Source: UNIVERSITY OF WASHINGTON submitted to NRP
BIGLEAF MAPLE DECLINE IN WESTERN WASHINGTON
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
MCINTIRE-STENNIS
Reporting Frequency
Annual
Accession No.
1009492
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Sep 16, 2016
Project End Date
Sep 30, 2018
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF WASHINGTON
4333 BROOKLYN AVE NE
SEATTLE,WA 98195
Performing Department
Forest Ecology
Non Technical Summary
Bigleaf maple, Acer macrophyllum, is a prominent component of the urban and suburban landscape in Western Washington, which lies at the heart of the native range of bigleaf maple. Bigleaf maple is one of the few commercially important hardwood species from Pacific coast forests, where it can be harvested for furniture and piano frames (Minore & Zasada 1990), and is also considered a species of cultural importance in the Pacific northwest (Turner & Hebda 1990). As a component of urban and suburban forests, bigleaf maple provides numerous ecosystem services and benefits (Fried et al. 1990; Peterson et al. 1999). It is an aesthetically pleasing shade tree, which when grown in residential areas can contribute to reduced cooling costs to residents (Dwyer et al. 1992; McPherson et al. 1997). It also provides habitat for the region's urban and suburban wildlife community, including birds, small mammals, and invertebrates (Neitlich & McCune 1997; Peterson et al. 1999). In heavily populated areas of Western Washington, it also is one of the few tree species seemingly able to support the region's iconic epiphytes, which are otherwise restricted on trees species growing in less populated areas and under lower levels of anthropogenic-derived pollution (Callahan and Tobin, unpublished data). These epiphytes contribute to a number of important and diverse ecosystem functions (Coxson & Nadkarni. 1995; Pettersson et al. 1995; Lindo & Gonzalez 2010), and are known to readily intercept atmospheric pollution (Reimann et al. 2005).However, beginning in 2010, bigleaf maple decline (BLMD) has been reported in both Western Oregon and Washington. Symptoms of this decline include deformed, wilted, and shrunken leaves; partial to entire crown dieback; and complete tree mortality. In 2014-2015, the Washington State Department of Natural Resources surveyed 63 sites scattered throughout Western Washington at which BLMD was observedto ascertain a causative agent for the decline. In collaboration with colleagues from Oregon State University and Washington State University-Puyallup, bioassays from leaf, branch, soil, root and decayed wood samples of symptomatic, dying or dead trees were collected in Washington State; however, to date, all samples have tested negative for many of the usual pathogen suspects that are often associated with the general symptoms of BLMD (e.g., Verticillium spp., Armillaria root rot., and Ganoderma root rot). Another important observation from these field observations is that both young and mature bigleaf maple trees appear to be susceptible to BLMD.Due to the importance of bigleaf maple in urban and suburban forests of Western Washington, and the recent emergence of BLMD, it is crucial to better understand the extent and severity of the problem, and to identify biotic and/or abiotic factors that are contributing to the decline. Such knowledge is particularly important in efforts to develop mitigating management strategies. We believe our proposed research is furthermore well timed given the seemingly rapid onset of BLMD in Western Washington and the lack of a known causative agent.We propose to investigate the extent and severity of a recently reported decline in bigleaf maple, Acer macrophyllum, in the urban and suburban forests of Western Washington, and to differentiate between possible abiotic and biotic drivers of the decline. Specifically, we propose to (1) survey the spatial extent of bigleaf maple decline (BLMD) and record associated environmental, anthropogenic, and weather conditions that are associated with BLMD presence and absence; (2) use dendrochronological techniques to analyze and compare growth rates of healthy and symptomatic trees to further differentiate the potential roles of abiotic and biotic drivers of the decline; and (3) to link the data collected under Objectives 1 and 2 with previous records of BLMD collected by the Washington State Department of Natural Resources to ascertain the spatialtemporal pattern associated with BLMD in Western Washington.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
12406991070100%
Knowledge Area
124 - Urban Forestry;

Subject Of Investigation
0699 - Trees, forests, and forest products, general;

