CANOPY TREE–SOIL INTERACTIONS WITHIN TEMPERATE FORESTS: SPECIES EFFECTS ON SOIL CARBON AND NITROGEN

In a northwestern Connecticut forest, we quantified the carbon (C) and ni- trogen (N) content of the forest floor and the top 15 cm of mineral soil and the rate of midsummer net N mineralization beneath six different tree species. There were large in- terspecific differences in forest floor depth and mass, in the size and distribution of C and N pools at varying soil depths, and in rates of midsummer net N mineralization and nitri- fication. Forest floor mass ranged from 3.2 kg/m 2 to 11.0 kg/m 2 and was smallest beneath sugar maple and largest beneath hemlock. The pool size of C in the forest floor ranged from 1.1 kg/m 2 to 4.4 kg/m 2 while the N content of the forest floor ranged from 83 g/m 2 to 229 g/m 2 . Forest floor C and N pools were smallest beneath sugar maple and highest beneath hemlock. Soil C:N ratios (range: 14.8-19.5) were lower beneath sugar maple, red maple, and white ash than beneath beech, red oak, and hemlock, whereas the opposite was true of the midsummer rate of net N mineralization (range: 0.91-2.02 g·m 22 ·28 d 21 ). The rate of net nitrification was positively correlated with the rate of net N mineralization. Interspecific differences in litter production and quality explain the large differences among species in the size of the forest floor C and N pools and in net N mineralization rates. The differences in the size and distribution of C and N pools beneath the different species suggest that the mechanisms regulating the process of species replacement in these forests will mediate the effects of anthropogenic, environmental changes in soil C and N dynamics.

[1]  D. Mladenoff.  Dynamics of Nitrogen Mineralization and Nitrification in Hemlock and Hardwood Treefall Gaps , 1987 .

[2]  S. Gower,et al.  Nitrogen and phosphorus distribution for five plantation species in southwestern Wisconsin , 1992 .

[3]  R. Boerner,et al.  Microsite variations in soil chemistry and nitrogen mineralization in a beech-maple forest , 1989 .

[4]  P. Kalisz,et al.  Single-Tree Influence on Soil Properties in the Mountains of Eastern Kentucky , 1990 .

[5]  Charles D. Canham,et al.  CANOPY TREE–SOIL INTERACTIONS WITHIN TEMPERATE FORESTS: SPECIES EFFECTS ON pH AND CATIONS , 1998 .

[6]  E. Paul,et al.  Soil microbiology and biochemistry. , 1998 .

[7]  W. Post,et al.  Influence of climate, soil moisture, and succession on forest carbon and nitrogen cycles , 1986 .

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

[9]  D. E. Hill,et al.  Soils of Connecticut. , 1980 .

[10]  B. R. Taylor,et al.  Nutrient release from decomposing litter in Rocky Mountain coniferous forests: influence of nutrient availability , 1993 .

[11]  D. Binkley,et al.  Biogeochemistry of adjacent conifer and alder-conifer stands , 1992 .

[12]  T. G. Piearce,et al.  Earthworms, Their Ecology and Relationships with Soils and Land Use. , 1987 .

[13]  D. Binkley.  The influence of tree species on forest soils: processes and patterns , 1995 .

[14]  C. F. Eno,et al.  Nitrate Production in the Field by Incubating the Soil in Polyethylene Bags , 1960 .

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

[16]  R. Boerner,et al.  Relative nitrogen mineralization and nitrification in soils of two contrasting hardwood forests: effects of site microclimate and initial soil chemistry , 1987 .

[17]  W. Parton,et al.  Analysis of factors controlling soil organic matter levels in Great Plains grasslands , 1987 .

[18]  S. Gower,et al.  Differences in Soil and Leaf Litterfall Nitrogen Dynamics for Five Forest Plantations , 1992 .

[19]  Charles D. Canham,et al.  Species diversity and ecosystem response to carbon dioxide fertilization: conclusions from a temperate forest model , 1995 .

[20]  E. Davidson,et al.  Internal Cycling of Nitrate in Soils of a Mature Coniferous Forest , 1992 .

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

[22]  D. Challinor.  Alteration of Surface Soil Characteristics by Four Tree Species , 1968 .

[23]  S. Hart,et al.  High rates of nitrification and nitrate turnover in undisturbed coniferous forests , 1997, Nature.

[24]  D. Binkley,et al.  Relationships Between Litter Quality and Nitrogen Availability in Rocky Mountain Forests , 1993 .

[25]  John Pastor,et al.  Aboveground Production and N and P Cycling Along a Nitrogen Mineralization Gradient on Blackhawk Island, Wisconsin , 1984 .

[26]  D. Binkley,et al.  Soil chemistry changes after 27 years under four tree species in southern Ontario , 1989 .

[27]  P. Vitousek,et al.  Causes of delayed nitrate production in two Indiana forests , 1985 .

[28]  Stephenie P. Joyner.  SAS/STAT guide for personal computers, version 6 edition , 1985 .

[29]  S. Sugita,et al.  A spatially explicit model of leaf litter fall in hemlock-hardwood forests , 1996 .

[30]  C. White.  The role of monoterpenes in soil nitrogen cycling processes in ponderosa pine , 1991 .

[31]  P. Zinke,et al.  The Pattern of Influence of Individual Forest Trees on Soil Properties , 1962 .

[32]  John Pastor,et al.  Response of northern forests to CO2-induced climate change , 1988, Nature.