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© 2016 Elsevier Ltd. Ecophysiological studies of remnant woodlands in saline environments are scarce. We investigated seasonal fluctuations in soil water and salinity together with leaf and branch traits (area-based maximum assimilation (Amax), foliar nitrogen, specific leaf area (SLA) and Huber value (Hv)) and sap velocities of Eucalyptus macrorhyncha at four semi-arid sites in south-eastern Australia. Summer and winter soil salinities (10 cm depth) were 15-35 dS m-1 and 8-10 dS m-1 respectively. Gravimetric soil water content in the upper 20 cm was 2-5% in summer and 7-23% in winter, resulting in a significant inverse correlation between soil water and soil salinity. We found significant correlations between soil conditions and plant traits and function across seasons. Soil water content was significantly correlated with foliar N, SLA, Hv and maximum sap velocity while soil salinity was significantly correlated with Amax, Hv and maximum sap velocity. Correlations indicate co-variation of soil conditions and plant physiology in response to environmental conditions such as solar radiation and vapour pressure deficit (D). E. macrorhyncha tolerates the dual stresses of high salinity and low soil water during summer. While the plants appeared unhealthy, our data show that remnant vegetation can remain functional even in close proximity to saline scalds.

We investigated how physiologically observed forward suppression interacts with stimulus frequency in neuronal responses in the guinea pig auditory cortex. The temporal order and frequency proximity of sounds influence both their perception and neuronal responses. Psychophysically, preceding sounds (conditioners) can make successive sounds (probes) harder to hear. These effects are larger when the two sounds are spectrally similar. Physiological forward suppression is usually maximal for conditioner tones near to a unit’s characteristic frequency (CF), the frequency to which a neuron is most sensitive. However, in most physiological studies, the frequency of the probe tone and CF are identical, so the role of unit CF and probe frequency cannot be distinguished. Here, we systemically varied the frequency of the probe tone, and found that the tuning of suppression was often more closely related to the frequency of the probe tone than to the unit’s CF, i.e. suppressed tuning was specific to probe frequency. This relationship was maintained for all measured gaps between the conditioner and the probe tones. However, when the probe frequency and CF were similar, CF tended to determine suppressed tuning. In addition, the bandwidth of suppression was slightly wider for off-CF probes. Changes in tuning were also reflected in the firing rate in response to probe tones, which was maximally reduced when probe and conditioner tones were matched in frequency. These data are consistent with the idea that cortical neurons receive convergent inputs with a wide range of tuning properties that can adapt independently.

© 2015 Royal Meteorological Society. We compared the capacity of woody versus grassy vegetation covers to buffer high temperatures during heat waves by partitioning turbulent heat between latent (λE) and sensible (H) fluxes, and quantifying advection using the Priestley-Taylor coefficient (α), for a16-year old grassland and an adjoining 6-year old plantation. We found that because λE dominated (>65%) the turbulent flux in the plantation and was at least twice as large as on the grassland (λE< 35% of the turbulent flux) during heat waves, the ambient temperature over the plantation was up to 5 °C lower in the afternoon, and averaged 1.2 °C lower for the whole day, compared with the grassland. Both vegetation covers emitted significant amounts of H when soil water availability was limited and also in winter when canopy cover was mostly inactive because of dormancy in the grassland and mutual shading in the plantation due to low solar angle. During the winter, advection of additional energy from surrounding vegetation suppressed λE and reduced α to 35°). Annual evapotranspiration was 54% lower from the grassland (384 mm) than from the plantation (834 mm). Woody vegetation covers dominated by broadleaved species are therefore preferred for buffering extreme high temperatures during heat waves and recommended for rehabilitating degraded landscapes in urban areas. We also present functions for approximating α for soil water limited conditions.

Revegetation to restore hydrological function to highly disturbed landscapes used for waste disposal or mining is often constrained by the initial low rates of water-use during the early phases of the developing vegetation. This problem is especially pronounced for revegetation that relies on trees due to their prolonged lead-time to achieve canopy closure. Initial low rates of water-use can however be overcome if a groundcover of quick-growing herbaceous species is planted first. To demonstrate the significance of groundcover in the early phase of revegetation, we undertook an energy balance analysis using the Bowen ratio technique for a juvenile plantation growing over a heavy groundcover of herbaceous species on a waste disposal site in 2006/2007 and 2007/2008. Latent heat flux (λE) from the landscape (trees plus groundcover and soil) fluctuated widely between 0.5 and 22MJm-2d-1 and accounted for between 60% and 90% of available energy at the site; this percentage exceeded 100% during periods with significant advection. The latent heat emanating from the tree canopy (λEc), derived from sapflow measurements in the trees, accounted for only between 4% and 18% of daily λE with the balance arising from the groundcover that intercepted more than 90% of incident solar radiation. The λEc was mostly smaller than the net radiation intercepted by the tree canopy (Rnc) with the excess energy expended by the canopy as sensible heat (Hc), which accounted for up to 18% of bulk sensible heat from the landscape. The λE expressed as ET was in excess (114%) of rainfall in the relatively dry first growing (September-May) season, when rainfall was only 87% of the long-term average. It was, however, smaller (80%) than rainfall during the second season, when the annual rainfall was close to the long-term average. We used these data to develop an empirical model for predicting λE from soil-water content and the prevailing evaporative demand. © 2010.

