geography department jiames cook university niimber eleven 19$2|., °* The Geomprphological and Zonational i Development of Mangrove Swamps in the Townsvil le Area, North Queensland I A THE GEOMORPHOLOGICAL AND ZONATIONAL DEVELOPMENT OF MANGROVE SWAMPS IN THE TOWNSVILLE AREA, NORTH QUEENSLAND A. P. SPENCELEY Monograph Series No 11 Department of Geography, James Cook University of North Queensland 1982 ©James Cook University of North Queensland 1982 First published 1982 National Library of Australia Cataloguing in Publication Data Spenceley, A, P. (Anthony Phillip), 1947- The geomorphological and zonational development of mangrove swamps in the Townsville area, North Queensland. Bibliography. ISBN 0 86443 075 2. ,;. I. Mangrove - Queensland - Townsville Region - Geographical distribution. I. James Cook University of North Queensland. Dept of Geography. II. Title. [Series: Monograph series (James Cook University of North Queensland. Dept of Geography); no. 11]. 583'.42 ISSN 0159-8273 Wholly set up and printed within the University FOREWORD The author then outlines the field, laboratory The significance of mangroves (or mangals) in and statistical analytical methods he employed the ecosystem of sections of tropical or warm temper­ Appendix 1 indicates the details of the techmques of ate coasts has been undergoing a re-assessment in the chemical analysis undertaken. The results of the recent years. No longer are mangroves viewed as analysis of the field data which cover both the differ­ something to be cleared and replaced, if possible, by ences between the individual mangrove zones and other and assumed to be preferred forms of land-use. those over the different months of the year is exten­ It is recognised now that mangroves have many sively summarised in the Appendices 2 and 3. The valuable attributes and functions and that it is essen­ data provided on the variation in the vanous soil tial that they should not be indiscriminately nutrients offer a valuable foundation for comparative destroyed. investigations by other workers in mangrove environ­ With this change of outlook increasing atten­ ments elsewhere. The results of a factor analysis at tion has been directed towards the scientific study of three levels, surface, 100 mm and 300 mm depths ot the mangrove associations. In composition and spatial the soil variables are tabulated and graphical represen­ patterns the internal differentiation and species tations of means and standard deviations for each site diversity has been increasingly appreciated. The zonal are included to illustrate the range of the soü sequence of different species of mangroves across the nutrients studied. intertidal areas has attracted increasing research and this enquiry has stimulated a lively debate on the The discussion is then directed to a considera­ operation and significance, at different scales, of tion of a number of questions that arise from the various environmental factors. general problems of trying to relate mangrove distributions to the multivariate soil profiles. The Despite the growing momentum of research outcome of the study demonstrates the complexity into mangroves many aspects are still imperfectly of the ecology of mangroves. No one vegeution understood, several controversial areas exist and group correlated with a particular set of soil nutrients. debate on different interpretations still proceeds. Local site factors cleariy played a significant role. Undoubtedly field observations and collection of These included the vegetation cover and the organic data from mangrove environments in different lower matter in the soil derived from it, the sediment tex­ latitude parts of the world are refining our knowledge ture, the rainfall seasonality and the related inflow and narrowing the disagreements. There is still a of fresh water and localized sources of nutrients considerable need for more information and it is in within the root zone of the mangroves. this respect that it has been felt worthwhile to publish this eleventh number in our Monograph The monograph will provide additional quanti­ Series. tative data which will in turn contribute to continuing research into mangroves. The specific data are there Dr Spenceley's interest in mangroves was for comparative studies of mangroves elsewhere in pursued particularly through his PhD researches. He Australia or in other low latitude regions. The mono­ directed his attention to the different mangrove graph follows in tiie pattern of tropical environmental situations in the Townsville area. Observing that the research tiiat has been a continued interest of the frequency of flooding, the height of the water table Department of Geography at James Cook University. and the salinity of the soil water, whüe relevant, do not provide a complete explanation of the zonal Professor]. Oliver distribution of species across the intertidal slope, September 1982 Dr Spenceley looked into other factors. In particular he focused his attention on the plant/soil relation­ ships, especially