ECOLOGICAL RESEARCH
Bigleaf Maple
(Acer macrophyllum)

This factsheet by Barb Lackenbruch provides an overview of sap flow processes in bigleaf maple and maples more generally.

This OSU Extension video presentation by Barb Lackenbruch provides an overview of prevailing knowledge about sap flow processes in bigleaf maple (Acer macrophyllum). This video is Part 1 of a two-part series. Part 2 on hobby tapping and processing can be found in the Hobby section of this website.

Abstract: The introduction, spread, and impact of fungal plant pathogens is a critical concern in ecological systems. In this study, we were motivated by the rather sudden appearance of Acer macrophyllum heavily infected with powdery mildew. We used morphological and genetic analyses to confirm the pathogen causing the epidemic was Sawadaea bicornis. In subsequent field studies, this pathogen was found in several locations in western North America, and in greenhouse studies, A. macrophyllum was found to be significantly more susceptible to S. bicornis than nine other Acer species tested. A genetic analysis of 178 specimens of powdery mildew from freshly collected and old herbarium specimens from 15 countries revealed seven different haplotypes. The high diversity of haplotypes found in Europe coupled with sequence results from a specimen from 1864 provides evidence that S. bicornis has a European origin. Furthermore, sequence data from a specimen from 1938 in Canada show that the pathogen has been present in North America for at least 82 years revealing a considerable lag time between the introduction and current epidemic. This study used old herbarium specimens to genetically hypothesize the origin, the native host, and the invasion time of a detrimental fungal plant pathogen.

[Copyright restrictions present us from providing the pdf version of the paper here. Key findings and the abstract are provided below. The full paper can be requested through your local university library] . 

Key points from Elsevier Website:

• Bigleaf maple decline has been reported across the Pacific Northwest region.

• We examined the role of abiotic and biotic factors on bigleaf maple decline.

• No plant pathogen or insect herbivore was implicated in the decline.

• Site conditions, especially hotter urban sites, are predisposing stems to decline.

Abstract: "Acer macrophyllum is a prominent component of the western Washington landscape where it performs ecological, economic, and cultural functions. Reports of its decline and increased mortality in the Pacific Northwest were documented beginning in 2011. Symptoms of this decline include a systemic loss of vigor, loss of transpiration, and reduced photosynthesis due to leaf loss. We conducted a preliminary study of A. macrophyllum decline across western Washington in 2014–2015 and observed decline symptoms across the region, but we did not detect any specific biotic causative agents. We subsequently conducted a multi-approach study in 2017 to quantify the spatial and temporal patterns of A.  macrophyllum  decline in western Washington, and to examine biotic and abiotic associations with its decline. We sampled in urban and suburban areas, and in wildland forests, and collected site-specific data to test for associations with decline. We also measured elemental concentrations in foliar and soil samples to determine their association with decline. Lastly, we conducted a dendrochronological analysis to ascertain the spatial and temporal patterns of decline. We report that A. macrophyllum decline is a recent phenomenon, particularly since 2011, that was positively associated with sites closer to roads and with increased development, and with increases in summer temperatures. Site conditions, especially hotter urban sites, are predisposing A. macrophyllum to mortality. We did not detect a consistent biotic agent that could be implicated in A.  macrophyllum  decline. We contend that abiotic factors are either causing direct mortality to A.  macrophyllum, or making then vulnerable to opportunistic biotic agents. The results of this study inform mitigating management strategies for A. macrophyllum in the forest of the Pacific Northwest".

[Copyright restrictions present us from providing the pdf version of the paper here. The paper is open source and the pdf version can be downloaded from Science Direct here]

This journal article offers a broad evolutionary history of the genus Acer. Bigleaf Maple (Acer macrophyllum) is discussed in two places. On Pg. 690 the authors write: "Acer first emerged in the fossil record of the Russian Far East and Alaska almost simultaneously [34,40,57]. The genus most likely originated in the north-eastern Palearctic from where it dispersed to North America soon after its appearance. Based on fossil evidence, it appears to have diversified rapidly in western North America to later undergo significant extinction in this continent. More than 50 fossil species from at least 15 sections are recorded just from the Eocene of North America compared to six in Asia [34,40], but only 12–13 American species exist today. Most of these, e.g., Acer macrophyllum Pursh, A. glabrum, and A. negundo L. are placed in our time-calibrated tree on long branches that go back to the Eocene and Oligocene (Figs. 2 and 3), reflecting the past extinctions along these old lineages". 

Figure 2 and Figure 3 referred to in the above quote provide an excellent visual snapshot of Acer macrophyllum alongside all known maple species currently alive and in the fossil record.