Revegetation is critical to restoring hydrological function on waste disposal sites in order to minimize runoff and drainage and safeguard the water quality of the catchment. In this study, we determined the components of soil-water balance between late 2006 and the end of 2008 for three vegetation types established over sites used for waste disposal: (i) a juvenile plantation of mixed Australian woody species; (ii) a block of mixed tree seedlings; (iii) and an ungrazed grass pasture. These were compared against a nearby natural woodland taken as an analogue of a pre-existing hydrological state. Evapotranspiration (ET) was the major component of the soil-water balance in all the four vegetation types. In the plantation and woodland, ET accounted for 60-93% of the annual rainfall compared to 44-88% in the grass and seedling blocks. While the balance of rainfall was largely lost to runoff in the plantation and the woodland, it was split almost equally between runoff and drainage in the other two vegetation covers. The plantation maintained parity in its ET with woodland due to groundcover that contributed at least 70% of the water use, while seasonal growth and periodic mowing reduced ET from the grass. Over the 2 years, the height of the deep (?19 m above sea level) water table under the plantation and grass declined by an average of 0?3 m, while it rose by a similar magnitude in the woodland. The height of the shallow water table (?8 m above sea level) showed no consistent change. We conclude that, with a good groundcover of mixed herbaceous species, a juvenile plantation can restore hydrological function and minimize deep recharge of a waste disposal site to the status of that under a pre-existing undisturbed woodland. Copyright © 2010 John Wiley & Sons, Ltd.

