THE NIAGARA ESCARPMENT ANCIENT TREE ATLAS PROJECT; THE HUNT FOR ONTARIO'S OLDEST TREES

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1 THE NIAGARA ESCARPMENT ANCIENT TREE ATLAS PROJECT; THE HUNT FOR ONTARIO'S OLDEST TREES Authors: Peter E. KELLY and Douglas W. LARSON Abstract: The Niagara Escarpment Ancient Tree Atlas Project began in 1998 with three principal goals. The first goal is to locate the oldest trees growing on individual sections of Niagara Escarpment cliff face. The second goal is to produce a document for landowners to help them gain a better understanding of the nature of the cliff-face forest on their properties. The final goal is to determine the environmental variables and specific site factors that lead to extreme age in trees on cliffs. Data is collected in two stages. In the first stage, the cliff face is examined from the talus and potential old candidate trees are marked for future reference. In the second stage, we return to the site, descend to the tree and use an increment borer to collect core samples for age determination. A portable GPS unit is used to determine the precise coordinates of the tree and each tree is sketched and where possible, photographed. Morphological and habitat data are also collected for each tree. Results to date indicate that four of the five sites sampled in 1998 supported trees over 500 years in age. This project will help landowners make educated decisions related to conservation issues on their properties along the Niagara Escarpment. Introduction Previous research has shown that an extensive presettlement forest that is dominated by eastern white cedar (Thuja occidentalis) occurs on the cliffs of the Niagara Escarpment. This forest has been the focal point of several studies involving tree age determinations including research on the impact of hiking on cliff-edge forest structure (Larson 1990), the age structure of the cliff-face forest (Larson and Kelly 1991), forest population dynamics (Kelly and Larson 1997a) and the impact of rock climbing on the cliff-face forest (Kelly and Larson 1997b). All previous research involving the determination of tree ages in these populations, however, have involved random sampling rather than targeted sampling. Unbiased sampling is a necessary requirement whenever subsamples are being used to infer patterns or processes occurring in the entire population. During our previous studies on these forests, random numbers (representing distances along the cliff from set points) were selected to determine sampling locations. Consequently, we neither actually sought old trees along the Niagara nor targeted individual living trees for age determinations. There is no record of the locations of the oldest individual trees along the escarpment because until this study no one has ever looked for them. The principal goal of the Niagara Escarpment Ancient Tree Atlas Project (NEATAP) therefore is to document the age and location of the oldest trees at each cliff location along the Niagara Escarpment. Information collected will provide landowners and managers with detailed knowledge on the nature of the cliff-face forest on their respective properties. This data will provide an important base line for future monitoring or conservation initiatives. The second goal

2 of NEATAP is to determine the specific habitat and environmental factors which lead to extreme age in the cliff-face cedars. This information will prove useful for predicting the likelihood of finding ancient forest on unknown sections of cliff face along the Niagara Escarpment or elsewhere. The third goal of NEATAP is to increase awareness amongst the public of the unique nature of the ancient forests of the Niagara Escarpment. This will be accomplished with the publication of a book that will include photographs and sketches of the oldest trees. Methods Fieldwork for this project occurs in two steps. The first step involves the location of potentially ancient trees. The talus of each selected cliff is traversed with the intent of spotting old trees on the cliff face. Previous experience with these trees reveals that the oldest individuals possess certain distinct morphological characteristics. These include an asymmetrical sharply tapered main axis with strip-bark growth pattern. Strip-bark trees have alternating longitudinal strips of living bark and exposed barkless dead wood. Strip-bark is created when portions of the root systems die leading to the death of the cambium in the connecting stem. The oldest cedars are often stunted compared with cedars in level-ground habitats and often grow upside down with their roots attached to the cliff face at a point higher than the terminal apex. The cliff-edge locations above trees selected for sampling are marked for future reference using flagging tape. After the locations of all potentially ancient trees have been marked at a site, we return to each cliff-edge location and set-up technical rock climbing that will allow us to rappel down to the tree in question. Upon arrival, we use an increment borer to remove a 4-mm-wide sample of wood that contains a complete tree-ring record of the growth of the tree. A quick estimate of age is made and if the tree has potential to be exceptionally old, the core is kept and other cores are extracted if necessary (depending on the completeness of the initial core). If the tree appears to be too young or hollow, the tree is not included in the survey. If a tree has been selected, a detailed sketch of the morphology of the tree is completed and photographs are taken where possible. Each tree is given an identification number. The diameter of the tree at core height and the functional tree height and basal diameter are recorded as well as a large number of morphological variables including main axis and secondary axis (or axes) length, height to first living branch, main axis taper, per cent living cambium on the main axis, maximum foliar extent from the cliff face, and main axis height and condition. Other variables recorded include tree species, site location, site coordinates (latitude and longitude recorded using a portable Global Positioning System unit), cliff aspect, cliff-edge canopy height, cliff-edge canopy composition, talus canopy height, cliff stability, overhang dimensions and shape, cliff height, distance of the tree below the cliff edge, rooting point, rooting point dimensions, soil cover, litter cover, faunal presence, evidence for fire and evidence for human disturbance. Upon completion, a permanent metal tag bearing an identification number is attached to the tree and to a tree at the cliff edge immediately above it s location. Following sampling, the tree cores are mounted, sanded and raw tree-ring counts completed under a stereomicroscope. Individual tree-ring widths are measured for those tree cores with problematic or missing rings. Program COFECHA of the International Tree-Ring

