Rates of carbon dioxide evolution from soil in mid—Missouri tallgrass prairie were highly correlated with temperature of the surface soil. Values increased exponentially with rising temperatures through the seasonal range under observation. Twenty—four—hour measurements employing infrared analysis were conducted periodically during all seasons from August 1968 to June 1970. Weekly averages calculated from regression for the entire year ranged from zero during the coldest period to 450 mg CO_2m⁽—2)hr⁽—1) during summer. The annual total was 1,675 g CO_2m⁽—2). The organic matter equivalent was 1,005 g, approximately 2.2 times the indicated biomass turnover for the root system for the same period. The difference was attributed to root respiration by determining a correlation between CO₂ evolution and root biomass with KOH absorption and titration and by converting these data to infrared equivalents. It was estimated that 60% of the total respiration (surface litter excluded) was due to microbial processes in organic turnover and the balance to root metabolism.

The development of bottom depostis and the distribution of the associated fauna were studied over a 2—year period in a drowned river "estuary" of the newly created Lake Kariba. The lake bottom was initially made up of submerged soil, the chemical characteristics of which could be related to the parent rock. However, the soil was found to be rapidly changing under the influence of shoreline erosion, river sediment, and the accumulation of organic debris. These factors also affected the distribution of bottom fauna, in which chironomid larvae predominated. Faunal biomass was positively correlated with the amount of organic carbon in the profundal zone and inversely associated with the quantity of coarse sand in the littoral. Superimposed on this pattern was a response to water depth. In the littoral zone, faunal biomass decreased with increasing depth. In the profundal region, benthos was absent when the lake was thermally stratified during the hot season. The annual regime of water—level fluctuation affected shoreline processes, for example by interrupting the development of barrier beaches and coastal erosion. Since these processes were fundamental to the development of sediment patterns, changes in water level influenced the distribution of bottom fauna as well.

Additions of montmorillonite (0.25–1.0%) and vermiculite and kaolinite (0.25%) to aerobic cultures of Hendersonula toruloidea, Stachybotrys spp., and Aspergillus sydowi, greatly accelerated growth, glucose utilization, CO₂ evolution, phenol synthesis and phenolic polymer formation. In some tests the clay increased total biomass formed, while in others the biomass of the checks eventually attained values of the cultures with clay. Montmorillonite was more effective than vermiculite or kaolinite. Nitrate-N was a poor N source for Stachybotrys spp., but was a relatively good source of N in the presence of montmorillonite. The presence of clays in the culture media exerted little effect on the N content, C content, exchange capacity, total acidity, phenols released upon Na-amalgam reduction, and decomposition rate in soil of the polymers formed. Phenolic polymers formed in cultures containing inorganic nitrogen contained about ⅓ to ½ the N of those produced in cultures with asparagine or peptone. The percentage of the N of the polymers released as alpha amino N upon 6N HCl hydrolysis was about 30–40% and was not influenced by the N content of the polymers.

Colonies of four clubmosses, Lycopodium tristachyum, L. complanatum, L. clavatum and L. obscurum, sometimes occur as “fairy rings”—densely stocked annuli that grow outward and die within. Readily soluble N, P, K, and Fe in the surface soil increased sharply at the point where roots first developed along the advancing lycopod rhizomes; maxima occurred near or beyond the zone of greatest biomass and usually levels declined inward. Extractable Mn was either higher or lower within the ring, depending on season of sampling; Ca and Mg were unaffected. These changes are attributed to increased mineralization of organic matter and altered solubility of Fe and Mn oxides. The capacity of the lycopod root- or root-fungus system to exploit reserves unavailable to other plants presumably conveys a competitive advantage and accounts for the abundance of Lycopodium on some low-fertility soils.

An ecosystem approach was used to assess the effects of soil contamination with an organophosphate insecticide on ecological succession in 3—acre old field on the Piedmont of New Jersey. Diazinon was applied to one—half of the field in May 1967 and again in May 1967 and again in May 1968 at a rate of 12 lbs of active ingredient per acre. A latin square experimental design was used to analyze the effects of the insecticide on the density, diversity, and production of vegetation; the density and diversity of herb—stratum arthropods; and the trophic relationships that developed on treated and untreated areas. In 1967, insecticide contamination produced a significant enrichment in both density and diversity of vegetation as well as a consistent trend toward greater plant biomass on treated areas. The vegetation changes represented a summation of small but consistent differences in major producers common to both treated and untreated areas. Plant differences were believed due to a phytotoxic effect of diazinon on Convolvulus sepium, which was significantly reduced on treated areas. Other plant species normally inhibited by Convolvulus subsequently flourished on treated areas. Herb—stratum arthropod populations were similar on treated and untreated areas in 1967, despite the vegetation differences. Only a trend toward greater insect diversity on treated areas was present. The failure of indirect arthropod differences to develop was due to the similar availability of dominant producers and thus food web bases on treated and untreated areas. Radionuclide tracer studies indicated that ragweed (Ambrosia artemisiifolia) was the major food web base for resident consumers in the latter part of the growing season. The trophic transfer from ragweed was quite similar in treated and untreated areas. The lack of arthropod differences was thus attributed to similar availability of ragweed biomass in both areas. Vegetation differences were absent in 1968 following a second treatment with diazinon. Moisture appeared to be a major factor influencing the impart of the insecticide during the two summers. Vegetation differences developed in June 1967 at a time when rainfall was almost absent. In 1968, however, considerable rainfall occurred during the same period. The increased rainfall stimulated a greater seedling development than in 1967, thus apparently overcoming the effects of the insecticide. Environmental factors such as soil moisture can therefore interact with pollutants and seriously influence the degree of ecosystem modification.