Transfer of Weeds to Queensland Native Forests by Horse Faeces — The viability and germination of plant seeds found in horse faeces — RIRDC Publication No. 11/109 RIRDCInnovation for rural Australia Transfer of Weeds to Queensland Native Forests by Horse Faeces The viability and germination of plant seeds found in horse faeces by Christopher C Pollitt and Longbin Huang October 2011 RIRDC Publication No. 11/109 RIRDC Project No. PRJ-000525 © 2011 Rural Industries Research and Development Corporation. All rights reserved. ISBN 978-1-74254-289-8 ISSN 1440-6845 Transfer of Weeds to Queensland Native Forests by Horse Faeces Publication No. 11/109 Project No. PRJ-000525 The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication. The Commonwealth of Australia, the Rural Industries Research and Development Corporation (RIRDC), the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors. The Commonwealth of Australia does not necessarily endorse the views in this publication. This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165. Researcher Contact Details Christopher C Pollitt Longbin Huang (Senior Research Fellow) School of Veterinary Science Centre for Mined Land Rehabilitation The University of Queensland Sustainable Minerals Institute Gatton QLD 4343 The University of Queensland Brisbane QLD 4072 Phone: 0419 721 682 Email: [email protected] Phone: 07 3346 3130 Email: [email protected] In submitting this report, the researchers have agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: 02 6271 4100 Fax: 02 6271 4199 Email: [email protected]. Web: http://www.rirdc.gov.au Electronically published by RIRDC in October 2011 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 634 313 ii Foreword There are environmental concerns associated with horse riding in conservation areas and national parks in Australia. One of the concerns is the potential risk of weed invasion into natural plant communities, through viable seeds contained in horse faeces, when environmental conditions are suitable (e.g. adequate nutrients and water). Both controlled and field studies are required to obtain further evidence for assessing the risk of weed invasion caused by horse faeces during horse riding in natural reserves and national parks in Queensland. Horse riding in safe, natural environments is a part of daily activities for many Australians and is likely to continue for either recreation or economic purposes. Management strategies based on empirical scientific knowledge are required to promote recreational riding with the minimum impact on natural ecosystems. This project investigated the following question: does horse faeces contain viable seeds which may be germinated under suitable conditions or persist in surface soil? The results showed that many plants germinate from horse faeces especially if the horses are grazing weed infested pastures. On the other hand, the faeces of stabled horses, fed manufactured feeds, contain relatively few viable seeds. To determine the role of horse faeces as a source of weeds in natural forests, plants growing on 100 m transects of the sampled pasture and transects of the trails in nearby native forests need to be compared. When complete these studies will supply objective data to assess the level of threat of weed invasion posed by horse riding in areas of native vegetation and will help formulate rational management strategies for recreational horse riding. The project was funded from industry revenue which is matched by funds provided by the Australian Government. This report is an addition to RIRDC’s diverse range of over 2000 research publications and it forms part of our Horse R&D Program, which aims to assist in developing the Australian horse industry and enhancing its potential. Most of RIRDC’s publications are available for viewing, free downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313. Craig Burns Managing Director Rural Industries Research and Development Corporation iii Acknowledgments David Bowen of the School of Land & Food Science, Faculty of Natural Resources, Agriculture and Veterinary Science, The University of Queensland, assisted greatly in the experiments in this report and is sincerely thanked. iv Contents Foreword ............................................................................................................................................... iii Acknowledgments ................................................................................................................................. iv Executive Summary............................................................................................................................. vii Introduction ........................................................................................................................................... 1 Objectives ............................................................................................................................................... 1 Methodology ........................................................................................................................................... 2 Sieving and seed viability testing ...................................................................................................... 2 Germination under controlled glasshouse conditions ....................................................................... 2 Data collection and Analysis............................................................................................................. 3 Results ..................................................................................................................................................... 4 Viability testing ................................................................................................................................. 4 Glasshouse trial: HU manure treatments .......................................................................................... 4 Glasshouse trial: EF manure treatments .......................................................................................... 14 Comparison of seed viability with glasshouse emergence .............................................................. 15 Discussion ............................................................................................................................................. 17 Recommendations................................................................................................................................ 19 Appendix 1. Numbers of seedlings in manure treatments (per 200g manure) at 36 days ............ 20 Appendix 2. Percent water in manure types ..................................................................................... 21 References ............................................................................................................................................ 22 v Tables Table 1 Sources of horse manure...................................................................................................... 2 Table 2 Percent viability of seed extracted from 3 horse manure types .......................................... 4 Table 3 Mean numbers of seedlings in manure treatments (/200g manure) at 36 days .................. 11 Table 4 Concordance between species extracted by wet sieving from manure and from glasshouse emergence........................................................................................................ 16 Table 5 Weed species germinating in horse manure ...................................................................... 17 Figures Figure 1 Mean number of monocotyledon and dicotyledonous seedlings in treated HU manure at 14 days ............................................................................................................................ 5 Figure 2 Mean number of monocotyledonous seedlings in treated HU manure at 21 days .............. 6 Figure 3 Mean number of seedlings of 4 dicotyledons and 1 monocotyledon (Cyperus polystachyos) in treated HU manure after 21 days .............................................................. 6 Figure 4 Mean number of seedlings of Queensland Blue couch (Digitaria didactyla) in 200g of HU manure (fresh