Land use impacts on physical properties of 28 years old reclaimed mine soils in Ohio

Reclamation enhances soil quality by improving physical and chemical properties, which helps in restoration of mine soils. Evaluation of the effects of post-reclamation land uses on physical and chemical properties of mine soils helps to identify suitable land uses for mining companies. The objectives of this study were to evaluate the effects of post-reclamation land uses (e.g., forest, hay and pasture) on selected physical properties of soil in relation to undisturbed forest and agricultural land use. Soil samples were collected from the 0- to 5-, 5- to 15- and 15- to 30-cm depths in order to determine particle size distribution, bulk density, water-stable aggregates, mean-weight diameter and soil moisture retention. Cone index and infiltration rate were determined at soil surface. After 28 years of reclamation, bulk density in the surface layer of all land uses in the reclaimed mine soil (RMS) was similar to that of undisturbed forest (1.1 Mg m⁻³) but lower than that of agricultural soils (1.3 Mg m⁻³). However, soil bulk density at lower depths was not affected. The cone index was higher in the RMS-pasture (2.6 MPa) than the RMS-forest (1.4 MPa) and RMS-hay (1.5 MPa) due to the trampling effect of grazing animals. The water-stable aggregates (>2 mm), of 5–8 mm aggregates, were higher in RMS-forest by 24%, 90%, 66%, and under RMS-hay by 13%, 74%, 43% for the 0- to 5-, 5- to 15-, and 15- to 30-cm depths, respectively, than that under undisturbed forest. The mean-weight diameter (0- to 30-cm) of aggregates under RMS-forest and RMS-hay were higher than that under undisturbed forest by 41% and 27%, respectively. The initial infiltration rates at 5 min in RMS under forest, hay and pasture were less by 20%, 53% and 85%, respectively, than that under undisturbed forest (19.3 cm min⁻¹). The reclamation of mine soils with forest and hay improved surface soil bulk density and cone index, and enhanced water infiltration capacity and water-stable aggregates at the lower depths. Therefore, establishment of forest and hay should be encouraged in the RMS.     

Cytophotometric analyses of mesencephalic reticular formation neuronal RNA in soman intoxicated rats

Quantitative azure B cytophotometry was used to monitor ribonucleic acid (RNA) responses of individual neurons within the nucleus cuneiformis (NC) and ventrotegmental nucleus (VTN) of the rat mesencephalic reticular formation following single subcutaneous soman (pinacolyl methylphosphonofluoridate) injections (0.5, 0.9 or 1.5 LD₅₀). The sub-lethal (0.5 LD₅₀) dosage of soman produced RNA accumulation in NC neurons, but VTN-RNA levels were not significantly altered. In contrast, both reticular nuclei exhibited prominent RNA depletion with higher soman dosages, the severity of which was greater with lethal (1.5 LD₅₀) than near-lethal (0.9 LD₅₀) dosages. These data indicate that metabolic correlates of enhanced activation of cholinergic reticular nuclei are present only with sub-lethal dosages, and that higher dosages produce characteristics of impaired activation of ascending cholinergic pathways. At present, mechanisms underlying soman-induced metabolic and neurologic deficits remain speculative.     

Sitosterol 3-O-α-riburonofuranoside from Bauhinia candicans

From the aerial parts of Bauhinia candicans a novel steroidal glycoside was isolated and identified as sitosterol 3-O-α-D-riburonofuranoside.     

Photosynthesis and transpiration in the upper crown of a mature spruce in purified and ambient atmosphere in a natural stand

Summary This study addresses the question of whether gaseous air pollutants are capable of damaging spruce foliage. For this purpose, several twig pairs of an adult tree in a natural stand from the western part of the Bavarian Forest were supplied with pure and ambient air and gas exchange was monitored. With the exception of insignificant and unexplained differences during winter, the gas exchange of the twigs showed no negative deviation due to the influence of gaseous air pollutants. Because visible damage arises only in older needles, the duration of measurement is not sufficient to exclude a long-term influence of gaseous air pollutants.     

Higher taxonomic descriptors for vegetation classification

A model of direct and diffuse solar radiation on slopes of varying angle and aspect suggests that radiation differences within hilly terrain are maximized in the beginning of the dry season in the monsoon tropics. The differences between north and south facing slopes are greater than those found during the summer in the temperate zone. Within a study area near Mt. Bundey, Northern Territory, floristic and structural vegetational variability is closely related to June radiation as estimated by the model. However, the distribution patterns of monsoon thicket and eucalypt forest relate more to relative five protection than to the effects of incident radiation on temporal patterns of moisture availability. Within both major formations, site rockiness is an important influence on vegetation floristics and structure, both for five protection and through its influence on moisture availability.     

