Nitrogen addition, not initial phylogenetic diversity, increases litter decomposition by fungal communities

• Published in: Frontiers in microbiology Vol. 6; p. 109
• Main Authors: Amend, Anthony S., Matulich, Kristin L., Martiny, Jennifer B. H.
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 18.02.2015
• Subjects: Climate Change; ecosystem function; Fungi; Leaf litter decomposition; Microbiology; nitrogen fertilization; phylogenetic diversity; microcosm; ecosystem function; fungi; phylogenetic diversity; nitrogen fertilization; climate change; leaf litter decomposition
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2015.00109

Fungi play a critical role in the degradation of organic matter. Because different combinations of fungi result in different rates of decomposition, determining how climate change will affect microbial composition and function is fundamental to predicting future environments. Fungal response to global change is patterned by genetic relatedness, resulting in communities with comparatively low phylogenetic diversity (PD). This may have important implications for the functional capacity of disturbed communities if lineages sensitive to disturbance also contain unique traits important for litter decomposition. Here we tested the relationship between PD and decomposition rates. Leaf litter fungi were isolated from the field and deployed in microcosms as mock communities along a gradient of initial PD, while species richness was held constant. Replicate communities were subject to nitrogen fertilization comparable to anthropogenic deposition levels. Carbon mineralization rates were measured over the course of 66 days. We found that nitrogen fertilization increased cumulative respiration by 24.8%, and that differences in respiration between fertilized and ambient communities diminished over the course of the experiment. Initial PD failed to predict respiration rates or their change in response to nitrogen fertilization, and there was no correlation between community similarity and respiration rates. Last, we detected no phylogenetic signal in the contributions of individual isolates to respiration rates. Our results suggest that the degree to which PD predicts ecosystem function will depend on environmental context.