The Effects of Calcium Content on the Federally Endangered Thalictrum Cooleyi of North Carolina Pocosins and Pine Savannas

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)
Ivy C Culver (Creator)
East Carolina University (ECU )
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Abstract: Thalictrum cooleyi Ahles (Cooley’s meadowrue) is a federally endangered, herbaceous perennial found in very wet, loamy pine savannas of North Carolina, Georgia, and Florida. Pine savannas are characterized by palustrine hydrology and oligotrophic, acidic soils. Some rare plant species are associated with high calcium soils (calcicoles). An unpublished report suggested that soils associated with populations of this meadowrue have different chemistry and plant nutrient abundances than do soils where the plant is not present. Knowledge of soils and other habitat characteristics is crucial to T. cooleyi conservation. I collected soil samples near and away from T. cooleyi plants at Shaken Creek Preserve, Pender Co., NC, and had their nutrients analyzed (labs noted later). Soil with T. cooleyi present was distinctive from that lacking T. cooleyi, i.e., higher mean calcium content (719 ± 108 vs. 248 ± 33 mg/dm3), cation exchange capacity (CEC) (6.6 ± 0.5 vs. 4.5 ± 0.3 meq/100 cm3), and base saturation (60 ± 4 vs. 32 ± 3 %). Such values are characteristic of sandy, clay-based soils of the Coastal Plain, considered as relatively infertile soils. These results suggest that higher calcium content, CEC, and base saturation may be associated with the presence of Cooley’s meadowrue. I also asked whether calcium contents affect growth of T. cooleyi. In a greenhouse, I grew 57 plants in Fafard 3B® soilless substrate mix, 19 plants in each of three treatments suggested by the literature: 1) none (control), 2) 0.5% (low), or 3) 2.0% (high) powdered calcium carbonate (CaC03) by weight. I measured several growth responses of each plant every month for 7 mo. The mean longest leaf length, number of leaves, and total plant biomass did not differ significantly among treatments. This lack of response is not surprising, for not all plant growth metrics respond to higher calcium levels in the greenhouse, particularly in artificial soil mixes; plant response is complex and confounded. Edaphic factors other than calcium positively and negatively influence plant response, such as exposure to exchangeable aluminum, which can inhibit the growth of calcicoles. Pine savannas are fire-dependent communities. Fires are an integral part of the ecology of pine savannas, allowing thinning of shrubby undergrowth and of the canopy so herbaceous plants receive more light. They also elevate the availability of nutrients and mineralization in the soil (Wilbur and Christensen 1983). Whether caused by or correlated with T. cooleyi presence, chemical properties of soils, including calcium content, CEC, and base saturation, are somehow related to distribution of this endangered plant species.

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Language: English
Date: 2016
calcium, Thalictrum cooleyi, pine savanna

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