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

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...

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Veröffentlicht in:Environmental research letters Jg. 15; H. 4; S. 44001 - 44010
Hauptverfasser: O'Connor, Rory C, Germino, Matthew J, Barnard, David M, Andrews, Caitlin M, Bradford, John B, Pilliod, David S, Arkle, Robert S, Shriver, Robert K
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Bristol IOP Publishing 01.04.2020
Schlagworte:
Aridity
Climate change
Drought
Drought index
ecological drought
Ecology
Ecosystems
Environmental impact
Evapotranspiration
fire
Land management
Moisture content
open climate campaign
Plant communities
Precipitation
Restoration
sagebrush
seeding
Seedlings
Seeds
Soil surfaces
Soil temperature
Soil water
Soil water potential
Water availability
Water deficit
Water potential
Wildfires
ISSN:1748-9326, 1748-9326
Online-Zugang:Volltext
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Zusammenfassung: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.
Bibliographie:ERL-108193.R1
ObjectType-Article-1
SourceType-Scholarly Journals-1
ObjectType-Feature-2
content type line 14
ISSN:1748-9326
1748-9326
DOI:10.1088/1748-9326/ab79e4