2012 NORTHEASTERN NATURALIST 19(4):535–540 Coral Lichen (Sphaerophorus globosus (Huds.) Vain) as an Indicator of Coniferous Old-Growth Forest in Nova Scotia Robert P. Cameron1,* and Soren Bondrup-Nielsen2 Abstract – Old-growth forests are rare and of conservation concern in Maritime Canada. A variety of methods have been proposed to identify old-growth forests including structural measurements and lichen surveys. Frequency and abundance of Sphaerophorus globosus (Coral Lichen), was measured in 6 old-growth and 6 mature second-growth coniferous forests in Nova Scotia. Total abundance (P = 0.013) and the tree frequency occurrence (P = 0.005) were significantly greater in old-growth forests compared with mature second growth in paired t-tests. We propose the abundance and frequency of occurrence of the easily identifiable lichen Sphaerophorus globosus as an indicator of old-growth forests. Forests with at least 25% of trees having Sphaerophorus globosus growing on them, or meeting the criteria of at least 50 trees/ha with dbh >40 cm and more than 25% of trees with Sphaerophorus globosus, should be studied further as potential candidates for being assigned old-growth forest status. Introduction Old-growth forests in Maritime Canada comprise less than 1% of the total forest (Mosseler et al. 2003). Because of this rarity and the unique assemblage of species often found there, Nova Scotia Department of Natural Resources has a policy of maintaining at least 8% of a forest management area in old growth (Nova Scotia Department of Natural Resources 2007). The forest industry has also recognized the importance of maintaining old growth and several large companies in Nova Scotia have established old-growth reserve policies (Bax 2010, Doucette and Miller 2009). Recognizing true old growth has become a management concern. Assessment methods and indicators have been developed in eastern North America to address this concern. For example, Stewart et al. (2003) developed a method for determining old growth in Nova Scotia which requires extensive field work involving multiple measurements including time-consuming increment coring of trees. Lichens were first proposed as indicators of ancient forests in Britain by Rose (1976), and later Selva (1994) proposed a suite of lichens that could be used to determine the continuity of forests in northeastern North America. Selva (2003) also proposed that stubble lichens could be indicators of old growth. Recently, McMullin et al. (2008) proposed another suite of lichen indicators for western Nova Scotia. The greatest difficulty in the use of indicator suites of lichens is that lichen experts are required to complete the assessment. Identification can be time-consuming, involving collection and later identification with microscopes and chemical tests. 1Nova Scotia Environment, PO Box 442, Halifax, NS, B3J 2P8, Canada. 2Department of Biology, Acadia University, Wolfville, NS, B4P 2R6, Canada. *Corresponding author - camerorp@gov.ns.ca. 536 Northeastern Naturalist Vol. 19, No. 4 Those old-growth lichen indicator suites use presence as an indicator of old growth but do not involve estimates of abundance or frequency. However, Whitman and Hagan (2004) use the frequency of Usnea thalli >15 cm long as part of an assessment of late successional coniferous forest in northern New England. The use of Usnea species appears not to be appropriate in Nova Scotia because the maritime influence results in Usnea species being ubiquitous and abundant. There are more than 20 Usnea species occurring in the province, and some are not exclusive to old forest (Cameron 2002, McMullin et al. 2008). Sphaerophorus globosus (Huds.) Vain. (Coral Lichen) is one of the larger fruticose lichens that is easily identified by amateurs (Fig. 1). The object of the present study was to measure the abundance and frequency of Sphaerophorus globosus on trees in old-growth forests and compare the data with studies in adjacent mature second-growth forests to establish if this species could be used as an old-growth coniferous forest indicator in Nova Scotia. Methods Six coniferous forests that were documented as being old growth (Cameron 2004) or met the criteria of Nova Scotia Department of Natural Resources (Stewart et al. 2003) were selected for study in Nova Scotia. As a comparison, 6 second-growth mature coniferous forests, within 5 km of each old-growth forest, were also selected using Nova Scotia Department of Natural Resources forest inventory database (Table 1, Fig. 2). Mature forest, as defined in the forest Figure 1. Sphaerophorus globosus (Coral Lichen) on Tsuga canadensis (L.) Carrière (Eastern Hemlock) in old-growth forest in central Nova Scotia. 