Forest Management and Catchment Hydrology Helga Van Miegroet Dept. - PowerPoint PPT Presentation

Forest Management and Catchment Hydrology Helga Van Miegroet Dept. Wildland Resources Dept. Watershed Sciences Utah State University Logan, Utah, USA COST FORMAN Meeting - Vienna, 15 September 2008

Catchment Water Balance Q = P – ET ( ± dS ± dG) Globally: P – ET = 0

Extracted from M. Bredemeier’s COST-FORMAN presentation

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG • Influence on Q (quantity) • Influence on timing of Q • Role of scale / spatial extent

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG The influences of management and environmental change on the components of the water balance are not entirely independent i.e., there are mutual feedbacks

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG

Influence of forest on large-scale climate � atmospheric models Source: Bonan, 2008 Science 320:1444-1449

Populus tremuloides (aspen) Example: Montane Forest in Northern Utah Spruce, fir, DF (conifer) How will this affect Q ? Source: Eric Lamalfa (photos/simulations)

Vegetation effects on snow accumulation Montane forests in Utah conifers aspen SWE difference ~ 200 - 300 mm (40 % less in conifers) Source: Lamalfa & Ryel, 2008 Ecosystems

Forest �� Harvested areas Snow redistribution Source: Brooks et al., 1991 Hydrology and management of watersheds

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG

US Forest Service Experimental Watersheds Bonanza Creek (1969) H.J. Andrews (1948) Hubbard Brook (1955) Fernow (1934) Fraser (1937) Coweeta (1934) www.fs.fed.us/research/efr/efr-sites/index.shtml

Original Objective : Influence of forest practices on water yield Fernow, WV Hubbard Brook, NH Sources: Bormann & Likens, 1979; Bormann & Buso, 2006 Biogeochemistry; M.B. Adams; DH Ramsay Library, UNC Coweeta, NC

Influence of forest cover / practices on runoff Coweeta, NC Source: Swank & Crossley, 1988 Forest Hydrology and Ecology at Coweeta

Influence of forest practices on runoff T vs E response Source: Swank & Crossley, 1988 Forest Hydrology and Ecology at Coweeta

Influence of forest practices on runoff Is this also valid in more arid environments?? Q = P – ET ± dS ± dG Source: Fisher & Binkley, 2000 Ecology and Management of Forest Soils

What about snow-dominated systems? Montane forests in Utah 70-85 % total precip as snow (October-April) conifers aspen

Vegetation affects snow accumulation and…. soil moisture aspen conifers Aspen = Greater soil water recharge (winter) � Greater potential water yield Source: Lamalfa & Ryel, 2008 Ecosystems

Climate and Vegetation Change Effects on site water balance 1920 2007 Photos: Courtesy R. Jandl (BFW)

Climate Vegetation Q = P – ET ± dS ± dG Landuse Extracted from C. Alewell presentation at 2008 Zagreb COST–FORMAN meeting

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG • Influence on Q (quantity) • Influence on timing of Q

Timing dG dS ± Q = P – ET ±

Flashfloods dG dS ± Q = P – ET ±

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG Rooting depth Soil volume • Naturally shallow soils / bedrock • Presence of clay lenses or hardpans • Compacted layers

Influence of forest vegetation on site water balance Rooting Depth /patterns • Environmental • Anthopogenic • Natural ( intrinsic ) Photo: Courtesy E. Leitgeb (BFW)

Influence of forest vegetation on site water balance (natural differences) Rooting Depth � Soil Volume � Transp � Q Species mixtures Species selection (target)

Influence of vegetation cover on frost Q = P – ET ± dS ± dG Rooting Volume Timing

Influence of climate change on snow cover Increased snowpack ambient Sources: Schimel et al., 2004 Soil Biol Biochem.; Peter Groffman, IES @ http://www.ecostudies.org/people_sci_groffman_snow_summary.html

Climate Change and Fire Regime • Climate shifts � changing fire regime Juniper • Change fire regime � shift in vegetation New Mexico Conifer forest Utah 1899 1920 1977 Source: 1988 http://biology.usgs.gov/luhna/chap9.html

Fire and Soil Hydrophobicity • Ic goes down • effective volume for dS down • erosion risk increases • loss soil = loss of dS Photos Courtesy Dan Neary (US Forest Service)

Reduced Infitration capacity Increased surface erosion Soil loss, reduction of dS function More overland flow

Effects of Forest Management and Changes in the Environment Q = P – ET ± dS ± dG • Management & climate influence individual components of the SWB • Some of these changes cascade to other components of the SWB • Effects have temporal & spatial dimensions