Summary Large amounts of terrestrial detritus enter many low‐order forested streams, and this organic material is often the major basal resource in the metazoan food webs of such systems. However, despite their apparently low biomass, algae are the dominant food of organisms in a number of aquatic communities which conventionally would have been presumed to be dependent on allochthonous detritus, particularly those in the tropics and also in lowland intermittent streams in arid Australia. The dual stable isotope signatures (δ13C and δ15N) of potential primary food sources were compared with the isotopic signatures of common aquatic animals in lowland intermittent streams in south‐eastern Australia, in both spring and summer, to determine whether allochthonous detritus was an important nutritional resource in these systems. The isotopic signatures of the major potential allochthonous plant food sources (Eucalyptus, Phalaris and Juncus) overlapped, but were distinct from algae and the dominant macrophytes growing in the study reaches. The isotopic signatures of biofilm were more spatially and temporally variable than those of the other basal resources. Despite allochthonous detritus having relatively high C : N ratios compared to other potential basal resources, results from isosource mixing model calculations demonstrated that this detritus, and the associated biofilm, were the major energy sources assimilated by macroinvertebrate primary consumers in both spring and summer. The importance of these energy sources was also reflected in animals higher in the food web, including predatory macroinvertebrates and fish. These resources were supplemented by autochthonous sources of higher nutritional value (i.e. filamentous algae and macrophytes, which had relatively low C : N ratios) when they became more prolific as the streams dried to disconnected pools in summer. The results highlight the importance of allochthonous detritus (particularly from Eucalyptus) as a dependable energy source for benthic macroinvertebrates and fish in lowland intermittent streams of south‐eastern Australia. This contrasts with previous stable isotope studies conducted in lowland intermittent streams in arid Australia, which have reported that the fauna are primarily dependent on autochthonous algae.

Until recent times, most studies on supporting simulation-based scientific discovery learning adopted the ad hoc strategies-oriented approach. This paper makes a systematic analysis of the internal conditions of scientific discovery learning to propose a triple scheme for learning support design that includes interpretative support (IS), experimental support (ES), and reflective support (RS). The experiment was conducted with 78 students (aged from 12 to 13 years) to examine the effects of the IS and ES using a 2x2 between-subjects design. The main results were: significant effects were observed for IS on the post-test of intuitive understanding, flexible application and knowledge integration; no main effect was demonstrated for ES, and there was a marginally significant interactive effect for ES and IS on the intuitive understanding test. A process analysis showed that the successful learners had designed more well-controlled experiments than the failing ones. Learning support in a simulation environment should be directed toward the three perspectives to invite meaningful, systematic and reflective discovery learning.

A series of twenty-one nitrogen fertilizer rates ranging from 0 to 800 lb nitrogen/ acre (897 kg/ha)/annum was applied on a pure S. 23 perennial ryegrass sward and on an S. 23 ryegrass sward containing S. 100 white clover. Total yields of herbage dry matter and crude protein from both swards at all the nitrogen rates were determined each year by cutting the herbage five times at approximately the same stage of growth on each occasion. Four-parameter growth curves relating herbage yield to nitrogen rate were fitted to the data, and are presented for the first 3 years of the experiment. On the pure-grass sward the response of dry-matter yield to nitrogen rate was almost linear between the 0 and 300 lb nitrogen/acre (336 kg/ha) rates, then it decreased steadily, becoming non-significant about the 500 lb/acre (560 kg/ha) rate. In contrast the response of crude-protein yield was virtually linear from the 0 to the 600-700 lb nitrogen/acre (673-785 kg/ha) rates. The inclusion of white clover in the sward increased the yields of dry matter and crude protein at the low nitrogen rates, but decreased the responses, with the result that the yields and responses of the grass + clover sward were not significantly different from those of the pure-grass sward at nitrogen rates above about 300 lb/ acre (336 kg/ha). In terms of profitability at present fertilizer prices the optimum nitrogen rate for dry-matter production on both swards was estimated to be 400-450 lb/ acre (448-504 kg/ha), whereas that for crude-protein production was greater than 600 lb/acre (673 kg/ha). The value of clover in a sward receiving nitrogen fertilizer is discussed. INTRODUCTIONfertilizer nitrogen between 0 and 800 lb/acre, with increments of 25 lb between rates, was applied on a The report of a preliminary experiment (Reid, pure-grass sward over one growing season. Curvi-1966) stated that few previous experiments had linear regression analysis showed that the dryprovided precise descriptions of the yield response matter and crude-protein yields were best fitted by curves of grassland to fertilizer nitrogen. The evi-a four-parameter growth curve dence available then suggested that herbage yields _ _ , _ ô f both dry matter and crude protein responded " * more or less linearly to increasing rate of fertilizerThe increase in dry-matter yields was almost nitrogen application up to at least 300 Ib/acre. The linear with nitrogen rates from 0 up to 300 lb/acre. first apparent decrease in the response occurred Thereafter the response to nitrogen decreased when applications were increased to slightly over steadily, approaching zero at the 500 lb nitrogen/ 300 lb nitrogen/acre. For example, Cowling & acre rate. The crude-protein response showed little Lockyer (1965) reported a small but significant fall decrease up to the 600 lb nitrogen/acre rate, and in response to 326 lb nitrogen/acre, which was the did not approach zero within the range tested, highest rate they tested. No estimates could be The present experiment was designed to provide found in the litera...