3 Data Bank Program Library is subsequently used to correct the raw tree-ring counts by crossdating the measured cores with cores from the same site that are lacking these same problems. Using methods outlined by Kelly and Larson (1997b), an estimation of the number of years lost due to coring height or a missed pith is then added to the correct tree-ring counts to provide the final tree age. Final ink drawings of the oldest trees at each site are completed using the sketches and photographs taken in the field. The final tree ages, locations and associated data will eventually be made available to the individual landowners. Results The Niagara Escarpment Ancient Tree Atlas Project is scheduled to include a minimum of two and a maximum of four full field seasons depending on funding and sponsorship. A half field season was completed in 1998 and a full field season was completed in 1999 although age data is only available for the trees sampled in Table 1. shows the data for the three oldest trees located at each of the five sites sampled in Maximum tree age at Beamer s Memorial Conservation Area (C.A) was a respectable 269 years. At each of the four sites in the Milton area, the age of the oldest tree exceeded 500 years including a 738-year-old tree located at Milton Heights. The oldest living cedar previously found on the cliff face is a 788-year-old individual that was sampled as part of a study on the impact of rock climbing on the cliff face forest at Mt. Nemo Conservation Area. Sections of the cliff face at Mt. Nemo were sampled in These are the oldest individual living trees in eastern Canada. Table 1. The germination dates of the three oldest living cliff-face eastern white cedars located at each of the five Niagara Escarpment sites sampled in Site Location Germination Dates (A.D.) Beamer s Memorial C.A Crawford Lake C.A Kelso C.A Rattlesnake Point C.A Milton Heights Future Plans It would be ideal if the entire Niagara Escarpment could be surveyed for old-growth forest but this is not possible in the time frame available given the amount of exposed cliff face along the escarpment. Therefore priority sites have been established for sampling that include: 1) sites which are prone to disturbance including cliffs near urban areas and cliffs where rock climbing is established, and 2) sites where exceptionally old dead or living trees have been located in the past.

4 The completion of fieldwork will mark the starting point for the preparation of the final atlas which will be given to all landowners along the Escarpment on which sampling was completed. As well, a publication will be prepared for a much broader audience that will include sketches and photographs of some of the oldest trees. It is hoped that both publications will aid in the conservation of the cliff-face forest. ACKNOWLEDGEMENTS The authors gratefully acknowledge the financial support of The Richard Ivey Foundation for allowing this project to get off the ground. Parks Canada and the Natural Sciences and Engineering Research Council of Canada also provided financial support. We would also like to acknowledge the logistical support provided by Fathom Five National Marine Park and the climbing expertise provided by Ailish Cullen and Raj Pal. We are also grateful to the landowners along the Niagara Escarpment who granted us permission to sample on their property, in particular; Halton Region Conservation Authority, Hamilton Region Conservation Authority, Niagara Peninsula Conservation Authority, Ontario Parks, Parks Canada, Royal Botanical Gardens and the Ministry of Natural Resources REFERENCES Larson, D.W Effects of disturbance on old-growth Thuja occidentalis at cliff edges. Canadian Journal of Botany 68: Larson, D.W. and P.E. Kelly The extent of old-growth Thuja occidentalis on cliffs of the Niagara Escarpment. Canadian Journal of Botany 69: Kelly, P.E. and D.W. Larson. 1997a. Dendroecological analysis of the population dynamics of an old-growth forest on cliff-faces of the Niagara Escarpment, Canada. Journal of Ecology 85: Kelly, P.E. and D.W. Larson. 1997b. Effects of rock climbing on populations of presettlement eastern white cedar (Thuja occidentalis) on cliffs of the Niagara Escarpment, Canada. Conservation Biology 11:

5 Contact: Peter E. Kelly and Douglas W. Larson Cliff Ecology Research Group Department of Botany University of Guelph Guelph, Ontario, Canada N1G 2W1 Phone: (519) x6008 Fax: (519)