The year under review has been abbreviated by my illness, and I would like to use this moment to extend my sincere thanks to all of you for your support and special wishes during this very difficult time. A highlight of my illness was the tremendous number of get well wishes and deep concern shown by all my colleagues. The wonders of modem communication have meant that I have been able to keep in touch with members and Councillors throughout the summer. It has also been possible to spend some time reviewing the documents pertaining to agricultural policy in South Africa. In this report I will focus on the efforts to keep the society functioning during 1998 and follow this with a detailed response to the challenges posed by the new national policy.During 1998 we completed the questionnaire survey, analysed the responses and provided a summary in the bulletin (Vol. 8(2)). It was very pleasing to see such a positive response from members, with some 132 questionnaires (28%) being returned. The results reflect a positive image of the society, with the journal, bulletin and annual congress continuing to be viewed as successful projects. There are some problems with the publication of the journal, but Council hopes to have our volume numbers back on track shortly. There was a request for more information on the Policy Response Protocol of the GSSA, and I will ensure that this is published in the next bulletin. In this protocol we hope to inspire members to take responsibility for responding to the opportunities provided by legislators for public comment on proposed legislation. The Strategic Plan for the GSSA has also been Televised in the year under review, with some amendments being made to the earlier drafts.In the spirit embodied by the Policy Response Protocol, I would now like to review the proposed Agricultural Policy document, and respond appropriately to those issues dealing with rangeland science which are raised, highlighting the opportunities which the policy provides to GSSA members.On the subject of research funding, the ministry has made it quite clear that there will be changes in the way agriculturaI research is funded. In SA this will occur in a number of ways. The first is that all agencies funded through DACST will be reviewed periodically and are encouraged to become increasingly accountable to clients. A policy is already in place for encouraging competition between the science councils by insisting that contracts over R1 mil should be awarded on tender. This places a great deal of responsibility on the Department of Agriculture for clearly defining its research needs. A possible mechanism for defining these needs was suggested in the formation of VELDSTOCK, but more progress must be made on increasing the credibility of VELDSTOCK. Secondly, research institutes are encouraged to explore the private sector for research funds. I believe this is generally acceptable if some incentives are provided to these private sector agencies for funding research. I am unaware of any incentives for commercial farmers to devote profits to research. In the field of rangeland science we can offer to marginally increase production by improving the use of rangeland. However, once an increase in production has been achieved by optimising use of the resource, there is no incentive to continue as the production in natural rangeland is directly related to precipitation and that we all know is finite.Of particular concern to rangeland science are the funds for long-term ecological research in the extremely variable climatic environment in which we live. In the policy document we are encouraged to explore alternative sources of funding e.g. trusts and endowments, for funding our research efforts, and I encourage you to develop the networks necessary to access these funds. Another change which is high-lighted in the document is a shift towards providing more funding to academic institutions with agriculture faculties. The policy document notes that tertiary education only accounts for 4% of research funding and suggests that more support be given to researchers at these institutions. This is an encouraging sign for those members of the society who are based at tertiary institutions. Members currently working for DACST-funded councils should be improving their links with the universities, and developing joint projects. The policy document justifies this shift in focus by saying that the universities have greater access to social scientists. It is clear that there is a greater need for contact between rangeland and social scientists, and this can be achieved by employing social scientists in the planning and execution of projects. The ARC-RFI and the CSIR Environmentek have both encouraged this direction by employing social scientists within their ranks to improve our understanding of management issues in communal rangeland. The GSSA has encouraged this further by welcoming social scientists into the society.Research priorities The former homelands occupy only 13% of the agricultural land, yet they contain some 30% of the national herd. The policy document suggests that a better understanding of these fanning systems should be developed. Projects to do this are well advanced in the ARC institutes and at universities, making use of social science expertise. Reassuringly, the document states that "rangeland management is also an important research component". One of the major problems in mobilizing the enormous production potential of the livestock in these traditional systems is the opportunities for marketing of animals, and the often un-realistic value (in monetary terms) placed on inferior condition livestock. The policy document addresses the problem by offering to improve effectiveness of support services (animal health, animal nutrition and marketing) to the producer. This offer needs to be taken seriously, and provides research opportunities in the field of animal nutrition. The marketing of livestock in poor condition in an already depressed red meat industry, requires some special skills and financial support. Numerous efforts have been undertaken in the fonner homelands. including the formation of livestock marketing boards and their associated feedlots. None of these initiatives can be regarded as successful in mobilising the economic potential of 4 million beef cattle. The reason may be a lack of confidence in "filthy lucre" and its associated growth instruments (money market. equities and unit trusts). The recent volatility in financial markets has further discouraged farmers from divesting in cattle and putting their assets into cash. It is clear that the intentions of the policy document are noble, but much more is required to be research if the interventions are to be successful. You may already be aware that the BP Agricultural scholarship has been awarded to a member of the GSSA, Andrew Ainslie, who will co-ordinate a survey of large stock numbers in the former Transkei and Ciskei.The degradation debateMuch has been written and said about the degradation of rangeland due to over-grazing, and the debate continues. The society has been actively involved in encouraging debate in the past year, and in promoting dialogue between scientists with diverging points of view. In the policy document there remains uncertainty about the nature of rangeland degradation and its impact on productivity and the other natural resources of the regions concerned. The document acknowledges that the soil erosion rates in the fonner homelands are some 5 times greater than those of the "commercial sector", yet goes on to state that the "degradation of the natural resources occurs..... irrespective of the sector or form of land tenure". Once again, research opportunities abound, and we are encouraged to assist in the assessment of degradation and to promote options for 4S the rehabilitation of degraded land. Research by aquatic scientists both here and in the US has shown that water quality is influenced negatively by the any significant surface disturbance in a catchment. In order to combat one of the obvious effects of rangeland degradation, namely a deterioration in water quality, we should be encouraging all initiatives which inculcate an ethic of stewardship over every hectare of land in South Africa. This stewardship, which could be incorporated into the Landcare Programme, should encourage individuals to take responsibility for all land which has been disturbed. including village roads, ploughed lands or over-grazed rangeland. Recent work in the Eastern Cape shows that erosion is worst in old arable lands (established circa 1935) which have not subsequently been managed. The individual who first breaks the surface to establish new lands should be encouraged to take responsibility for maintaining erosion control structures.In the policy the government has assumed the "polluter pays" principle, which means that the originator of degradation should be required to rehabilitate the land. In the case of rangeland the current user is seldom the originator of the problem, and responsibility should now lie with the state to fund the rehabilitation of these rangelands. Numerous examples of these degraded situations have been identified, and efforts to rehabilitate using state intervention are strongly encouraged and applauded in areas such as the southern Kalahari and Northern Province. Because of the vast area of degraded land, these programmes are likely to be expensive and carry ample opportunity to conduct research into rehabilitation techniques and to monitor progress. All current programmes to rehabilitate degraded land contain budgets for the monitoring of progress, both in terms of improvements to human living standards and environmental condition. It is essential that members become aware of these initiatives and associate themselves with the projects, providing expertise both in project management and in their various rangeland disciplines. It is clear that the pool of expertise that we represent should be used in project management if the development objectives of the government are to be achieved. One of the primary goals of the new policy is household food security, with special emphasis on female-headed households. I am sure we all agree that this is a noble ideal and I encourage you to plan new project proposals with the themes of poverty, women and the environment as key elements.GeneralThe policy document attempts to address the funding of uncertain events e.g. drought. This is a daunting challenge in a country which has not experienced a serious drought since the legitimate government came to power. There will be great pressure to intervene when the country faces the ravages of drought, and the members of the society should be available to assist in providing concrete evidence for the success or lack thereof of historical interventions. The document acknowledges that drought has a serious knock-on effect in allied industries, and the nett result of droughts are often more dramatic than simply a reduction in nett primary production.Is there any evidence of a response to these policies in the activities of the GSSA? The period of less than 5 years is extremely short, but I believe that the society has made a special effort to transform its membership by encouraging membership from young rangeland scientists. These young scientists are the back-bone of any society and their needs and aspirations must be met by the services offered by the society. Contact between individuals and organizations with contrasting viewpoints has been encouraged and the editorial policy of the bulletin and the journal has encouraged the publication of diverse points of view.I would like to take this opportunity to thank all those who have supported me during the past year, especially the administrator, councillors and editors.African Journal of Range and Forage Science 16(1): 44–46

