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Harvard Forest Symposium Abstract 2009

• Title: Hydrologic-controls on organic matter dynamics in a forested-headwater stream
• Primary Author: William Sobczak (College of the Holy Cross)
• Additional Authors: Emery Boose (Harvard Forest); Adrien Finzi (Boston University); Peter Raymond (Yale University); Jim Saiers (Yale University)
• Abstract:

  The objective of the proposed work is to identify linkages between forest and stream ecosystem fluxes of energy and nutrients at hourly to annual and longer timescales. Specifically, we seek to identify controlling factors in C, N, and P transfers from a mature forest to a coupled headwater stream among and throughout diverse hydrologic conditions. Based on preliminary data, we hypothesize that stream export of C, N, and P is coupled to short-term storm events in which dissolved organic matter is conservatively transported from an upland forest to downstream ecosystems. Our collaborative-research program integrates three important frontier areas of ecosystem science and global change biology: 1) defined linkages between coupled biogeochemical cycles in terrestrial and aquatic ecosystems in regards to carbon and nutrient losses, 2) rapid assessment of ecosystem-level processes with continuous, “real-time” stream hydrology and biogeochemistry data that is quickly distributed to the scientific community, and 3) delineation of underlying biogeochemical mechanisms resulting in periodic and continuous carbon and nutrient losses from terrestrial ecosystems that occur at disparate temporal scales ranging from hour to decade.
  
  
  
  We have designed a new, highly-choreographed project that stands to make important discoveries in the fields of hydrology, ecosystem science and organic geochemistry through intensive, collaborative study of a small forested watershed at the Harvard Forest. First and foremost, our project aims to determine how biological, physical and hydrologic processes that impact DOM quantity and composition react to hydrologic events. This will be achieved through what we believe is an unprecedented integration coupling of hydrologic modeling, ecosystem level measurements and experiments, high temporal resolution monitoring during events, and in-depth organic geochemistry, and hydrologic modeling. In addition we will characterize the composition of DOM produced by rainfall and different biological components of the ecosystem and determine how DOM compositions from these components change with events. We will also couple high temporal resolution multi-probe measurements of the optical properties of DOM with less temporally intensive yet cutting edge organic matter and inorganic geochemistry along flow-paths and within biological compartments to greatly enhance the predictive capacity of oura hydrologic models predictive capacity. With this approach we aim to significantly enhance the understanding of the importance of hydrologic events to forest biogeochemistry and to advance methodology in a way forward that will be transferable to other forested watershedsfield sites worldwide.

• Research Category: Watershed Ecology