Carbon Storage by Carex stricta Tussocks: A Restorable Ecosystem Service?

Tussock-forming plants are globally widespread and enhance ecosystem services. We hypothesized that tussocks of Carex stricta store carbon (C) in addition to enhancing microtopography and biodiversity. We characterized tussock size, composition, and carbon pools associated with three undisturbed C. stricta-dominated tussock meadows in the Upper Midwest, USA. Remnant meadow tussocks were tall (17.2 cm), voluminous (4,113 cm(3)), and largely organic (95 %), indicating their ability to accumulate organic matter and store carbon. Tussocks were the second largest C pool (next to soil) in these ecosystems; they comprised 41-62 % of total biomass C. Using bomb C-14 dating, we estimated that reference-site tussocks were over 50 years old. Their long-term persistence is consistent with lower leaf decomposition rates on tussocks (k = 0.26 years(-1)) than in tussock interspaces (k = 0.39 years(-1)). An urban tussock meadow had tussocks that were shorter than those of remnant sites, but less dense than a restored meadow. The restored meadow (a parts per thousand currency sign15 years) had smaller, structurally distinct tussocks that stored less C. Among the five sites, C stocks were lowest in the urban and restored meadows, supporting the need to conserve existing C stores in remnant meadows and to restore tussock sedge for multiple ecosystem services.