2012 R.P. Cameron and S. Bondrup-Nielsen 537 inventory database, are stands ranging in age from 80 to 150 years as estimated from remote data. Transect lines were established that bisected each stand, and 6 points were located at 35-m intervals along these transect lines and at least 50 m from the edge of the stand. Each point became the center of a plot where a glass wedge prism, with a basal area factor of 2 m2/ha, was used to identify trees to be sampled. Of the trees identified from the prism sweep, 24 were selected such that 4 were picked from each of the 6 plots per stand. The first tree from each plot Table 1. Coordinates of study sites in Nova Scotia, Canada where abundance and tree frequency of Sphaerophorus globosus were measured. Site name Stand maturity Longitude Latitude S-Road Mature -64.1100 44.7500 Dayspring Mature -62.5830 45.2170 Governor Lake Mature -62.6700 45.1830 Armstrong Lake Mature -64.1830 44.8170 Panuke Lake Old growth -64.1100 44.7800 Abraham Lake Old growth -62.6300 45.1500 Card Lake Old growth -64.2600 44.7500 Rocky Lake Old growth -62.5500 45.2300 Calvary River Old growth -63.0393 45.4191 Browns Brook Mature -63.0411 45.4179 North River Old growth -60.6637 46.3184 MacDonald Brook Mature -60.6621 46.3185 Figure 2. Locations of Sphaerophorus globosus study sites in Nova Scotia, Canada. Circles indicate locations of old-growth forest, and pluses indicate locations of mature coniferous forest comparison sites. 538 Northeastern Naturalist Vol. 19, No. 4 to be sampled for lichens was selected randomly, and the subsequent 3 trees were selected sequentially and evenly from the trees identified from the prism sweep. Since a prism sweep samples from a variable-sized plot, there was no dependence in terms of the distance between sampled trees, which ensured that the 24 trees sampled for lichens within a stand were independent. Both live and dead trees were sampled. The occurrence of Sphaerophorus globosus up to 2 m from the ground on tree trunks was recorded for each tree, and its abundance was measured as percent cover of the tree surface. Percent cover was estimated from ground level to 2 m up the bole of each tree on all sides of the tree and scored according to the following scale: 1 = rare (<1% cover); 2 = occasional (1 to 2% cover); 3 = common (2 to 10% cover); and 4 = abundant (>10% cover). Cumulative abundances and tree frequency occurrence was calculated for each stand for use in comparative analyses. Presence of fruiting bodies on thalli was not recorded. Paired t-test was used to compare differences between cumulative abundance and tree frequency occurrence of Sphaerophorus globosus for each site between old growth and second growth. Results and Discussion Sphaerophorus globosus is a lichen that in Nova Scotia occurs in greatest abundance in old-growth forests (Cameron 2002). It was included by McMullin et al. (2008) and Selva (1996) in their old-growth forest indicator suites. In the present study, the total abundance (P = 0.013) and tree frequency occurrence (P = 0.005) were significantly greater in old-growth forest compared to second growth with paired t-tests (Table 2). Only 1 old-growth stand had fewer than 10 trees per 24 with Sphaerophorus globosus. The presence of Sphaerophorus globosus alone appears not be a useful predictor of old-growth coniferous forest in Nova Scotia since it can also be found in second-growth forest. However, as stated above, its abundance and frequency on trees may enable it to be a rapid and easily assessed identifier of old-growth forests. Sphaerophorus globosus is well-known to be common in old-growth forests (Cameron 2002, McMullin et al. 2008, Selva 1994, Sillet and Goslin 1999). Of 51 forest stands studied by McMullin et al. (2008) in southwest Nova Scotia, Sphaerophorus globosus was found only in stands greater than 211 years old. When Sphaerophorus globosus was found in second-growth forest in Nova Table 2. Sphaerophorus globosus total abundance and