Plant Production in Relation to Foliage Illumination

The intensity of light received by plants can be specified interms of its extinction with depth in the foliage. Various light-extinctionfunctions are introduced to specify the light received by plantswith different patterns of foliage development (viz. standardexponential, best exponential, and ideal). The implicationsof these extinction functions are discussed and the productionassociated with each foliage type is studied as a function ofleaf area index, LAI (the ratio of leaf area to ground area).The concepts of optimum LAI and ceiling LAI are considered inrelation to these foliages. It is shown that, contrary to whathas previously been thought, a foliage in which the bottom leavesare at compensation point is not necessarily at optimum LAI.It also becomes possible to reconcile conflicting views on therelationship between optimum LAI and ceiling LAI.     

Isozymes of Glutamate Dehydrogenase in Chlamydomonas reinhardi*, †

SYNOPSIS. Two electrophoretically distinct forms of glutamate dehydrogenase were found in extracts of Chlamydomonas reinhardi. The slower moving of these was detectable only when the cells were grown organotrophically. The other, more active, enzyme copurified with chloroplasts and was not electrophoretically detectable in extracts of organotrophically grown cultures of the y-2 mutant strain; this absence was not apparent in wild type or in the mutant strain y-1. Both forms of the enzyme were cofactor non-specific.     

Isolation of a Strain of Chlamydomonas reinhardi with Altered Control of Glyceraldehyde 3-Phosphate Dehydrogenase*, †

SYNOPSIS. A strain of Chlamydomonas reinhardi is described in which the control of glyceraldehyde 3-P dehydrogenase is altered; the activity of the NADP-dependent enzyme is apparently independent of chlorophyll content.     

Misclassified Resource Selection: Compositional Analysis and Unused Habitat

Abstract: During the past decade, compositional analysis (CA) has been used widely in animal—habitat and resource selection studies. Despite this popularity, CA has not been tested for potential systematic biases such as incorrect identification of preferred resources. We used computer-simulated data based on known habitat use and availability parameters to assess the potential for CA to incorrectly identify preferred habitat use. We consider in particular the situation when available habitat categories not used by all animals are included in the resource selection analysis, with substitution of a relatively small value, such as 0.01, for each 0% utilization value. Progressively larger misclassification-error*** rates in preferred habitat use resulted from substituting progressively smaller positive values for each 0% utilization of a habitat category.     

A trial to control the tsetse fly,Glossina morsitans centralis,with low densities of odour-baited targets in west Zambia

Abstract. A large-scale trial investigated the possibility of eradicating G.m.centralis from a traditional cattle rearing area using odour-baited targets at a reduced overall target density from 4 to 0.5-2.3 per km², thus cutting down initial material costs by about 50%. Only the periphery of what was thought to be prime tsetse habitat (dense woodland) was treated with targets. These were all black or blue/black cloth (1.8 × 1m), sprayed with deltamethrin suspension concentrate and baited with butanone and/or acetone (40-130mg/h) and l-octen-3-ol (0.5mg/h). Although fly catches from traps and flyrounds initially dropped by approximately 3% per day and trypanosomiasis cases declined by 99% within a year, eradication was not achieved, so that more targets were deployed at a later stage. Although initially cheaper, the option of using reduced target densities proved financially unattractive because of prolonged periods of target maintenance prior to eradication. Revised strategies for tsetse control with odour-baited, insecticide-impregnated targets in west Zambia are presented.     

Discrepancies Between Euclidean Distance and Compositional Analyses of Resource Selection Data With Known Parameters

ABSTRACT A Euclidean distance (ED) method of wildlife habitat analysis has recently been proposed as an alternative to compositional analysis (CA). We performed simulation analyses to compare performance of ED to that of CA, using data sets with known parameters, where habitat patch size and shape remained the same. We observed extensive misclassification rates for ED but not for CA. For each of the 16 utilization permutations we modeled, of 3 avoided and 2 preferred habitats, results for CA and ED differed. Differences depended on the particular utilization permutations (i.e., juxtaposition of habitats) and did not seem to occur in any clear or predictable pattern. We recommend that ED not be used for future analyses of habitat use or resource selection until or unless these analytical problems can be rectified.     

Constraints on home range behaviour affect nutritional condition in urban house sparrows (Passer domesticus)

In human‐dominated landscapes (semi)natural habitats are typically embedded in tracts of unsuitable habitat. Under such conditions, habitat characteristics and grain size of the surrounding landscape may affect how much food, and at what cost, is available for sedentary species with low home‐range plasticity. Here we combine behavioural radio‐tracking, feather ptilochronology, and landscape analysis to test how nutritional condition varies with home range size in 13 house sparrow [Passer domesticus (Linnaeus, 1758)] populations along an urban gradient. Urban individuals occupied smaller home ranges than conspecifics from rural areas, most distinctly if key cover was highly scattered. In urban plots, patch connectivity, home range sizes, and activity areas were positively correlated, indicating that individual ranging behaviour was related to the spatial distribution of suitable habitat. Urban House sparrows also showed the smallest feather growth bars, which were positively related to home range size at plot level. In contrast, growth bar widths and home range sizes were negatively related in rural populations, whereas in suburban populations, both variables varied independently. We conclude that individuals from progressively more built‐up areas show a restricted ability to adjust their daily ranging behaviour to the scattered distribution of critical resources. This may complement other putative causes of the widespread population decline of urban house sparrows. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 41–50.     

Synthesis of NADP-Dependent Triosephosphate Dehyrogenase Independent of Illumination in Chlorella variegata*†

SYNOPSIS. Growth conditions for Chlorella variegata are described which permit induction of chlorosis in the light and partial development of the chloroplast in the dark. Growth in the light in the presence of Na acetate and NO^?3 leads to chlorosis in the light. The presence of a reduced nitrogen source permits chlorophyll synthesis in the light, and, to a lesser extent, in the dark. Synthesis of NADP-dependent triosephosphate dehydrogenase is directly correlated with chlorophyll synthesis and independent of illumination.