Agenda for Workshop I of Decomposition Synthesis Working Group

January 30-February 4^th 2004

January 29^th Most participants arrive in Santa Barbara

January 30^th

9 am- Review objectives of the workshop, review timing of events

10:30 am Break into session groups to plan lines of attack

noon –lunch

2 pm NCEAS briefing

3 pm Mats Olsson presentation

4 pm Discussion and continued planning

January 31st

Analysis and writing day

3:30 pm review days progress

February 1^st

Analysis and writing day

3:30 pm review days progress

February 2^nd

9 am Group photo

Presentations of the session groups; 1 hour presentation and discussion each

noon lunch

2 pm Re-evaluation of analysis based on feedback

February 3^rd

9 am Presentations of the session groups; 1 hour presentation and discussion each

noon lunch

2 pm schedule next workshop, review participants list, list of tasks to prepare for that effort

February 4^th

Participants meet in morning to list next steps to bring initial analysis phase to a close

Participants leave

Workshop Objectives: We will examine the changing paradigms of long term and large scale controls over decomposition using LIDET results. Three subsets of activities are proposed.

The first session, led by Harmon, will examine organic matter dynamics to test the generality of the Aber et al paradigm. Recent work has reinforced the idea that a ‘limit value’ of decomposition is reached, beyond which little mass loss occurs. The idea of a putative stable fraction or limit value derives chiefly from shorter-term studies. LIDET data suggests mass continues to be lost during the 5-10 year interval.

The second session, led by Burke and Currie, will examine Meentemeyer’s paradigm that climate and litter quality interactions exert control over rates of litter decomposition. Hundreds of individual studies have been conducted to further develop, refine, and test this view. Moreover, this paradigm is the foundation for litter decomposition rates in virtually every ecosystem model. LIDET data provides an opportunity to test the Meentemeyer paradigm with a breadth not available in the 1970s.

The third session, lead by Hart and Burke, would examine internal versus external controls of nitrogen dynamics. Theoretically, decomposition is controlled by soil nutrient availability. Although C:N ratios have been shown to correlate with decomposition rates in numerous studies, tests of the effects of exogenous nutrient availability on decomposition using natural soil fertility gradients and experimental fertilization are mixed. It is important to note that all these tests have been based on short-term (1-2 years) patterns. Exogenous nutrient availability at each LIDET site was assessed using inorganic N and P accumulation on ion exchange resin bags placed in the field, as well as with estimates of net N mineralization and nitrification determined under laboratory conditions. These data, along with 10 years of decomposition and nutrient content information, will allow the best test to date of the relative importance of external and internal nutrient factors in regulating decomposition patterns and nutrient release.