temporal and spatial variations of Acknowledgments soil nutrients. The Townsville area afforded a valuable opportunity to examine the differences between estuarine systems and open coastal accreting systems Data for this monograph were collected whilst in close proximity to each other. the author undertook postgraduate research in the This monograph represents a shortened selec­ Geography Department, James Cook University of tive version of Dr Spenceley's PhD thesis. Following North Queensland under the supervision of Associate a brief introductory survey of current views on the Professor D. Hopley. I would like to thank him for distribution and characteristics of mangrove associa­ the many hours of useful discussion that we had on tions there is a summary of the relevant conditions this and many other topics. My thanks are extended of the natural environment of the Townsville area. to Professor Oliver for assistance given to me during The specific local features of the investigation sites my stay in Townsville; and to J. Patrick, Technician, on Magnetic Island and at Saunders Beach, including Geology Department, James Cook University of detailed tabulations of the characteristics of soil North Queensland for his assistance whilst I under­ texture, are presented. In addition for each of these took the soil analyses. The maps were drawn by the areas vegetation transects from low water inland are Cartographic Centre, Department of Geography, described. James Cook University of North Queensland. (iii) TABLE OF CONTENTS FOREWORD AND ACKNOWLEDGEMENTS LIST OF TABLES LIST OF FIGURES INTRODUCTION CHAPTER 1 Regional Setting and Methodology 2 Variations in Soil Nutrients on Magnetic Island and at Saunders Beach 3 The Effect of Soils on the Distribution of Mangroves in the Townsville Region BIBLIOGRAPHY APPENDICES 1 Chemical Analyses 2 Soil Chemical Data for Stations on Magnetic Island 1975 3 Soil Chemical Data for Stations at Saunders Beach 1975-76 (iv) LIST OF TABLES Page Table 12 Ll Sediment textural analysis, Magnetic Island 13 1.2 Sediment textural analysis, Saunders Beach 18 2.1 Trends in the soil chemical data, Magnetic Island 19 2.2 Trends in the soil chemical data, Saunders Beach 20 2.3 Factor analysis results for surface data, 12v and lOv, Magnetic Island 20 2.4 Factor analysis results for 100 mm data, 12v and lOv, Magnetic Island 21 2.5 Factor analysis results for 300 mm data, 12v and lOv, Magnetic Island 21 2.6 Factor analysis results for surface data, Saunders Beach 1 22 2.7 Factor analysis results for 100 mm data, Saunders Beach 1 22 2.8 Factor analysis results for 300 mm data, Saunders Beach 1 23 2.9 Factor analysis results for surface data, Saunders Beach 2 23 2.10 Factor analysis results for 100 mm data, Saunders Beach 2 24 2.11 Factor analysis results for 300 mm dau, Saunders Beach 2 24 2.12 Discriminant analysis results for surface, 100 mm and 300 mm data, Saunders Beach 1 25 2.13 Discriminant analysis results for surface, 100 mm and 300 mm data, Saunders Beach 2 (v) LIST OF FIGURES Figure Page 1.1 Location of sites 3 1.2 (a) Geomorphological map of mangal on the west coast of Magnetic Island 7 (b) Zonation through the mangal on Magnetic Island 1.3 Plots of sorting v. mean, skewness v. mean and skewness v. kurtosis for 8 surface samples from Magnetic Island and Saunders Beach 1.4 Zonation of vegetation tiirough the mangal at Saunders Beach 9 2.1 Means and 1 standard deviation for pH(KCl) and pH(H2 O), Magnetic Island 26 2.2 Means and 1 standard deviation for water soluble chloride and water soluble 27 sulphate, Magnetic Island 2.3 Means and 1 standard deviation for soluble sodium and soluble potassium 28 Magnetic Island ' 2.4 Means and 1 standard deviation for soluble calcium and soluble magnesium 29 Magnetic Island ' 2.5 Means and 1 standard deviation for exchangeable sodium and exchangeable 30 potassium, Magnetic Island 2.6 Means and 1 standard deviation for exchangeable calcium and exchangeable 31 magnesium. Magnetic Island 2.7 Ratio data. ExNa/ExK; ExCa/ExMg, for Magnetic Island 32 2.8 Means and 1 standard deviation for pH(Ka) and pHd-Tj O), Saunders Beach 36 2.9 Means and 1 standard deviation for water soluble chloride and water soluble 37 sulphate, Saunders Beach 2.10 Means and 1 standard deviation for soluble sodium and soluble potassium, 38 Saunders Beach 2.11 Means and 1 standard deviation for soluble calcium and soluble magnesium, 39 Saunders Beach 2.12 Means and 1 standard deviation for exchangeable sodium and exchangeable 40 potassium, Saunders Beach ^ 2.13 Means and 1 standard deviation for exchangeable calcium and exchangeable 41 magnesium, Saunders Beach 2.14 Ratio data. ExNa/ExK for Saunders Beach 42 2.15 Ratio data. ExCa/ExMg for Saunders Beach 43 (vi) THE GEOMORPHOLOGICAL AND ZONATIONAL DEVELOPMENT OF MANGROVE SWAMPS IN THE TOWNSVILLE AREA, NORTH QUEENSLAND INTRODUCTION Viewed from the air, mangals frequently present Tomlinson, 1957a; Hesse, 1961a, b; Thornton and a picture of an orderly distribution of mangroves Giglioli, 1965).