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Home , Detritivore, Laricifomes officinalis, Phylloporus arenicola, Primary succession, Xeromphalina campanella

The among us: within communities

Marta Alvarez1, Ashlyn Bahrychuk2, Kellie Cutsinger1, Alexander Gallandt3, Thomas Lenihan4

1University of California, Santa Cruz, 2University of California, San Diego 3University of California, Berkeley, 4University of California, Santa Barbara

ABSTRACT

The process of succession can be a major driving force in sculpting ecological communities over time. play a crucial role in forest succession, recycling from fallen logs back into the . In this study, we examined the of , fungi, and living in fallen log microhabitats across stages in a mixed forest. We predicted there would be a shift in composition among decomposer communities in Douglas fir logs across varying degrees of decay. There was greater of fungi, mosses and invertebrates across decompositional stages, which suggests a pattern of community-wide succession. Decomposers are critical regulators of forest succession, and the diversity exhibited within these cryptic communities may be essential for maintaining forest ecosystem health.

INTRODUCTION , tree mortality is a sporadic but common occurrence. A large part of the All ecological communities are naturally process of forest succession entails dynamic, and while the direct causes of replacement of the canopy as new species succession are random, one can often ascend to replace fallen trees, but the fallen predict the changes that will arise in species tree itself undergoes a sequence of change composition during succession. Succession at its own scale as well. When a tree dies, plays a crucial role in determining decomposers colonize the rotting wood to ecosystem structure. Different species make nutrients such as nitrogen available become more or less prevalent in the for new . community over time, affecting the entire Decomposers, such as fungi and (Turner et al. 1998). For example, detritivores, are essential in facilitating wildfires clear out understory vegetation cycles (Kubortova 2008). Fungi, as and enable new plant species to establish, one of the few decomposers with the and volcanic activity results in new islands capacity to process tough plant tissue like forming and becoming colonized by a host heartwood and bark, have the ability to of species adapted to populate an abiotic cycle that has been effectively landscape (Heinselman 1981; Kamijo et al. removed from the food web (Fukusawa 2002). However, patterns of succession are 2018). This makes decomposed material not always marked by such dramatic accessible to other organisms, such as changes to the environment. In forest and occupants of higher trophic

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levels (Marcot 2017). Different decaying trees (Franklin et al. 1987). While decomposers assume specialized roles in many of the species in these this process. A previous study examining remain elusive, studying changes in fungi species on a decaying tree found community composition on a continually evidence supporting a pattern of fungal decaying tree makes it possible to tease succession, with peak concentrations of apart the interactions between species. specialists arising at different times during Fallen trees are in a continuous state of the process of decay (Fukusawa 2018). decay. From the moment of mortality to the Communities arising throughout the disappearance of all woody material from process of decomposition are largely the forest floor, these distinct states of ephemeral, with food webs establishing on decomposition can be used as a proxy for a fallen log and dispersing when decay time elapsed since tree (Maser 1984). subsides and is replaced (Franklin et al. Consistent changes in species composition 1987). The fungi and other decomposers over time could indicate a common pattern make up the backbone of these of succession within communities communities, facilitating forest succession throughout the process of tree by cycling nutrients from fallen trees to decomposition. Our research examined feed a new generation. different organisms present on fallen In a mixed conifer forest largely Douglas firs in varying states of decay in an composed of pine and hardwood trees, attempt to document a potential adult trees support a large proportion of community-wide succession within these the ecosystem’s , such as bird microhabitats. We predicted there would and populations (Uchytil be a shift in species composition among the 1991). A diverse array of fungi is present on different functional groups of the living trees; with over 1000 species of fungi communities living on decaying logs. Such a found to have symbiotic relationships with change in community structure could a single tree species, suggest a small-scale succession occurring menziesii, or Douglas fir (Aurora 1979). in decomposing trees. However, decaying trees often host more life than living trees, even if these are often METHODS less charismatic species. In a living conifer, 2.1 Natural History of Study System roughly 10% of tree cells are alive, compared to a tree in an optimal state of We conducted research at UC Berkeley’s decay, where 35% of total tree biomass is field research station at Angelo Range comprised of living fungi cells (Swift 1973). Reserve from May 4–9, 2018. The reserve is While much research has been conducted approximately 30 km2 and located in on the communities revolving around living Mendocino County, California, on the trees, relatively little is understood about headwaters of the South Fork of the Eel the communities that arise when these River. Average precipitation is around 216 trees die and begin the process of cm annually. Elevation ranges from 400 to decomposition (Franklin et al. 1987). Many 1300 meters. Habitats include mixed conifer decomposer species are overlooked, as they and hardwood forests, riparian are often hidden beneath bark or under

