Forrest L. Johnson

Biomass, Annual Net Primary Production, and Dynamics of Six Mineral Elements in a Post Oak‐Blackjack Oak Forest

A bstract. Dimension analysis was used to estimate biomass and annual net primary production for a post oak-blackjack oak (Quercus stellata-Q. marilandica) forest in central Oklahoma. Concentrations of six mineral elements in various plant tissues were determined and used with biomass and production estimates to calculate the annual cycle of N, P, K, Ca, Mg, and Mn in the forest. Total organic material in the forest is 245,000 kg/ha, of which 1.6% is leaves, 26.4% live branches, 5.9% dead branches, 44.8% trunks, 15.9% roots, 9.6% understory, and 4.4% litter. Annual net primary production is 14,900 kg/ha, distributed as follows: 32.0% leaves, 28.0% twigs and branches, 24.9% trunks, 15.1% roots, and 2.0% understory. Maximum leaf area index was 4.8. Yearly mean litterfall is 5,400 kg/ha and is distinctly biomodal, with peaks in November and March. The biomass contains 1,157 kg/ha N, 101 kg/ha P, 1,258 kg/ha K, 4,549 kg/ha Ca, 311 kg/ha Mg, and 124 kg/ha Mn. Yearly mineral budgets were determined for the six elements. Unusually high values for Ca in the biomass and in the mineral cycle were due to high concentrations of Ca in post oak bark (90,200 tg/g). High annual values for increment of biomass and for retention of mineral elements indicate that the stand has not reached a steady state, a conclusion that is confirmed by observations of stand structure.

Some Vegetation-Environment Relationships in the Upland Forests of Oklahoma

This study represents a continuation of the series of investigations in the deciduous forest frontier initiated at the University of Oklahoma in 1953. The objectives of the present study were to determine the effect of certain climatic, topographic, soil physical, and soil chemical factors on stand composition and biomass (as measured by basal area) in relation to the four most important upland forest species in the state. Post oak (Quercus stellata Wang.) and blackjack (Q. marilandica Muenchh.) are by far the most important upland tree species in the state, accounting for almost 70%/ of the total basal area (Rice & Penfound 1959). The most important of the minor species are black hickory (Carya texana Buckl.) and black oak (Quercus velutina Lam.), both being widely distributed in the eastern half of the state. Important statewide ecological investigations have been made in Oklahoma by Bruner (1931) and by Rice & Penfound (1959). These studies, however, were more concerned with the characterization of vegetational relationships than with quantitative determination of environmental factors. Studies dealing with vegetation-environment relationships on a quantitative basis have been confined to smaller areas within the state (Rice 1960, 1962, 1965; Buck 1964). Investigations with objectives similar to those of the present study have been made in other areas (McBride 1933; Turner 1937; Lunt 1939; Einspahr & McComb 1951; Pluth & Arneman 1963; Waring & Major 1964). Results of these studies indicate that factors affecting the supply of available moisture usually have the greatest influence on the vegetation of an area.

Revegetation of Unreclaimed Coal Strip-Mines In Oklahoma: I. Vegetation Structure and Soil Properties

(1) Forty-nine unreclaimed coal strip-mines between 10 and 70-yr old were sampled for soil properties (texture, pH, Ca, K, Fe, Mn, Cu, Zn, N, P) and vegetation structure (density of trees and woody understorey, tree basal area, vegetation height, ground cover, species diversity). (2) Definite soil horizons had not yet formed but chemical and physical weathering was occurring rapidly in the soft sedimentary rocks of the spoils. (3) Biomass-related measures of vegetation structure on older sites approached values found in surrounding upland forests and were significantly correlated with soil properties, especially N and Ca. (4) The sites were classified into four groups on the basis of soil properties. The groups are also significantly different with respect to some vegetation structural properties.Based on the topographic maps (1:50,000) in 1955, MSS images in 1972, and TM images in 1986 and 2000, the dynamic changes of land use during lately 50 years in Three Gorges Reservoir Area were quantitatively analyzed, with their driving forces discussed. The results showed that during lately 50 years, the structure of land use in the study area changed obviously, with a decrease of woodland, water area and unused land, and an increase of cultivated land, grassland and construction land. During the periods of 1955-1972, 1972-1986 and 1986-2000, woodland had a persistent and gradual decrease, grassland and cultivated land underwent a process of increase-decrease-increase and of increase-increase-decrease, respectively, construction land increased continually, while water area and unused land kept decreasing. Policy, economic development, and population growth were the main driving factors of the land use change in the study area.

A Model for Phosphorus and Potassium Flux in a Tall-Grass Prairie

A mechanistic simulation model is presented for the dynamics of phosphorus and potassium in a tall-grass prairie ecosystem in northeastern Oklahoma. Values for certain abiotic factors in 1970 were used as input to the model. Output consisted of predicted time-series of values for the amounts of phosphorus and potassium present in the different compartments of the ecosystem. Predicted values agreed quite well in some but not all cases with observed values. Grasslands represent a major portion of the terrestrial vegetation. Grasses are the basis of the food chain from which man derives most of his energy, and maintenance of this food source implies that it is necessary to understand the grassland ecosystem. Research involving the flow of energy and materials through the ecosystem is vital for the determination of the most efficient utilization of natural resources. Most nutrient flux studies have been done in forest ecosystems (Likens, et al. 1970; Duvigneaud and Denaeyer-de Smet 1970; Siccama, Bormann and Likens 1970). Because of the fundamental differences between the structure and function of grasslands and forests, it may not be possible to apply the results obtained in forest ecosystems to the grasslands. Several studies have been done involving plant nutrition or mineral content in grasslands (Harper, Daniel and Murphy 1933; Gerloff, Moore and Curtis 1964; Old 1969), but there are apparently none in which a complete nutrient budget has been compiled. A few studies have utilized radioactive tracers to construct nutrient cycles (Dodd and VanAmburg 1970a, 1970b, Till and May 1970). A mechanistic simulation model of an ecosystem is a complex hypothesis concerning the structure and function of that ecosystem. The purpose of this paper is to present such a model for the dynamics of phosphorus and potassium in a tall-grass prairie. SITE DESCRIPTION. Data were collected at the OSAGE Comprehensive Network Site of the U.S. International Biological Program Grassland Biome. The site is

PHYTOSOCIOLOGY OF SECOND-GROWTH FORESTS IN BOWIE COUNTY, TEXAS

Forty-year old second-growth noncommericial forest stands developed on aban- doned farmland in the northeast corner of Texas are usually dominated by oaks, hickories, and elms, with pine as a minor component in the forest. The leading dominant tree species is post oak, and species composition resembles that of nearby old-growth upland forests. The average stand has 15 tree species, 1467 stems/ha larger than 2cm dbh, and a basal area of 23.5 m2/ha.