Ecosystems and Disturbance: Drought, Disease, Fire

Ecosystems are not static! From semi-arid shrublands to conifer forests in snowy mountains, to urban greenspaces they are continually changing. Some changes are gradual whereas others are more dramatic.

Gradual changes, such as the year to year changes in forest biomass that can be observed by looking at tree rings or through remote sensing of vegetation greenness. 

Other changes are more dramatic: fires, vegetation mortality due to insects, disease and drought or flooding.  These changes can substantially alter both the structure of the ecosystem (how much biomass it has, how deep the roots are, how much carbon is sequestered) and how the system uses water, energy and materials (ecosystem function). Human activities from fuel treatments and restoration activities to large scale land use change also dramatically alter ecosystem structure and function.

Understanding the dynamics of ecosystems – how ecosystem structure and function evolve through time under different conditions and in different places – is important for human communities who rely on the services provided by ecosystem.  Changing conditions – such a warming climate, changes in nitrogen deposition, or changes in land management can all alter the way ecosystems evolve through time and their sensitivity to disturbances such as fire or extreme drought. 

A good example of research related to ecosystem dynamics is the investigation of how changing fire frequency may influence hydrology and biogeochemical cycling both immediately following fire and during post fire recovery (See some recent lab papers that describe this issue). Our group is now working on a new interdisciplinary project that examines linkages between fires, climate and management actions (SERI Fire project).  

By integrating eco-hydrologic processes into a single modeling framework, this project allow us to ask a wide range of both applied and fundamental science questions – that include looking at how quickly ecosystem carbon stores, nutrient cycling and water use recover from fire or from fuel treatments and how a changing climate might impact both the likelihood of fire and what happens to the ecosystem following the fire.


Research Questions

  • How will a changing climate influence ecosystem productivity, biogeochemical cycling and the intensity and frequency of disturbances such as fire and drought related mortality
  • How does setting (soil, slope/aspect, elevation) and the current structure and composition of an ecosystem (e.g species types) influence how sensitive the ecosystems is drought related disturbances.
  • What is the trajectory of post-disturbance recovery of biomass vary with inter-annual climate variability? And under warmer climates?
  • How does ecosystem function (water use, nutrient dynamics, sediment retention, carbon sequestration) respond to a variety of disturbances (i.e., mortality, fire) at different spatial extents—for example, a fire that covers the entire watershed versus a fire that leaves the riparian zone intact?
  • How do land management actions – fuel treatments, logging, land terracing or in urban environments the configuration of vegetated patches include ecosystem productivity, water use and nutrient cycling and responses to disturbances?

Projects

  • Post-Fire Recovery of Chaparral Systems in Mission Creek Watershed, Santa Barbara, CA
  • Relationship of Fire Frequency and Biomass Recovery in the HJ Andrews Experimental Forest, OR
  • Climate Change Impacts on Sierra Critical Zone Observatory (CZO)
  • Eco-hydrologic Responses to Climate Change in Western U.S. Mountain Watersheds (WMI)
  • SERI Fire Project
  • NSF SEES Project
  • SESYNC Fire Project

Relevant Posters

The following are recent poster presentations given by members of our lab at various conferences. Click a figure to view the presentation.


Relevant Publications

Our lab uses models to help to understand the relationships among climate, human actions, ecosystems and disturbances.  (For more on design and application of models check out our Informatics section). Here are some recent papers where we’ve used models to look at ecosystems as dynamic systems.

  • Hanan, E.J., Ren, J., Tague, C.L., Kolden, C.A, Abatzoglou, J.T., Bart, R.R., Kennedy, M.C., Liu, M., Adam, J. (2020) How climate change and fire exclusion drive wildfire regimes at actionable scales, Environmental Research Letters 
  • Burke, W.D., Tague, C., Kennedy, M.C., Moritz, M.A. (2020) Understanding How Fuel Treatments Interact With Climate and Biophysical Setting to Affect Fire, Water, and Forest Health: A Process-Based Modeling Approach, Frontiers in Forests and Global Change 3. doi.org/10.3389/ffgc.2020.591162 
  • Saksa, P.C., Bales, R.C., Tague, C.L., Battles, J.J., Tobin, B.W., Conklin, M.H. (2019) Fuels treatment and wildfire effects on runoff from Sierra Nevada mixed-conifer forests, Ecohydrology 13(3): e2151. Doi.org/10.1002/eco.2151  
  • Boisrame, G.F.S, Thompson, S.E., Tague C., Stephens, S.L. (2019) Restoring a Natural Fire Regime Alters the Water Balance of a Sierra Nevada Catchment, WRR https://doi.org/10.1029/2018WR024098