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Shaw DC, Beedlow PA, Lee EH, Woodruff DR, Meigs GW, Calkins SJ, Reilly MJ, Merschel AG, Cline SP, Comeleo RL. The complexity of biological disturbance agents, fuels heterogeneity, and fire in coniferous forests of the western United States. FOREST ECOLOGY AND MANAGEMENT 2022; 525:1-27. [PMID: 36968296 PMCID: PMC10031511 DOI: 10.1016/j.foreco.2022.120572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Forest biological disturbance agents (BDAs) are insects, pathogens, and parasitic plants that affect tree decline, mortality, and forest ecosystems processes. BDAs are commonly thought to increase the likelihood and severity of fire by converting live standing trees to more flammable, dead and downed fuel. However, recent research indicates that BDAs do not necessarily increase, and can reduce, the likelihood or severity of fire. This has led to confusion regarding the role of BDAs in influencing fuels and fire in fire-prone western United States forests. Here, we review the existing literature on BDAs and their effects on fuels and fire in the western US and develop a conceptual framework to better understand the complex relationships between BDAs, fuels and fire. We ask: 1) What are the major BDA groups in western US forests that affect fuels? and 2) How do BDA-affected fuels influence fire risk and outcomes? The conceptual framework is rooted in the spatiotemporal aspects of BDA life histories, which drive forest impacts, fuel characteristics and if ignited, fire outcomes. Life histories vary among BDAs from episodic, landscape-scale outbreaks (bark beetles, defoliators), to chronic, localized disturbance effects (dwarf mistletoes, root rots). Generally, BDAs convert aboveground live biomass to dead biomass, decreasing canopy fuels and increasing surface fuels. However, the rate of conversion varies with time-since-event and among BDAs and forest types, resulting in a wide range of effects on the amount of dead fuels at any given time and place, which interacts with the structure and composition of the stand before and subsequent to BDA events. A major influence on fuels may be that BDAs have emerged as dominant agents of forest heterogeneity creation. Because BDAs play complex roles in fuels and fire heterogeneity across the western US which are further complicated by interactions with climate change, drought, and forest management (fire suppression), their impacts on fuels, fire and ecological consequences cannot be categorized simply as positive or negative but need to be evaluated within the context of BDA life histories and ecosystem dynamics.
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Affiliation(s)
- David C. Shaw
- Department of Forest Engineering, Resources, and Management, Oregon State University, 216 Peavy Forest Science Complex, 3100 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Peter A. Beedlow
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| | - E. Henry Lee
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| | - David R. Woodruff
- USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97333, USA
| | - Garrett W. Meigs
- Washington State Department of Natural Resources, 1111 Washington St. SE, Olympia, WA 98504, USA
- Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, 3180 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Stephen J. Calkins
- Department of Forest Engineering, Resources, and Management, Oregon State University, 216 Peavy Forest Science Complex, 3100 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Matthew J. Reilly
- USDA Forest Service, Pacific Northwest Research Station, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97333, USA
| | - Andrew G. Merschel
- Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, 3180 SW Jefferson Way, Corvallis, OR 97331, USA
| | - Steven P. Cline
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
| | - Randy L. Comeleo
- U.S. Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA
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2
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LeBoldus JM, Navarro SM, Kline N, Ritokova G, Grünwald NJ. Repeated Emergence of Sudden Oak Death in Oregon: Chronology, Impact, and Management. PLANT DISEASE 2022; 106:3013-3021. [PMID: 35486603 DOI: 10.1094/pdis-02-22-0294-fe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
It has been two decades since the first detection of the sudden oak death pathogen Phytophthora ramorum in Oregon forests. Although the epidemic was managed since its first discovery in 2001, at least three invasions of three separate variants (clonal lineages), NA1, EU1, and NA2, are documented to have occurred to date. Control of this epidemic has cost over US$32 million from 2001 to 2020. This is dwarfed by the predicted cost of the closure to the Coos Bay export terminal, estimated at $58 million per year, if the epidemic was allowed to spread unchecked. Management efforts in Oregon have reduced inoculum and limited the spread of the pathogen. An outreach and citizen scientist program has been piloted to help in early detection efforts and search for disease-resistant tanoak. This feature article documents the repeated emergence, impact, costs, and lessons learned from managing this devastating invasive pathogen.
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Affiliation(s)
- Jared M LeBoldus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
- Forest Engineering, Resources and Management Department, Oregon State University, Corvallis, OR
| | | | - Norma Kline
- Forest Engineering, Resources and Management Department, Oregon State University, Corvallis, OR
| | | | - Niklaus J Grünwald
- Horticultural Crops Research Laboratory, United States Department of Agriculture-Agricultural Research Service, Corvallis, OR
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3
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Drake-Schultheis L, D'Antonio CM, Oono R. Patterns and Distribution of Botryosphaeriaceae Fungi Related to Dieback in Big Berry Manzanita. PHYTOPATHOLOGY 2022; 112:2341-2350. [PMID: 35731020 DOI: 10.1094/phyto-02-22-0044-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Dieback and mortality in wildland plant species due to climate change have been on the rise in recent decades, and latent fungal pathogens might play a significant role in these events. During a severe multiyear drought, canopy dieback associated with latent pathogens in the Botryosphaeriaceae (Bot) family was observed in stands of a dominant shrub species, big berry manzanita (Arctostaphylos glauca), across chaparral landscapes in California. These fungi are significant pathogens of woody agricultural species, especially in hosts experiencing stress, and have become a threat to economically important crops worldwide. However, little is known regarding their occurrence, distribution, and impact in wildland systems. We conducted a field survey of 300 A. glauca shrubs across an elevational gradient to identify Bot species infection as it relates to (i) A. glauca dieback severity and (ii) landscape variables associated with plant drought stress. Our results show that Bots are widely infecting A. glauca across the landscape, and there is a significant correlation between elevation and dieback severity. Dieback severity was significantly higher at lower elevations, suggesting that infected shrubs at lower elevations are at greater risk than those at higher elevations. Furthermore, two Bot species, Neofusicoccum australe and Botryosphaeria dothidea, were most frequently isolated, with N. australe being the most common and, based on haplotype analysis, likely the most recently introduced of the two. Our results confirm the wide distribution of latent Bot fungi in a wild shrubland system and provide valuable insight into areas of greatest risk for future shrub dieback and mortality. These findings could be particularly useful for informing future wildlands management strategies with regard to introduced latent pathogens.