Recent successional processes investigated by pollen analysis of closedcanopy forest sites

Forest succession was investigated by pollen analysis of two mor-humus sections and of peat from a 3 m-diameter hollow under mixed conifer-hardwood forest in north-central Massachusetts, USA. The humus profiles recorded a major forest perturbation caused by the removal of Castanea dentata by the chestnut blight (1910–1912), and the peat from the hollow extended the record beyond the time of colonial settlement (1733). Fagus grandifolia was a forest dominant before 1733 but declined abruptly upon settlement. Castanea, a late Holocene immigrant to the area, rapidly increased its pollen representation after settlement until the epidemic of the chestnut blight. Forest succession following the loss of Castanea involved the successive rise to dominance of Betula, Quercus, Acer rubrum, and Tsuga canadensis. These vegetational changes conform to observations made during studies of forest-stand composition by other workers. Allogenic factors such as logging, disease, and wind have initiated major compositional change, which has been modified by autogenic successional processes such as the gradual rise to dominance of Tsuga canadensis around one of the humus sections. The two humus sites resolve fine-scale pattern in former vegetation such as differences in the distribution of Pinus strobus and Castanea over 200 m, the distance between the mor-humus sites. These within-forest sites permit investigations of fine-scale vegetational patterns and processes that are of interest to forest ecologists.     

Phenology of nine common woody species in semi-arid,deciduous Kalahari Sand vegetation

The phenological patterns of 9 woody species that are common components of Kalahari Sand communities were observed over a period of 32 months. The observations were made on plants adjacent to the soil moisture study sites which have been described earlier (Childes & Walker 1987). A pre-rain flush was noted in the 2 shrub/small tree species Ochna pulchra and Terminalia sericea. Leaf fall in all species was related to a decrease in soil moisture and minimum temperature. The rooting habits and other adaptations of the species resulted in a sequential leaf fall in the communities. Open woodland and scrub species such as Pterocarpus angolensis showed a generally synchronised pre-rain flowering, while the closed woodland species e.g. Baikiaea plurijuga had protracted asynchronous flowering periods. Fruit ripening generally occurred in the dry season when conditions were ideal for fruit and seed dispersal.     

Tree uprooting: review of impacts on forest ecology

This paper reviews the ecological effects of tree uprooting. In many forests, disturbance by uprooting is the primary means of maintaining species richness and diversity. Treefall may be due to exogenous factors or it may be endogenously created, although the former predominate. The canopy gap formed by downed trees is often vital to community vegetation dynamics and successional pathways, by providing high light niches (gaps) for pioneer species, by encouraging release of suppressed, shade-tolerant saplings, and through recruitment of new individuals. Nutrient cycling may be affected by uprooting as subsoil materials are brought to the surface, via additions of woody debris to the forest floor, through exposure of bare mineral soil, and by changes in throughfall chemistry. The influence of the resultant pit/mound microtopography on understorey herb distribution is largely due to microclimatic and microtopographic variation. Tree seedling distribution, however, is related to microtopography primarily through differences in soil morphology, nutrition, and moisture content of mound and pit sites.     

Performance of two Picea abies (L.) Karst. stands at different stages of decline

Summary The water relations of Picea abies in a healthy stand with green trees only and a declining stand with trees showing different stages of needle yellowing were investigated in northern Bavaria. The present study is based on observations of trees differing in their nutritional status but apparently green on both sites in order to identify changes in the response pattern which might be caused by atmospheric concentrations of air pollutants and could lead to the phenomenon of decline. Transpiration was measured as water flow through the hydroactive xylem using an equilibrium mass-flow measurement system. Total tree transpiration was monitored diurnally, from July 1985 until October 1985 at both sites. The relationship between transpiration and meteorological measurements indicated that transpiration was a linear function of the vapor pressure deficit. No differences in transpiration of green trees were observed between the two sites. Canopy transpiration was 57%–68% of total throughfall and 41%–54% of total rainfall. Due to this positive water balance, soil water potential at 10 and 20 cm depths remained close to-0.02 MPa (max.-0.09 MPa) for most of the summer. Soil water potential was correlated with the difference between the weekly precipitation and transpiration. No differences in the water relations of apparently healthy trees in the two P. abies stands were observed. It is concluded that differences between green trees at the two sites in terms of nutrient relations or growth rate cannot be explained by changes in whole-tree transpiration or soil water status.