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The Rangeland Journal Abstracts

The full text of the papers is available to members of The Australian Rangeland Society at http://www.publish.csiro.au/nid/202.htm

 These abstracts are from the latest issue of The Rangeland Journal.

 

The Rangeland Journal

Vol. 39 (2)

May, 2017

Frequent fires reduce the nutritional quality of Sorghum stipoideum seed, a keystone food resource for the Gouldian finch (Erythrura gouldiae)

Anna Weier A , Ian J. Radford B E , Alan Manson C , Lesley J. Durrans D and Michael J. Lawes A

A Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia.

B Department of Parks and Wildlife, PO Box 942, Lot 248 Ivanhoe Road, Kununurra, WA 6743, Australia.

C KwaZulu-Natal Department of Agriculture and Rural Development, Private Bag X9059, Pietermaritzburg, 3200, South Africa.

D PO Box 746, Hilton, KwaZulu-Natal, 3245, South Africa.

E Corresponding author. Email: Ian.Radford@DPaW.wa.gov.au

The Rangeland Journal 39(2) 105-112 https://doi.org/10.1071/RJ16124
Submitted: 28 November 2016  Accepted: 9 February 2017   Published: 14 March 2017

Abstract

Fire is a pervasive feature of the tropical savannas of northern Australia. Increasingly extensive and intensive fires have had an adverse effect on grass layer diversity. Reduced grass species diversity and abundance are important correlates of the decline of granivores in these tropical savannas. The Gouldian finch (Erythrura gouldiae), an endangered species that is endemic to northern Australia, is particularly vulnerable to changes to the grass layer as its diet comprises only grass seed, and it relies mostly on Sorghum stipoideum during the breeding season. Although this annual grass species is abundant at breeding sites, the finches do not always choose to breed at these sites, raising the possibility that seed quality may vary from year to year. This study examines the effect of fire (time since last fire; fire frequency) on soil fertility and seed nutritional quality. We hypothesise that recently burnt sites produce a flush of soil nutrients and Sorghum stipoideum seed at these sites is of higher nutritional quality. Furthermore, we posit that frequently burnt sites become depleted of soil nutrients and their seeds are of lower nutritional quality. There was a significant increase in inorganic nitrogen in soils following a fire, but no notable change in other soil nutrients. Contingent on this increase in soil inorganic nitrogen, seed nutrient levels, particularly essential proteins, were greater at sites that were recently, but infrequently burnt. Fires appear to affect soil nitrogen and in turn seed nutrition, providing a plausible explanation for why Gouldian finches choose recently, but infrequently burnt breeding sites.

Additional keywords: annual grass species, essential proteins, fire regime, seed nutrition, soil nitrogen, tropical savanna.

 

Impala, Aepyceros melampus: does browse quality influence their use of sites originally utilised as short-duration kraals in a southern African savanna?

Rangarirai Huruba A B E , Peter J. Mundy A , Allan Sebata A , Gianetta K. Purchase C and Duncan N. MacFadyen D

A Department of Forest Resources and Wildlife Management, National University of Science and Technology, PO Box AC 939, Ascot, Bulawayo, Zimbabwe.

B Debshan Ranch, PO Box 24, Shangani, Zimbabwe.

C PO Box 2633, Bulawayo, Zimbabwe.

D E Oppenheimer and Son (Pty) Limited, 6 St Andrew’s Road, Parktown 2193, South Africa.

E Corresponding author. Email: rhuruba@gmail.com

The Rangeland Journal 39(2) 113-121 https://doi.org/10.1071/RJ16016
Submitted: 25 September 2015  Accepted: 5 January 2017   Published: 31 January 2017