Field Of Science
1070 - Ecology;
Goals / Objectives
In this study, we propose:(1) To sample the spatial extent of bigleaf maple decline (BLMD) and record associated environmental, anthropogenic, and weather conditions that are associated with both BLMD presence and absence throughout the Western Washington region.(2) To use dendrochronological techniques to analyze and compare growth rates of bigleaf maple trees that are symptomatic for BLMD or not symptomatic for BLMD to further differentiate the potential roles of abiotic and biotic drivers of the decline.(3) To link the data collected under Objectives 1 and 2 with previous records of BLMD collected by the Washington State Department of Natural Resources to better quantify spatial patterns and to ascertain space-time patterns associated with BLMD.
Project Methods
Objective 1: To sample the spatial extent of bigleaf maple decline (BLMD) and record associated environmental, anthropogenic, and weather conditions that are associated with both BLMD presence and absence throughout the Western Washington region. We will spatially document the presence or absence of BLMD and record associated conditions. We will initially use surveys conducted by Washington State Department of Natural Resources to guide and supplement our sampling efforts in urban and suburban areas of Western Washington. Existing sites present a list of locations in which BLMD has already been detected at varying levels of intensity. We will also expand on these efforts to find locations where symptoms of BLMD are not at detectable levels. We will then use adaptive sampling (Thompson 1990) by specifically increasing sampling efforts in locations with either a high occurrence of BLMD (e.g., high proportion of stems with reduced leaves) or a lack of symptomatic trees. At these locations, we will install intensive study plots. In these intensive plots, we will record associated forest conditions (i.e., relative proportion of bigleaf maple basal area relative to other tree species, canopy cover), environmental conditions (e.g., elevation, slope and variation in hilliness that might affect water flow), quantify anthropogenic influences (e.g., human population density, distance from pollution sources and major roads), and obtain recent weather data (e.g., temperature and precipitation) from NOAA and PRISM (National Climatic Data Center 2015; PRISM Climate Group 2015). We will use this information to develop a geospatial database to associate site conditions with the presence or absence of BLMD, and the intensity of BLMD. We will test for spatial clustering using Ripley's L on the presence of BLMD (spatstat package in R, ref), and use a nonparametric spatial autocorrelation function to test for spatial clustering in continuous spatial data (ncf package in R). Depending on details of spatial autocorrelation, we will associate site condition variables (e.g. forest, environmental, anthropogenic, and weather conditions) with the presence or absence of BLMD, and the intensity of BLMD, using generalized additive models while accounting for spatial autocorrelation (Walter et al. 2015). We will collect leaves, branches, soil, roots and decayed wood samples from sites with a high occurrence of BLMD to continue bioassays conducted by the Washington State Department of Natural Resources in an effort to isolate a causative agent.Objective 2: To use dendrochronological techniques to analyze and compare growth rates of bigleaf maple trees that are symptomatic for BLMD or not symptomatic for BLMD to further differentiate the potential roles of abiotic and biotic drivers of the decline. We will use our sites identified under Objective 1 and select bigleaf maple trees that represent the range of BLMD intensity. Trees that are not symptomatic for BLMD will be included as well as trees representing a range of symptom intensity. Increment cores samples will be collected and used to quantify tree growth rates and determine potential roles of abiotic factors (e.g., increased surface temperatures and/or drought conditions) and biotic factors (e.g., a disturbance organism) of BLMD. We will also consider growth rates relative to site conditions quantified under Objective 1.We hypothesize that the presence of a biotic agent as a cause of BLMD, either directly or indirectly, will reveal a different growth rate pattern in symptomatic trees relative to trees growing under similar abiotic conditions but in the absence of BLMD symptoms. Dendrochronological techniques have been used in similar studies involving the spread and impact of a biotic agent on host trees (Agrawal 1995; McEwan 2006; Siegert et al. 2014), and are a useful tool in this investigation.Objective 3: To link the data collected under Objectives 1 and 2 with previous records of BLMD collected by the Washington State Department of Natural Resources to better quantify spatial patterns and to ascertain space-time patterns associated with BLMD. We will combine data collected under Objectives 1 and 2 with previous records of BLMD collected by the Washington State Department of Natural Resources. We will also seek out additional records using data available through annual reports of Forest Health available from the Washington State Department of Natural Resources. We will also consider possible dates of BLMD occurrence by considering the initial year of significant reductions in growth rates of symptomatic trees (from Objective 2) that are not explained by background variation in growth (i.e., reduced growth in drought years) (e.g., Agrawal 1995). Our goal is to add a temporal index to the occurrence of BLMD. The inclusion of an estimated time of BLMD occurrence by study site will allow for the quantification of an index of space-time clustering (Knox 1964; Kulldorff & Hjalmars 1999; Baker 2004) associated with BLMD presence. Under a realized spatial and temporal process initialized by a spatially structured biotic factor (such as an insect or pathogen, and especially for a recently introduced insect or pathogen), estimates of the joint spatial and temporal properties exhibit a specific space-time signature (Tobin 2007). Furthermore, a system of interacting species, such as host tree-pathogen complex or a host tree-insect complex, likewise exhibits a specific spatial pattern through time that is conceptually different from a space-time process initialized in random space and at random points in time (Tobin 2004; Tobin & Bjørnstad 2005). We will compare our empirical observations of space-time clustering with the theoretical expectations estimated in silico when assuming complete spatial randomness, a region-wide stochastic disturbance, and a locally spatially structured stochastic process.