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Affiliation(s)
- Laura Drake-Schultheis
- Ecology, Evolution, and Marine Biology Department, University of California, Santa Barbara, CA 93106
- Life Sciences Department, Westmont College, Santa Barbara, CA 93108
| | - Carla M D'Antonio
- Ecology, Evolution, and Marine Biology Department, University of California, Santa Barbara, CA 93106
| | - Ryoko Oono
- Ecology, Evolution, and Marine Biology Department, University of California, Santa Barbara, CA 93106
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Daniels HA, Navarro SM, LeBoldus JM. Local Eradication of Phytophthora ramorum Is Effective on Both NA1 and EU1 Lineages in Oregon Tanoak Forests. PLANT DISEASE 2022; 106:1392-1400. [PMID: 35100027 DOI: 10.1094/pdis-07-21-1588-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Sudden oak death (SOD), caused by the oomycete Phytophthora ramorum, has been actively managed in Oregon since its discovery there in 2001. SOD is a devastating disease affecting an ecologically and culturally important tree species in southwestern Oregon. Initially infested with the NA1 lineage, the more virulent EU1 lineage was discovered in 2015. Management has adapted over time in response to experimental findings and administrative limitations. Current management practices present an opportunity to compare the efficacy of treatment on these lineages by analyzing P. ramorum inoculum at untreated and treated sites. Current treatment includes herbicide treatment on host stems followed by felling, piling, and burning on site. Infested sites were visited between 2018 and 2020 (n = 88), where understory vegetation and soil was collected. Generalized linear modeling demonstrated that treatment had a significant impact on P. ramorum prevalence from vegetation samples, with an average of 33% (± 10%) fewer positive samples at treated sites. Linear mixed-effects modeling of a subpopulation of EU1 sites visited before and after treatment showed a similar effect of treatment, with a 43% (± 15%) reduction in P. ramorum prevalence. Prevalence of P. ramorum in soil was not affected by treatment in either analysis. A third analysis taking into consideration recent wildfire incursion into infested areas revealed that wildfire alone is insufficient to reduce prevalence of P. ramorum. These results strongly suggest that management is successfully reducing P. ramorum inoculum found on understory vegetation, and that treatment remains necessary to reduce the spread of this major forest pathogen.
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Affiliation(s)
- Hazel A Daniels
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
| | - Sarah M Navarro
- United States Department of Agriculture Forest Service, State and Private Forestry, Forest Health Protection, Portland, OR
| | - Jared M LeBoldus
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR
- Department of Forest Engineering, Resources, and Management, Oregon State University, Corvallis, OR
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A Barcode-Based Phylogenetic Characterization of Phytophthora cactorum Identifies Two Cosmopolitan Lineages with Distinct Host Affinities and the First Report of Phytophthora pseudotsugae in California. J Fungi (Basel) 2022; 8:jof8030303. [PMID: 35330305 PMCID: PMC8950362 DOI: 10.3390/jof8030303] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 03/11/2022] [Accepted: 03/12/2022] [Indexed: 02/04/2023] Open
Abstract
A collection of 30 Phytophthora cactorum and 12 P. pseudotsugae (subclade 1a) strains isolated from several recent surveys across California was phylogenetically compared to a worldwide collection of 112 conspecific strains using sequences from three barcoding loci. The surveys baited P. cactorum from soil and water across a wide variety of forested ecosystems with a geographic range of more than 1000 km. Two cosmopolitan lineages were identified within the widespread P. cactorum, one being mainly associated with strawberry production and the other more closely associated with apple orchards, oaks and ornamental trees. Two other well-sampled P. cactorum lineages, including one that dominated Californian restoration outplantings, were only found in the western United States, while a third was only found in Japan. Coastal California forest isolates of both Phytophthora species exhibited considerable diversity, suggesting both may be indigenous to the state. Many isolates with sequence accessions deposited as P. cactorum were determined to be P. hedraiandra and P. ×serendipita, with one hybrid lineage appearing relatively common across Europe and Asia. This study contains the first report of P. pseudotsugae from the state of California and one of the only reports of that species since its original description.
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Enright DJ, Frangioso KM, Isobe K, Rizzo DM, Glassman SI. Mega‐fire in Redwood Tanoak Forest Reduces Bacterial and Fungal Richness and Selects for Pyrophilous Taxa that are Phylogenetically Conserved. Mol Ecol 2022; 31:2475-2493. [DOI: 10.1111/mec.16399] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 01/19/2022] [Accepted: 02/03/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Dylan J. Enright
- Department of Microbiology and Plant Pathology University of California 3401 Watkins Drive Riverside CA 92521 USA
| | - Kerri M. Frangioso
- Department of Plant Pathology University of California 1 Shields Ave Davis CA 95616 USA
| | - Kazuo Isobe
- Department of Applied Biological Chemistry Graduate School of Agricultural and Life Sciences The University of Tokyo 1‐1‐1 Yayoi, Bunkyo‐ku Tokyo 113‐8657
| | - David M. Rizzo
- Department of Plant Pathology University of California 1 Shields Ave Davis CA 95616 USA
| | - Sydney I. Glassman
- Department of Microbiology and Plant Pathology University of California 3401 Watkins Drive Riverside CA 92521 USA
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7
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Rosenthal LM, Simler-Williamson AB, Rizzo DM. Community-level prevalence of a forest pathogen, not individual-level disease risk, declines with tree diversity. Ecol Lett 2021; 24:2477-2489. [PMID: 34510681 DOI: 10.1111/ele.13871] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/18/2021] [Accepted: 08/10/2021] [Indexed: 11/27/2022]
Abstract
Understanding why diversity sometimes limits disease is essential for managing outbreaks; however, mechanisms underlying this 'dilution effect' remain poorly understood. Negative diversity-disease relationships have previously been detected in plant communities impacted by an emerging forest disease, sudden oak death. We used this focal system to empirically evaluate whether these relationships were driven by dilution mechanisms that reduce transmission risk for individuals or from the fact that disease was averaged across the host community. We integrated laboratory competence measurements with plant community and symptom data from a large forest monitoring network. Richness increased disease risk for bay laurel trees, dismissing possible dilution mechanisms. Nonetheless, richness was negatively associated with community-level disease prevalence because the disease was aggregated among hosts that vary in disease susceptibility. Aggregating observations (which is surprisingly common in other dilution effect studies) can lead to misinterpretations of dilution mechanisms and bias towards a negative diversity-disease relationship.
