Twenty-year changes in biomass and nutrient distribution in forests of Walker Branch Watershed, Tennessee
Changes in biomass and nutrient distribution in forests of Walker Branch Watershed from 1967 to 1987 are reviewed. There have been major changes in species composition in certain forest types: yellow-poplar (Liriodendron tulipifera) has largely been replaced by shortleaf pine (Pinus echinata) in what was formerly the pine forest type, and chestnut oak (Quercus prinus) appears to be replacing hickory in the oak-hickory forest type. In both cases, insect attacks (bark beetles and borers) precipitated the changes by inducing heavy mortality in native pines and hickory species in the 1970s. Subsoil (Bt horizon) exchangeable Ca/sup 2 +/ and Mg/sup 2 +/ have decreased markedly over a period of only 11 years in certain poor, upper-slope stands with oak and oak-hickory vegetation. From nutrient flux and mass balance analyses, we conclude that the Ca/sup 2 +/ changes can be attributed primarily to the sequestering of calcium in biomass. The situation with respect to Mg/sup 2 +/ is less clear; leaching was low relative to uptake in the one plot where Mg/sup 2 +/ decreases were statistically significant (95% level, t-test), yet it was clearly the dominant mechanism of Mg/sup 2 +/ export in all other plots where less significant (85% level, t-test) decreases were noted. It is noteworthy that leaching is dominated by SO/sub 4//sup 2/minus//, implying that acid deposition may be a major cause of the subsoil exchangeable Mg/sup 2 +/ decreases in some cases. 31 refs., 11 figs., 3 tabs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7055323
- Report Number(s):
- CONF-8807107-2; ON: DE88016804
- Resource Relation:
- Conference: 7. North American forest soils conference, Vancouver, Canada, 25 Jul 1988; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ECOLOGICAL SUCCESSION
EVALUATION
NUTRIENTS
SPATIAL DISTRIBUTION
PLANT GROWTH
MONITORING
BIOMASS
INSECTS
LEACHING
MAGNESIUM
MASS BALANCE
MINERAL CYCLING
MODIFICATIONS
OAK RIDGE RESERVATION
OAKS
PINES
POPLARS
SOILS
SULFATES
ALKALINE EARTH METALS
ANIMALS
ARTHROPODS
CONIFERS
DISSOLUTION
DISTRIBUTION
ELEMENTS
ENERGY SOURCES
GROWTH
INVERTEBRATES
METALS
NATIONAL ORGANIZATIONS
OXYGEN COMPOUNDS
PLANTS
RENEWABLE ENERGY SOURCES
SEPARATION PROCESSES
SULFUR COMPOUNDS
TREES
US DOE
US ERDA
US ORGANIZATIONS
140504* - Solar Energy Conversion- Biomass Production & Conversion- (-1989)