The effect of canopy position on growth and mortality in mixed sapling communities during self-thinning

This research investigates how species in the sapling phase differ in growth and survival depending on light availability (as estimated by canopy position) by means of tree-ring analysis and modelling mortality. We harvested 120 live and 158 dead saplings in self-thinning communities consisting of Silver birch (Betula pendula Roth.), Scots pine (Pinus sylvestris L.), Japanese larch (Larix kaempferi Carr.) and Douglas fir (Pseudotsuga menziesii Mirb. Franco) in the Netherlands. Results are evaluated within the framework of a trade-off between high-light growth and low-growth survival. Radial growth, measured at ground level, generally declined over time. In addition, a decreasing light availability further reduced growth in all species except Douglas fir. Trees died when radial growth was reduced to about 0.5 mm year¿1. Mortality in all species except Scots pine was significantly related to recent growth, but mortality curves were not different. The light-demanding Silver birch and Japanese larch differed from the shade-tolerant Douglas fir in both high-light growth and low-growth mortality, in line with a growth-survival trade-off. The light-demanding Scots pine did not fit this pattern as it was unable to transfer high radial growth into height gain, leaving it in suppressed canopy positions. This indicates the importance of height growth in the growth-survival trade-off. Differences in mortality probabilities affect the potential for coexistence, however, in all species also fast-growing individuals died suggesting additional factors causing mortality during self-thinning, other than direct competition for ligh

Further Studies of Non-Nuclear Structures in the Basidium

Pursuing a further analysis of the so-called Golgi apparatus in the basidium, tests were made with some accepted chondriosome techniques. Typical chondriosomes were found to be present, quite unlike the bodies associated with the Golgi apparatus. It is suggested that the Nebenkern and Golgi material are discrete cell bodies, apart from nucleus, chondriosomes and centrosomal mechamsm

Cytoplasmic Structures in the Basidium Revealed by Silver Impregnation

Basidia of Coprinus fimetarius treated by silver impregnation methods exhibit blackened bodies in the cytoplasm. The size, shape, position and distribution of these bodies correspond to those of bodies demonstrated by mitochondrial techniques. The silver-absorbing bodies in the basidium are unlike the Golgi bodies demonstrated in some animal cells by silver impregnation, but bear much resemblance to mitochondria

Some Cytological Details of Ceresan Poisoning in Seedlings

Heavy overdoses of Ceresan induces the formation of giant cells in seedlings of corn and small grains. Cell division is inhibited. Nuclear division occurs, with more or less normal prophases. Anaphase separation of halves of split chromosomes fails to take place, accompanied by apparent failure of the sprindle mechanism. Cell wall formation may he initiated, but the evidence suggests subsequent dissolution of partial cell walls

Pathological Polyploidy in Seedlings of Corn and Sorghum

The writer had demonstrated that Coprinus sterquilinus contains an extra-nuclear mechanism which bears structural homologies with the Golgi apparatus in animal spermatocytes. Numerous other Hymenomycetes have been examined. Coprinus atramentarius contains a distinct Nebenkern sphere, consisting of a large hyaline sphere, in which there are peripheral, chromophilic granules. This body is most distinct just before the meiotic division of the fusion nucleus occurs. It is probable that the sterigmatic bodies described by various workers, are derived from this Golgi apparatus, rather than from the centrosomes

The Presence of a Nebenkern In Coprinus atramentarius

The writer had demonstrated that Coprinus sterquilinus contains an extra-nuclear mechanism which bears structural homologies with the Golgi apparatus in animal spermatocytes. Numerous other Hymenomycetes have been examined. Coprinus atramentarius contains a distinct Nebenkern sphere, consisting of a large hyaline sphere, in which there are peripheral, chromophilic granules. This body is most distinct just before the meiotic division of the fusion nucleus occurs. It is probable that the sterigmatic bodies described by various workers, are derived from this Golgi apparatus, rather than from the centrosomes

The Nuclear Cycle and Sexuality of Trametes peckii

Trametes peckii is a heterothallic member of the Polyporaceae. The sex classes exhibit considerable irregularity, making any attempt to classify this organism as bipolar or tetrapolar highly questionable. Segregation of monosporous haplonts into cottony and non-cottony mycelia is clearly indicated. The dikaryotic secondary mycelium is always cottony, suggesting the possibility of the dominance of the cotton character. Repulsion between certain combinations of two mycelia of opposite sex groups, and the absence of repulsion between other pairs, resembles the phenomenon designated as Barrage by Vandendries. This fungus appears to exhibit three segregating characters; sex potentiality, haploid mycelial character, and repulsion

Aerogel Insulation Applications for Liquid Hydrogen Launch Vehicle Tanks

Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined

The West Falmouth oil spill

A spill of 650,000 to 700,000 1iters of #2 fuel oil in Buzzards Bay, Mass., USA, on September 16, 1969, has severely polluted the coastal waters, the marshes, the offshore sediments and the shell fish resources of Falmouth and of Bourne, Mass. In preliminary publications and reports we have discussed the chemical and biological data available during the first few months after the accident. The present report documents the continuation of our analytical effort; we include analyses of stations that had not previously been covered and present the data that were available by October, 1971. Three distinct, though partly overlapping, series of events followed the spill. First, within the first few hours or days after the accident, there was a very heavy kill of those organisms which came into contact with the oil. It extended over all phyla and over benthic and intertidal organisms. Next, within weeks or months after the spill, the oil pollution spread to areas that had not been immediately affected; and the kill extended, though in some cases more slowly than the spread of the oil, to outlying areas. Oil entered the marine food web and made the shellfish resources of our area unacceptable to human nutrition. The oil showed an unexpected persistence in the sediments and in marine life, especially in view of its relatively low boiling range and of earlier assertions that fuel oil pollution was transitory in nature and without long term consequences. For considerable time after the spill, the oil pollution of the sediments prevented the resettlement by the original fauna. Now, degradation of the oil has become evident. Biochemical and physical processes lead to a gradual reduction of the oil content of the polluted sediments. Concurrent with the degradation, there has been a gradual reduction in the immediate toxicity of the oil in the sediments. This has permitted resettlement of the polluted region first by the most resistant opportunists and later by a more varied and more normal fauna. However, oil-derived hydrocarbons have remained at all stations during the entire two year span for which data are now available, and it appears that the life span of pollution, even by a low boiling fuel oil must be measured in terms of many years. The eventual aim of this study is the documentation of the effects, the persistence and the eventual disappearance of pollutant hydrocarbons from a relatively small spill in a limited and previously clean coastal area. Of necessity, most of our analytical effort in the past was aimed at a survey of the extent of the oiling of the sediments and of some of the commercially important animals. As the degradation proceeds, we expect to devote a greater effort to a more detailed chemical analysis of the hydrocarbons remaining in the environment in order to define and understand the modes of degradation and to correlate chemical analyses with biological data. Parallel investigations on the weathering of different oils under other ecological and climatic circumstances are under way here and should, in combination with the West Falmouth study, give a more realistic assessment of the environmental hazard and persistence of crude oil than has been available until now.Prepared for the Office of Naval Researoh under Contract N00014-66-C0241; NR 083-0043 The. Environmental Protection Administration (Contract 18050 EBN) and the National Science Foundation (GA-19472)