Formation and Properties of Clay-Polymer Complexes. Developments in Soil Science: 9. B.K.G. Theng. Elsevier,Amsterdam, 1979, 362 pp., U.S.$64.50, Dfl. 132.00

Weathering products of Vitrandept profiles on the Kaingaroa plateau, central North Island, New Zealand, were investigated by analysis of oxalate extracts and by chemical and mineralogical analysis of clays of selected soil horizons. Comparisons were made between profiles under a Pinus radiata (D. Don) stand and profiles under an adjacent area of manuka native scrub, Leptospermum scoparium (Myrtaceae).Clay fractions (< 2 μm) of A₁₁ horizon under pine had significantly higher SiO₂/Al₂O₃ mole-ratios (mean SiO₂/Al₂O₃ = 12.2) than A₁₁ horizon under manuka (mean SiO₂/Al₂O₃ = 7.1). No effect of vegetation on clay fractions of B horizon was evident, these clays having much lower SiO₂/Al₂O₃ mole-ratio (1.5). Oxalate-extractable Al, Fe and Si values of < 8-mm fractions of A, B and C horizons showed no differences attributable to present vegetative cover.SiO₂/Al₂O₃ mole-ratios of oxalate extracts increased with increasing depth, and paleosols at > 2 m depth under pine had significantly higher SiO₂/Al₂O₃ mole-ratios in oxalate extracts (mean SiO₂/Al₂O₃ = 2.0) than paleosols under manuka (mean SiO₂/Al₂O₃ = 1.6). That soil horizons at > 2 m depth are in the zone of resilication is indicated by: (1) the greater SiO₂/Al₂O₃ mole-ratios of oxalate extracts of paleosols than surface horizons; (2) lysimeter leachate composition; and (3) the presence of authigenic halloysite at > 2 m depth in soil profiles.     

Morphology,composition and age of a buried paleosol,front range,Colorado, U.S.A.

A turf-banked lobe with a ground soil of post-Pinedale age overlies a buried paleosol which, although thin, appears to have been developed in situ. Organic matter from the Ab horizon of the paleosol yields a radiocarbon age of $\text{10,400 ± 400}\text{yrs}$ BP (Gak-3823) which corresponds with the waning stages of the Pinedale Glaciation in the Rocky Mountains. Abundant kaolinite and high amounts of silt and clay suggest that it may have developed over a long time interval.     

Single species island biogeography and Montana mule deer

The theory of island biogeography supplemented with dynamic concepts from other areas of biology can be applied to a single species. Data series from mule deer Odocoileus hemonius hemonius populations inhabiting diverse mountain as well as prairie habitats were compared. The fawn-doe ratios obtained at 6 months of age were inversely correlated (r = ?0·97; p < 0·01) with ‘island’ size as indicated by the percentage of cover. Populations inhabiting small islands of cover in the prairie consistently had higher winter fawn-doe ratios than those of the relatively secure mountain habitats. Cover fragmentation and low security level of the prairi populations relates to a high annual turnover rate compared with that of the mountain populations. The impact of cover fragmentation is consistent with this interpretation of theory which pictures reproduction as annual recolonisation. This approach may be useful in predicting hunting and ecological impact effects.     

Breeding habitat use by colonially nesting waterbirds in two mid-atlantic US regions under different regimes of human disturbance

More than 80% of the beach-nesting seabirds (common tern, least tern, black skimmer, and herring gull) in coastal Virginia nest on natural barrier island beaches, while in New Jersey the vast majority nest on dredge deposition material or natural marsh islands. This contrast probably results from the differences in human disturbance in the two regions. Although 75% of all oceanfront in New Jersey allows unrestricted recreation, about 85% of the Virginia beaches are ‘protected’ under the ownership of several conservation agencies. Attendant with changes in habitat utilisation in New Jersey, competitive interactions have apparently intensified with herring gulls usurping tern and laughing gull nest sites. Other implications are discussed.     

