Abstract
Although ecological disturbances can have a strong influence on pollinators through changes in habitat, virtually no studies have quantified how characteristics of wildfire influence the demography of essential pollinators. Nevertheless, evaluating this topic is critical for understanding how wildfire is linked to pollinator population dynamics, particularly given recent changes in wildfire frequency and severity in many regions of the world. In this study, we measured the demographic response of the blue orchard bee (Osmia lignaria) across a natural gradient of wildfire severity to assess how variation in wildfire characteristics influenced reproductive output, offspring sex ratio, and offspring mass. We placed nest blocks with a standardized number and sex ratio of pre-emergent adult bees across the wildfire gradient, finding some evidence for a positive but highly variable relationship between reproductive output and fire severity surrounding the nest site at both local (100 m) and landscape (750 m) scales. In addition, the production of female offspring was > 10% greater at nest sites experiencing the greatest landscape-scale fire severity relative to the lowest-severity areas. The finding that blue orchard bees biased offspring production towards the more expensive offspring sex with increasing fire severity shows a functional response to changes in habitat quality through increased density of flowering plants. Our findings indicate that burned mixed-conifer forest provides forage for the blue orchard bee across a severity gradient, and that the increase in floral resources that follows high-severity fire leads females to shift resource allocation to the more costly sex when nesting.





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Bogusch P, Blažej L, Trýzna M, Heneberg P (2014) Forgotten role of fires in Central European forests: critical importance of early post-fire successional stages for bees and wasps (Hymenoptera: Aculeata). Eur J Forest Res 134(1):153–166. https://doi.org/10.1007/s10342-014-0840-4
Bosch J, Kemp WP (2000) Development and emergence of the orchard pollinator Osmia lignaria (Hymenoptera: Megachilidae). Environ Entomol 29(1):8–13
Bosch J, Kemp WP (2001) How to manage the blue orchard bee. Sustain Agric Netw, Beltsville
Boyle NK, Artz DR, Lundin O, Ward K, Picklum D, Wardell GI, Williams NM, Pitts-Singer TL (2020) Wildflower plantings promote blue orchard bee, Osmia lignaria (Hymenoptera: Megachilidae), reproduction in California almond orchards. Ecol Evol 10(7):3189–3199
Brown J, York A, Christie F, McCarthy M (2017) Effects of fire on pollinators and pollination. J Appl Ecol 54(1):313–322. https://doi.org/10.1111/1365-2664.12670
Buckles BJ, Harmon-Threatt AN (2019) Bee diversity in tallgrass prairies affected by management and its effects on above-and below-ground resources. J Appl Ecol 56(11):2443–2453
Burkle LA, Simanonok MP, Durney JS, Myers JA, Belote RT (2019) Wildfires increase density and diversity of native bees and floral resources, but unburned areas maintain interspecific and intraspecific trait variation of bees and plants in landscape mosaics. Front Ecol Evol 7:252
Carbone LM, Tavella J, Pausas JG, Aguilar R (2019) A global synthesis of fire effects on pollinators. Glob Ecol Biogeogr 00:1–12
Dennison PE, Brewer SC, Arnold JD, Moritz MA (2014) Large wildfire trends in the western United States, 1984–2011. Geophys Res Lett 41(8):2928–2933
Donato DC, Fontaine JB, Campbell JL (2016) Burning the legacy? Influence of wildfire reburn on dead wood dynamics in a temperate conifer forest. Ecosphere 7(5):e01341
Driscoll DA, Lindenmayer DB, Bennett AF, Bode M, Bradstock RA, Cary GJ, Clarke MF, Dexter N, Fensham R, Friend G, Gill M (2010) Fire management for biodiversity conservation: key research questions and our capacity to answer them. Biol Cons 143(9):1928–1939
Ferrez J, Davison AC, Rebetez M (2011) Extreme temperature analysis under forest cover compared to an open field. Agric For Meteorol 151(7):992–1001
Flannigan M, Cantin AS, De Groot WJ, Wotton M, Newbery A, Gowman LM (2013) Global wildland fire season severity in the 21st century. For Ecol Manage 294:54–61
Fliszkiewicz M, Kusnierczak A, Szymas B (2015) Reproduction of the red mason solitary bee Osmia rufa (syn. Osmia bicornis) (Hymenoptera: Megachilidae) in various habitats. Eur J Entomol 112(1):100–105