Abstract: "Acer (Sapindaceae) is an exceptional study system for understanding the evolutionary history, divergence, and assembly of broad-leaved deciduous forests at higher latitudes. Maples stand out due to their high diversity, disjunct distribution pattern across the northern continents, and rich fossil record dating back to the Paleocene. Using a genome-wide supermatrix combining plastomes and nuclear sequences (~585 kb) for 110 Acer taxa, we built a robust time-calibrated hypothesis investigating the evolution of maples, inferring ancestral ranges, reconstructing diversification rates over time, and exploring the impact of mass-extinction on lineage accumulation. Contrary to fossil evidence, our results indicate Acer first originated in the (north)eastern Palearctic region, which acted as a source for recurring outward migration. Warm conditions favored rapid Eocene-onward divergence, but ranges and diversity declined extensively as a result of the Plio-Pleistocene glacial cycles. These signals in genome-wide sequence data corroborate paleobotanical evidence for other major woody northtemperate groups, highlighting the significant (disparate) impact of climatic changes on the evolution, composition, and distribution of the vegetation in the northern hemisphere."

This video by presentation by Dr. Greg Ettl from the University of Washington Bigleaf Maple research team presents first year results of research on sap flow and other aspects of sap collection and processing. The video also contains useful information for beginners on setup and processing.

A short article in the Bulletin of the Native Plant Society of Oregon by Hladky and Mathews comparing bigleaf maple and Oregon Ash. 

A poster by Daniel Omdal and Amy Ramsey-Kroll describing results of a study on bigleaf maple dieback that concludes the cause is something other than verticillium wilt, soilborne fungi that invade the host tree xylem.  

A 2006 Master of Science thesis by Tanya Turklts suggesting "bigleaf maple has the potential to increase nutrient cycling and availability in deciduous-conifer mixed stands in temperate coast forests.

PDF version of Fire Effects Information System (FEIS) webpage (equal to 38 printed pages) on Acer macrophyllum that includes distribution and occurrence, botanical and ecological characteristics, fire effects, and management information. Written by Janet Fryer, 2011.

"Bigleaf maple (Acer macrophyllum Pursh) is a common tree species in coastal forests of the Pacific Northwest. We studied the influence of bigleaf maple on forest floor and mineral soil properties in a forest dominated by Douglas-fir [Pseudotsuga menziessi (Mirb.) Franco] and western hemlock [Tsuga heterophylla (Raf.) Sarg.]. Twelve plots containing bigleaf maple were compared to paired plots without the influence of bigleaf maple. Compared to conifer plots, forest floors at bigleaf maple plots were significantly thinner, but the total contents of C in both forest floor and surface mineral soils did not differ between bigleaf maple and conifer plots. This suggests that the bigleaf maple litter may not be fully decomposing; rather a portion of the decomposing litter may be transforming into recalcitrant soil organic matter. Bigleaf maple plots had significantly higher pH, NO3-N concentrations and contents and mineralizable N contents in the forest floor as well as significantly higher cation exchange capacity and concentrations of N (total, mineralizable and NO3-N) and exchangeable K, Ca and Mg in the mineral soil. The changes in soil chemical properties suggest that the presence of bigleaf maple in conifer forests may cause a modest improvement in soil fertility". 2007 Elsevier B.V. All rights reserved.

Forest Ecology and Management 255 (2008) 1874–1882

A 2005 doctoral dissertation by Mohammed Nurudeen Iddrisu at the University of British Columbia.

A 2001 publication by R.W. Fonda describing a post-fire study of selected PNW hardwood trees published in Northwest Science, v75,n1. [link to open source pdf at WSU Libraries Research Exchange]

A 113 page handbook written by Peterson et al. in 1999 for the British Columbia Ministry of Forests Research Program covering biological, ecological, and managerial information on bigleaf maple. 

Description of a study by John TGappeiner, John Zasada, David Huffman, and Bruce Maxwell published in the Western Journal of Applied Forestry in 1996.

This webpage version of a book chapter from Hardwoods of the Pacific Northwest includes the following topics on bigleaf maple including general characteristics, biology & management, harvest & utilization, wood properties, related literature, and Oregon producers and users of bigleaf maple.

Study by John Tappeiner and John Zasada published in 1993 in the Canadian Journal of Forest Resources.

1990 book chapter by Don Minore and John Zasada in Silvics of North American vol. 2 on ecology and management of bigleaf maple.

Article by John Zasada, John Tappeiner, and Timothy Max published in the Western Journal of Applied Forestry. v5,n2 1990.

Study by Fried and Hibbs looking at survival, age, height distributions, and stocking of bigleaf maple seedlings in 1 - 250 year-old Douglas fir forests in western Oregon.

A 1985 Oregon State University Forest Management Master of Science thesis by Jeremy Fried. 

This webpage from Julie Goldstein & Wayne Loescher at the WSU Dept. of Horticulture & Landscape Architecture provides a science brief on germination requirements of bigleaf maple.

This pamphlet provides information on kiln drying bigleaf maple.