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Harvard Forest REU Symposium Abstract 2023
- Title: Going Underground: Root Exudation in Response to Soil Warming, Nitrogen Addition, and Tree-Fungal Association
- Author: Anisa Z Robinson (University of Pennsylvania)
- Abstract:
Forest soils are among the world’s largest organic carbon stocks. However, the effect of global change on belowground carbon cycling remains unclear. New England woodlands in the US serve as critical carbon sinks, and throughout these temperate regions, trees govern soil carbon dynamics via root exudation (release of organic carbon into soil) with the help of their mycorrhizae. Trees commonly interact with two types of mycorrhizal fungi to facilitate nutrient acquisition: ectomycorrhizal (EM) and arbuscular mycorrhizal (AM). AM and EM trees may respond differently to soil warming and nitrogen deposition because they are adapted to different nutrient economies. AM trees are typically situated in areas where inorganic nitrogen is more mobile in soils, making them suitable to inorganic nutrient economies. On the other hand, EM fungi produce enzymes which can acquire nitrogen from organic sources, making EM trees more suited to organic nutrient economies. So far, ongoing research has considered separate effects of soil warming, nitrogen availability, and tree-fungal associations on root exudation and soil carbon storage, but few studies have demonstrated their combined impacts. Here, we investigate how long-term soil warming and nitrogen fertilization alter root exudation rates and whether roots associated with different mycorrhizal types exude carbon differently in response to increased temperature and nitrogen availability. Roots and their exudates were sampled from a long-term interactive soil warming and nitrogen addition experiment at the Harvard Forest. We measured root exudation rates and expected for EM trees to respond more negatively to soil warming by nitrogen addition than AM trees, potentially reducing soil carbon inputs to EM dominated northern forests.
- Research Category: Soil Carbon and Nitrogen Dynamics
