1. ARC LTER Long-term (~30 yr) N+P fertilization of moist acidic tundra Factorial N, P, greenhouse, shade house experiment on 5 tundra types Herbivore exclosure, N+P fertilizer in moist acidic and heath tundra Species removal, N+P fertilizer in moist acidic tundra Multi-level factorial N,P fertilization of moist acidic tundra Stream P fertilization/ 15 N labeling Stream recovery from P fertilization Stream moss re-establishment with 2 nd fertilization Whole-lake NP fertilization Lake recovery from fertilization Inorganic Nutrient Research Toolik Lake ARCTIC- LTER ARC LTER Long-term (~30 yr) N+P fertilization of moist acidic tundra Factorial N, P, greenhouse, shade house experiment on 5 tundra types Herbivore exclosure, N+P fertilizer in moist acidic and heath tundra Species removal, N+P fertilizer in moist acidic tundra Multi-level factorial N,P fertilization of moist acidic tundra Stream P fertilization/ 15 N labeling Stream recovery from P fertilization Stream moss re-establishment with 2 nd fertilization Whole-lake NP fertilization Lake recovery from fertilization

2. Forbs Evergreen Deciduous Graminoids Recent Key Findings - Inorganic Nutrients Toolik Lake ARCTIC- LTER ARC-LTER Reference Fertilized 198519952005 Epilithic Chl-a (  g cm -2 ) % Moss Cover Not Present?? 200020052010 Chl-a (  g L -1 ) Sechi depth (m) Zooplankton (  g L -1 ) Fish (N) 0 6 12 0 6 0 600 300 600 300 900 Recovery from Thermokarst

3. Syntheses ideas - Inorganic Nutrients Toolik Lake ARCTIC- LTER ARC-LTER Soil to plant redistribution of nutrients, reset plant- soil balance and synchrony among nutrient cycles The entrainment of nutrients into the ecosystem cycle requires a continuous balance between plant and soil processes. Disturbance disrupts that balance and the synchrony of N & P cycles. 2 nd succession first reestablishes the soil-plant balance by a redistribution of nutrients, then re-accumulates lost nutrients. Re-accumulate lost nutrients Plant biomass Years of nutrient entrainment