frequency of occurrence on trees in old -growth and second-growth coniferous forest in Nova Scotia. Total abundance Frequency Forest pair Old growth Second growth Old growth Second growth 1 34 0 16 0 2 43 2 14 2 3 20 1 10 1 4 69 1 23 1 5 5 0 3 0 6 29 0 19 0 2012 R.P. Cameron and S. Bondrup-Nielsen 539 Scotia, it was associated with legacy trees (Cameron 2002). Sillet and Goslin (1999) found a similar trend with second growth in British Columbia, Canada. In old-growth forests, it is found on the trunks of hemlock, pine (Pinus spp.), and spruce (Picea spp.) but it can also be found on soil or rock (Hinds and Hinds 2007). Sphaerophorus globosus is easily identified in the field. It usually consists of several main branches ascending from a central larger main stem (Fig. 1). The sides and tips of main branches have tufts of fine branches, giving the lichen a delicate appearance. The color varies from green to greenish gray to brown, often with an orange tinge. Reproductive structures that consist of round apothecia may occur at the ends of branches. Some caution may be required when using Sphaerophorus globosus as an oldgrowth forest indicator in coastal forests. A greater level of moisture, as a result of frequent fog and high rainfall, may result in a high abundance of Sphaerophorus globosus in forests that are not true old growth. The number of old-growth forests sampled in this study was necessarily low because there are so few old-growth forest stands left in Nova Scotia. Further studies in adjacent provinces, such as Newfoundland and Labrador, could increase sample size and help determine if this species is a reliable old-growth indicator for a wider geographic region. Interestingly, Sphaerophorus globosus is only found on trees at one site in Maine, USA—Roque Island—which is one of the few remaining old-growth forest stands in the state (D. Richardson, Saint Mary’s University, Halifax, NS, Canada and M. Seaward, Bradford University, Bradford, UK, unpubl. data). Sphaerophorus globosus could be used as an indicator in two ways. Firstly, it can be used as an initial rapid assessment for potential old-growth forests. Surveyers can first assess the abundance of Sphaerophorus globosus and if old growth is indicated, they can follow up with more detailed protocols as outlined by Selva (1994), Stewart et al. (2003) or McMullin et al. (2008). Based on the results of the present study, indication of old growth is when at least 25% of trees have Sphaerophorus globosus. At least 20 trees should be examined from ground level to 2 m above ground on the bole. Surveyors should look for well-developed, mature, easily identifiable lichens. If 5 or more trees per 20 have Sphaerophorus globosus, then the stand has a high likelihood of being old growth and further assessment should be done. The second approach is to use Sphaerophorus globosus in concert with other indicators, as suggested by Whitman and Hagan (2004). These researchers used lichen density and large-diameter tree density to assess late successional forest. They found tree diameter to be the single best indicator of late successional forest in northeastern US. This method could be adapted to Nova Scotia by using both Sphaerophorus globosus frequency and tree-diameter criteria suggested by Stewart et al. (2003) for Nova Scotia. To qualify as old growth, a forest would need to meet the criteria of at least 50 trees/ha with a diameter at breast height greater than or equal to 40 cm. In addition, greater than or equal to 25% of the trees in the stand would have to have Sphaerophorus globosus. 540 Northeastern Naturalist Vol. 19, No. 4 Acknowledgments We would like to thank field assistants Jan McPhee and Glenn Davis. Special thanks to Julie Towers for review of an early draft and assistance in the field. We also thank David Richardson, Jim Hinds, and Scott LaGreca for helpful comments on the submitted manuscript. Financial support was provided by Bowater Mersey Paper Company Ltd., Kimberly-Clark Ltd., Nova Scotia Department of Natural Resources-Wildlife Division, and StoraEnso Port Hawkesbury Ltd. Financial and technical support was made possible by the following people of these organizations: Tony Duke, Peter Jones, Bevan Lock, Gerald Peters, John Porter, Steve Rutledge, and Russ Waycott. 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