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Differences in soil nutrients beneath different tree species are often attributed to the impacts of species-level patterns of nutrient uptake and litter chemistry. However, in naturally established forests it is difficult to isolate tree species' influence on soil development from differences in underlying soil properties that can affect tree species establishment. To discern the impacts of tree species on soil properties, we investigated how Norway spruce (Picea abies (L.) H. Karst.), red oak (Quercus rubra L.), and sugar maple (Acer saccharum Marshall) influence the distribution of carbon, nitrogen, and calcium in a 67-year-old common garden. We expected these species would produce foliar litter with contrasting chemistry, resulting in corresponding variation in organic matter (OM) turnover and nutrient accumulation in soils. Instead, we found that forest floor mean residence time correlated negatively with earthworm density and did not correlate with any measurement of litter chemistry. Red oak exhibited the fastest OM turnover and highest earthworm densities and Norway spruce showed the greatest OM accumulation and fewest earthworms. These findings suggest that future changes in earthworm invasion and forest tree species composition may have strong implications for ecosystem nutrient cycling and retention. Resume: Le fait que les nutriments different dans le sol sous differentes especes d'arbre est souvent attribue aux impacts du caractere specifique de l'absorption des nutriments et des processus chimiques dans la litiere. Cependant, dans les forets qui se sont etablies naturellement, il est difficile d'isoler l'influence d'une espece d'arbre sur le developpement du sol a partir des differences dans les proprietes du sol sous-jacent qui peuvent influencer l'etablissement d'une espece d'arbre. Pour discerner les impacts de l'espece d'arbre sur les proprietes du sol, nous avons etudie comment l'epicea commun (Picea abies (L.) H. Karst.), le chene rouge (Quercus rubra L.) et l'erable a sucre (Acer saccharum Marshall) influencent la repartition du carbone, de l'azote et du calcium dans une meme plantation agee de 67 ans. Nous nous attendions a ce que ces especes produisent une litiere de feuilles dont les caracteristiques chimiques seraient differentes, entrainant une variation correspondante dans le renouvellement de la matiere organique (MO) et l'accumulation des nutriments dans le sol. Au contraire, nous avons trouve que le temps de residence moyen de la couverture morte etait negativement correle avec la densite des vers de terre et n'etait correle avec aucune des mesures des caracteristiques chimiques de la litiere. La densite des vers de terre etait la plus elevee et le renouvellement de la matiere organique etait le plus rapide sous le chene rouge tandis que c'est sous l'epicea commun qu'il y avait le moins de vers de terre et que l'accumulation de MO etait la plus forte. Ces resultats indiquent que des changements futurs dans l'invasion des vers de terre et la composition en especes d'arbre forestier pourraient avoir d'importantes consequences sur la retention et le recyclage des nutriments dans l'ecosysteme. [Traduit par la Redaction], Introduction Forest tree species composition across the northeastern US is expected to change. Species-specific pests and pathogens, such as the hemlock woolly adelgid [Adeldes tsugae (Annand)], beech bark disease, and [...]

Environmental problems are generally complex and blind to disciplinary boundaries. Efforts to devise long-term solutions require collaborative research that integrates knowledge across historically disparate fields, yet the traditional model for training new scientists emphasizes personal independence and disciplinary focus. Growing awareness of the limitations of the traditional model has spurred a reexamination of graduate training in the environmental sciences. Many institutions are implementing novel training approaches, with varying degrees of success. In this article, a group of current and former doctoral students evaluates our collective experience in one such program, the Biogeochemistry and Environmental Biocomplexity Program at Cornell University, funded by an Integrative Graduate Education and Research Traineeship grant from the National Science Foundation. We identify aspects of the program that contributed to our integrative research training experience, and discuss stumbling blocks that may arise in such programs. We conclude with recommendations for students and faculty interested in facilitating cross-disciplinary interactions at their home institutions. INSET: Box 1. Surveys: Graduate student perceptions of opportunities and. [ABSTRACT FROM AUTHOR]