Abstract

In eastern and southern Africa, some ranch owners are now keeping cattle overnight in temporary corrals (hereafter referred to as kraals) within rangelands for short durations to improve grass production. However, this has profound effects on the woody plant community. For instance, cattle break woody plant stems and strip them of foliage, initiating resprouting. The resprouts produced have high foliar nitrogen (N) and reduced condensed tannin (CT) concentrations, making them attractive to herbivores. The aim of this study was to determine the key nutrient-quality parameters of resprouts that make previously kraaled sites attractive to impala soon after cattle removal at Debshan Ranch in central Zimbabwe. We determined resprout length, foliar N, phosphorus (P), potassium, CT, fibre and rumen fermentation of three browse species, viz. Grewia monticola Sond., Terminalia sericea Burch. ex DC. and Dichrostachys cinerea (L.) Wight and Arn., and related them to impala use of previously kraaled sites. We used impala dung density to determine the use patterns of previously kraaled sites 2, 4, 12 and 24 weeks after cattle removal and compared them with the surrounding vegetation. Impala use of previously kraaled sites was highest 4 weeks after cattle removal and lowest in the surrounding vegetation. Resprout length increments were 6-fold over a 10-week growth period in all three woody species. Foliar N and P were generally higher, whereas CT was lower, in previously kraaled sites than the surrounding vegetation in all three of the plant browse species. Impala use of previously kraaled sites showed a strong negative relationship with foliar CT. We conclude that kraaling initiates strong resprout responses by woody plants soon after cattle removal, to produce resprouts of high nutrient quality, which attract herbivores such as impala.

Additional keywords: defoliation, disturbance, foraging, rangelands.

 

Plant species selection by sheep in semi-natural dry grasslands extensively grazed in the south-western Italian Alps

Marco Pittarello A B , Alessandra Gorlier A , Giampiero Lombardi A and Michele Lonati A

A Department of Agricultural, Forest and Food Sciences, University of Torino, Largo Braccini 2, Grugliasco, I 10095, Italy.

B Corresponding author. Email: marco.pittarello@unito.it

The Rangeland Journal 39(2) 123-131 https://doi.org/10.1071/RJ16068
Submitted: 19 July 2016  Accepted: 25 January 2017   Published: 16 February 2017

Abstract

Sheep can have an important role in the conservation of abandoned and shrub- and tree-encroached, semi-natural dry grasslands because their feeding behaviour is known to affect plant diversity and structure. Nevertheless, little information is available about feeding preferences of sheep at the sward-patch scale and about the effects of stocking density on their selectivity. Consequently, we investigated plant-species selection by sheep managed with a low-intensity grazing, examining the influence of stocking density and plant species abundance by means of vegetation surveys and animal GPS tracking. Sheep grazed a graminoid-dominated, semi-natural dry grassland (Festuco–Brometea) in Piedmont Region, north-west Italy. Plant species, classified into graminoids, suffruticose forbs, and herbaceous forbs, were selected with a different intensity by sheep, which preferred graminoids over suffruticose and herbaceous forbs. Plant species showing a high consumption ratio (CR), i.e. the level of selection of plant species (CR >10%), were mostly graminoids (e.g. Bromus erectus, Koeleria vallesiana and Stipa pennata). Furthermore, Carex species were also noticeably selected, in particular C. humilis, whereas spiny species and those with a rosette or prostrate forms were rarely grazed. The heterogeneity of stocking density over the pasture allowed testing of the relationships between stocking density and CR. For many species, the higher the stocking density, the higher was the CR, regardless of the abundance of dominant neighbouring species. Results suggest that sheep under low-intensity grazing conditions exert a specific plant-species selection in abandoned dry grasslands. By regulating the stocking density through the management of grazing sheep, it may be possible to condition the consumption of certain plant species, with medium–long-term effects on the botanical composition.

Additional keywords: extensive grazing management, Global Positioning System, grazing spatial patterns, intake value, plant functional group, selective foraging behavior.

 

Plateau pika disturbances alter plant productivity and soil nutrients in alpine meadows of the Qinghai-Tibetan Plateau, China

Xiao Pan Pang A and Zheng Gang Guo A B

A State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, P. R. China.