Folke C, Carpenter S, Walker B, Scheffer M, Elmqvist T, Gunderson L, Holling CS (2004) Regime shifts, resilience, and biodiversity in ecosystem management. Annu Rev Ecol Evol Syst 35:557–581
Forrest JR, Chisholm SP (2017) Direct benefits and indirect costs of warm temperatures for high-elevation populations of a solitary bee. Ecology 98(2):359–369
Galbraith SM, Cane JH, Moldenke AR, Rivers JW (2019a) Wild bee diversity increases with local fire severity in a fire-prone landscape. Ecosphere 10(4):e02668
Galbraith SM, Cane JH, Moldenke AR, Rivers JW (2019b) Salvage logging reduces wild bee diversity, but not abundance, in severely burned mixed-conifer forest. For Ecol Manage 453:117622
Goodell K (2003) Food availability affects Osmia pumila (Hymenoptera: Megachilidae) foraging, reproduction, and brood parasitism. Oecologia 134:518–527
Guedot C, Bosch J, Kemp WP (2009) Relationship between body size and homing ability in the genus Osmia (Hymenoptera; Megachilidae). Ecol Entomol 34(1):158–161
Hanula JL, Ulyshen MD, Horn S (2016) Conserving pollinators in North American forests: a review. Nat Areas J 36(4):427–439
He T, Lamont BB, Pausas JG (2019) Fire as a key driver of Earth’s biodiversity. Biol Rev 94:1983–2010
Hobbs RJ, Huenneke LF (1992) Disturbance, diversity, and invasion: implications for conservation. Conserv Biol 6(3):324–337
Huston M (1979) A general hypothesis of species diversity. Am Nat 113(1):81–101
Ivanov SP (2006) The nesting of Osmia rufa (L.) (Hymenoptera, Megachilidae) in the Crimea: structure and composition of nests. Entomol Rev 86(5):524–533
Johnstone JF, Allen CD, Franklin JF, Frelich LE, Harvey BJ, Higuera PE, Mack MC, Meentemeyer RK, Metz MR, Perry GLW, Schoennagel T (2016) Changing disturbance regimes, ecological memory, and forest resilience. Front Ecol Environ 14(7):369–378
Jolly WM, Cochrane MA, Freeborn PH, Holden ZA, Brown TJ, Williamson GJ, Bowman DM (2015) Climate-induced variations in global wildfire danger from 1979 to 2013. Nat Commun 6:7537
Keeley JE (2009) Fire intensity, fire severity and fire severity: a brief review and suggested usage. Int J Wildland Fire 18(1):116–126
Kim YJ (1999) Influence of resource level on maternal investment in a leaf-cutter bee (Hymenoptera:Megachilidae). Behav Ecol 10(5):552–556
Lazarina M, Devalez J, Neokosmidis L, Sgardelis SP, Kallimanis AS, Tscheulin T, Tsalkatis P, Kourtidou M, Mizerakis V, Nakas G, Palaiologou P (2019) Moderate fire severity is best for the diversity of most of the pollinator guilds in Mediterranean pine forests. Ecology 100(3):e02615
Love BG, Cane JH (2016) Limited direct effects of a massive wildfire on its sagebrush steppe bee community. Ecol Entomol 41:317–326
Miller JD, Thode AE (2007) Quantifying fire severity in a heterogeneous landscape with a relative version of the delta Normalized Burn Ratio (dNBR). Remote Sens Environ 109(1):66–80
Mola JM, Williams NM (2018) Fire-induced change in floral abundance, density, and phenology benefits bumble bee foragers. Ecosphere 9(1):e02056
Nielson RM, Sugihara RT, Boardman TJ, Engeman RM (2004) Optimization of ordered distance sampling. Environmetrics 15(2):119–128
Palladini JD, Maron JL (2014) Reproduction and survival of a solitary bee along native and exotic floral resource gradients. Oecologia 176:789–798
Pausas JG (2019) Generalized fire response strategies in plants and animals. Oikos 128(2):147–153
Peterson JC, Roitberg BD (2006) Impacts of flight distance on sex ratio and resource allocation to offspring in the leafcutter bee. Megachile rotundata. Behav Ecol Sociobiol 59(5):589–596
Phillips JK, Klostermeyer EC (1978) Nesting behavior of Osmia lignaria propinqua Cresson (Hymenoptera: Megachilidae). J Kansas Entomol Soc 51:91–108
Pickett STA, White PS (1985) The ecology of natural disturbance and patch dynamics. Academic Press, Orlando
Ponisio LC, Wilkin K, Mgonigle LK, Kulhanek K, Cook L, Thorp R, Griswold T, Kremen C (2016) Pyrodiversity begets plant–pollinator community diversity. Global Change Biol 22(5):1794–1808. https://doi.org/10.1111/gcb.13236
Potts SG, Vulliamy B, Dafni A, Ne’eman G, O’Toole C, Roberts S, Willmer P (2003) Response of plant-pollinator communities to fire: changes in diversity, abundance and floral reward structure. Oikos 101(1):103–112
Potts SG, Vulliamy B, Roberts S, O’Toole C, Dafni A, Ne’eman G, Willmer P (2005) Role of nesting resources in organising diverse bee communities in a Mediterranean landscape. Ecol Entomol 30(1):78–85
