title: Biogeochemistry of beetle-killed forests: explaining a weak nitrate response.
abstract: A current pine beetle infestation has caused extensive mortality of lodgepole pine (Pinus contorta) in forests of Colorado and Wyoming; it is part of an unprecedented multispecies beetle outbreak extending from Mexico to Canada. In United States and European watersheds, where atmospheric deposition of inorganic N is moderate to low (<10 kg⋅ha⋅y), disturbance of forests by timber harvest or violent storms causes an increase in stream nitrate concentration that typically is close to 400% of predisturbance concentrations. In contrast, no significant increase in streamwater nitrate concentrations has occurred following extensive tree mortality caused by the mountain pine beetle in Colorado. A model of nitrate release from Colorado watersheds calibrated with field data indicates that stimulation of nitrate uptake by vegetation components unaffected by beetles accounts for significant nitrate retention in beetle-infested watersheds. The combination of low atmospheric N deposition (<10 kg⋅ha⋅y), tree mortality spread over multiple years, and high compensatory capacity associated with undisturbed residual vegetation and soils explains the ability of these beetle-infested watersheds to retain nitrate despite catastrophic mortality of the dominant canopy tree species.
authors: US Department of Agriculture Forest Service, Rocky Mountain Research Station, Fort Collins, CO 80523, USA.
authors: Charles C
authors: CC
authors: Rhoades
authors: James H
authors: JH
authors: McCutchan
authors: Leigh A
authors: LA
authors: Cooper
authors: David
authors: D
authors: Clow
authors: Thomas M
authors: TM
authors: Detmer
authors: Jennifer S
authors: JS
authors: Briggs
authors: John D
authors: JD
authors: Stednick
authors: Thomas T
authors: TT
authors: Veblen
authors: Rachel M
authors: RM
authors: Ertz
authors: Gene E
authors: GE
authors: Likens
authors: William M
authors: WM
authors: Lewis
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D003120:Colorado; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data; D005618:Fresh Water / Q000032:analysis; D005843:Geography; D006790:Host-Parasite Interactions; D009566:Nitrates / Q000378:metabolism*; D058458:Nitrogen Cycle; D028223:Pinus / Q000378:metabolism / Q000469:parasitology*; D045483:Rivers / Q000737:chemistry; D012987:Soil / Q000032:analysis; D013997:Time Factors; D014197:Trees / Q000378:metabolism / Q000469:parasitology*; D014959:Wyoming
chemical_list: D009566:Nitrates; D012987:Soil