The Effects of Leaf Litter on Germination in The Serpentine Endemic Boechera constancei

Abstract

Leaf litter accumulation may negatively impact seedling germination by altering key ecosystem properties, such as light availability and soil moisture. The impacts of litter depth may be particularly strong for species in dry environments with low vegetative cover and high light availability. The rare species Boechera constancei (Rollins) Al-Shehbaz (Brassicaceae) is endemic to the serpentine outcrops of Plumas and Sierra Counties, where litter accumulation is highly variable and B. constancei inhabits a range of litter depths (0–40 mm). In this study, we tested whether increased litter depth impedes germination, and whether populations vary in tolerance to litter depth. Specifically, we quantified the impacts of treatments representing the observed range of litter depth occupied by B. constancei on the germination of seed collected from nine populations. Differences in germination were analyzed using a two-way ANOVA. While both source population and litter treatment influenced germination, the interaction term was not significant. Post-hoc Tukey's honest significance tests revealed that germination under both median and high litter treatments was significantly lower than under no litter. The median and high litter treatments did not differ significantly. Differences in germination were observed during dark, cold stratification, suggesting that light availability was not a factor. These results indicate that early life stages of this species may benefit from litter reduction treatments, as both median and high litter treatments reduced germination.