Progress 09/16/16 to 09/30/18

Outputs
Target Audience:Washington State Department of Natural Resources City of Seattle USDA Forest Service Changes/Problems:No major changes or problems encountered. What opportunities for training and professional development has the project provided?Jacob Betzen was trained under this project, and successfully defended his M.S. Thesis, titled "Bigleaf maple decline in western Washington," in December 2018. How have the results been disseminated to communities of interest?Presentations to user groups, such as Seattle Parks and Recreation and the Northwest Scientific Association, were made during the duration of the project to ensure that the results of the project would be extended to groups outside of the academic and scientific community. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Bigleaf maple is a prominent component of the urban and suburban landscape in Western Washington. It performs many important ecological, economic, and cultural functions, and its decline in the region could have cascading impacts. In 2011, increases in bigleaf maple mortality were documented throughout the distributional range of the species. Symptoms of this decline included a systemic loss of vigor, loss of transpiration, and a reduction in photosynthetic potential, but did not display any signs or symptoms indicative of a specific causative agent. No pathogenic microbes, insects, or other biotic agents were initially implicated in causing or predisposing bigleaf maple to decline. In this project, we quantified the spatial extent and severity of bigleaf maple decline in the urban, suburban, and wildland forests of western Washington, identified potential abiotic and biotic disturbance agents that are contributing to the decline, and conducted a dendrochronological analysis to ascertain the timing of the decline. During the project, we surveyed 22 sites that were previously reported as containing declining bigleaf maple, and sampled 156 individual A. macrophyllum, of which 65 (41.7%) were observed to symptoms of declining health. In addition, we sampled 59 sites that were randomly selected from within the range of bigleaf maple in western Washington, and sampled 132 individual bigleaf maple trees, of which 29 (22.0%) were observed to symptoms of declining health. By comparing qualitative and quantitative measurements of bigleaf maple decline severity, and dendrochronological patterns of tree growth and decline, elemental concentrations in soil and foliage, and geographic records of weather, landcover classes, and soil characteristics, we identified several environmental variables that are associated with mortality and loss of vigor in bigleaf maple. We observed that sites with higher temperatures, increased vapor pressure deficits, decreased precipitation, high levels of developed land, low levels of forested or herbaceous land, and proximity to paved roads were all positively associated with increased prevalence of bigleaf maple decline. Ring widths of bigleaf maple were negatively correlated with summertime temperatures, vapor pressure deficits, and drought, signifying reduced growth and vigor in the hotter, drier summers of the Pacific Northwest. Dendrochronologically-derived spatio-temporal estimations of bigleaf maple decline did not indicate a spatially-correlated spread of symptoms characteristic of pathogen or disease introductions. Increased human habitation, activity, and development, as well as predicted increases in summer temperatures and drought, in the western coast of North America will likely continue, which could lead to increased mortality in bigleaf maple in the future. The results of this study could be used to assist managers in their efforts to develop mitigating management strategies and adapt to changing conditions in the forest of the Pacific Northwest.

Publications

  • Type: Conference Papers and Presentations Status: Other Year Published: 2017 Citation: Betzen, J., A. Ramsey, D. Omdal, P.C. Tobin (2017) Bigleaf Maple Decline in Western Washington. 65th Annual Western International Forest Disease Work Conference, Parksville, BC, Canada.


Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Washington State Department of Natural Resources City of Seattle USDA Forest Service Changes/Problems:No major changes or problems encountered. What opportunities for training and professional development has the project provided?Jacob Betzen was trained under this project, and successfully defended his M.S. Thesis, titled "Bigleaf maple decline in western Washington," in December 2018. How have the results been disseminated to communities of interest?Presentations to user groups, such as Seattle Parks and Recreation and the Northwest Scientific Association, were made during the duration of the project to ensure that the results of the project would be extended to groups outside of the academic and scientific community. What do you plan to do during the next reporting period to accomplish the goals?The project ended during this reporting period.