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Affiliation(s)
- Lisa M Rosenthal
- Graduate Group in Ecology, University of California, Davis, California, USA.,Department of Plant Pathology, University of California, Davis, California, USA
| | | | - David M Rizzo
- Department of Plant Pathology, University of California, Davis, California, USA
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8
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Rosenthal LM, Fajardo SN, Rizzo DM. Sporulation Potential of Phytophthora ramorum Differs Among Common California Plant Species in the Big Sur Region. PLANT DISEASE 2021; 105:2209-2216. [PMID: 33200968 DOI: 10.1094/pdis-03-20-0485-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Sudden oak death (SOD), caused by the generalist pathogen Phytophthora ramorum, has profoundly impacted California coastal ecosystems. SOD has largely been treated as a two-host system, with Umbellularia californica as the most transmissive host, Notholithocarpus densiflorus less so, and remaining species as epidemiologically unimportant. However, this understanding of transmission potential primarily stems from observational field studies rather than direct measurements on the diverse assemblage of plant species. Here, we formally quantify the sporulation potential of common plant species inhabiting SOD-endemic ecosystems on the California coast in the Big Sur region. This study allows us to better understand the pathogen's basic biology, trajectory of SOD in a changing environment, and how the entire host community contributes to disease risk. Leaves were inoculated in a controlled laboratory environment and assessed for production of sporangia and chlamydospores, the infectious and resistant propagules, respectively. P. ramorum was capable of infecting every species in our study and almost all species produced spores to some extent. Sporangia production was greatest in N. densiflorus and U. californica and the difference was insignificant. Even though other species produced much less, quantities were nonzero. Thus, additional species may play a previously unrecognized role in local transmission. Chlamydospore production was highest in Acer macrophyllum and Ceanothus oliganthus, raising questions about the role they play in pathogen persistence. Lesion size did not consistently correlate with the production of either sporangia or chlamydospores. Overall, we achieved an empirical foundation to better understand how community composition affects transmission of P. ramorum.
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Affiliation(s)
- Lisa M Rosenthal
- Department of Plant Pathology, University of California, Davis, CA 95616
- Graduate Group in Ecology, University of California, Davis, CA 95616
| | | | - David M Rizzo
- Department of Plant Pathology, University of California, Davis, CA 95616
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9
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Wayman RB, Safford HD. Recent bark beetle outbreaks influence wildfire severity in mixed-conifer forests of the Sierra Nevada, California, USA. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02287. [PMID: 33426715 DOI: 10.1002/eap.2287] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 09/11/2020] [Accepted: 10/06/2020] [Indexed: 06/12/2023]
Abstract
In temperate forests, elevated frequency of drought related disturbances will likely increase the incidence of interactions between disturbances such as bark beetle epidemics and wildfires. Our understanding of the influence of recent drought and insect-induced tree mortality on wildfire severity has largely lacked information from forests adapted to frequent fire. A recent unprecedented tree mortality event in California's Sierra Nevada provides an opportunity to examine this disturbance interaction in historically frequent-fire forests. Using field data collected within areas of recent tree mortality that subsequently burned in wildfire, we examined whether and under what conditions wildfire severity relates to severity of prefire tree mortality in Sierra Nevada mixed-conifer forests. We collected data on 180 plots within the 2015 Rough Fire and 2016 Cedar Fire footprints (California, USA). Our analyses identified prefire tree mortality as influential on all measures of wildfire severity (basal area killed by fire, RdNBR, and canopy torch) on the Cedar Fire, although it was less influential than fire weather (relative humidity). Prefire tree mortality was influential on two of three fire-severity measures on the Rough Fire, and was the most important predictor of basal area killed by fire; topographic position was influential on two metrics. On the Cedar Fire, the influence of prefire mortality on basal area killed by fire was greater under milder weather conditions. All measures of fire severity increased as prefire mortality increased up to prefire mortality levels of approximately 30-40%; further increases did not result in greater fire severity. The interacting disturbances shifted a pine-dominated system (Rough Fire) to a cedar-pine-fir system, while the pre-disturbance fir-cedar system (Cedar Fire) saw its dominant species unchanged. Managers of historically frequent-fire forests will benefit from utilizing this information when prioritizing fuels reduction treatments in areas of recent tree mortality, as it is the first empirical study to document a relationship between prefire mortality and subsequent wildfire severity in these systems. This study contributes to a growing body of evidence that the influence of prefire tree mortality on wildfire severity in temperate coniferous forests may depend on other conditions capable of driving extreme wildfire behavior, such as weather.
