The population ecology of a perennial clonal herb Acorus calamus L. (Acoraceae) in southeast Ohio, United States.

摘要

Acorus calamus L. (Sweetflag, family Acoraceae) is an economically important helophyte found in temperate and subtropical wetlands. I examined edaphic factors influencing distribution of A. calamus populations; potential of the rhizome in wetland restoration; genetic diversity of populations; and, environmental factors influencing seed germination. Redundancy analysis (RDA) indicated that rhizome length and biomass, total number of leaf scars and leaf scars per unit length in A. calamus are positively related to a soil calcium content gradient. Shoot density is influenced most by a silt and nitrogen gradient but negatively related to organic matter. Multivariate Analysis of Variance indicated that light (lambda = 0.762, P 0.001), nutrient (lambda = 0.449, P 0.001) and moisture (lambda = 0.508, P 0.001) had significant effects on rhizome growth. A. calamus grows best in open light, waterlogged conditions and is best planted at the very onset of a wetland mitigation project.; I estimated genetic diversity in populations of Acorus calamus L. in southeast Ohio using Intersimple sequence repeats. Indices of genetic diversity, evenness, expected heterozygosity and percentage of polymorphic loci were low. Analysis of Molecular variance (AMOVA) indicated that most of the variation (58%) is among populations and a moderate amount (42%) is within populations. Cluster analysis, Principal Coordinates Analysis and the coefficient of genetic variation among populations (Gst = 0.7188) and gene flow (Nm = 0.1956) indicated little gene flow among populations. My results suggest that A. calamus populations in southeast Ohio are primarily clonal in nature.; Seed germination occurred only in light and varied significantly ( F = 8.42, p 0.0001) across temperatures with seeds germinating maximally in spring (15/25°C) and summer (20/35°C) in submerged conditions. Germination velocity (Timson's Index) was greater in moist acidic conditions in spring temperatures. There was no significant difference in seed germination after storage for 24 months. Results indicate that A. calamus seeds are adapted to germinate in wide variety of wetlands in summer and spring but are limited by light availability. They can create persistent seed banks. Seeding of A. calamus in wetland restoration projects is best conducted at the very onset when there is more light at the soil surface.