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environments, and abandoned river terraces, with patches of chaparral and meadow interspersed throughout the ecosystem. The reserve has historically been protected from deforestation from the timber industry (Johnson 1979). Angelo is host to the state’s largest Douglas fir community undisturbed by human impacts. Seasonal shifts in weather can be dramatic, and the 8 inches of snowfall Angelo experienced in the winter of 2018 Table 1. Classification of decay states of Douglas fir trees. Higher classes are more decayed, with class IV contributed to the of downed representing the final stage of decomposition before trees present in the ecosystem. the tree loses all original structure. Shown are Forest systems at Angelo include mixed diagnostic characteristics of different parts of the conifer, mixed hardwood, and old-growth logs at each state of decomposition. redwood groves. Mixed conifer forests We began by measuring the length of consist of predominantly Douglas firs, a each tree. In order to measure and long-lived coniferous species with a natural moss percent cover, we counted point range from West British Columbia to estimates using a quadrat placed at three Central California. At Angelo reserve, random locations along the transect. We Douglas fir has an expanding local then spent a 10 minute treatment period distribution, spreading to cover substantial counting and recording different species of tracts of traditionally mixed hardwood fungi, invertebrates, amphibians, and plants forest, replacing madrone and oak trees. present on and within the fallen log. To This shift could be due in part to increased search for organisms inside the log, we fire suppression across mixed conifer pulled up sections of bark and dug into the forests, allowing more of the shade-tolerant wood with trowels. For fungi, the underside Douglas fir to survive and take over canopy of the log was inspected using a trowel, space (Arno et al. 1995). Growing alongside flashlight, and a magnifying loop. We old-growth coastal redwood, Oregon oak, differentiated species by distinct physical California bay laurel and big leaf maple characteristics, taking pictures of trees, Douglas firs are increasingly ambiguous or unknown species, which we abundant throughout Angelo reserve. later identified. After determining the 2.2 Research Design morphospecies we created functional groups for both invertebrates and fungi We examined the community of plants, based on their roles in the environment and fungi, invertebrates, and on for ease of analysis. A total of 6 fallen Douglas fir within mixed conifer invertebrate and 8 fungi groups were habitats across Angelo Reserve. A total of created. The functional group of predators 52 trees were sampled. Each tree was included organisms such as spiders, categorized into one of four decomposition scorpions, and centipedes, while classes based on Maser et al. (1988) (Table 1). detritivores included , isopods,

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and . Functional groups for fungi included gilled , perennials such as shelf fungi, clustered fungi, and cup fungi.

2.3 Statistical Analysis

We examined differences in moss and lichen percent cover by decomposition stage using ANOVA. We also used ANOVA to examine the change in species richness of invertebrate functional groups at different stages of decomposition. Functional groups for both invertebrates and fungi were analyzed using ANOVA to Fig. 1. Total species richness by stage of decomposition. Data represent means + 1 standard see if there was any effect of error. Stage 1 represents the least decomposed decomposition level on these groups. All stage of Douglas fir log, while stage 4 represents the analyses were conducted using JMP most decayed logs. Species richness was significantly statistical software v13. greater in the final two stages of decomposition than in the first stage (P < 0.0001). RESULTS greater in the final two stages of We identified 43 morphospecies of decomposition (P = 0.0015, Figure 2). When fungus, 4 morphospecies of invertebrates were analyzed by functional , and 34 morphospecies of groups, predator and detritivore richness invertebrate across our 52 samples. were both significantly higher in the last Total richness among sampled stages of decomposition compared to the morphospecies was greater for the final first stage (P = 0.0018; P = 0.0089), while two stages of decomposition than the first richness was significantly higher in stage, with an average of 15 species the first stage compared to the later stages identified across the 12 samples at stage 4, (P = 0.0012, Figure 3). Moss percent cover and an average of 14 species at the third was significantly higher in the final stage of stage of decay, identified across the 12 decomposition than the first two stages (P = samples (n = 52, P < 0.0001, Figure 1). 0.0037, Figure 4). Overall fungi richness was Invertebrate richness was significantly significantly higher in the final stage of decomposition compared to the first and second stage (P = 0.0012, Figure 5). Also, when analyzing functional groups for fungi, we found perennial richness decreases as a tree decays (P = 0.0055), while gilled mushroom richness increases throughout the decomposition process (P = 0.0077, Figure 6). There seems to be an optimal timing for clustered fungi as well, as stages 2 and 3 had a higher richness of

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these when compared with stages 1 and 4 (P = 0.0147, Figure 6). Lichen did not demonstrate any significant trends between stages of decomposition.

