TY - JOUR
T1 - A multi-scale perspective of water pulses in dryland ecosystems
T2 - Climatology and ecohydrology of the western USA
AU - Loik, Michael E.
AU - Breshears, David D.
AU - Lauenroth, William K.
AU - Belnap, Jayne
N1 - Funding Information:
Acknowledgements This paper resulted from discussions at the Workshop on Resource Pulse Effects In Arid and Semi-Arid Ecosystems, 2–4 August 2002 in Tuscon, Arizona, USA. The authors thank Cathy Smith of the NOAA-CIRES Climate Diagnostics Center for help with state climate division data. D.D.B. received support from Los Alamos National Laroratory—Directed Research and Development Funds.
PY - 2004/10
Y1 - 2004/10
N2 - In dryland ecosystems, the timing and magnitude of precipitation pulses drive many key ecological processes, notably soil water availability for plants and soil microbiota. Plant available water has frequently been viewed simply as incoming precipitation, yet processes at larger scales drive precipitation pulses, and the subsequent transformation of precipitation pulses to plant available water are complex. We provide an overview of the factors that influence the spatial and temporal availability of water to plants and soil biota using examples from western USA drylands. Large spatial- and temporal-scale drivers of regional precipitation patterns include the position of the jet streams and frontal boundaries, the North American Monsoon, El Niño Southern Oscillation events, and the Pacific Decadal Oscillation. Topography and orography modify the patterns set up by the larger-scale drivers, resulting in regional patterns (102-106 km2) of precipitation magnitude, timing, and variation. Together, the large-scale and regional drivers impose important pulsed patterns on long-term precipitation trends at landscape scales, in which most site precipitation is received as small events (<5 mm) and with most of the intervals between events being short (<10 days). The drivers also influence the translation of precipitation events into available water via linkages between soil water content and components of the water budget, including interception, infiltration and runoff, soil evaporation, plant water use and hydraulic redistribution, and seepage below the rooting zone. Soil water content varies not only vertically with depth but also horizontally beneath versus between plants and/or soil crusts in ways that are ecologically important to different plant and crust types. We highlight the importance of considering larger-scale drivers, and their effects on regional patterns; small, frequent precipitation events; and spatio-temporal heterogeneity in soil water content in translating from climatology to precipitation pulses to the dryland ecohydrology of water availability for plants and soil biota.
AB - In dryland ecosystems, the timing and magnitude of precipitation pulses drive many key ecological processes, notably soil water availability for plants and soil microbiota. Plant available water has frequently been viewed simply as incoming precipitation, yet processes at larger scales drive precipitation pulses, and the subsequent transformation of precipitation pulses to plant available water are complex. We provide an overview of the factors that influence the spatial and temporal availability of water to plants and soil biota using examples from western USA drylands. Large spatial- and temporal-scale drivers of regional precipitation patterns include the position of the jet streams and frontal boundaries, the North American Monsoon, El Niño Southern Oscillation events, and the Pacific Decadal Oscillation. Topography and orography modify the patterns set up by the larger-scale drivers, resulting in regional patterns (102-106 km2) of precipitation magnitude, timing, and variation. Together, the large-scale and regional drivers impose important pulsed patterns on long-term precipitation trends at landscape scales, in which most site precipitation is received as small events (<5 mm) and with most of the intervals between events being short (<10 days). The drivers also influence the translation of precipitation events into available water via linkages between soil water content and components of the water budget, including interception, infiltration and runoff, soil evaporation, plant water use and hydraulic redistribution, and seepage below the rooting zone. Soil water content varies not only vertically with depth but also horizontally beneath versus between plants and/or soil crusts in ways that are ecologically important to different plant and crust types. We highlight the importance of considering larger-scale drivers, and their effects on regional patterns; small, frequent precipitation events; and spatio-temporal heterogeneity in soil water content in translating from climatology to precipitation pulses to the dryland ecohydrology of water availability for plants and soil biota.
KW - Drought duration
KW - El Niño Southern Oscillation
KW - Evapotranspiration
KW - Infiltration depth
KW - Pacific Decadal Oscillation
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U2 - 10.1007/s00442-004-1570-y
DO - 10.1007/s00442-004-1570-y
M3 - Review article
C2 - 15138879
AN - SCOPUS:6044271836
SN - 0029-8549
VL - 141
SP - 269
EP - 281
JO - Oecologia
JF - Oecologia
IS - 2
ER -