Vascular Plants of Adjacent Serpentine and Granite Outcrops on the Deer Isles, Maine, U.S.A

Abstract

We performed a comparative study of the vascular flora of a serpentine outcrop, Pine Hill, and that of a granite outcrop, Settlement Quarry, from Little Deer Isle and Deer Isle, respectively, Hancock County, Maine. We established four transects along a gradient from exposed to forested areas within each outcrop. Plants were recorded for presence and percent cover from circular plots along each transect. Soil and tissue samples were collected to examine soiltissue elemental relations. One hundred thirty-two taxa were recorded from serpentine and 89 from granite. Fifty-seven taxa were shared by both sites. Species richness (a diversity) and diversity indices (Shannon-Weaver and Simpson) suggested significant differences between sites and within sites. Principle Component Analysis suggested substrates differed significantly between sites and between exposures within sites. Tissue analyses suggested intraspecific variation with respect to tissue elemental concentrations, especially in Achillea millefolium, Oenothera biennis, Prunus virginiana, Selaginella rupestris, Spiraea alba var. latifolia, and Vaccinium angustifolium. Serpentine populations of many taxa showed low tissue Ca:Mg ratios (, 1) and high Ni concentrations. Two-way ANOVA showed significant substrate 3 species effects for several elements, including those that typically characterize serpentine substrates (Ca, Mg, Cr, Ni), suggesting significant genetic variation within species with respect to substrate. Finally, we compared our species list for Pine Hill with a plant survey done at Pine Hill and five additional serpentine sites of Maine in 1977 and provide a list of 285 vascular plant taxa from 62 families for serpentine in Maine.

Species specific plant-soil interactions influence plant distribution on serpentine soils

“…Examination of foliar elemental concentrations measured in native species on two British serpentine soils by Johnston and Proctor (1977) generally shows lower heavy metal concentrations (Fe, Ni, Co, and Cr) and higher Ca:Mg ratios in the woody plants (particularly Juniperus communis-common juniper) than in the herbaceous plants, which included both grasses and forbs. With the notable exception of Mn, a similar pattern (generally lower heavy metals and higher Ca: Mg in woody plant foliage) was observed for 12 herbaceous and 5 woody species growing on a serpentine soil in Maine, USA (Pope et al 2010).…”

“…Many bodenvag species have serpentine edaphic ecotypes that perform better on serpentine soils than nonserpentine ecotypes (Kruckeberg 1951;O'Dell and Claassen 2006;O'Dell and Rajakaruna 2011). Different species growing together on the same soils often have different foliar elemental concentrations, indicating different nutrient selectivities (Lyon et al 1971;Johnston and Proctor 1977;Koenigs et al 1982;Alexander et al 1989;Pope et al 2010). Different chemical elements may limit different species on serpentine, resulting in species-specific responses to substrate amendments (e.g., Koide and Mooney 1987;Huenneke et al 1990;Nagy and Proctor 1997).…”

Small-scale diversity of plant communities and distribution of species niches on a copper rock outcrop in Upper Katanga, D.R.Congo

“…Our results also indicate that maintaining the diversity of plant assemblages in post-mining rehabilitation programmes might be challenging, due to significant small-scale variation within those plant assemblages. With regard to restoration, actions to be promoted to limit the impact of mining activities on those ecosystems should pay special attention to the recreation of heterogeneous and specific conditions similar to those of plant communities (Pope et al 2010, Lazarus et al 2011). However, full restoration after re-establishing historic soil conditions will be achieved by avoiding changes in soil conditions, such as nutrient pollution, which alleviate edaphic stress (O'Dell & Classen 2011).…”

Limestone flora of the Simonton Corner Quarry Preserve, Rockport, Maine, USA

“…The acidic pH at the Preserve may result from higher organic matter content in the soil or be an indication of the generally lower pH found in coastal forests in Maine. For example, at a serpentine outcrop on Little Deer Isle, Maine, average pH was 5.3 on exposed serpentine and 3.96 on forested serpentine (Pope et al 2010), indicating that vegetation has a large influence on soil pH. But the influence of bedrock is still quite important: The average pH values of granite-derived soils in the same study were 4.1 on exposed granite and 3.3 on forested granite.…”