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Affiliation(s)
- Rebecca B Wayman
- Department of Environmental Science and Policy, University of California, Davis, 95616, USA
| | - Hugh D Safford
- Department of Environmental Science and Policy, University of California, Davis, 95616, USA
- Pacific Southwest Region, USDA Forest Service, Vallejo, California, 94592, USA
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10
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Disease-mediated ecosystem services: Pathogens, plants, and people. Trends Ecol Evol 2020; 35:731-743. [DOI: 10.1016/j.tree.2020.04.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 04/03/2020] [Accepted: 04/07/2020] [Indexed: 01/05/2023]
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11
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Terpenoid Accumulation Links Plant Health and Flammability in the Cypress-Bark Canker Pathosystem. FORESTS 2020. [DOI: 10.3390/f11060651] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To explore the possible relationship between diseased trees and wildfires, we assessed the flammability of canker-resistant and susceptible common cypress clones that were artificially infected with Seiridium cardinale compared to healthy trees. This study explored the effect of terpenoids produced by the host plant in response to infection and the presence of dead plant portions on flammability. Terpenoids were extracted and quantified in foliage and bark samples by gas chromatography–mass spectrometry (GC–MS). A Mass Loss Calorimeter was used to determine the main flammability descriptors. The concentration of terpenoids in bark and leaf samples and the flammability parameters were compared using a generalized linear mixed models (GLMM) model. A partial least square (PLS) model was generated to predict flammability based on the content of terpenoid, clone response to bark canker and the disease status of the plants. The total terpenoid content drastically increased in the bark of both cypress clones after infection, with a greater (7-fold) increase observed in the resistant clone. On the contrary, levels of terpenoids in leaves did not alter after infection. The GLMM model showed that after infection, plants of the susceptible clone appeared to be much more flammable in comparison to those of resistant clones, showing higher ignitability, combustibility, sustainability and consumability. This was mainly due to the presence of dried crown parts in the susceptible clone. The resistant clone showed a slightly higher ignitability after infection, while the other flammability parameters did not change. The PLS model (R2Y = 56%) supported these findings, indicating that dead crown parts and fuel moisture content accounted for most of the variation in flammability parameters and greatly prevailed on terpenoid accumulation after infection. The results of this study suggest that a disease can increase the flammability of trees. The deployment of canker-resistant cypress clones can reduce the flammability of cypress plantations in Mediterranean areas affected by bark canker. Epidemiological data of diseased tree distribution can be an important factor in the prediction of fire risk.
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12
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Gaydos DA, Petrasova A, Cobb RC, Meentemeyer RK. Forecasting and control of emerging infectious forest disease through participatory modelling. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180283. [PMID: 31104598 PMCID: PMC6558554 DOI: 10.1098/rstb.2018.0283] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Epidemiological models are powerful tools for evaluating scenarios and visualizing patterns of disease spread, especially when comparing intervention strategies. However, the technical skill required to synthesize and operate computational models frequently renders them beyond the command of the stakeholders who are most impacted by the results. Participatory modelling (PM) strives to restructure the power relationship between modellers and the stakeholders who rely on model insights by involving these stakeholders directly in model development and application; yet, a systematic literature review indicates little adoption of these techniques in epidemiology, especially plant epidemiology. We investigate the potential for PM to integrate stakeholder and researcher knowledge, using Phytophthora ramorum and the resulting sudden oak death disease as a case study. Recent introduction of a novel strain (European 1 or EU1) in southwestern Oregon has prompted significant concern and presents an opportunity for coordinated management to minimize regional pathogen impacts. Using a PM framework, we worked with local stakeholders to develop an interactive forecasting tool for evaluating landscape-scale control strategies. We find that model co-development has great potential to empower stakeholders in the design, development and application of epidemiological models for disease control. This article is part of the theme issue ‘Modelling infectious disease outbreaks in humans, animals and plants: epidemic forecasting and control’. This theme issue is linked with the earlier issue ‘Modelling infectious disease outbreaks in humans, animals and plants: approaches and important themes’.
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Affiliation(s)
- Devon A Gaydos
- 1 Department of Forestry and Environmental Resources, North Carolina State University , 2800 Faucette Drive, Raleigh, NC 27606 , USA.,2 Center for Geospatial Analytics, North Carolina State University , 2800 Faucette Drive, Raleigh, NC 27606 , USA
| | - Anna Petrasova
- 2 Center for Geospatial Analytics, North Carolina State University , 2800 Faucette Drive, Raleigh, NC 27606 , USA
| | - Richard C Cobb
- 3 Department of Natural Resources and Environmental Science, California Polytechnic State University , San Luis Obispo, CA 93407 , USA
| | - Ross K Meentemeyer
- 1 Department of Forestry and Environmental Resources, North Carolina State University , 2800 Faucette Drive, Raleigh, NC 27606 , USA.,2 Center for Geospatial Analytics, North Carolina State University , 2800 Faucette Drive, Raleigh, NC 27606 , USA
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13
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Simler‐Williamson AB, Metz MR, Frangioso KM, Meentemeyer RK, Rizzo DM. Compound disease and wildfire disturbances alter opportunities for seedling regeneration in resprouter‐dominated forests. Ecosphere 2019. [DOI: 10.1002/ecs2.2991] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
| | - Margaret R. Metz
- Department of Biology Lewis & Clark College Portland Oregon 97219 USA
| | - Kerri M. Frangioso
- Department of Plant Pathology University of California Davis California 95616 USA
| | - Ross K. Meentemeyer
- Department of Forestry and Environmental Resources & the Center for Geospatial Analytics North Carolina State University Raleigh North Carolina 27695 USA
| | - David M. Rizzo
- Department of Plant Pathology University of California Davis California 95616 USA
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14
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Dillon WW, Meentemeyer RK. Direct and indirect effects of forest microclimate on pathogen spillover. Ecology 2019; 100:e02686. [PMID: 30854627 DOI: 10.1002/ecy.2686] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 02/21/2019] [Indexed: 11/09/2022]
Abstract
Disease dynamics are governed by variation of individuals, species, and environmental conditions across space and time. In some cases, an alternate reservoir host amplifies pathogen loads and drives disease transmission to less competent hosts in a process called pathogen spillover. Spillover is frequently associated with multi-host disease systems where a single species is more tolerant of infection and more competent in pathogen transmission compared to other hosts. Pathogen spillover must be driven by biotic factors, including host and community characteristics, yet biotic factors interact with the abiotic environment (e.g., temperature) to create disease. Despite its fundamental role in disease dynamics, the influence of the abiotic environment on pathogen spillover has seldom been examined. Improving our understanding of disease processes such as pathogen spillover hinges on disentangling the effects of interrelated biotic and abiotic factors over space and time. We applied 10 yr of fine-scale microclimate, disease, and tree community data in a path analysis to investigate the relative influence of biotic and abiotic factors on pathogen spillover for the emerging infectious forest disease sudden oak death (SOD). Disease transmission in SOD is primarily driven by the reservoir host California bay laurel, which supports high foliar pathogen loads that spillover onto neighboring oak trees and create lethal canker infections. The foliar pathogen load and susceptibility of oaks is expected to be sensitive to forest microclimate conditions. We found that biotic factors of pathogen load and tree diversity had relatively stronger effects on pathogen spillover compared to abiotic microclimate factors, with pathogen load increasing oak infection and tree diversity reducing oak infection. Abiotic factors still had significant effects, with greater heat exposure during summer months reducing pathogen loads and optimal pathogen conditions during the wet season increasing oak infection. Our results offer clues to possible disease dynamics under future climate change where hotter and drier or warmer and wetter conditions could have opposing effects on pathogen spillover in the SOD system. Disentangling direct and indirect effects of biotic and abiotic factors affecting disease processes can provide key insights into disease dynamics including potential avenues for reducing disease spread and predicting future epidemics.