Evolution of a paleo-argillic brown earth (paleudalf) from oxfordshire,England

The complex developmental history of a paleo-argillic brown earth in Plateau Drift has been investigated using mainly micromorphological techniques. Eight kinds of pedological features are identified, quantified and related to a probable sequence of soil-forming events. Three “stable” periods of soil formation are recognised, one pre-dating emplacement of the Plateau Drift and the other two associated respectively with one or more interglacial periods between deposition of the drift and the onset of the last glaciation (Devensian) and the post-Devensian period. Clay illuviation and reduction and segregation of iron oxides are the main processes recognised in all three periods and reddening is associated with the periods before the last glaciation. Although the soil was probably subjected to several “unstable” periods only two are distinguished. The first is associated with erosion, disruption and mixing of soils and sediments, followed by transport and emplacement of the Plateau Drift. The second is related to the Devensian glaciation and is characterised by erosion, cryoturbation and deposition of loess on the eroded surface.     

Fractionation of organo-mineral complexes by sedimentation and density techniques

Soil samples were fractionated by sedimentation in water and by flotation in heavy liquids to separate complexed and uncomplexed organic and inorganic components. Flocculation of clays in heavy organic liquids was delayed by addition of a surfactant. Heavy liquids and surfactants sorbed by soil components were removed by washing with acetone-water mixtures.In a sample of a red-brown earth, the organic carbon and nitrogen contents were highest in the finest separates. In samples of a ground-water rendzina and a chernozemic soil, the coarse clay and silt separates had the highest organic carbon and nitrogen contents. Organic matter was concentrated in low density fractions in all separates. Carbon/nitrogen ratios were lowest in the finer and heavier separates. Calcium, and to a lesser extent manganese, iron and phosphorus, were concentrated in low density fractions: thus these elements appear to be associated with organic matter and may be important in organo-mineral complex formation. Carbonates, titanium, iron, silicon and potassium were concentrated at the highest densities.Organic fractions < 2.06 g cm^?3 from sand size separates were insoluble in alkali and had wide carbon/nitrogen ratios characteristic of plant debris. The light fractions from fine silt and coarse clay separates were more soluble in alkali but showed high ratios of humic to fulvic materials and high absorption at 280 nm. Such materials were considered to be microbial cell debris and were associated with high contents of disordered aluminium and iron oxides and expanding lattice silicates in 1 to 5 μm aggregates.Heavier fractions, particularly of finer clay separates, contained more fulvic and humic materials of a more aliphatic nature than those in < 2.06 g cm^?3 fractions. It is suggested that physical sorption on clay surfaces may be more important in these fractions. Ellite and kaolinite were concentrated in medium density fractions, and contents of some iron oxides and titanium minerals were highest in fractions > 2.06 g cm^?3. Such minerals plus quartz and feldspars were associated with minor amounts of organic matter or possibly were not involved in organo-mineral associations.     

Comparisons of soil organic matter and its fractions by pyrolysis mass-spectrometry

Pyrolysis mass-spectra from a sample of the A₁-horizon of a soil from southern Spain showed predominant peaks related to furan derivatives similar to those observed from complex polysaccharides in which not only hexoses but also pentoses and deoxyhexoses were constituent units. Smaller peaks, typical for protein materials and phenolic units, were also observed. On the other hand, typical peaks for the methoxyphenols of lignins were very small and indicated only limited amounts of undecomposed lignin residues in this soil sample. Peaks related to benzene or toluene were also very small.Humic acid samples from this soil showed much more prominent signals related to protein materials, benzene and phenolic derivatives and weaker polysaccharide-related signals than did the entire sample. Typical lignin related peaks were small or insignificant. Spectra from the grey or brown humidic acid fractions were much like those of the parent humic acid. Brown humic acid, however, showed stronger signals for nitrogen and sulphur compounds, indicating a higher content of protein-like materials in this fraction. Preparations of humic acid hydrolyzed by 6 N HCl showed in their pyrolysis products a marked increase in phenols and methoxyphenols.In its pyrogram, humin resembled humic acid, but signals for complex polysaccharides were more evident. Lignin-like materials seem not to be higher in this fraction. Hymatomelanic acid showed prominent signals related to polysaccharides and lignin. Pyrograms from the soil polysaccharides showed the characteristic pattern of a complex polysaccharide with the presence of fragments from polymers of amino acids or amino sugars. Fulvic acid spectra showed obvious dissimilarities to those from humic acid in that signals for protein, as well as those related to phenols, were low. Depending upon the isolation method, the fulvic acid preparations showed differing signals related to polysaccharide or phenolic materials.