Polar Biology 32:751-758

Polar Biol (2009) 32:751–758 DOI 10.1007/s00300-008-0578-x ORIGINAL PAPER Fungal diversity and deterioration in mummiWed woods from the ad Astra Ice Cap region in the Canadian High Arctic Joel A. Jurgens · Robert A. Blanchette · Timothy R. Filley Received: 2 October 2008 / Revised: 16 December 2008 / Accepted: 17 December 2008 / Published online: 14 January 2009 © Springer-Verlag 2009 Abstract Non-permineralized or mummiWed ancient Introduction wood found within proglacial soil near the ad Astra Ice Cap (81°N, 76°W), Ellesmere Island, Canada was investigated The Canadian High Arctic contains several deposits of to ascertain the identiWcation of the trees, current non-permineralized, ancient woody materials in various morphological and chemical characteristics of the woods states of preservation (Francis 1988; Basinger et al. 1988; and the fungi within them. These woods, identiWed as Wheeler and Arnette 1994). Perhaps the most well studied Betula, Larix, Picea and Pinus, were found with varying of these deposits is located on Axel Heiberg Island near the states of physical and chemical degradation. Modern Geodetic Hills. These woods have been primarily dated to microbial decomposition caused by soft rot fungi was the Eocene period (34–55 million years ago) based on geo- evident and rDNA sequencing of fungi obtained from the morphology and vertebrate fossils found in the same strata samples revealed several species including Cadophora sp., layers. However, other sites such as the region near the ad Exophiala sp., Phialocephala sp., as well as others. Analyt- Astra Ice Cap, Ellesmere Island, Nunavut Province, Canada ical 13C-labeled tetramethylammonium hydroxide thermo- (Fig. 1) also have mummiWed woods that have not been chemolysis showed the lignin from the ancient wood was in adequately studied. Unlike the woods of Axel Heiberg that a high degree of preservation with minor side chain have been dated using features in the surrounding sedimen- alteration and little to no demethylation or ring hydroxyl- tary strata layers, the woods near the ad Astra Ice Cap have ation. The exposure of these ancient woods to the young been displaced from their original location to proglacial soils, where woody debris is not usually prevalent, provides soils (Fig. 2) and their age cannot be determined with accu- carbon and nutrients into the polar environment that are racy making dating diYcult. However, they are likely to be captured and utilized by unique decay fungi at this Arctic of a similar age ranging from the Paleocene–Eocene transi- site. tion period of »55 million years ago when dramatic global warming occurred (Zachos et al. 2001) and the Eocene– Keywords Non-permineralized wood · Ellesmere Island · Oligocene boundary »33 million years ago when a pro- Fungi · Wood decay · Biodeterioration · Lignin chemistry nounced cooling initiated (Zanazzi et al. 2007), as this period of time provided temperatures adequate to support Xora of this type in the Arctic. This age is further supported by the proximity to the dated material on Axel Heiberg and species composition similarities between the two sites J. A. Jurgens (&) · R. A. Blanchette (Jahren 2007). The current environment, based on data col- Department of Plant Pathology, University of Minnesota, St Paul, lected by the Meteorological Service of Canada from 1971 MN 55108-6030, USA to 2000 at the nearest weather station to the collection site e-mail: [email protected] (Eureka, Nunavut, Canada, latitude 79°58.800ЈN; longitude 85°55.800ЈW), has an average annual temperature of T. R. Filley Department of Earth and Atmospheric Sciences, ¡19.7°C, with the highest average monthly temperature of Purdue University, West Lafayette, IN 47907, USA 5.7°C occurring in July and the lowest of ¡38.4°C in 123 752 Polar Biol (2009) 32:751–758 review of these studies has been presented by Basinger (1991) and Jahren (2007). Although, similar Wndings of fruit, leaves, nuts and palynomorphs of dicot angiosperms have been found in these same assemblages with the gymnosperms, limited evidence of wood from the angio- sperm group persist. Only one example was found in the Geodetic Hills of Axel Heiberg Island as an in situ stump and tentatively identiWed by Jagels et al. (2005) as belonging to either, the Lauraceae, Euphorbiaceae or Flacourtiaceae families. Previous micromorphological and chemical investigations of mummiWed woods from diVerent regions of the Canadian Arctic have shown that extensive alterations within these woods had taken place. In these studies, the residual wood had high but variable lignin content, thought to be controlled by the degree of vitriWcation (Kaelin et al. 2006) with the lignin from some samples being methoxyl Fig. 1 Map of the Canadian High Arctic Region indicating mummi- group deWcient, sidechain degraded and of a more Wed wood collection location near the ad Astra Ice Cap on Ellesmere condensed lignin state as compared to lignin in modern Island wood (Blanchette et al. 1991; Obst et al. 1991). Many of the woods from