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Affiliation(s)
- Whalen W Dillon
- Department of Forestry & Environmental Resources, North Carolina State University, Raleigh, North Carolina, 27695, USA.,Center for Geospatial Analytics, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - Ross K Meentemeyer
- Department of Forestry & Environmental Resources, North Carolina State University, Raleigh, North Carolina, 27695, USA.,Center for Geospatial Analytics, North Carolina State University, Raleigh, North Carolina, 27695, USA
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15
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Simler-Williamson AB, Rizzo DM, Cobb RC. Interacting Effects of Global Change on Forest Pest and Pathogen Dynamics. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2019. [DOI: 10.1146/annurev-ecolsys-110218-024934] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Pathogens and insect pests are important drivers of tree mortality and forest dynamics, but global change has rapidly altered or intensified their impacts. Predictive understanding of changing disease and outbreak occurrence has been limited by two factors: ( a) tree mortality and morbidity are emergent phenomena determined by interactions between plant hosts, biotic agents (insects or pathogens), and the environment; and ( b) disparate global change drivers co-occur, obscuring net impacts on each of these components. To expand our understanding of changing forest diseases, declines, and outbreaks, we adopt a framework that identifies and organizes observed impacts of diverse global change drivers on the primary mechanisms underlying agent virulence and host susceptibility. We then discuss insights from ecological theory that may advance prediction of forest epidemics and outbreaks. This approach highlights key drivers of changing pest and pathogen dynamics, which may inform forest management aimed at mitigating accelerating rates of tree mortality globally.
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Affiliation(s)
| | - David M. Rizzo
- Department of Plant Pathology, University of California, Davis, California 95616, USA;,
| | - Richard C. Cobb
- Department of Natural Resources Management and Environmental Science, California Polytechnic State University, San Luis Obispo, California 93407, USA
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Simler AB, Metz MR, Frangioso KM, Meentemeyer RK, Rizzo DM. Novel disturbance interactions between fire and an emerging disease impact survival and growth of resprouting trees. Ecology 2018; 99:2217-2229. [PMID: 30129261 DOI: 10.1002/ecy.2493] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 05/30/2018] [Accepted: 07/17/2018] [Indexed: 11/11/2022]
Abstract
Human-altered ecological disturbances may challenge system resilience and disrupt biological legacies maintaining ecosystem recovery. Yet, the extent to which novel regimes challenge these legacies varies. This may be partially explained by differences in the vulnerability of life history strategies to disturbance characteristics. In the fire-prone, resprouter-dominated coast redwood forests of California, the introduced disease sudden oak death (SOD) alters fuel profiles, fire behavior, and aboveground tree mortality; however, this system is dominated by resprouting trees that are well-adapted to aboveground damage, and belowground survival of individuals may represent the principal biological legacy connecting pre- and post-fire communities. Much of the research exploring altered disturbances and forest recovery has focused on legacies determined by seed dispersal and aboveground survival of adults. In this work, we use pre- and post-fire data from a long-term monitoring network to assess the impacts of novel disturbance interactions between wildfire and SOD on the belowground survival and vegetative reproduction of resprouters. We found that increasing accumulation of coarse woody surface fuels from SOD-killed hosts decreased the likelihood of belowground survival for resprouting tanoak trees, but not for redwoods. Tanoaks' belowground survival was negatively related to substrate burn severity, which increased with the volume of surface fuels from hosts, suggesting heat damage as a possible mechanism influencing altered patterns of resprouter mortality. These impacts increased with decreasing tree size. By contrast, redwood and tanoak trees that survived both disturbances resprouted more vigorously, regardless of post-fire infection by P. ramorum, and generated similar recruitment at the stand level. Our results demonstrate that disease-fire interactions can narrow recruitment filters for resprouters, which could impact long-term population and demographic structure; yet, compounded disturbance may also reduce stand density and disease pressure, allowing competitive release of survivors. Resprouters displayed vulnerabilities to altered disturbance, but our research suggests that legacies maintained by resprouting may be more resilient to certain compounded disturbances, compared to seed-obligate species, because of high rates of individual survival under increasingly severe events. These trends have important implications for conservation of declining tree species in SOD-impacted forests, as well as predictions of human impacts in other disturbance-prone systems where resprouters are present.
