Soil-Litter Mixing Accelerates Decomposition in a Chihuahuan Desert Grassland

Daniel B. Hewins, Steve Archer, Gregory S. Okin, Rebecca L. McCulley, Heather L. Throop

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

Decomposition models typically under-predict decomposition relative to observed rates in drylands. This discrepancy indicates a significant gap in our mechanistic understanding of carbon and nutrient cycling in these systems. Recent research suggests that certain drivers of decomposition that are often not explicitly incorporated into models (for example, photodegradation and soil-litter mixing; SLM) may be important in drylands, and their exclusion may, in part, be responsible for model under-predictions. To assess the role of SLM, litterbags were deployed in the Chihuahuan Desert and interrelationships between vegetation structure, SLM, and rates of decomposition were quantified. Vegetation structure was manipulated to simulate losses of grass cover from livestock grazing and shrub encroachment. We hypothesized that reductions in grass cover would promote SLM and accelerate mass loss by improving conditions for microbial decomposition. Litter mass decreased exponentially, with the greatest losses occurring in concert with summer monsoons. There were no differences in decay constants among grass cover treatments. A significant, positive relationship between mass loss and SLM was observed, but contrary to expectations SLM was independent of grass cover. This suggests that processes operating at finer spatial scales than those in our grass removal treatments were influencing SLM. Shifts in litter lipid composition suggest increased bacterial contribution to decomposition through time. SLM, which is seldom included as a variable controlling decomposition in statistical or mechanistic models, was a strong driver of decomposition. Results are discussed in the context of other known drivers of decomposition in drylands (for example, UV radiation and climate) and more mesic systems.

Original languageEnglish (US)
Pages (from-to)183-195
Number of pages13
JournalEcosystems
Volume16
Issue number2
DOIs
StatePublished - Mar 2013

Fingerprint

Chihuahuan Desert
litter
desert
grasslands
grassland
decomposition
Decomposition
Soils
degradation
soil
grass
grasses
arid lands
vegetation structure
photolysis
mechanistic models
Photodegradation
photodegradation
lipid composition
nutrient cycling

Keywords

  • arid
  • carbon cycle
  • dryland
  • dust
  • erosion
  • livestock grazing
  • phospholipid fatty acids
  • Prosopis
  • shrub encroachment

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Environmental Chemistry

Cite this

Soil-Litter Mixing Accelerates Decomposition in a Chihuahuan Desert Grassland. / Hewins, Daniel B.; Archer, Steve; Okin, Gregory S.; McCulley, Rebecca L.; Throop, Heather L.

In: Ecosystems, Vol. 16, No. 2, 03.2013, p. 183-195.

Research output: Contribution to journalArticle

Hewins, Daniel B. ; Archer, Steve ; Okin, Gregory S. ; McCulley, Rebecca L. ; Throop, Heather L. / Soil-Litter Mixing Accelerates Decomposition in a Chihuahuan Desert Grassland. In: Ecosystems. 2013 ; Vol. 16, No. 2. pp. 183-195.
@article{bd4b0d3279ee41cdaff3c404530457bb,
title = "Soil-Litter Mixing Accelerates Decomposition in a Chihuahuan Desert Grassland",
abstract = "Decomposition models typically under-predict decomposition relative to observed rates in drylands. This discrepancy indicates a significant gap in our mechanistic understanding of carbon and nutrient cycling in these systems. Recent research suggests that certain drivers of decomposition that are often not explicitly incorporated into models (for example, photodegradation and soil-litter mixing; SLM) may be important in drylands, and their exclusion may, in part, be responsible for model under-predictions. To assess the role of SLM, litterbags were deployed in the Chihuahuan Desert and interrelationships between vegetation structure, SLM, and rates of decomposition were quantified. Vegetation structure was manipulated to simulate losses of grass cover from livestock grazing and shrub encroachment. We hypothesized that reductions in grass cover would promote SLM and accelerate mass loss by improving conditions for microbial decomposition. Litter mass decreased exponentially, with the greatest losses occurring in concert with summer monsoons. There were no differences in decay constants among grass cover treatments. A significant, positive relationship between mass loss and SLM was observed, but contrary to expectations SLM was independent of grass cover. This suggests that processes operating at finer spatial scales than those in our grass removal treatments were influencing SLM. Shifts in litter lipid composition suggest increased bacterial contribution to decomposition through time. SLM, which is seldom included as a variable controlling decomposition in statistical or mechanistic models, was a strong driver of decomposition. Results are discussed in the context of other known drivers of decomposition in drylands (for example, UV radiation and climate) and more mesic systems.",
keywords = "arid, carbon cycle, dryland, dust, erosion, livestock grazing, phospholipid fatty acids, Prosopis, shrub encroachment",
author = "Hewins, {Daniel B.} and Steve Archer and Okin, {Gregory S.} and McCulley, {Rebecca L.} and Throop, {Heather L.}",
year = "2013",
month = "3",
doi = "10.1007/s10021-012-9604-5",
language = "English (US)",
volume = "16",
pages = "183--195",
journal = "Ecosystems",
issn = "1432-9840",
publisher = "Springer New York",
number = "2",

