Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands

Kolb, Thomas and Dore, Sabina and Montes-Helu, Mario (2013) Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands. Environmental Research Letters, 8 (1). ISSN 1748-9326

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Abstract

We assessed the impacts of extreme late-summer drought on carbon balance in a semi-arid forest region in Arizona. To understand drought impacts over extremes of forest cover, we measured net ecosystem production (NEP), gross primary production (GPP), and total ecosystem respiration (TER) with eddy covariance over five years (2006-10) at an undisturbed ponderosa pine (Pinus ponderosa) forest and at a former forest converted to grassland by intense burning. Drought shifted annual NEP from a weak source of carbon to the atmosphere to a neutral carbon balance at the burned site and from a carbon sink to neutral at the undisturbed site. Carbon fluxes were particularly sensitive to drought in August. Drought shifted August NEP at the undisturbed site from sink to source because the reduction of GPP (70%) exceeded the reduction of TER (35%). At the burned site drought shifted August NEP from weak source to neutral because the reduction of TER (40%) exceeded the reduction of GPP (20%). These results show that the lack of forest recovery after burning and the exposure of undisturbed forests to late-summer drought reduce carbon sink strength and illustrate the high vulnerability of forest carbon sink strength in the southwest US to predicted increases in intense burning and precipitation variability.

Item Type:	Article
Publisher’s Statement:	© 2013 IOP Publishing Ltd
ID number or DOI:	10.1088/1748-9326/8/1/015015
Keywords:	America; APEC countries; Arizona; Atmosphere; burning; carbon; Carbon balance; Developed Countries; Drought; ecosystem carbon; eddy covariance; eukaryotes; flaming; Fluxes; Forest Fires (KK130); Forests and Forest Trees (Biology and Ecology) (KK100); Grasslands; Grasslands and Rangelands (PP350); gymnosperms; Meteorology and Climate (PP500); Mountain States of USA; net carbon; net primary production; North America; north-american monsoon; OECD Countries; Pinaceae; Pinopsida; Pinus; Pinus Ponderosa; Plants; ponderosa pine; precipitation; precipitation variability; respiration; semiarid zones; soil; Southwestern States of USA; Spermatophyta; summer; United States of America; USA; Water relations; Western States of USA; western united-states
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QK Botany
NAU Depositing Author Academic Status:	Faculty/Staff
Department/Unit:	College of Engineering, Forestry, and Natural Science > School of Forestry
Date Deposited:	30 Sep 2015 18:24
URI:	http://openknowledge.nau.edu/id/eprint/576

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