Reports on a study conducted to identify and classify the vegetation of the mid-Fish River valley into floristically homogeneous units, using a direct gradient analysis. Also identifies the shifts in the vegetation in response to different land-use treatments. Illustrates with tables, a map and graphsKeywords: Commercial rangelands; Communal rangelands; Direct gradient analyses; Eastern Cape; Fish River Valley; Grazing gradients; Structural analyses; Thicket Biome; TWINSPAN; Valley Bushveld; Vegetation degradationAfrican Journal of Range & Forage Science, Vol. 14, Iss 2, p. 68–74

Reports the results of a study conducted in which satellite-derived vegetation indices were used to identify a geochemical mound of higher active greenness in the Karoo National Park, Beaufort West. Illustrate a potential role for satellite imagery in developing management systems for arid shrublands, and highlights the importance of considering abiotic factors in the assessment of rangeland conditions. Illustrates with a mono-chromatic aerial photograph, a satellite image, tables and graphsKeywords Assimilation rates; Beaufort West; Eriocephalus ericoides Druce; Geochemical mounds; Karoo National Park; NDVIs; Normalized difference vegetation indices; Nutrients; Plant cover; Plants; Remote sensing; Rhigozum obovatum Burch; Satellite-derived vegetation indices; Woody species; patchiness; semi-arid; dwarf shrubland; shrublands; co2; assimilation; karoo; south africa; ndvi; satellite imagery; geochemical mound; rhigozum obovatum; eriocephalus ericoides; pentzia incana; vegetation; botanyAfrican Journal of Range & Forage Science, Vol. 14, Iss 3, p.75–80

A renewed interest in mixed cropping for its potential to boost yields through increased capture and use of solar radiation and soil-water by the component species. This led to the present study, in which we assessed the performance of wheat and chickpea, grown as sole crops or mixed at half their sole crop populations for their capacity to capture and use solar radiation and soil-water. Trials were conducted in the drought season of 1994 and with or without supplementary irrigation in an average rainfall season of 1995. For the rainfed crops in both years, there was no advantage of mixed crops over wheat grown as a sole crop (wheat-s) either in terms of green area index (GAI), fraction of photosynthetically active radiation intercepted by the canopy (iPAR), dry matter (DM) or grain yield produced. The lack of a yield advantage of mixed cropping was associated with poor canopy development and low yielding capacity of chickpea; it was unable to compensate for its reduced population density in the mixture. Grain yield for chickpea in the mixed crop (chickpea-m) averaged just 29% that of its sole crop (chickpea-s), whereas wheat grown in mixture (wheat-m) produced 72% the yield for wheat-s. Supplementary irrigation from early spring onwards in 1995 increased yield for chickpea-m by 44% over that of chickpea-s, while yield for wheat-m fell to 65% that for wheat-s. Every millimetre of irrigation water increased yield by 10.0, 3.8 and 12.5 kg ha-1 for wheat-s, mixed crop and chickpea-s, respectively. Mixed cropping did not affect the time taken by either wheat or chickpea to attain maximum growth rate, flowering or maturity. The land equivalent ratio (LER) based on grain yields for wheat-chickpea intercropping were 1.01 in 1994, 1.02 without irrigation in 1995, and 1.10 with irrigation in 1995. Neither radiation-use-efficiency nor water-use-efficiency was improved by mixed cropping compared with wheat-s. The poor performance of the mixed crop was ascribed to its poor canopy development early in the season, especially by the chickpea that resulted in low iPAR and transpiration. It is concluded that there was no advantage of growing wheat and chickpea in mixed crops in southern cereal belts of Australia if total biomass or grain yield is the primary purpose. © 2006 Elsevier B.V. All rights reserved.

