Ecologists have long been interested in how ecosystems change over time in response to both natural and anthropogenic disturbances. Long-term monitoring at multiple scales is necessary to accurately predict trends. In addition, understanding the natural range of variability of ecosystems is important to interpreting change caused by anthropogenic stressors, land use, invasive species, or climate change. Ecological classifications can play a important role in defining that range of variation. The USNVC (US National Vegetation Classification) can provide critical help in the choice of monitoring sites by ensuring that they are representative and not redundant—as well as providing an interpretation of the monitoring data. Our session will bring together researchers of long-term ecosystem changes and those involved in the development and use of USNVC and foster dialog about forecasting global ecosystem changes. The session will focus on summarizing data about spatial and temporal vegetation dynamics, ecosystem diversity, ecosystem processes, and analysis of indicator species -- all of which address the need for monitoring long-term ecosystem changes. Presentations will cover questions on: (1) developing monitoring networks and interpreting monitoring results, (2) distinguishing between vegetation changes that may or may not be related to climate change, (3) how global ecosystem change is addressed by US National and State Parks and natural resource agencies (USFS, USFWS, USGS), and (4) supporting policy-making decisions derived from long-term monitoring. While the session focuses on interdisciplinary cooperation to facilitate needs to monitor and interpret ecosystem changes, individual talks will address a broader range of issues related to concepts, methods, and implementations of long-term environmental studies.