Carbon and nitrogen cycling immediately following bark beetle outbreaks in southwestern ponderosa pine forests

K. Morehouse, T. Johns, Jason Philip Kaye, Margot Wilkinson Kaye

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

Bark beetle infestation is a well-known cause of historical low-level disturbance in southwestern ponderosa pine forests, but recent fire exclusion and increased tree densities have enabled large-scale bark beetle outbreaks with unknown consequences for ecosystem function. Uninfested and beetle-infested plots (n = 10 pairs of plots on two aspects) of ponderosa pine were compared over one growing season in the Sierra Ancha Experimental Forest, AZ to determine whether infestation was correlated with differences in carbon (C) and nitrogen (N) pools and fluxes in aboveground biomass and soils. Infested plots had at least 80% of the overstory ponderosa pine trees attacked by bark beetles within 2 years of our measurements. Both uninfested and infested plots stored ∼9 kg C m-2 in aboveground tree biomass, but infested plots held 60% of this aboveground tree biomass in dead trees, compared to 5% in uninfested plots. We hypothesized that decreased belowground C allocation following beetle-induced tree mortality would alter soil respiration rates, but this hypothesis was not supported; throughout the growing season, soil respiration in infested plots was similar to uninfested plots. In contrast, several results supported the hypothesis that premature needlefall from infested trees provided a pulse of low C:N needlefall that altered soil N cycling. The C:N mass ratio of pine needlefall in infested plots (∼45) was lower than uninfested plots (∼95) throughout the growing season. Mineral soils from infested plots had greater laboratory net nitrification rates and field resin bag ammonium accumulation than uninfested plots. As bark beetle outbreaks become increasingly prevalent in western landscapes, longer-term biogeochemical studies on interactions with other disturbances (e.g. fire, harvesting, etc.) will be required to predict changes in ecosystem structure and function.

Original languageEnglish (US)
Pages (from-to)2698-2708
Number of pages11
JournalForest Ecology and Management
Volume255
Issue number7
DOIs
StatePublished - Apr 20 2008

Fingerprint

Pinus ponderosa
bark beetles
bark
coniferous forests
beetle
carbon
nitrogen
growing season
soil respiration
ecosystem function
Coleoptera
experimental forests
ecosystems
biomass
tree mortality
dead wood
overstory
nitrification
mineral soils
aboveground biomass

All Science Journal Classification (ASJC) codes

  • Forestry
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law

Cite this

@article{2b09d7ee8b744a55b42df5dcddcb132a,
title = "Carbon and nitrogen cycling immediately following bark beetle outbreaks in southwestern ponderosa pine forests",
abstract = "Bark beetle infestation is a well-known cause of historical low-level disturbance in southwestern ponderosa pine forests, but recent fire exclusion and increased tree densities have enabled large-scale bark beetle outbreaks with unknown consequences for ecosystem function. Uninfested and beetle-infested plots (n = 10 pairs of plots on two aspects) of ponderosa pine were compared over one growing season in the Sierra Ancha Experimental Forest, AZ to determine whether infestation was correlated with differences in carbon (C) and nitrogen (N) pools and fluxes in aboveground biomass and soils. Infested plots had at least 80{\%} of the overstory ponderosa pine trees attacked by bark beetles within 2 years of our measurements. Both uninfested and infested plots stored ∼9 kg C m-2 in aboveground tree biomass, but infested plots held 60{\%} of this aboveground tree biomass in dead trees, compared to 5{\%} in uninfested plots. We hypothesized that decreased belowground C allocation following beetle-induced tree mortality would alter soil respiration rates, but this hypothesis was not supported; throughout the growing season, soil respiration in infested plots was similar to uninfested plots. In contrast, several results supported the hypothesis that premature needlefall from infested trees provided a pulse of low C:N needlefall that altered soil N cycling. The C:N mass ratio of pine needlefall in infested plots (∼45) was lower than uninfested plots (∼95) throughout the growing season. Mineral soils from infested plots had greater laboratory net nitrification rates and field resin bag ammonium accumulation than uninfested plots. As bark beetle outbreaks become increasingly prevalent in western landscapes, longer-term biogeochemical studies on interactions with other disturbances (e.g. fire, harvesting, etc.) will be required to predict changes in ecosystem structure and function.",
author = "K. Morehouse and T. Johns and Kaye, {Jason Philip} and Kaye, {Margot Wilkinson}",
year = "2008",
month = "4",
day = "20",
doi = "10.1016/j.foreco.2008.01.050",
language = "English (US)",
volume = "255",
pages = "2698--2708",
journal = "Forest Ecology and Management",
issn = "0378-1127",
publisher = "Elsevier",
number = "7",

}

Carbon and nitrogen cycling immediately following bark beetle outbreaks in southwestern ponderosa pine forests. / Morehouse, K.; Johns, T.; Kaye, Jason Philip; Kaye, Margot Wilkinson.