Available from: Van Schaik, Pretoria, South Africa ISBN 0 627 02471 8709pp, hard coverAfrican Journal of Range & Forage Science 2003, 20(3): 275

Effects of sound level on auditory cortical activation are seen in neuroimaging data. However, factors such as the cortical response to the intense ambient scanner noise and to the bandwidth of the acoustic stimuli will both confound precise quantification and interpretation of such sound-level effects. The present study used temporally "sparse" imaging to reduce effects of scanner noise. To achieve control for stimulus bandwidth, three schemes were compared for sound-level matching across bandwidth: component level, root-mean-square power and loudness. The calculation of the loudness match was based on the model reported by Moore and Glasberg [Acta Acust. 82, 335–345 (1996)]. Ten normally hearing volunteers were scanned using functional magnetic resonance imaging (fMRI) while listening to a 300-Hz tone presented at six different sound levels between 66 and 91 dB SPL and a harmonic-complex tone (F0 = 186 Hz) presented at 65 and 85 dB SPL. This range of sound levels encompassed all three bases of sound-level matching. Activation in the superior temporal gyrus, induced by each of the eight tone conditions relative to a quiet baseline condition, was quantified as to extent and magnitude. Sound level had a small, but significant, effect on the extent of activation for the pure tone, but not for the harmonic-complex tone, while it had a significant effect on the response magnitude for both types of stimulus. Response magnitude increased linearly as a function of sound level for the full range of levels for the pure tone.

A discrepancy exists between the dynamic range of peripheral auditory neurones and the range over which the human ear maintains fine intensity discrimination. Psychophysical experiments, using simultaneous high and low pass (bandstop) masking noise, indicate that intensity discrimination at high intensities under these specific conditions is unlikely to be mediated by a spread of activity to neurones innervating neighbouring regions of the basilar membrane.\ud A conclusion from these psychophysical data is that neurones coming from a limited region of the basilar membrane must, at least under bandstop noise masking conditions, be capable of signalling small intensity differences over a wide dynamic range. It is the validity of this conclusion which the experiments reported in this dissertation have sought to test.\ud A related but separate problem is the way in which the absolute intensity of a signal is represented in the activity of the cochlear nerve. The encoding of absolute intensity is therefore considered and briefly discussed in relation to the results of the present study.\ud Microelectrode recordings from the cochlear nerve and nucleus of the anaesthetised cat led to the following conclusions:\ud 1. The range of minimum thresholds of neurones in the cochlear nerve and nucleus of a single ear is limited, at any frequency, to 20-JO dB, which is consistent with the literature and probably excludes the possibility that a high threshold population of neurones had been previously overlooked.\ud 2. The dynamic range of some monotonio cochlear nucleus neurones measured after adaptation is wider than that measured under unadapted conditions. However, the dynamic ranges of cochlear nerve fibres and iii - all monotonic cochlear nucleus neurones, even allowing for the extension afforded by the adaptation process, are still insufficient to account for the wide dynamic range shown psychophysically. Non­monotonic cochlear nucleus neurones have dynamic ranges of up to 100 dB, which may reflect inhibitory input to such cells from fibres of differing characteristic frequency.\ud 3. Under conditions of bandstop noise masking, analogous to those used in the psychophysical studies, some two-thirds of the neurones in the dorsal cochlear nucleus (with characteristic frequencies from 0.7-29 kHz) have very wide dynamic ranges, some of which were up to 110 dB. In contrast, cochlear fibre dynamic ranges in response to tones are the same, whether or not the bandstop noise masker is present. The results of parametric studies of the responses of cochlear nucleus neurones are consistent with the suggestion that the wide dynamic range, under bandstop noise masking conditions, results from lateral inhibition induced by the masking noise.\ud 4. Under conditions of bandstop noise masking, intensity differences at high intensity levels are not encoded in the cochlear nerve by large differences in the mean discharge rate of single fibres, but could possibly be encoded by small differences in the mean discharge of a minority of fibres. A second possibility for the encoding of intensity differences, under these conditions, is the fine time structure of the cochlear fibre discharge.