Fig. 4. Percent cover of moss by stage of decomposition. Data represent means + 1 standard error. Stage 1 represents the least decomposed stage of Douglas fir logs, while stage 4 represents the most decayed logs. There was a significant Fig. 2. Invertebrate species richness by stage of increase in moss cover on logs in the final stages of decomposition. Data represent means + 1 standard decomposition when compared to the first two error. Stage 1 represents the least decomposed stages (P < 0.01). stage of Douglas fir logs, while stage 4 represents the most decayed logs. Invertebrate species richness was significantly greater in the final two stages of decomposition than in the first stage (P < 0.01).

Fig. 5. Fungi species richness by stage of decomposition. Data represent means + 1 standard Fig. 3. Trends in invertebrate functional group error. There was a significant increase in richness in richness across differing stages of decomposition. the last stage of decomposition (P > 0.001). Points along the lines represent the mean group richness at each stage of decomposition. The blue line shows an increase of predator richness in later stages (P > 0.001). The green line shows an increase of detritivore richness in later stages of decomposition (P > 0.001). The red line shows a decrease in termite richness after the first stage of decomposition (P < 0.01)

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Fig. 6. Fungal composition of fallen logs at each stage of decomposition. Each color represents a different fungi functional group. Solid filled groups indicate a significant difference across stages of decomposition, while the striped groups indicate no significant differences. Stage 1 represents the least decomposed stage of Douglas fir logs, while stage 4 represents the most decayed logs. Red shows stage 1 has a higher percentage of perennial fungi (n = 52, P < 0.01). Blue shows stages 3 and 4 have a higher percentage of gilled fungi (P < 0.01). Green shows stages 2 and 3 have a higher percentage of clustered fungi (P < 0.05). Purple shows stage 4 has a higher percentage of cup fungi compared with stage 1 (P < 0.05).

DISCUSSION play in breaking down a log occurs early in the process. Studies have indicated We found clear differences in both higher activity of , microbes, and invertebrate and fungi richness in later levels of nitrogen fixation in logs that have stages of decomposition in Douglas firs. As been broken down by wood boring insects a tree decays, termite richness decreases than on those without (Fukusawa 2018; while detritivore, predator, and fungi Franklin et al. 1987). Wood borers’ initial richness increases. This suggests a pattern act of decomposition could potentially of change in community structure within a facilitate further colonization by other fallen tree as it decomposes. Wood boring species of invertebrates and fungi as time insects such as termites and carpenter ants passes. Once termites begin the process of are important in initiating early stages of decomposition, it creates for decomposition (Franklin et al. 1987). The detritivores to move in as the wood decrease in termites after the first stage of becomes softer with rot and more nutrient decomposition suggests that the role rich. With the increase of detritivores, we

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also see an increase of predators. This could in a specific ecosystem, comparing be due to increased prey availability or decomposer communities across tree more accessible inner habitat space. Not species could further our understanding of only do logs in peak decay exhibit greater these diverse, little-known microhabitats, fungi species richness, but certain and potentially provide insight into functional groups of fungi only appear in conservation and management practices. the later stage of decomposition, Studying how decomposer communities overtaking previously dominant form on other dominant such as decomposers. Our results suggest redwoods or hardwoods like live oak, community-level succession is occurring madrone, and bay laurel, could provide a within microhabitats formed on fallen logs. more comprehensive picture of whether However, our study system is comprised similar succession patterns occur across of a robust community of Douglas firs that species. It is likely the decomposer have not been logged or clear cut, an communities inhabiting different tree increasingly uncommon ecosystem in the species would differ in species composition Pacific Northwest of the anthropocene to some extent, and a comparison of these (Duffy et al. 2007). Patterns of succession patterns could reveal the diversity found on within similar microhabitats may not be as Douglas fir logs that is unique to the clear in habitats disturbed by human species. Research often overlooks these industry. Forest ecosystems are under cryptic communities, but these threat by human impact, including logging microhabitats are home to diverse systems to conifer forests like our study system of of tremendous ecological importance. Angelo Reserve (Duffy et al. 2007). Douglas fir trees are one of biggest sources of ACKNOWLEDGMENTS logging in North America (Fowells 1965). When a tree is cut down and immediately This work was performed at the taken out of the ecosystem, there is no University of California’s Angelo Coast opportunity for early stage decomposers to Range Reserve, doi:10.21973/N3R94R. establish, and the communities that utilize REFERENCES decaying logs as microhabitats could experience marked declines. Reduction in Arno, S. F., Scott, J. H., & Hartwell, M. G. (1995). Age- richness and complexity of decomposer class structure of old growth ponderosa communities has serious implications for pine/Douglas-fir stands and its relationship to fire forest health, as it might inhibit the nutrient history (p. 25). US Department of Agriculture, Forest Service, Research Paper INT-RP-481. 31 pp. cycling that plays a vital role in plant growth. Our results can be utilized to Aurora, D. (1979). Mushrooms Demystified. Ten showcase what could be lost in diversity Speed Press, 170 pp. and ecosystem dynamics when logging or Duffy, J. E., Cardinale, B. J., France, K. E., McIntyre, P. removing fallen trees. B., Thebault, E., & Loreau, M. (2007). The We hope our study provides a baseline functional role of biodiversity in ecosystems: understanding of patterns of community incorporating trophic complexity. Letters succession. We realize that while our results 10(6):522–538. only represent a single species of host tree