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Affiliation(s)
- Allison B Simler
- Department of Plant Pathology, University of California, Davis, California, 95616, USA
| | - Margaret R Metz
- Department of Biology, Lewis & Clark College, Portland, Oregon, 97219, USA
| | - Kerri M Frangioso
- Department of Plant Pathology, University of California, Davis, California, 95616, USA
| | - Ross K Meentemeyer
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, 27695, USA.,Center for Geospatial Analytics, North Carolina State University, Raleigh, North Carolina, 27695, USA
| | - David M Rizzo
- Department of Plant Pathology, University of California, Davis, California, 95616, USA
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Cobb RC, Ruthrof KX, Breshears DD, Lloret F, Aakala T, Adams HD, Anderegg WRL, Ewers BE, Galiano L, Grünzweig JM, Hartmann H, Huang CY, Klein T, Kunert N, Kitzberger T, Landhäusser SM, Levick S, Preisler Y, Suarez ML, Trotsiuk V, Zeppel MJB. Ecosystem dynamics and management after forest die-off: a global synthesis with conceptual state-and-transition models. Ecosphere 2017. [DOI: 10.1002/ecs2.2034] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Richard C. Cobb
- Natural Resources Management & Environmental Sciences Department; California State Polytechnic University; San Luis Obispo California 93407 USA
| | - Katinka X. Ruthrof
- School of Veterinary and Life Sciences; Murdoch University; 90 South Street Perth Western Australia 6150 Australia
- Botanic Gardens and Parks Authority; Perth Western Australia 6005 Australia
| | - David D. Breshears
- School of Natural Resources and the Environment, and Department of Ecology and Evolutionary Biology; University of Arizona; 1064 East Lowell Street Tucson Arizona 85721 USA
| | - Francisco Lloret
- Center of Ecological Research and Forestry Applications (CREAF); Universitat Autònoma of Barcelona; Edifici C, Campus UAB, 08193 Bellaterra 26 Barcelona Spain
| | - Tuomas Aakala
- Department of Forest Sciences; University of Helsinki; Latokartanonkaari 7 Helsinki FI-00014 Finland
| | - Henry D. Adams
- Department of Plant Biology, Ecology, and Evolution; Oklahoma State University; 301 Physical Sciences Stillwater Oklahoma 74074 USA
| | | | - Brent E. Ewers
- Department of Botany and Program in Ecology and Wyoming EPSCoR; University of Wyoming; Laramie Wyoming 82071 USA
| | | | - José M. Grünzweig
- Robert H. Smith Faculty of Agriculture, Food and Environment; The Hebrew University of Jerusalem; P.O. Box 12 Rehovot Israel
| | - Henrik Hartmann
- Department of Biogeochemical Processes; Max-Planck Institute for Biogeochemistry; Hans Knöll Strasse 10 Jena 07745 Germany
| | - Cho-ying Huang
- Department of Geography; National Taiwan University; 1 Sec. 4, Roosevelt Road Taipei 10617 Taiwan
| | - Tamir Klein
- Weizmann Institute of Science; Rehovot 76100 Israel
| | - Norbert Kunert
- University of Freiburg; Tennenbacherstrasse 4 Freiburg 79106 Germany
| | - Thomas Kitzberger
- Departamento de Ecología; INIBIOMA-CONICET; Universidad Nacional del Comahue; Quintral 1250 Bariloche 8400 Argentina
| | - Simon M. Landhäusser
- Department of Renewable Resources; University of Alberta; Edmonton Alberta T6G 2E3 Canada
| | - Shaun Levick
- Department of Biogeochemical Processes; Max-Planck Institute for Biogeochemistry; Hans Knöll Strasse 10 Jena 07745 Germany
- Research Institute for the Environment and Livelihoods; Charles Darwin University; Darwin Northern Territory 0909 Australia
| | - Yakir Preisler
- Robert H. Smith Faculty of Agriculture, Food and Environment; The Hebrew University of Jerusalem; P.O. Box 12 Rehovot Israel
- Department of Earth and Planetary Science; Weizmann Institute of Science; Herzl St 234 Rehovot 7610001 Israel
| | - Maria L. Suarez
- INIBIOMA-Universidad Nacionaldel Comahue; Quintral 1250 Bariloche 8400 Argentina
| | - Volodymyr Trotsiuk
- Faculty of Forestry and Wood Sciences; Czech University of Life Sciences Prague; Kamycka 129 Prague 16521 Czech Republic
| | - Melanie J. B. Zeppel
- Faculty of Pharmacy; University of Sydney; Camperdown New South Wales 2006 Australia
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Tree Diseases as a Cause and Consequence of Interacting Forest Disturbances. FORESTS 2017. [DOI: 10.3390/f8050147] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Fires without tanoak: the effects of a non-native disease on future community flammability. Biol Invasions 2017. [DOI: 10.1007/s10530-017-1443-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Cobb RC, Meentemeyer RK, Rizzo DM. Wildfire and forest disease interaction lead to greater loss of soil nutrients and carbon. Oecologia 2016; 182:265-76. [PMID: 27164911 DOI: 10.1007/s00442-016-3649-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 04/29/2016] [Indexed: 10/21/2022]
Abstract
Fire and forest disease have significant ecological impacts, but the interactions of these two disturbances are rarely studied. We measured soil C, N, Ca, P, and pH in forests of the Big Sur region of California impacted by the exotic pathogen Phytophthora ramorum, cause of sudden oak death, and the 2008 Basin wildfire complex. In Big Sur, overstory tree mortality following P. ramorum invasion has been extensive in redwood and mixed evergreen forests, where the pathogen kills true oaks and tanoak (Notholithocarpus densiflorus). Sampling was conducted across a full-factorial combination of disease/no disease and burned/unburned conditions in both forest types. Forest floor organic matter and associated nutrients were greater in unburned redwood compared to unburned mixed evergreen forests. Post-fire element pools were similar between forest types, but lower in burned-invaded compared to burned-uninvaded plots. We found evidence disease-generated fuels led to increased loss of forest floor C, N, Ca, and P. The same effects were associated with lower %C and higher PO4-P in the mineral soil. Fire-disease interactions were linear functions of pre-fire host mortality which was similar between the forest types. Our analysis suggests that these effects increased forest floor C loss by as much as 24.4 and 21.3 % in redwood and mixed evergreen forests, respectively, with similar maximum losses for the other forest floor elements. Accumulation of sudden oak death generated fuels has potential to increase fire-related loss of soil nutrients at the region-scale of this disease and similar patterns are likely in other forests, where fire and disease overlap.
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Affiliation(s)
- Richard C Cobb
- Department of Plant Pathology, University of California, One Shields Ave., Davis, CA, 95616, USA.
