Persistence of velvet worms (Onychophora: Peripatopsidae): effects of fire and climate in forests of south-west Western Australia Allan J. Wills, Paul F. Van Heurck and Janet D. Farr Department of Parks and Wildlife, Locked Bag 104 Bentley Delivery Centre 6983 Western Australia Email: [email protected]

12 Dwellingup 35 Introduction

10 30 In south-west Western Australia onychophorans are represented by the

25 8 species Occiperipatoides gilesii and the genus Kumbadjena including three 20 O. gilesii (Reid 2002) 6 described species K. kaata, K. occidentalis and K. shannonensis, within a 15 O. gilesii Forestcheck C) or Rainfall (cm) Rainfall or C)

4 o Kumbadjena O. gilesii 10 species complex of spp. (Reid 2002). is known from Mean maximum 2 5 temperature isolated occurrences in a wetland and karst units of the Swan Coastal Plain Number collections of Number Mean monthly rainfall 0 0 (Van Der Lande 1978, Reid 2002) and from a more extensive distribution in

Jan FebMar AprMayJun Jul AugSep OctNovDec Temperature ( Month jarrah (Eucalyptus marginata) forest of the eastern periphery of the Swan 18 Pemberton 35 Coastal Plain (SCP) and the Darling Plateau from the Mount Helena area 16 30 14 south to about Collie (Reid 2002, data this paper). Kumbadjena spp. have a 25 Kumbadjena spp. (Reid 12 2002) southern distribution in an arc from the SCP near Bunbury, the jarrah 10 20 Kumbadjena spp. 8 Forestcheck and Fire forest north of Collie (data this paper) and from the Leeuwin-Naturalist 15 Mosaic C) or Rainfall (cm) Rainfall or C) 6 o Mean maximum 10 temperature Ridge to an eastern inland outlier in the Stirling Range north of Albany. 4

Number collections of Number 5 Mean monthly rainfall 2 Reid (2002) noted the importance of karri (Eucalyptus diversicolor) forest 0 0 Temperature ( JanFebMar AprMayJun Jul AugSepOctNovDec as a provider of habitat for Kumbadjena spp. though the genus is also Month known from jarrah forest and Allocasuarina dominated patches within jarrah forest. Observations and specimens of O. gilesii and Kumbadjena Climate effects spp. collected during the FORESTCHECK jarrah forest biodiversity monitoring Long- term mean monthly maximum temperature and rainfall data were project (Farr et al. 2011, McCaw et al. 2011) and an investigation of effects obtained for Dwellingup and Pemberton from the Bureau of Meteorology (BOM) of fine grain mosaic burning on biodiversity near Walpole Western web site in 2012. Collection frequencies for each month of O. gilesii and Australia are reported here. Kumbadjena spp.and were plotted along with mean monthly temperature and mean monthly rainfall for Dwellingup and Pemberton, locations central to the ranges of these taxa (Figures above right). Mean annual point potential 2500 evapotranspiration and mean annual rainfall for the period 1961-1990 were interpolated from gridded surfaces obtained from the BOM for localities listed in 2000 Reid (2002), and FORESTCHECK collection and fine grain fire mosaic collection (mm)

