Temporal fluctuations in young-of-the-year yellow perch mercury bioaccumulation in lakes of northeastern Minnesota.

Identifying what determines fish mercury (Hg) bioaccumulation remains a key scientific challenge. While there has been substantial research on spatial variation in fish Hg bioaccumulation, the factors that influence temporal fluctuations in fish Hg have received less attention to date. In this study, we built upon a growing body of research investigating young-of-the-year (YOY) yellow perch Hg bioaccumulation and investigated annual fluctuations in YOY yellow perch Hg in six lakes in northeastern Minnesota over eight years.

Yellow Perch () Mercury Unaffected by Wildland Fires in Northern Minnesota.

Wildland fire can alter mercury (Hg) cycling on land and in adjacent aquatic environments. In addition to enhancing local atmospheric Hg redeposition, fire can influence terrestrial movement of Hg and other elements into lakes via runoff from burned upland soil. However, the impact of fire on water quality and the accumulation of Hg in fish remain equivocal.

An experimental test of fitness variation across a hydrologic gradient predicts willow and poplar species distributions.

Environmental filtering is an important community assembly process influencing species distributions. Contrasting species abundance patterns along environmental gradients are commonly used to provide evidence for environmental filtering. However, the same abundance patterns may result from alternative or concurrent assembly processes.

Pervasive and strong effects of plants on soil chemistry: a meta-analysis of individual plant 'Zinke' effects.

Plant species leave a chemical signature in the soils below them, generating fine-scale spatial variation that drives ecological processes. Since the publication of a seminal paper on plant-mediated soil heterogeneity by Paul Zinke in 1962, a robust literature has developed examining effects of individual plants on their local environments (individual plant effects). Here, we synthesize this work using meta-analysis to show that plant effects are strong and pervasive across ecosystems on six continents.

Contrasting effects of plant species traits and moisture on the decomposition of multiple litter fractions.

Environmental variation in moisture directly influences plant litter decomposition through effects on microbial activity, and indirectly via plant species traits. Whether the effects of moisture and plant species traits are mutually reinforcing or counteracting during decomposition are unknown. To disentangle the effects of moisture from the effects of species traits that vary with moisture, we decomposed leaf litter from 12 plant species in the willow family (Salicaceae) with different native habitat moisture preferences in paired mesic and wetland plots.

A resurrection study reveals rapid adaptive evolution within populations of an invasive plant.

The future spread and impact of an introduced species will depend on how it adapts to the abiotic and biotic conditions encountered in its new range, so the potential for rapid evolution subsequent to species introduction is a critical, evolutionary dimension of invasion biology. Using a resurrection approach, we provide a direct test for change over time within populations in a species' introduced range, in the Asian shade annual Polygonum cespitosum. We document, over an 11-year period, the evolution of increased reproductive output as well as greater physiological and root-allocational plasticity in response to the more open, sunny conditions found in the North American range in which the species has become invasive.