Aspects of community ecology, population growth and genetic structure applied to the conservation of Polemonium pectinatum (Polemoniaceae), a rare and threatened shrub-steppe perennial.

摘要

In this study, I examine aspects of community ecology and population biology to aid conservation efforts for Polemanium pectinatum, a threatened herbaceous perennial restricted to bottomlands of eastern Washington's channeled scablands. Land conversion due to farming has reduced potential habitat for new populations. Additional threats include noxious weeds and grazing.; A majority of the chemical and physical soil components measured at sites in different bottomlands which support Polemonium pectinatum suggests this rare plant can grow across wider soil conditions than expected from its restricted distribution. The significantly greater total carbon and nitrogen measured in soils under P. pectinatum compared to the adjacent vegetation may be due to decomposition of roots and a litter layer. Reintroduction sites lacking these conditions would benefit from application of short-term fertilizer as well as incorporation of organic matter.; A significant F{dollar}rmsb{lcub}st{rcub}{dollar} value of 0.23, identified using microsatellite markers, suggests high genetic differentiation among four populations sampled from four different bottomlands. This high interpopulation variation suggests historical isolation and it is conceivable given the geographical containment created by the channeled topography where Polemonium pectinatum grows.; Demographic analysis revealed that stage-based transition matrices were not significantly different across three transition years measured during years of above-average precipitation for two large ({dollar}>{dollar}1000 individuals) Polemonium pectinatum occurrences. Associated projections of population growth suggested short-term persistence. However, a P. pectinatum transition matrix for plants under Russian knapweed invasion was dominated by stasis and regression. Decline in growth rate projected from this matrix suggests the weeds have a negative impact on short-term persistence.; Maintaining extant Polemonium pectinatum populations within different bottomlands should be a top priority for short and long term conservation efforts. A reintroduction in the depauperate eastern edge of the current distribution must be critically evaluated as a way to reduce the chances of complete loss in this area. Finally, it is important to quantify how the combination of dry years and direct threats (both weeds and grazing) affects demographic performance.