| | - Ross K Meentemeyer
- Department of Forestry and Environmental Resources, North Carolina State University, Campus Box 8008, Raleigh, NC, 27695, USA
| | - David M Rizzo
- Department of Plant Pathology, University of California, One Shields Ave., Davis, CA, 95616, USA
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Incorporating Anthropogenic Influences into Fire Probability Models: Effects of Human Activity and Climate Change on Fire Activity in California. PLoS One 2016; 11:e0153589. [PMID: 27124597 PMCID: PMC4849771 DOI: 10.1371/journal.pone.0153589] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/31/2016] [Indexed: 11/19/2022] Open
Abstract
The costly interactions between humans and wildfires throughout California demonstrate the need to understand the relationships between them, especially in the face of a changing climate and expanding human communities. Although a number of statistical and process-based wildfire models exist for California, there is enormous uncertainty about the location and number of future fires, with previously published estimates of increases ranging from nine to fifty-three percent by the end of the century. Our goal is to assess the role of climate and anthropogenic influences on the state’s fire regimes from 1975 to 2050. We develop an empirical model that integrates estimates of biophysical indicators relevant to plant communities and anthropogenic influences at each forecast time step. Historically, we find that anthropogenic influences account for up to fifty percent of explanatory power in the model. We also find that the total area burned is likely to increase, with burned area expected to increase by 2.2 and 5.0 percent by 2050 under climatic bookends (PCM and GFDL climate models, respectively). Our two climate models show considerable agreement, but due to potential shifts in rainfall patterns, substantial uncertainty remains for the semiarid inland deserts and coastal areas of the south. Given the strength of human-related variables in some regions, however, it is clear that comprehensive projections of future fire activity should include both anthropogenic and biophysical influences. Previous findings of substantially increased numbers of fires and burned area for California may be tied to omitted variable bias from the exclusion of human influences. The omission of anthropogenic variables in our model would overstate the importance of climatic ones by at least 24%. As such, the failure to include anthropogenic effects in many models likely overstates the response of wildfire to climatic change.
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Johnston SF, Cohen MF, Torok T, Meentemeyer RK, Rank NE. Host Phenology and Leaf Effects on Susceptibility of California Bay Laurel to Phytophthora ramorum. PHYTOPATHOLOGY 2016; 106:47-55. [PMID: 26439707 DOI: 10.1094/phyto-01-15-0016-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Spread of the plant pathogen Phytophthora ramorum, causal agent of the forest disease sudden oak death, is driven by a few competent hosts that support spore production from foliar lesions. The relationship between traits of a principal foliar host, California bay laurel (Umbellularia californica), and susceptibility to P. ramorum infection were investigated with multiple P. ramorum isolates and leaves collected from multiple trees in leaf-droplet assays. We examined whether susceptibility varies with season, leaf age, or inoculum position. Bay laurel susceptibility was highest during spring and summer and lowest in winter. Older leaves (>1 year) were more susceptible than younger ones (8 to 11 months). Susceptibility was greater at leaf tips and edges than the middle of the leaf. Leaf surfaces wiped with 70% ethanol were more susceptible to P. ramorum infection than untreated leaf surfaces. Our results indicate that seasonal changes in susceptibility of U. californica significantly influence P. ramorum infection levels. Thus, in addition to environmental variables such as temperature and moisture, variability in host plant susceptibility contributes to disease establishment of P. ramorum.
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Affiliation(s)
- Steven F Johnston
- First, second, and fifth authors: Department of Biology, Sonoma State University, Rohnert Park, CA 94928; third author: Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA 94720; and fourth author: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27606
| | - Michael F Cohen
- First, second, and fifth authors: Department of Biology, Sonoma State University, Rohnert Park, CA 94928; third author: Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA 94720; and fourth author: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27606
| | - Tamas Torok
- First, second, and fifth authors: Department of Biology, Sonoma State University, Rohnert Park, CA 94928; third author: Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA 94720; and fourth author: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27606
| | - Ross K Meentemeyer
- First, second, and fifth authors: Department of Biology, Sonoma State University, Rohnert Park, CA 94928; third author: Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA 94720; and fourth author: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27606
| | - Nathan E Rank
- First, second, and fifth authors: Department of Biology, Sonoma State University, Rohnert Park, CA 94928; third author: Lawrence Berkeley National Laboratory, Earth Sciences Division, Berkeley, CA 94720; and fourth author: Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC 27606
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White AM, Manley PN, Tarbill GL, Richardson TW, Russell RE, Safford HD, Dobrowski SZ. Avian community responses to post-fire forest structure: implications for fire management in mixed conifer forests. Anim Conserv 2015. [DOI: 10.1111/acv.12237] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. M. White
- Pacific Southwest Research Station; USDA Forest Service; Davis CA USA
| | - P. N. Manley
- Pacific Southwest Research Station; USDA Forest Service; Davis CA USA
| | - G. L. Tarbill
- Pacific Southwest Research Station; USDA Forest Service; Davis CA USA
- Oak Ridge Institute for Science and Education; Oak Ridge TN USA
| | | | - R. E. Russell
- National Wildlife Health Center; USGS; Madison WI USA
| | - H. D. Safford
- USDA Forest Service; Pacific Southwest Region; Vallejo CA USA
- Department of Environmental Science and Policy; University of California; Davis CA USA
| | - S. Z. Dobrowski
- College of Forestry and Conservation; University of Montana; Missoula MT USA
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Zhang Y, Liang S. Changes in forest biomass and linkage to climate and forest disturbances over Northeastern China. GLOBAL CHANGE BIOLOGY 2014; 20:2596-2606. [PMID: 24687944 DOI: 10.1111/gcb.12588] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 02/19/2014] [Accepted: 02/27/2014] [Indexed: 06/03/2023]
Abstract
The forests of northeastern China store nearly half of the country's total biomass carbon stocks. In this study, we investigated the changes in forest biomass by using satellite observations and found that a significant increase in forest biomass took place between 2001 and 2010. To determine the possible reasons for this change, several statistical methods were used to analyze the correlations between forest biomass dynamics and forest disturbances (i.e. fires, insect damage, logging, and afforestation and reforestation), climatic factors, and forest development. Results showed that forest development was the most important contributor to the increasing trend of forest biomass from 2001 to 2010, and climate controls were the secondary important factor. Among the four types of forest disturbance considered in this study, forest recovery from fires, and afforestation and reforestation during the past few decades played an important role in short-term biomass dynamics. This study provided observational evidence and valuable information for the relationships between forest biomass and climate as well as forest disturbances.
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Affiliation(s)
- Yuzhen Zhang
- State Key Laboratory of Remote Sensing Science, College of Global Change and Earth System Science, Beijing Normal University, Beijing, China
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Wu Z, He HS, Liang Y, Cai L, Lewis BJ. Determining relative contributions of vegetation and topography to burn severity from LANDSAT imagery. ENVIRONMENTAL MANAGEMENT 2013; 52:821-36. [PMID: 23887487 DOI: 10.1007/s00267-013-0128-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 07/09/2013] [Indexed: 05/12/2023]
Abstract
Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.