In: Forest Ecology and Management, Vol. 255, No. 7, 20.04.2008, p. 2698-2708.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Carbon and nitrogen cycling immediately following bark beetle outbreaks in southwestern ponderosa pine forests

AU - Morehouse, K.

AU - Johns, T.

AU - Kaye, Jason Philip

AU - Kaye, Margot Wilkinson

PY - 2008/4/20

Y1 - 2008/4/20

N2 - Bark beetle infestation is a well-known cause of historical low-level disturbance in southwestern ponderosa pine forests, but recent fire exclusion and increased tree densities have enabled large-scale bark beetle outbreaks with unknown consequences for ecosystem function. Uninfested and beetle-infested plots (n = 10 pairs of plots on two aspects) of ponderosa pine were compared over one growing season in the Sierra Ancha Experimental Forest, AZ to determine whether infestation was correlated with differences in carbon (C) and nitrogen (N) pools and fluxes in aboveground biomass and soils. Infested plots had at least 80% of the overstory ponderosa pine trees attacked by bark beetles within 2 years of our measurements. Both uninfested and infested plots stored ∼9 kg C m-2 in aboveground tree biomass, but infested plots held 60% of this aboveground tree biomass in dead trees, compared to 5% in uninfested plots. We hypothesized that decreased belowground C allocation following beetle-induced tree mortality would alter soil respiration rates, but this hypothesis was not supported; throughout the growing season, soil respiration in infested plots was similar to uninfested plots. In contrast, several results supported the hypothesis that premature needlefall from infested trees provided a pulse of low C:N needlefall that altered soil N cycling. The C:N mass ratio of pine needlefall in infested plots (∼45) was lower than uninfested plots (∼95) throughout the growing season. Mineral soils from infested plots had greater laboratory net nitrification rates and field resin bag ammonium accumulation than uninfested plots. As bark beetle outbreaks become increasingly prevalent in western landscapes, longer-term biogeochemical studies on interactions with other disturbances (e.g. fire, harvesting, etc.) will be required to predict changes in ecosystem structure and function.

AB - Bark beetle infestation is a well-known cause of historical low-level disturbance in southwestern ponderosa pine forests, but recent fire exclusion and increased tree densities have enabled large-scale bark beetle outbreaks with unknown consequences for ecosystem function. Uninfested and beetle-infested plots (n = 10 pairs of plots on two aspects) of ponderosa pine were compared over one growing season in the Sierra Ancha Experimental Forest, AZ to determine whether infestation was correlated with differences in carbon (C) and nitrogen (N) pools and fluxes in aboveground biomass and soils. Infested plots had at least 80% of the overstory ponderosa pine trees attacked by bark beetles within 2 years of our measurements. Both uninfested and infested plots stored ∼9 kg C m-2 in aboveground tree biomass, but infested plots held 60% of this aboveground tree biomass in dead trees, compared to 5% in uninfested plots. We hypothesized that decreased belowground C allocation following beetle-induced tree mortality would alter soil respiration rates, but this hypothesis was not supported; throughout the growing season, soil respiration in infested plots was similar to uninfested plots. In contrast, several results supported the hypothesis that premature needlefall from infested trees provided a pulse of low C:N needlefall that altered soil N cycling. The C:N mass ratio of pine needlefall in infested plots (∼45) was lower than uninfested plots (∼95) throughout the growing season. Mineral soils from infested plots had greater laboratory net nitrification rates and field resin bag ammonium accumulation than uninfested plots. As bark beetle outbreaks become increasingly prevalent in western landscapes, longer-term biogeochemical studies on interactions with other disturbances (e.g. fire, harvesting, etc.) will be required to predict changes in ecosystem structure and function.

UR - http://www.scopus.com/inward/record.url?scp=41949107900&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=41949107900&partnerID=8YFLogxK

U2 - 10.1016/j.foreco.2008.01.050

DO - 10.1016/j.foreco.2008.01.050

M3 - Article

VL - 255

SP - 2698

EP - 2708

JO - Forest Ecology and Management

JF - Forest Ecology and Management

SN - 0378-1127

IS - 7

ER -