of the 11Environmental Planning and Climate Protection Department of eThekwini Municipality as well as the 12Reserve Managers and staff of the Scientific Services Department of Ezemvelo KZN Wildlife for 13access to the reserve management records and nature reserves under their management. 14 15Special acknowledgement is given to Dr D Roberts for her pivotal role in motivating for this research 16project to be considered for a post graduate study through the Durban Research Action Partnership 17between Ethekwini Municipality and the University of KwaZulu-Natal and finally to Professor Peter F 18Scogings and Professor Himansu Baijnath my supervisors at UKZN for their continual guidance and 19patience during this post graduate research. 20 21 22 23 24 3 1 VII 2 1TABLE OF CONTENTS 2 Page 3PREFACE........................................................................................................................................ I 4DECLARATION 1: PLAGIARISM................................................................................................ II 5DECLARATION 2: PUBLICATIONS.......................................................................................... IV 6ABSTRACT................................................................................................................................... V 7ACKNOWLEDGEMENTS........................................................................................................... VI 8TABLE OF CONTENTS..............................................................................................................