## Breadcrumb

-  Publications 
-  Articles 

#           Small-scale water deficits after wildfires create long-lasting ecological impacts      

      March 13, 2020    

Ecological droughts are deficits in soil–water availability that induce threshold-like ecosystem responses, such as causing altered or degraded plant-community conditions, which can be exceedingly difficult to reverse. However, 'ecological drought' can be difficult to define, let alone to quantify, especially at spatial and temporal scales relevant to land managers. This is despite a growing need to integrate drought-related factors into management decisions as climate changes result in precipitation instability in many semi-arid ecosystems. We asked whether success in restoration seedings of the foundational species big sagebrush (Artemisia tridentata) was related to estimated water deficit, using the SoilWat2 model and data from >600 plots located in previously burned areas in the western United States. Water deficit was characterized by: (1) the standardized precipitation-evapotranspiration index (SPEI), a coarse-scale drought index, and (2) the number of days with wet and warm conditions in the near-surface soil, where seeds and seedlings germinate and emerge (i.e. days with 0–5 cm deep soil water potential >−2.5 MPa and temperature above 0 °C). SPEI, a widely used drought index, was not predictive of whether sagebrush had reestablished. In contrast, wet-warm days elicited a critical drought threshold response, with successfully reestablished sites having experienced seven more wet-warm days than unsuccessful sites during the first March following summer wildfire and restoration. Thus, seemingly small-scale and short-term changes in water availability and temperature can contribute to major ecosystem shifts, as many of these sites remained shrubless two decades later. These findings help clarify the definition of ecological drought for a foundational species and its imperiled semi-arid ecosystem. Drought is well known to affect the occurrence of wildfires, but drought in the year(s) after fire can determine whether fire causes long-lasting, negative impacts on ecosystems.

## Citation Information

## Related Content

                  -              Data           
                  -              Connect           

February 27, 2020

####                 Ecological drought for sagebrush seedings in the Great Basin              

Forest and Rangeland Ecosystem Science Center

#### Matthew J Germino

##### Supervisory Research Ecologist

Forest and Rangeland Ecosystem Science Center

mgermino@usgs.gov

208-221-4638

####             Caitlin M Andrews (Former Employee)          

##### Ecologist

Southwest Biological Science Center

#### John B Bradford, Ph.D.

##### Research Ecologist, Northwest CASC

Climate Adaptation Science Centers

jbradford@usgs.gov

928-380-4671

#### David S Pilliod

##### Supervisory Research Ecologist

Forest and Rangeland Ecosystem Science Center

dpilliod@usgs.gov

208-387-1363

#### Robert S Arkle

##### Ecologist

Forest and Rangeland Ecosystem Science Center

rarkle@usgs.gov

208-426-5205

## Related Content

February 27, 2020

####                 Ecological drought for sagebrush seedings in the Great Basin              

Forest and Rangeland Ecosystem Science Center

#### Matthew J Germino

##### Supervisory Research Ecologist

Forest and Rangeland Ecosystem Science Center

mgermino@usgs.gov

208-221-4638

####             Caitlin M Andrews (Former Employee)          

##### Ecologist

Southwest Biological Science Center

#### John B Bradford, Ph.D.

##### Research Ecologist, Northwest CASC

Climate Adaptation Science Centers

jbradford@usgs.gov

928-380-4671

#### David S Pilliod

##### Supervisory Research Ecologist

Forest and Rangeland Ecosystem Science Center

dpilliod@usgs.gov

208-387-1363

#### Robert S Arkle

##### Ecologist

Forest and Rangeland Ecosystem Science Center

rarkle@usgs.gov

208-426-5205

### Study Area

### Contact

####               Forest and Rangeland Ecosystem Science Center (FRESC) Headquarters          

777 NW 9th StSuite 400Corvallis, OR97330United States

fresc_outreach@usgs.gov

541-750-1030

541-750-1069

### Explore Search

                  - United  States
                  - Oregon
                  -  Idaho
                  -  Nevada
                  -  Utah

View All **