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Affiliation(s)
- Zhiwei Wu
- State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110164, People's Republic of China,
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Metz MR, Varner JM, Frangioso KM, Meentemeyer RK, Rizzo DM. Unexpected redwood mortality from synergies between wildfire and an emerging infectious disease. Ecology 2013; 94:2152-9. [DOI: 10.1890/13-0915.1] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Cobb RC, Rizzo DM, Hayden KJ, Garbelotto M, Filipe JAN, Gilligan CA, Dillon WW, Meentemeyer RK, Valachovic YS, Goheen E, Swiecki TJ, Hansen EM, Frankel SJ. Biodiversity Conservation in the Face of Dramatic Forest Disease: An Integrated Conservation Strategy for Tanoak (Notholithocarpus densiflorus) Threatened by Sudden Oak Death. ACTA ACUST UNITED AC 2013. [DOI: 10.3120/0024-9637-60.2.151] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Beh MM, Metz MR, Frangioso KM, Rizzo DM. The key host for an invasive forest pathogen also facilitates the pathogen's survival of wildfire in California forests. THE NEW PHYTOLOGIST 2012; 196:1145-1154. [PMID: 23046069 DOI: 10.1111/j.1469-8137.2012.04352.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Accepted: 08/23/2012] [Indexed: 06/01/2023]
Abstract
The first wildfires in sudden oak death-impacted forests occurred in 2008 in the Big Sur region of California, creating the rare opportunity to study the interaction between an invasive forest pathogen and a historically recurring disturbance. To determine whether and how the sudden oak death pathogen, Phytophthora ramorum, survived the wildfires, we completed intensive vegetation-based surveys in forest plots that were known to be infested before the wildfires. We then used 24 plot-based variables as predictors of P. ramorum recovery following the wildfires. The likelihood of recovering P. ramorum from burned plots was lower than in unburned plots both 1 and 2 yr following the fires. Post-fire recovery of P. ramorum in burned plots was positively correlated with the number of pre-fire symptomatic California bay laurel (Umbellularia californica), the key sporulating host for this pathogen, and negatively correlated with post-fire bay laurel mortality levels. Patchy burn patterns that left green, P. ramorum-infected bay laurel amidst the charred landscape may have allowed these trees to serve as inoculum reservoirs that could lead to the infection of newly sprouting vegetation, further highlighting the importance of bay laurel in the sudden oak death disease cycle.
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Affiliation(s)
- Maia M Beh
- Department of Plant Pathology, University of California, One Shields Ave, Davis, CA, 95616, USA
| | - Margaret R Metz
- Department of Plant Pathology, University of California, One Shields Ave, Davis, CA, 95616, USA
| | - Kerri M Frangioso
- Department of Plant Pathology, University of California, One Shields Ave, Davis, CA, 95616, USA
| | - David M Rizzo
- Department of Plant Pathology, University of California, One Shields Ave, Davis, CA, 95616, USA
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Garbelotto M, Hayden KJ. Sudden oak death: interactions of the exotic oomycete Phytophthora ramorum with naïve North American hosts. EUKARYOTIC CELL 2012; 11:1313-23. [PMID: 23002108 PMCID: PMC3486021 DOI: 10.1128/ec.00195-12] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ten years after a threatening and previously unknown disease of oaks and tanoaks appeared in coastal California, a significant amount of progress has been made toward the understanding of its causal agent Phytophthora ramorum and of the novel pathosystems associated with this exotic organism. However, a complete understanding of the ecology and epidemiology of this species still eludes us. In part, our inability to fully understand this organism is due to its phylogenetic, phylogeographic, phenotypic, and epidemiological complexities, all reviewed in this paper. Most lines of evidence suggest that the high degree of disease severity reported in California is not simply due to a generalized lack of resistance or tolerance in naïve hosts but also to an innate ability of the pathogen to survive in unfavorable climatic conditions and to reproduce rapidly when conditions become once again favorable.
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Affiliation(s)
- Matteo Garbelotto
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA.
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31
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Metz MR, Frangioso KM, Wickland AC, Meentemeyer RK, Rizzo DM. An emergent disease causes directional changes in forest species composition in coastal California. Ecosphere 2012. [DOI: 10.1890/es12-00107.1] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Meentemeyer RK, Haas SE, Václavík T. Landscape epidemiology of emerging infectious diseases in natural and human-altered ecosystems. ANNUAL REVIEW OF PHYTOPATHOLOGY 2012; 50:379-402. [PMID: 22681449 DOI: 10.1146/annurev-phyto-081211-172938] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A central challenge to studying emerging infectious diseases (EIDs) is a landscape dilemma: Our best empirical understanding of disease dynamics occurs at local scales, whereas pathogen invasions and management occur over broad spatial extents. The burgeoning field of landscape epidemiology integrates concepts and approaches from disease ecology with the macroscale lens of landscape ecology, enabling examination of disease across spatiotemporal scales in complex environmental settings. We review the state of the field and describe analytical frontiers that show promise for advancement, focusing on natural and human-altered ecosystems. Concepts fundamental to practicing landscape epidemiology are discussed, including spatial scale, static versus dynamic modeling, spatially implicit versus explicit approaches, selection of ecologically meaningful variables, and inference versus prediction. We highlight studies that have advanced the field by incorporating multiscale analyses, landscape connectivity, and dynamic modeling. Future research directions include understanding disease as a component of interacting ecological disturbances, scaling up the ecological impacts of disease, and examining disease dynamics as a coupled human-natural system.
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Affiliation(s)
- Ross K Meentemeyer
- Center for Applied GIScience, Department of Geography and Earth Sciences, University of North Carolina, Charlotte, North Carolina 28223, USA.
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33
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Common Factors Drive Disease and Coarse Woody Debris Dynamics in Forests Impacted by Sudden Oak Death. Ecosystems 2011. [DOI: 10.1007/s10021-011-9506-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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34
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Scientific Opinion on the Pest Risk Analysis onPhytophthora ramorumprepared by the FP6 project RAPRA. EFSA J 2011. [DOI: 10.2903/j.efsa.2011.2186] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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35
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Ramage BS, O'Hara KL, Caldwell BT. The role of fire in the competitive dynamics of coast redwood forests. Ecosphere 2010. [DOI: 10.1890/es10-00134.1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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