these investigations also had extensive carbohydrate degradation with complete loss of hemicellulose and very little crystalline cellulose remaining. Others, however, have been able to extract hemicellulose and cellulose from wood samples collected in this region (Jahren and Sternberg 2003; Jagels and Day 2004) indicating that some polysaccharides can survive in the residual cell wall layers. Ultrastructural studies of mummiWed wood samples removed from sedimentary layers at Axel Heiberg and other locations in the Arctic have shown no evidence of microbial degradation, paleo or modern (Blanchette et al. 1991). Although free of attack from fungi and bacteria, advanced stages of degradation were evident and deterioration appeared to be driven by nonbiological chemical hydrolysis mechanisms (Kaelin et al. 2006). The reasons Fig. 2 Valley at the base of the retreating ad Astra Ice Cap on Elles- for the lack of paleo biological degradation are uncertain mere Island, Nunavut, Canada where mummiWed wood was found but most likely involve a unique burial condition or condi- tions that limited microbial activity quickly. These condi- February. The average annual precipitation over the 30-year tions included rapid and deep burial (some reaching depths period was 75.5 mm, with the greatest amount falling in of 300 m) that restricted oxygen and possibly preserved an August (14.9 mm) and the least in February (2.6 mm). abundance of tannin-like compounds in some of the plant Investigations of these woods provide an excellent opportu- materials that may have helped to suppress microbial nity to gain a better understanding of the past landscape of decomposition at early stages of burial (Schoenhut et al. this region, as well as an opportunity to study the micro- 2004). Although microbial attack was inhibited, the wood organisms that utilize this labile food source, relative to glacial appeared to be aVected by a gradual hydrolysis and chemi- soils with sparse organic matter, in this harsh environment. cal attack (Obst et al. 1991). The loss of carbohydrates and Much of the mummiWed wood that has been investigated conversion of lignin by abiotic processes, as well as the in the Canadian High Arctic has been from the class gym- ultrastructural changes that were observed corresponded to nospermea, belonging primarily to Metasequoia (Visscher the changes taking place during the formation of coaliWed and Jangels 2003) or Larix (Jagels et al. 2001) genera. wood (Blanchette et al. 1991). Additional evidence of members from Cupressaceae, Pina- This study was done to identify the type of ancient ceae and Taxodiaceae in the form of cones, leaves, needles, woods found at this high Arctic site and to ascertain their palynomorphs, twigs and wood have been identiWed and a current morphological and chemical characteristics, as 123 Polar Biol (2009) 32:751–758 753 well as to determine the fungal diversity within the woods microscopy (SEM) using previously described techniques after release from the glacier and exposure to the polar (Blanchette and Simpson 1992) and images taken using a environment. Hitachi S3500 N SEM. Hand sections of samples were also made and viewed under a Nikon Eclipse E600 with images captured using ACT1 software connected to a Nikon DXM Materials and methods 1200F digital camera. Lignin chemistry of the wood was assessed using MummiWed wood samples were initially found in the west 13C-labeled tetramethyl ammonium hydroxide (TMAH) valley below the retreating ad Astra Ice cap, Ellesmere thermal chemolysis according to methods outlined in Filley Island, Nunavut, Canada (81°N, 76°W) by Parks Canada (2003) and Filley et al. (2006). This procedure decomposes personnel from the Quttinirpaaq National Park (Figs. 2, 3). lignin into methylated monomers for gas chromatographic In cooperation with Parks Canada and under Park Permit # analysis and permits the assessment of the number of free QQ-01-01 and Nunavut Research Institute Research hydroxyls on the lignin structure, thereby assessing micro- License # 0100501 N-M, several sites near the ad Astra Ice bial or chemical demethylation and the contribution of tan- Cap were visited and small sections of wood in contact with nin and phenol components to the lignin monomers (Filley the ground were collected, placed in sterile bags and kept et al. 2006). BrieXy, 100–300 g of dried and powdered cool during transport to the University of Minnesota where sample were added to a platinum cup along with 3 l of a they were investigated. Wood segments from the samples 25% w/v solution of 13C-TMAH in water. The sample was were cultured for microorganisms using three types of then placed into an isothermally heated (350°C) Shimadzu growth medium: 1.5% Difco malt extract agar (MEA), Pyr4A pyrolyzer, interfaced to a GC17A gas chromato- MEA with 2 ml of lactic acid added after autoclaving and a graph containing a Restek Rtx-5MS capillary column with semi-selective media for Basidiomycetes that included 15 g helium Xow.

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