Intensively Managed Landscapes: Anthropocene in Action

2016 CUAHSI Biennial Colloquia

Praveen Kumar / University of Illinois at Urbana-Champaign

Finding Your Place in Big Data: Using Observations to Understand Hydrologic Processes for Predicting a Changing World

Wolman Lecture

Background: The Wolman Lecture is named after M. Gordon “Reds” Wolman (1924-2010). Wolman was a prominent and much-beloved fluvial geomorphologist who taught at Johns Hopkins University from 1958 until his death in 2010. He advanced the quantitative and interdisciplinary study of rivers, contributed to solving a multitude of water management problems around the world, and was well-known for his insight, humor, and thoughtful mentoring of dozens of graduate students.

Talk Description:

Intensively managed landscapes in the glaciated mid-western U.S. are relatively young. After the end of glaciation, rapid changes in soil and vegetation took place on these landscapes as climate transitioned. Wind driven soils (loess) provided a backdrop for the establishment of pioneer vegetation species followed with nitrogen fixing plants leading to the eventual establishment of climax species, the prairies. Loess deposited over glacial drift supported rich environment for biodiversity through competition, mutualism and mosaicking. In areas impacted by Wisconsian episode (latest glacial episode), this happened about eight thousand years ago. Heterogeneity of vegetation, soil organic carbon, nitrogen, etc. arose from differentiated accumulation over till, which has high water holding capacity, and outwash, which has lower water holding capacity. Transformations and transport was dominated by large residence times over low gradient landscape. Since European settlement and the trajectory of large-scale adoption of industrial agriculture, these landscapes have been rapidly modified. Reduced residence time no longer mutes event scale response. Landscape has switched to transport dominated system due to anthropogenic modifications, which includes deployment of tile drains, ditching, and channel straightening. This amplifies event scale dynamics, changes dominant processes, and alters process connectivity across time and space with non-reversible, often threshold dominated, cascading effects. Annual tillage and nitrogen application alters the stocks and flows of carbon and nutrients through the soils and water bodies. Understanding the deep couplings between landscape evolution, climate change, and anthropogenically driven dis-equilibrium arising from the alterations of coupled water, carbon and nutrient cycles across scales remains a challenge. This talk will present insights gained towards this challenge from the efforts of the Intensively Managed Landscape Critical Zone Observatory.