Preliminary observations on the effects of burning on the hemiptera (Heteroptera and Auchenorhyncha) of limestone grassland

Samples of Hemiptera were taken in September 1972, from areas of carboniferous limestone grassland which were burnt in April and May 1972, and from adjacent unburnt areas. Significantly larger numbers of species, of both Heteroptera and Auchenorhyncha, were recorded from the unburnt areas, and the species-diversity of the samples was significantly greater. The effects of burning on individual species are considered in relation to their biology and the effects of other kinds of management. The results are discussed in relation to the management of grassland for the conservation of wildlife, and a short review of the effects of burning on populations of invertebrate animals is made.     

The exploitation of helix pomatia L.

The evidence at present available, although incomplete, gives rise to fears for the future of the edible snail Helix pomatia L. The scale of exploitation is increasing, particularly in Eastern Europe, to meet growing demand, mainly from the West. The growth of legislation to control collecting supports the evidence of declining numbers, but the legislation does not appear to be backed by sufficiently detailed population ecology studies. The need for co-ordinated international action on farming, legislation and ecological study is urged.     

Chemical Control of the Pine Shoot Moth, Rhyacionia buoliana (Denis and SchiffermUller) (Lepidoptera: Tortricidae) in Seed Orchards in Britain

In 1970 and 1971 a high population of Rhyacionia buoliana (Denisand SchiffermÜller), the Pine shoot moth, appeared in aseed orchard of Pinus contorta Douglas ex Loud, in Wiltshire.The opportunity was taken to compare several alternative insecticideswith DDT. Field trials in March and August showed that fenitrothioncan be used as an alternative to DDT to control the Pine shootmoth.     

A comparison of some red and yellow earths in tropical queensland and northeast Brazil

Red and yellow earths are kaolinitic and generally sesquioxidic soils having massive B horizons with porous, earthy fabrics and weak profile differentiation but usually displaying a gradual increase in clay content with depth. They are widespread in tropical Queensland and northeast Brazil where comparable climates prevail although the vegetation is markedly different. Their parent materials are mostly quartzitic sedimentary rocks or unconsolidated sediments and the soils occur in a wide variety of topographic and geomorphic situations. In both regions it is probable that many of the soils have not formed under the present climatic conditions.Profile morphology, drainage, silt and clay contents, clay mineralogy, and soil chemistry have been compared and contrasted between the red and yellow earths within and between the two regions. Canonical variate analysis has shown that, on the basis of surface soil chemical attributes, the red earths can be separated from the yellow earths within each region and that the Queensland soils can be separated from the Brazilian soils.     

Long-term effects of five ameliorants on a saline-sodic soil of South Africa

The effects of five ameliorants for saline-sodic soil reclamation on certain chemical and physical soil properties over a four-year period of observation are reported. Of these ameliorants, three are conventionally used (gypsum, sulphur, manure); the other two are for this purpose either unusual (potassium sulphate) or relatively unknown (molasses meal). Results published in a previous paper demonstrated that molasses meal had a very rapid-acting favourable effect on most soil physical properties whilst soil chemical conditions remained essentially unchanged. The effect on physical properties was presumably due to soil aggregation by the polysaccharide component of molasses meal. As a follow-up this paper shows, however, that this aggregation does not last long; the rigidly arid climatic conditions under which this experiment was carried out apparently do not favour the preservation of structural bonds consisting of polysaccharide gums. Consequently, a gradual decline of structural conditions took place after the second year. Although initially not as effective as molasses meal, gypsum and sulphur retained their favourable influence on physical properties over a longer period. Potassium sulphate and farmyard manure provided virtually no benefits.     

Gibbsite and halloysite decomposition in strongly acid podzolic soils developed from granitic saprolite of the Bayerischer Wald

The present study reports the occurrence of gibbsite and halloysite in soils derived from granitic saprolites and from glacial deposits formed from granitic saprolites of the Bayerischer Wald (Germany). Both minerals are common in soils of this area. They were formed in the initial stages of weathering, most probably before the Pleistocene and in a warmer climate. Under present conditions halloysite and gibbsite are unstable in the surface soils, as indicated by a decrease in gibbsite concentration towards the surface and by an undersaturation of the equilibrium soil solution with respect to both minerals. It is assumed that the strongly acid conditions and the high concentration of organic compounds in the surface horizons lead to dissolution of gibbsite and possibly to transformation of halloysite to kaolinite.     