localities (Figure right). All O. gilesii and Kumbadjena spp. collection sites except the montane sites of the Porongurup and Stirling Ranges experienced mean 1500 annual rainfall greater than or equal to 743 mm in the period 1961 and 1990. Kumbadjena spp. and O. gilesii collection sites were segregated by mean annual Occiperipatoides gilesii 1000 point potential evapotranspiration with a maximum value for O. gilesii of 1983 Kumbadjena spp. mm and a maximum value for Kumbadjena spp. of 1644 mm. Kumbadjena sp. Stirling Range Kumbadjena kaata Porongurup Range There are almost no mechanisms for physiological regulation of water loss in evapotranspiration Mean annual point potential point potential annual Mean 500 Lower rainfall limit (Excluding montane habitat) onychophorans. However, closely related species, and males and females of the Upper limit point potential evapotranspiration O. gilesii same species, can differ in their rates of respiratory water loss under the same Upper limit point potential evapotranspiration Kumbadjena spp. conditions (Weldon et al. 2013). Differences in seasonal activity, and the 0 apparent difference in climatic tolerances of Occiperipatoides and Kumbadjena 500 600 700 800 900 1000 1100 1200 1300 1400 1500 suggest that differences in respiratory water loss, and or life cycle traits may Mean annual rainfall 1961-1990 (mm) play a part in the distribution limits of Western Australian onychophorans. Time since fire and collection frequency Litter is an important though insecure habitat for onychophorans in Western Australia. Three quarters of the specimens collected in the FORESTCHECK and fine grain fire mosaic projects were collected from litter or from pitfall traps in litter beds. The remaining specimens were collected from movable woody debris. Logs were not dissected. Much of the fine fuels that constitute the litter habitat used by onychophorans in jarrah forest is likely to be consumed in fires of the low intensities encountered in prescribed fuel reduction fires (61-98% fine fuel consumption in jarrah forest fires, with fire intensities < 700 kWm-1 (Hollis et al. 2010)). This highlights the ephemeral nature of litter habitat and the importance of fire durable fallen logs for onychophorans. Collection sites were subjected to a variety of fire intensities ranging from wildfire (Photo left top) to cool controlled fire (Photo left bottom), under Western Australian conditions of fire management, and across a mix of unharvested, regeneration after partial harvest and regeneration after gap harvest silvicultural treatments (i.e. fire and silvicultural history effects were not controlled in the data presented here). Sampling took place in Autumn and Spring, times of low collection success rate for O. gilesii . Kumbadjena sp. were collected from a single site 6 months after a cool, late spring prescribed fire, while no O. gilesii were collected less than 17 years after fire (Figure below, top). Success rate of onychophoran collection increased with time since fire on both FORESTCHECK and fine grain fire mosaic sites. Highest rate of collection was from 10.1 or more years after fire in the FORESTCHECK collection and 5.1 or more years after fire in the fine grain fire mosaic collection (Figure below, bottom). Fisher’s exact probabilities of observed or more extreme collection frequencies were significant for FORESTCHECK sampling (Probability of zero samples of post-fire age 5 or less years containing onychophora = 0.027), and not significant for fine grain mosaic samples (Probability of 3 or less samples of post-fire age 5 or less years containing onychophora = 0.367). From the present studies, collection rates from non-log habitat in samples categorized by time since fire tend to indicate that recovery of onychophoran populations after fires takes 5 to 10 years (southern) and at least 10 years (central and northern Acknowledgements jarrah forest) to recover to pre-fire levels. We thank DPaW districts staff and the many 7 students and volunteers who have assisted in

specimen collection and sorting for the 6 FORESTCHECK and Walpole small grain fire mosaic O. gilesii projects. The above image of aftermath of 5 Kumbadjena spp. wildfire was provided courtesy of Ted Middleton. 4

References 3 Farr J.D., Wills A.J., Van Heurck P.F., Mellican A.E., Williams M.R. (2011) FORESTCHECK: the response of macro-invertebrates to silviculture in jarrah 2 (Eucalyptus marginata) forest. Australian Forestry 74(4), 315-327 1 Number of Numberof collection sites Hollis J.J., Matthews S., Ottmar R.D., Prichard S.J., Slijepcevic A., Burrows N.D., Ward B., Tolhurst K.G., Anderson W.R., Gould J.S. (2010) Testing woody fuel 0 0 - 1 1.1 - 5 5.1 - 10 10.1 + consumption models for application in Australian southern eucalypt forest fires. Time since fire (years) Forest Ecology and Management 260(6), 948-964

0.12 McCaw W.L., Robinson R.M., Williams M.R. (2011) Integrated biodiversity Forestcheck monitoring for the jarrah (Eucalyptus marginata) forest in south-west Western 20 68 0.10 Fire mosaic Australia: the FORESTCHECK project. Australian Forestry 74(4), 240-253 Numbers above columns

indicate number of samples Reid A. (2002) Western Australian Onychophora (Peripatopsidae): a new genus, 0.08 Kumbadjena, for a southern species-complex. Records of the Western 0.06 Australian Museum 21, 129-155 20

per sample sites 46 67 Van der Lande V. (1978) The occurrence, culture and reproduction of 0.04 Peripatoides gilesii Spencer (Onychophora) on the Swan Coastal Plain. The Western Australian Naturalist 14(2) 29-35 0.02

Collection 16 41 2* Weldon C.W., Daniels S.R., Clusella-Trullas S., Chown S.L. (2013) Metabolic and 0.00 Kumbadjena sp. water loss rates of two cryptic species in the African velvet worm genus 0 - 1 1.1 - 5 5.1 - 10 10.1 + Opisthopatus (Onychophora). Journal of Comparative Physiology B 183(3), 323- Time since fire (years) 332