PHENOLOGY PAPER 2 Trends in fruiting and flowering phenology with relation to abiotic variables in Bornean peat-swamp forest tree species suitable for restoration activities M. E. Harrison, Simon J. Husson, Nicole Zweifel, Laura J. D’Arcy, Helen C. Morrogh-Bernard, Maria A. van Noordwijk and Carel P. van Schaik, as part of the OuTrop multi-disciplinary research project and University of Zurich. Kalimantan Forests and Climate Partnership (KFCP) PHENOLOGY PAPER 2 Trends in fruiting and flowering phenology with relation to abiotic variables in Bornean peat-swamp forest tree species suitable for restoration activities. M. E. Harrison, Simon J. Husson, Nicole Zweifel, Laura J. D’Arcy, Helen C. Morrogh-Bernard, Maria A. van Noordwijk and Carel P. van Schaik, as part of the OuTrop multi-disciplinary research project and University of Zurich. May 2013 This report was prepared in accordance with the guidelines at the time of writing, including the overview of the KFCP project below. This research was carried out in collaboration with the Governments of Australia and Indonesia, but the analysis and findings in this paper represent the views of the author/s and do not necessarily represent the views of those Governments. Phenology Paper 2 Page i EXECUTIVE SUMMARY In this report, we present the results of a six-year study of the fruiting phenology of Bornean peat-swamp forest trees at two sites: Sabangau and Tuanan. The objective of this report is “to determine the phenology of a broad range of tropical peat-swamp forest tree species found in Central Kalimantan”, in order to facilitate peat-swamp forest restoration activities in Indonesia. Particularly, our aim here was to provide information on the timing, duration and amount of fruit produced during fruiting events, and to identify potential abiotic triggers of fruiting and flowering for a selected sub-set of species identified by KFCP as being potentially best suited for restoration activities. In doing so, we provide the first analysis of potential triggers for flowering and fruiting in Bornean peat-swamp forest; provide insight into potential intra-specific variations in flowering and fruiting phenology, and phenological triggers, between sites; present novel methods for assessing abiotic triggers of flowering and fruiting; and present information useful for the establishment of seed collection protocols for forest restoration practices. Analyses are presented in the form of both summary tables and figures comparing information between sites, and species accounts, in which the different investigations are described in detail for each species. In addition to the data provided to assist with the development of species-specific seed collection protocols, the following key findings emerged from this analysis: 1. The timing of the onset of flowering and fruiting was related between sites for some species, but this was not true in the majority of cases. In most cases, this appears related to the frequency of flowering and fruiting events at the two sites. 2. At least some species appear to have different abiotic triggers that trigger flowering and fruiting events. 3. Comparison of the most likely potential abiotic triggers of flowering and fruiting indicates that different abiotic variables trigger flowering and fruiting in different species. 4. In apparent contrast to the fact that peat-swamp forest is not a masting habitat, some species in the sample do appear to respond to abiotic triggers hypothesised to be associated with SAMF events. 5. Solar equinox was the most frequently identified trigger of both flowering and fruiting among the species sampled. 6. The same potential abiotic triggers of flowering and fruiting for a species were shared between the two sites in some, but not the majority, of species. In most cases where there was no congruence, the species in question either flowered/fruited very rarely or very often. 7. In cases with multiple species analysed in a genera, most species were identified as sharing the same potential abiotic trigger of flowering and/or fruiting in both sites (e.g., Calophyllum: onset of wet season; Cratoxylon: spring equinox). The exception to this was Palaquium, which appears to respond to a number of different potential abiotic triggers. Highlights: • Most likely abiotic triggers of flowering and fruiting identified (p179) • Calendar showing likelihood of fruiting throughout the year (p185) Phenology Paper 2 Page ii CONTENTS EXECUTIVE SUMMARY ............................................................................................................................................ ii CONTENTS ..............................................................................................................................................................iii ACKNOWLEDGEMENTS .......................................................................................................................................... v ACRONYMS ............................................................................................................................................................. vi INTRODUCTION ...................................................................................................................................................... 1 Fruiting Phenology in Tropical Peat-Swamp Forests .......................................................................................... 1 Studies of Abiotic Triggers of Flowering and Fruiting ........................................................................................ 2 METHODS ............................................................................................................................................................... 3 Definitions .......................................................................................................................................................... 3 Site Locations and Descriptions .......................................................................................................................... 3 Sabangau ........................................................................................................................................................ 4 Tuanan ............................................................................................................................................................ 4 Phenology Sampling Methods ............................................................................................................................ 4 Sabangau ........................................................................................................................................................ 4 Tuanan ............................................................................................................................................................ 5 Sampling Period .............................................................................................................................................. 5 Enumeration ................................................................................................................................................... 5 Species Identification ..................................................................................................................................... 5 Monthly data collection ................................................................................................................................. 5 Tree Species Included in the Sample .................................................................................................................. 6 Abiotic Data Collection and Analysis Methods ................................................................................................... 9 Rainfall ............................................................................................................................................................ 9 Temperature ................................................................................................................................................... 9 Occurrence of El Niño conditions and events ................................................................................................ 9 Haze from forest fires ..................................................................................................................................... 9 Day length ..................................................................................................................................................... 10 Data Analysis .................................................................................................................................................... 10 Analysis of Potential Phenological Triggers ...................................................................................................... 11 RESULTS ................................................................................................................................................................ 14 Variations in Abiotic Variables .......................................................................................................................... 14 Temperature and Rainfall ............................................................................................................................. 14 Visibility .......................................................................................................................................................