Reilly MJ, Dunn CJ, Meigs GW, Spies TA, Kennedy RE, Bailey JD, Briggs K (2017) Contemporary patterns of fire extent and severity in forests of the Pacific Northwest, USA (1985–2010). Ecosphere 8(3):e01695
Rivers JW, Galbraith SM, Cane JH, Schultz CB, Ulyshen MD, Kormann UG (2018) A review of research needs for pollinators in managed conifer forests. J Forest 116(6):563–572
Roulston TAH, Goodell K (2011) The role of resources and risks in regulating wild bee populations. Annu Rev Entomol 56:293–312
Rust RW (1990) Spatial and temporal heterogeneity of pollen foraging in Osmia lignaria propinqua (Hymenoptera: Megachilidae). Environ Entomol 19(2):332–338
Simanonok MP, Burkle LA (2019) Nesting success of wood-cavity-nesting bees declines with increasing time since wildfire. Ecol Evol 9:12436–12445
Stephen WP, Undurraga JM (1976) X-radiography, an analytical tool in population studies of the leafcutter bee Megachile pacifica. J Apic Res 15(2):81–87
Stevens-Rumann CS, Kemp KB, Higuera PE, Harvey BJ, Rother MT, Donato DC, Morgan P, Veblen TT (2018) Evidence for declining forest resilience to wildfires under climate change. Ecol Lett 21(2):243–252
Swetnam TW, Allen CD, Betancourt JL (1999) Applied historical ecology: using the past to manage for the future. Ecol Appl 9:1189–1206
Taylor AH, Skinner CN (2003) Spatial patterns and controls on historical fire regimes and forest structure in the Klamath Mountains. Ecol Appl 13(3):704–719
Tepedino VJ, Torchio PF (1982) Temporal variability in the sex ratio of a non-social bee, Osmia lignaria propinqua: extrinsic determination or the tracking of an optimum? Oikos 38(2):77–182
Tepedino VJ, Torchio PF (1994) Founding and usurping: equally efficient paths to nesting success in Osmia lignaria propinqua (Hymenoptera: Megachilidae). Ann Entomol Soc Am 87(6):946–953
Torchio PF, Tepedino VJ (1980) Sex ratio, body size and seasonality in a solitary bee, Osmia lignaria propinqua Cresson (Hymenoptera: Megachilidae). Evolution 34(5):993–1003
Turner MG (2010) Disturbance and landscape dynamics in a changing world. Ecology 91(10):2833–2849
Ulbrich K, Seidelmann K (2001) Modeling population dynamics of solitary bees in relation to habitat quality. Web Ecol 2:57–64
van Mantgem PJ, Nesmith JC, Keifer M, Knapp EE, Flint A, Flint L (2013) Climatic stress increases forest fire severity across the western United States. Ecol Lett 16(9):1151–1156
Vicens N, Bosch J (2000) Pollinating efficacy of Osmia cornuta and Apis mellifera (Hymenoptera: Megachilidae, Apidae) on ‘Red Delicious’ apple. Environ Entomol 29(2):235–240
Westerling AL, Hidalgo HG, Cayan DR, Swetnam TW (2006) Warming and earlier spring increase western US forest wildfire activity. Science 313(5789):940–943
Whittaker RH (1960) Vegetation of the Siskiyou Mountains, Oregon and California. Ecol Monogr 30(3):279–338
Williams NM, Kremen C (2007) Resource distributions among habitats determine solitary bee offspring production in a mosaic landscape. Ecol Appl 17(3):910–921
Williams NM, Tepedino VJ (2003) Consistent mixing of near and distant resources in foraging bouts by the solitary mason bee Osmia lignaria. Behav Ecol 14(1):141–149
Zald HS, Dunn CJ (2018) Severe fire weather and intensive forest management increase fire severity in a multi-ownership landscape. Ecol Appl 28(4):1068–1080
Zurbuchen A, Landert L, Klaiber J, Müller A, Hein S, Dorn S (2010) Maximum foraging ranges in solitary bees: only few individuals have the capability to cover long foraging distances. Biol Cons 143(3):669–676
Acknowledgements
Funding for this work was provided by the U.S. Bureau of Land Management (Grant#L16AC00229), the Mealey/Boise Cascade/Boone, and Crockett/Noble Endowment Fund from the College of Forestry at Oregon State University, and the Fish and Wildlife Habitat in Managed Forests Research Program in the College of Forestry at Oregon State University.
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All authors contributed to conceiving and designing the experiments. SMG performed the experiments and analyzed the data. All authors contributed to writing the manuscript.
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Communicated by Sylvain Pincebourde.
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Galbraith, S.M., Cane, J.H. & Rivers, J.W. Wildfire severity influences offspring sex ratio in a native solitary bee. Oecologia 195, 65–75 (2021). https://doi.org/10.1007/s00442-020-04809-3
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DOI: https://doi.org/10.1007/s00442-020-04809-3