Adsorption sur les argiles de deux lipopolysaccharides rhizosphériques

The adsorption with time has been measured of two well characterized lipopolysaccharides onto aqueous suspensions of a montmorillonite, a kaolinite and an illite at one fixed polymer-clay ratio. The clays were prepared in the Fe⁺⁺⁺ or Ca⁺⁺ forms by washing with FeCl₃ or CaCl₂ followed with water. The competitive sorption of the two polymers was measured also in the presence of an equal concentration of a protein or a basic amino-acid. Sorption of the polymers by themselves was approximately proportional to the external areas of the three clays and independent of the exchangeable cation. The presence of the protein inhibited completely the adsorption of both polymers onto the Ca⁺⁺ clays, but usually enhanced sorption onto the Fe⁺⁺⁺ clays. Sorption in the presence of the amino-acid differed both for each polymer and according to the form of the clay. Possible reasons for the various sorption patterns are discussed.     

Diurnal changes in acetylene reduction in field-grown cowpeas and soybeans

The effects of five environmental factors on variation in the rate of C₂H₂ reduction in two cowpea (Vigna unguiculata L. Walp.) and two soybean (Glycine max L. Merrill) cultivars were examined at two stages of growth in the field. Diurnal changes in C₂H₂ reduction, estimated as μmoles C₂H₄ produced·g^?1 nodules·h^?1, over a 30 h period were compared with changes in soil, canopy and air temperatures, global radiation, and vapour pressure deficit. Although the environmental factors showed one maximum and one minimum during a diurnal cycle, the C₂H₂ reduction rate in nodulated cowpea roots showed two peaks: one between 0600–1200 and another between 1800–2400 and two minima: one between 1200–1600 and another between 2400–0600. Variation in C₂H₂ reduction in soybean nodules did not show any definite pattern. Vapour pressure deficit appeared the most likely factor influencing the decline in C₂H₂ reduction between 1200–1600.The rate of C₂H₂ reduction in cowpeas was greater at the pre-flower than at the early pod-fill period; the rate in soybeans was not greatly different at early flower or early pod-fill.     

Soil protozoan dynamics in a shortgrass prairie

Soil Protozoa (primarily small naked amoebae and flagellates) were counted under control conditions and with stresses of nitrogen, water, or nitrogen and water under field conditions (Ecosystem Stress Area, Pawnee Site, northeastern Colorado, USA) in the summer of 1974. Protozoan populations were also measured in soil cores removed from the field and incubated under a wet-dry cycle. Protozoan numbers were higher in the top 1 cm of soil and overlying litter than at a depth of 5–6 cm in all treatments. After rainfall totaling 35 mm, the control and fertilized only treatments showed population increases with the fertilized only treatment showing the greater change. Protozoa showed marked responses to the addition of water to soil cores, with the largest numbers appearing after peak CO₂ evolution. Numbers of active (trophic) forms ranged from about 20.000. g^?1 dry soil in the control treatment under dry conditions to over 100,000. g^?1 dry soil in the irrigated plus fertilized plot. There were few (<5%) cystic (dormant) forms in all treatments contrary to earlier studies in mesic climates. A rough estimate of protozoan production is presented.     

Some observations on plant lectins and Rhizobium specificity

The ability of fluorescein isothiocyanate (FITC) labelled lectins extracted from the legumes Aspalathus linearis, Glycine max, Lotononis bainesii, Phaseolus vulgaris and Pisum sativum, respectively, to react with strains of various Rhizobium spp. was studied. With the exception of six out of ten strains of R. phaseoli and two out of ten strains of R. japonicum, none of the Rhizobium strains tested were able to bind lectin from their normal host plants. Many strains of R. leguminosarum, R. trifolii and R. phaseoli bound each of the plant lectins studied with the exception of the P. sativum lectin. This lectin was only bound by two strains of R. meliloti and a slow-growing strain isolated from Macroptilium atropurpureum. These results do not support suggestions by other workers that plant lectins play an important role in Rhizobium specificity.