Traits that permit successful invasions have often seemed idiosyncratic, and the key biological traits identified vary widely among species. This fundamentally limits our ability to determine the invasion potential of a species. However, ultimately, successful invaders must have positive growth rates that longer term result in higher biomass accumulation than competing established species. In m...

Cover crops are a major focus of conservation agriculture efforts because they can provide soil cover and increase nutrient availability after their mineralization in cropping systems. To evaluate the effect of residue type and placement on rate of decomposition and carbon (C) and nitrogen (N) mineralization, residues from two food crops, maize (Zea mays L.) and common bean (Phaseolus vulgaris ...

The assimilation (uptake or immobilization) of inorganic nitrogen (N) and the production of ammonium (NH(4)(+)) from organic N compounds are universal functions of microorganisms, and the balance between these two processes is tightly regulated by the relative demands of microbes for N and carbon (C). In a heterogeneous environment, such as soils, bulk measurements of N mineralization or immobi...

Microbial nitrogen use efficiency (NUE) describes the partitioning of organic N taken up between growth and the release of inorganic N to the environment (that is, N mineralization), and is thus central to our understanding of N cycling. Here we report empirical evidence that microbial decomposer communities in soil and plant litter regulate their NUE. We find that microbes retain most immobili...

The role of plant intraspecific variation in plant-soil linkages is poorly understood, especially in the context of natural environmental variation, but has important implications in evolutionary ecology. We utilized three 18- to 21-year-old common gardens across an elevational gradient, planted with replicates of five Populus angustifolia genotypes each, to address the hypothesis that tree gen...

We measured annual net nitrogen (N) mineralization, nitrification, and amino acid production in situ across a primary successional sequence in interior Alaska, USA. Net N mineralization per gram dry soil increased across the successional sequence, but with a sharp decline in the oldest stage (black spruce). Net N mineralization expressed per gram soil organic matter exhibited the opposite patte...