Species control variation in litter decomposition in a pine forest exposed to elevated CO2

Net primary production and the flux of dry matter and nutrients from vegetation to soils has increased following four years of exposure to elevated CO2 in a southern pine forest in NC, USA. This has increased the demand for nutrients to support enhanced rates of NPP and altered the conditions for litter decomposition on the forest floor. We quantified the chemistry and decomposition dynamics of leaf litter produced by five of the most abundant tree species in this ecosystem during the third and fourth growing seasons under elevated CO2. The objectives of this study were to determine (i) if there were systemic or species-specific changes in leaf litter chemistry associated with a sustained enhancement of plant growth under elevated CO2; and (ii) whether the process of litter decomposition was altered by increased inputs of energy and nutrients to the forest floor in the plots under elevated CO2. Leaf litter chemistry, including various C fractions and N concentration, was virtually unchanged by elevated CO2. With few exceptions, plant litter produced under elevated CO2 lost mass or N at the same relative rate as that produced under ambient CO2. The relationship between initial litter chemistry and decomposition was not altered by elevated CO2. The greater forest floor mass and nutrient content in the plots under elevated CO2 had no consistent or long-term effect on litter decomposition. Thus, we found no evidence that plant and microbial processes under elevated CO2 resulted in systemic changes in mass loss or N dynamics during decomposition. In contrast to the limited effects of elevated CO2 on litter chemistry and decomposition, there were large differences among species in initial litter chemistry, mass loss and N dynamics during decomposition. If the species composition of this forest community is altered by elevated CO2, the indirect effect of a change in species composition will exert greater control over the long-term rate of nutrient cycling than the direct effect of elevated CO2 on litter chemistry and decomposition dynamics alone.

[1]  P. Curtis,et al.  Elevated atmospheric CO2 and feedback between carbon and nitrogen cycles , 1993, Plant and Soil.

[2]  C. Prescott,et al.  Immobilization and availability of N and P in the forest floors of fertilized Rocky Mountain coniferous forests , 1992, Plant and Soil.

[3]  J. Aber,et al.  Immobilization of a 15N-labeled nitrate addition by decomposing forest litter , 2004, Oecologia.

[4]  G. Katul,et al.  Hydrologic balance in an intact temperate forest ecosystem under ambient and elevated atmospheric CO2 concentration , 2002 .

[5]  W. Schlesinger,et al.  The nitrogen budget of a pine forest under free air CO2 enrichment , 2002, Oecologia.

[6]  W. Schlesinger,et al.  Forest carbon balance under elevated CO2 , 2002, Oecologia.

[7]  T. M. Bezemer,et al.  Herbivory in global climate change research: direct effects of rising temperature on insect herbivores , 2002 .

[8]  William H. Schlesinger,et al.  Limited carbon storage in soil and litter of experimental forest plots under increased atmospheric CO2 , 2001, Nature.

[9]  G. Katul,et al.  Soil fertility limits carbon sequestration by forest ecosystems in a CO2-enriched atmosphere , 2001, Nature.

[10]  Philip Ineson,et al.  Elevated CO2, litter chemistry, and decomposition: a synthesis , 2001, Oecologia.

[11]  D. Ellsworth,et al.  Forest litter production, chemistry and decomposition following two years of Free-Air CO2 Enrichment , 2001 .

[12]  K. Pregitzer,et al.  Chemistry and decomposition of litter from Populus tremuloides Michaux grown at elevated atmospheric CO2 and varying N availability , 2001 .

[13]  Christian Körner,et al.  Biosphere responses to CO2 enrichment. , 2000 .

[14]  W. Schlesinger,et al.  Effects of elevated atmospheric CO2 on fine root production and activity in an intact temperate forest ecosystem , 2000 .

[15]  P. Vitousek,et al.  NUTRIENT LIMITATION OF DECOMPOSITION IN HAWAIIAN FORESTS , 2000 .

[16]  Björn Berg,et al.  Litter decomposition in a transect of Norway spruce forests: substrate quality and climate control , 2000 .

[17]  C. Field,et al.  Diverse mechanisms for CO2 effects on grassland litter decomposition , 2000 .

[18]  James F. Reynolds,et al.  VALIDITY OF EXTRAPOLATING FIELD CO2 EXPERIMENTS TO PREDICT CARBON SEQUESTRATION IN NATURAL ECOSYSTEMS , 1999 .

[19]  Finzi,et al.  Net primary production of a forest ecosystem with experimental CO2 enrichment , 1999, Science.

[20]  A. Raschi,et al.  Influence of increased atmospheric CO(2) concentration on quality of plant material and litter decomposition. , 1999, Tree physiology.

[21]  J. Nagy,et al.  A free‐air enrichment system for exposing tall forest vegetation to elevated atmospheric CO2 , 1999 .

[22]  R. Norby,et al.  Global change: A question of litter quality , 1998, Nature.

[23]  Charles D. Canham,et al.  Non-additive effects of litter mixtures on net N mineralization in a southern New England forest , 1998 .

[24]  P. Dardenne,et al.  Chemical composition and carbon mineralisation potential of Scots pine needles at different stages of decomposition , 1998 .

[25]  P. Ineson,et al.  Elevated CO2 reduces the nitrogen concentration of plant tissues , 1998 .

[26]  D. Binkley,et al.  Foliage litter quality and annual net N mineralization: comparison across North American forest sites , 1997, Oecologia.

[27]  G. Berntson,et al.  Nitrogen cycling in microcosms of yellow birch exposed to elevated CO2: simultaneous positive and negative below‐ground feedbacks , 1997 .

[28]  Edward B. Rastetter,et al.  RESPONSES OF N‐LIMITED ECOSYSTEMS TO INCREASED CO2: A BALANCED‐NUTRITION, COUPLED‐ELEMENT‐CYCLES MODEL , 1997 .

[29]  D. F. Grigal,et al.  NITROGEN MINERALIZATION AND PRODUCTIVITY IN 50 HARDWOOD AND CONIFER STANDS ON DIVERSE SOILS , 1997 .

[30]  F. Chapin,et al.  Decomposition of litter produced under elevated CO2: Dependence on plant species and nutrient supply , 1997 .

[31]  H. L. Allen,et al.  Foliar nutrient dynamics of 11-year-old loblolly pine (Pinus taeda) following nitrogen fertilization , 1996 .

[32]  J. P. Grime,et al.  Evidence of a feedback mechanism limiting plant response to elevated carbon dioxide , 1993, Nature.

[33]  K. Iiyama,et al.  Determination of lignin in herbaceous plants by an improved acetyl bromide procedure , 1990 .

[34]  B. R. Taylor,et al.  Nitrogen and Lignin Content as Predictors of Litter Decay Rates: A Microcosm Test , 1989 .

[35]  J. Aber,et al.  Forest Litter Decomposition in Relation to Soil Nitrogen Dynamics and Litter Quality , 1985 .

[36]  F. Stuart Chapin,et al.  Seasonal Changes in Nitrogen and Phosphorus Fractions and Autumn Retranslocation in Evergreen and Deciduous Taiga Trees , 1983 .

[37]  John F. Muratore,et al.  Nitrogen and Lignin Control of Hardwood Leaf Litter Decomposition Dynamics , 1982 .

[38]  G. Henderson,et al.  Effects of Nitrogen and Phosphorus Additions on Deciduous Litter Decomposition , 1978 .

[39]  F. Smith,et al.  Colorimetric Method for Determination of Sugars and Related Substances , 1956 .