}

TY - JOUR

T1 - Soil-Litter Mixing Accelerates Decomposition in a Chihuahuan Desert Grassland

AU - Hewins, Daniel B.

AU - Archer, Steve

AU - Okin, Gregory S.

AU - McCulley, Rebecca L.

AU - Throop, Heather L.

PY - 2013/3

Y1 - 2013/3

N2 - Decomposition models typically under-predict decomposition relative to observed rates in drylands. This discrepancy indicates a significant gap in our mechanistic understanding of carbon and nutrient cycling in these systems. Recent research suggests that certain drivers of decomposition that are often not explicitly incorporated into models (for example, photodegradation and soil-litter mixing; SLM) may be important in drylands, and their exclusion may, in part, be responsible for model under-predictions. To assess the role of SLM, litterbags were deployed in the Chihuahuan Desert and interrelationships between vegetation structure, SLM, and rates of decomposition were quantified. Vegetation structure was manipulated to simulate losses of grass cover from livestock grazing and shrub encroachment. We hypothesized that reductions in grass cover would promote SLM and accelerate mass loss by improving conditions for microbial decomposition. Litter mass decreased exponentially, with the greatest losses occurring in concert with summer monsoons. There were no differences in decay constants among grass cover treatments. A significant, positive relationship between mass loss and SLM was observed, but contrary to expectations SLM was independent of grass cover. This suggests that processes operating at finer spatial scales than those in our grass removal treatments were influencing SLM. Shifts in litter lipid composition suggest increased bacterial contribution to decomposition through time. SLM, which is seldom included as a variable controlling decomposition in statistical or mechanistic models, was a strong driver of decomposition. Results are discussed in the context of other known drivers of decomposition in drylands (for example, UV radiation and climate) and more mesic systems.

AB - Decomposition models typically under-predict decomposition relative to observed rates in drylands. This discrepancy indicates a significant gap in our mechanistic understanding of carbon and nutrient cycling in these systems. Recent research suggests that certain drivers of decomposition that are often not explicitly incorporated into models (for example, photodegradation and soil-litter mixing; SLM) may be important in drylands, and their exclusion may, in part, be responsible for model under-predictions. To assess the role of SLM, litterbags were deployed in the Chihuahuan Desert and interrelationships between vegetation structure, SLM, and rates of decomposition were quantified. Vegetation structure was manipulated to simulate losses of grass cover from livestock grazing and shrub encroachment. We hypothesized that reductions in grass cover would promote SLM and accelerate mass loss by improving conditions for microbial decomposition. Litter mass decreased exponentially, with the greatest losses occurring in concert with summer monsoons. There were no differences in decay constants among grass cover treatments. A significant, positive relationship between mass loss and SLM was observed, but contrary to expectations SLM was independent of grass cover. This suggests that processes operating at finer spatial scales than those in our grass removal treatments were influencing SLM. Shifts in litter lipid composition suggest increased bacterial contribution to decomposition through time. SLM, which is seldom included as a variable controlling decomposition in statistical or mechanistic models, was a strong driver of decomposition. Results are discussed in the context of other known drivers of decomposition in drylands (for example, UV radiation and climate) and more mesic systems.

KW - arid

KW - carbon cycle

KW - dryland

KW - dust

KW - erosion

KW - livestock grazing

KW - phospholipid fatty acids

KW - Prosopis

KW - shrub encroachment

UR - http://www.scopus.com/inward/record.url?scp=84874578980&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84874578980&partnerID=8YFLogxK

U2 - 10.1007/s10021-012-9604-5

DO - 10.1007/s10021-012-9604-5

M3 - Article

VL - 16

SP - 183

EP - 195

JO - Ecosystems

JF - Ecosystems

SN - 1432-9840

IS - 2

ER -