Impacts
What was accomplished under these goals? Bigleaf maple is a prominent component of the urban and suburban landscape in Western Washington. It performs many important ecological, economic, and cultural functions, and its decline in the region could have cascading impacts. In 2011, increases in bigleaf maple mortality were documented throughout the distributional range of the species. Symptoms of this decline included a systemic loss of vigor, loss of transpiration, and a reduction in photosynthetic potential, but did not display any signs or symptoms indicative of a specific causative agent. No pathogenic microbes, insects, or other biotic agents were initially implicated in causing or predisposing bigleaf maple to decline. In this project, we quantified the spatial extent and severity of bigleaf maple decline in the urban, suburban, and wildland forests of western Washington, identified potential abiotic and biotic disturbance agents that are contributing to the decline, and conducted a dendrochronological analysis to ascertain the timing of the decline. During the project, we surveyed 22 sites that were previously reported as containing declining bigleaf maple, and sampled 156 individual A. macrophyllum, of which 65 (41.7%) were observed to symptoms of declining health. In addition, we sampled 59 sites that were randomly selected from within the range of bigleaf maple in western Washington, and sampled 132 individual bigleaf maple trees, of which 29 (22.0%) were observed to symptoms of declining health. By comparing qualitative and quantitative measurements of bigleaf maple decline severity, and dendrochronological patterns of tree growth and decline, elemental concentrations in soil and foliage, and geographic records of weather, landcover classes, and soil characteristics, we identified several environmental variables that are associated with mortality and loss of vigor in bigleaf maple. We observed that sites with higher temperatures, increased vapor pressure deficits, decreased precipitation, high levels of developed land, low levels of forested or herbaceous land, and proximity to paved roads were all positively associated with increased prevalence of bigleaf maple decline. Ring widths of bigleaf maple were negatively correlated with summertime temperatures, vapor pressure deficits, and drought, signifying reduced growth and vigor in the hotter, drier summers of the Pacific Northwest. Dendrochronologically-derived spatio-temporal estimations of bigleaf maple decline did not indicate a spatially-correlated spread of symptoms characteristic of pathogen or disease introductions. Increased human habitation, activity, and development, as well as predicted increases in summer temperatures and drought, in the western coast of North America will likely continue, which could lead to increased mortality in bigleaf maple in the future. The results of this study could be used to assist managers in their efforts to develop mitigating management strategies and adapt to changing conditions in the forest of the Pacific Northwest.

Publications

  • Type: Theses/Dissertations Status: Other Year Published: 2018 Citation: Betzen, J. (2018) Bigleaf maple decline in western Washington. MS Thesis, University of Washington.
  • Type: Other Status: Other Year Published: 2018 Citation: Betzen, J., A. Ramsey, D. Omdal, P.C. Tobin (2018) Bigleaf Maple Decline in Western Washington. Seattle Parks and Recreation, Seattle, WA.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Betzen, J., A. Ramsey, D. Omdal, P.C. Tobin (2018) Bigleaf Maple Decline in Western Washington. Northwest Scientific Association 2018 Meeting, Olympia, WA.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2018 Citation: Betzen, J., A. Ramsey, D. Omdal, P.C. Tobin (2018) Bigleaf Maple Decline in Western Washington. Ecological Society of America Annual Meeting, New Orleans, LA.


Progress 10/01/16 to 09/30/17

Outputs
Target Audience: Washington State Department of Natural Resources City of Seattle, Seattle Parks and Recreation City of Seattle, Seattle Public Utilities USDA Forest Service, Region 6 National Park Service Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Professional development opportunities for graduate student included working to develop research partnerships with city, state, and Federal forest health professionals. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?During the next reporting period, efforts will focus on completing data analyses, synthesizing the findings, and preparing presentation and publication products.

Impacts
What was accomplished under these goals? During this reporting period, field collection was accomplished. Sampling was conducted at a total of 117 sites located throughout the range of bigleaf maple in western Washington. Sites included both public and private lands. At each site, data were collected within a series of 1/10 acre plots. Data that were collected included (1) status of bigleaf maple decline as well as signs of decline such as the presence of epicormic branching, extent of crown dieback, extent and severity of thinning, extent and severity of discoloration, extent and severity of reduced leaf size; (2) forest composition data; (3) environmental variables such as elevation and soil type; (4) distance from major roads that could be a source of pollution; and (5) presence of insect herbivores or pathogens on bigleaf maple. In addition, we sampled a random subset of bigleaf maple tree through the extraction of tree cores, and collected soil and foliar samples for use in elemental analyses. Additional metrics, such as climate data from the PRISM Climate Group, land cover data from the National Land Cover Database, and soil survey data from the USDA NRCS Soil Survey Geographic Database, were also compiled for all sites in a GIS.

Publications


    Progress 09/16/16 to 09/30/16

    Outputs
    Target Audience:This project was initiated during the current reporting period; thus, there are no target audiences to date. Future target audiences include forest health professionals from local, state, and Federal government, and scientific researchers at state, federal, and University institutions. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The graduate student on the project has been involved in meetings with Washington State Department of Natural Resources forest health professionals to facilitate the development of sampling programs to best meet the needs of the project goals. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Initial field data collection will begin during the next reporting period.

    Impacts
    What was accomplished under these goals? This project was initiated during the current reporting period. So far, we have met to develop sampling programs to best meet the needs of the project goals.

    Publications