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Fowells, H. A. (1965). Silvics of forest trees of the Agriculture, Forest Service, Pacific Northwest United States. Agric. Handb. US Dep. Agric., (271). Research Station. 31 p.

Franklin, J. F., Shugart, H. H., & Harmon, M. E. Maser, C., Mate, B. R., Franklin, J. F., & Dyrness, C. T. (1987). Tree death as an ecological process. (1981). Natural history of Oregon coast mammals. BioScience 37(8):550–556. Gen. Tech. Rep. PNW-GTR-133. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Fukasawa, Y. (2018). Fungal succession and Northwest Forest and Range Experiment Station. decomposition of Pinus densiflora snags. 524 p. Ecological Research 33(2):435–444. Maser, C. et al. (1988). From the forest to the : a Heinselman, M. L. (1981). Fire and succession in the story of fallen trees. Gen. Tech. Rep. PNW-GTR- conifer forests of northern North America. In 229. Portland, OR: U.S. Department of Agriculture, Forest succession (pp. 374–405). Springer, New Forest Service, Pacific Northwest Research Station. York, NY. 153 p.

Johnson, S. (1979). The land history use of the Coast Swift, M. J. (1973). The estimation of mycelial Range Preserve, Mendocino County, California. biomass by determination of the hexosamine Master’s thesis, San Francisco State University, 11 content of wood tissue decayed by fungi. Soil pp. Biology and Biochemistry 5(3):321–332.

Kamijo, T., Kitayama, K., Sugawara, A., Urushimichi, Turner, M. G., Baker, W. L., Peterson, C. J., & Peet, R. S., & Sasai, K. (2002). Primary succession of the K. (1998). Factors influencing succession: lessons warm-temperate broad-leaved forest on a from large, infrequent natural disturbances. volcanic island, Miyake-jima, Japan. Folia Ecosystems 1(6):511-523. Geobotanica 37(1):71–91. Uchytil, R. (1991). Pseudotsuga menziesii var. Kubartová, A., Ranger, J., Berthelin, J., & Beguiristain, menziesii. In: Fire Effects Information System. U.S. T. (2009). Diversity and decomposing ability of Department of Agriculture, Forest Service, Rocky saprophytic fungi from temperate forest litter. Mountain Research Station, Fire Sciences 58(1):98–107. Laboratory.

Marcot, B. G. (2017). A review of the role of fungi in wood decay of forest ecosystems. Res. Note. PNW-RN-575. Portland, OR: US Department of

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APPENDIX

Fungi found with/near Douglas fir (Pseudotsuga menziesii)

Phylloporus arenicola - Western Gilled Mycena rosella - Rosy Pink Mycena

Fuligo septica - Dog Vomit Slime Mold or Scrambled Egg Slime Mold

Fomitopsis pinicola - Red Belted Conk

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Phaeolus schweinitzii - Dyer’s Polypore

Ceriporia spissa - Orange Pored Crust Tomentella spp.

Nidula candida - Bird’s Nest

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Trametes versicolor - Turkey Tail

Plectania milleri

Xeromphalina campanella - Fuzzy Foot

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Ceratiomyxa fruticulosa - Coral Slime Mold

Geopyxis vulcanalis - Fairy Fart

Cryptoporus volvatus - Hard Veiled Puffball Laricifomes officinalis - Agarikon

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Pleurotus sp. – Oyster

Other Fungi found at Angelo Reserve

Hygrophorus species

Amanita species

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Helvella - Elfin Saddle Species Annulohypoxylon thouarsianum - Carbon Balls

Lycoperdon pyriforme - Gem Studded Puffball Other Decomposer Species Found at Angelo

Paeromopus angusticeps Harpaphe haydeniana - Black and yellow

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Unidentified Species Found

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