Effective policies promoting diversity in geoscience require understanding of how the values and practices of the community support the inclusion of different social groups. As sites of knowledge exchange and professional development, academic conferences are important culturing institutions that can alleviate or reproduce barriers to diversity in geoscience. This study examines diversity at a 2017 geoscience conference, the joint Canadian Geophysical Union and Canadian Society of Agricultural and Forest Meteorology annual meeting, through observation of participation, presentation content, and behaviour in conference sessions. Across 256 observed presentations, women constituted 28% of speakers, whereas women of colour made up only 5%. Participation rates differed between disciplinary sections, with the most populous sessions (Hydrology and Earth Surface) having the lowest percentage of women. Examination of presentation content reveals that the methods and scholarly contributions of both women and people of colour differed from the majority, suggesting an intellectual division of labour in geoscience. Examination of audience behaviours between presenters reveals how a "chilly climate" can be experienced by women and other marginalized demographics in conferences. We argue that there is more to be done than simply increasing numbers of women or other minorities in geoscientific spaces, and we suggest pathways to making geoscience a more inclusive and democratic pursuit.

Learning support studies involving simulation-based scientific discovery learning have tended to adopt an ad hoc strategies-oriented approach in which the support strategies are typically pre-specified according to learners' difficulties in particular activities. This article proposes a more integrated approach, a triple scheme for learning support design on the basis of the systematic analysis of the internal conditions of scientific discovery learning. The triple learning support scheme involves: (a) interpretative support that helps learners with knowledge access and the generation of meaningful and integrative understandings; (b) experimental support that scaffolds learners in systematic and valid experimental activities; and (c) reflective support that increases learners' self-awareness of the discovery processes and prompts their reflective abstraction and integration. Two experiments were conducted with eighth graders (13-year-olds) to examine the effects of these learning supports embedded into a simulation program on floating and sinking. The overall results support the main hypotheses that learning supports in a simulation environment should be directed towards the three perspectives to invite meaningful, systematic, and reflective discovery learning.

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Experiments reported by Holmes (1948Holmes ( , 1949Holmes ( , 1951a and by Holmes & MacLusky (1954, 1955 have provided much valuable information on the fertilizer aspects of the intensive production of herbage for crop drying. A fairly standard management was applied throughout these experiments, and little attention was paid to the possible modifying influence of cutting management systems on the response of the grass-clover sward to fertilizer treatment. The management consisted of cutting the herbage four or five times per season at the long leafy stage with a reciprocating-blade mower. Jones (1933) conclusively demonstrated in a series of experiments that the balance of grass and clover in a sward can be altered by the particular grazing technique adopted. Since this undoubtedly applies under a cutting management also, studies were begun at the Hannah Institute in 1954 on the reaction of the grass-clover sward to varying cutting systems.In the experiment described in this paper the effects on the sward of cutting to two heights above ground level were compared under two cutting frequencies, and six fertilizer nitrogen treatments were superimposed. The results relating to the effects of the treatments on the clover fraction of the sward in this experiment have been reported in detail elsewhere (Reid, 1958) and this paper deals mainly with the overall reaction of the sward to the treatments. EXPERIMENTALThe experiment began in 1954 on a perennial ryegrass sward in its fourth harvest year. This sward proved to have an unevenly distributed clover population, so the experiment was transferred to another site in the spring of 1955. The sward on this second site was also perennial rye-grass dominant, but it was only in its third harvest year, and it had a much more uniformly distributed clover population than the sward on the first site. The experiment was continued for two seasons on the second site.

Abstract. The utility of near infrared spectroscopy as a non-invasive technique for the assessment of internal eating quality parameters of mandarin fruit (Citrus reticulata cv. Imperial) was assessed. The calibration procedure for the attributes of TSS (total soluble solids) and DM (dry matter) was optimised with respect to a reference sampling technique, scan averaging, spectral window, data pre-treatment (in terms of derivative treatment and scatter correction routine) and regression procedure. The recommended procedure involved sampling of an equatorial position on the fruit with 1 scan per spectrum, and modified partial least squares model development on a 720-950-nm window, pre-treated as first derivative absorbance data (gap size of 4 data points) with standard normal variance and detrend scatter correction. Calibration model performance for the attributes of TSS and DM content was encouraging (typical R c 2 of >0.75 and 0.90, respectively; typical root mean squared standard error of calibration of <0.4 and 0.6%, respectively), whereas that for juiciness and total acidity was unacceptable. The robustness of the TSS and DM calibrations across new populations of fruit is documented in a companion study.Additional keywords: spectral window, non-invasive.