Ecosystems are not static! Ecosystems of all types (from semi-arid shrublands to conifer forests in snowy mountains, to urban greenspaces) are in a continual state of change. Some changes are gradual, 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.
Our lab uses models to help to understand the relationships among climate, human actions, ecosystems and disturbances. (To learn more about the 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
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 here). Our group is now working on a new interdisciplinary project that examines linkages between fires, climate and management actions.
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.
- 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?
- 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 (https://www.nsf.gov/awardsearch/showAward?AWD_ID=1520847&HistoricalAwards=false and to SERI site on Bren)
- SESYNC Fire Project (https://www.sesync.org/project/data-intensive-analysis-andor-modeling-for-socio-environmental-synth>
SERI Fire Project
Over-arching Research Questions
How do fuel treatments alter ecosystem services (water provision, carbon sequestration, mortality and fire risk – maybe reservoir sedimentation)
– for a “patch”
– across a watershed
Key point is that we seek to answer this question by considering ecosystem services both immediately after a disturbance (fire, fuel treatments) and during the recovery period – therefore we must account for inter-annual climate variation and change
COUPLING with SOCIAL SCIENCE
How does salience (as a control on when and where fuel treatments occur) influence ecosystem services – by comparing estimation of ecosystem services (water, carbon, fire and mortality risk) at decadal time scales for scenarios
a) where fuel treatments “optimize” particular services
b) no fuel treatments
c) salience-driven fuel treatments
- Peng, H., Tague, C., Jia, Y. (Accepted) Evaluating the eco-hydrological impacts of reforestation in the Loess Plateau, China using an eco-hydrological model, Ecohydrology
- Anderegg, W., Hicke, J., Fisher, R., Allen C., Bentz, B., Hood, S., Lichstein, J., Macalady, A., McDowell, N., Yude, P., Raffa, K., Sala, A., Shaw, J., Stephenson, N., Tague, C., Zeppel, M. (In Press) Tree mortality from drought, insects and their interactions in a changing climate, New PhytologistPDF here
- Tague, C.L., McDowell, N.G., Allen, C.D. (2013) An integrated model of environmental effects on growth, carbohydrate balance, and mortality of Pinus ponderosa forests in the Southern Rocky Mountains, PLoS ONE 8(11): e80286. doi: 10.1371/journal.pone.0080286.
- Vicente-Serrano, S.M., Camarero J.J., Zabalza, J., SanGüesa-Barreda, G., López-Moreno, J.I., Tague, C. (2015) Evapotranspiration deficit controls net primary production and growth of silver fir: implications for Circum-Mediterranean forests under forecasted warmer and drier conditions, Agricultural and Forest Meteorology 206: 45-54. doi:10.1016/j.agrformet.2015.02.017.
- López-Morenoa, J.I., Zabalzaa, J., Vicente-Serranoa, S.M., Revueltoa, J., Gilabertea M., Azorin-Molinaa, C., Morán-Tejedab, E., García-Ruiza, J.M., Tague, C. (2014) Impact of climate and land use change on water availability and reservoir management: Scenarios in the Upper Aragón River, Spanish Pyrenees, Science of the Total Environment 493(15): 1222-1231. doi: 10.1016/j.scitotenv.2013.09.031. PDF here
- Tague, C., Seaby, L., and Hope, A. (2008) Modeling the eco-hydrologic response of a Mediterranean type ecosystem to the combined impacts of projected climate change and altered fire frequencies, Climatic Change 93: 137-155.
- Hyde, K., Dickinson, M.B., Bohrer, G., Calkin, D., Evers, L., Gilbertson-Day, J., Nicolet, T., Ryan, K., Tague, C. (2013) Research and development supporting risk-based wildfire effects prediction for fuels and fire management: Status and needs, International Journal of Wildland Fire 22: 37-50.