B Corresponding author. Email: guozhg@lzu.edu.cn

The Rangeland Journal 39(2) 133-144 https://doi.org/10.1071/RJ16093
Submitted: 13 September 2016  Accepted: 4 April 2017   Published: 28 April 2017

Abstract

Plateau pika (Ochotona curzoniae) is an endemic mammal in the Qinghai-Tibetan Plateau, and its activities create extensive disturbances on vegetation and soil of alpine meadow. Field surveys at two sites were conducted to determine the effects of plateau pika disturbances on important soil factors and plant biomass of vegetated land, and their relationships of the same alpine meadow type. Our study showed that plateau pika disturbances significantly increased soil organic carbon, soil total nitrogen, graminoid biomass and the number of plant species, and significantly decreased soil moisture and forb biomass, although they had no significant impacts on soil total phosphorus, soil total potassium and total biomass on vegetated land. Our study further showed that soil organic carbon, soil total nitrogen, graminoid biomass and the number of plant species were much higher at intermediate disturbance intensities than those at low and high disturbance intensities in the disturbed areas, and soil moisture showed a decreasing trend with the increase of disturbance intensity. Plateau pika disturbances altered the contribution of some important soil nutrients and moisture to plant biomass, and had different impact on the best models between plant biomass (total biomass, graminoid biomass and forb biomass) and predominant soil factors. Our results demonstrated that the optimal disturbance intensities of plateau pika were beneficial to alpine meadow. These results highlighted the influence of the presence of plateau pika and its disturbance intensity on key soil nutrients and plant productivity on vegetated land of the same alpine meadow type, which will help us better understand the role of plateau pika in the alpine meadow ecosystem.

Additional keywords: correlation relationship, plateau pika disturbance, plant productivity, soil moisture, soil nutrients.

 

Managing rain-filled wetlands for carbon sequestration: a synthesis

Susanne C. Watkins A E , Darren S. Baldwin B C , Helen P. Waudby C D and Sarah E. M. A. Ning A

A Murray Darling Wetlands Working Group Ltd, PO Box 7016, East Albury, NSW 2640, Australia.

B CSIRO Land and Water and Murray–Darling Freshwater Research Centre, La Trobe University, PO Box 821, Wodonga, Vic. 3689, Australia.

C Present address: Institute for Land, Water and Society, Charles Sturt University, Thurgoona, NSW 2640, Australia.

D Murray Local Land Services, PO Box 797, North Albury, NSW 2640, Australia.

E Corresponding author. Email: s.watkins7@bigpond.com

The Rangeland Journal 39(2) 145-152 https://doi.org/10.1071/RJ16077
Submitted: 8 August 2016  Accepted: 20 January 2017   Published: 23 February 2017

Abstract

Global acknowledgement of climate change and its predicted environmental consequences has created a need for practical management techniques that increase a landscape’s ability to capture and store atmospheric carbon (C). Globally, wetlands sequester disproportionally more C per unit surface area than many other components of the landscape. However, wetlands vary in their capacity to store C and regulate greenhouse gas emissions. Hydrology, in particular, is a critical driver of wetland C capture and storage. Rain-filled wetlands offer a challenge for the management of C sequestration and storage because the hydrology of these systems is almost entirely driven by rainfall. We present a conceptual model of how management options, including weed and pest control, grazing and crop management and revegetation, will affect C sequestration and storage in rain-filled wetlands. Given the intensive nature of agricultural activities in areas where rain-filled wetlands are common, further work is needed to increase our understanding of the effects of these activities on wetland C capture and storage. Key knowledge gaps relating to the effect of management actions on wetland C sequestration include: (a) the benefits of integrated wetland management; (b) the appropriateness of different grazing regimes and the effect of total grazing pressure; (c) the effects of fire; and (d) the extent to which wetland function (C storage) can be restored following agricultural activities, such as cropping.

Additional keywords: cropping, fire, grazing, pests, weeds, wetland rehabilitation.

 

Sensitivity of soil organic carbon to grazing management in the semi-arid rangelands of south-eastern Australia

S. E. Orgill A C , C. M. Waters B , G. Melville B , I. Toole B , Y. Alemseged B and W. Smith B

A New South Wales Department of Primary Industries, Pine Gully Road, Wagga Wagga, NSW 2650, Australia.

B New South Wales Department of Primary Industries, Pastures and Rangelands, PMB 19, Trangie, NSW 2823, Australia.

C Corresponding author. Email: susan.orgill@dpi.nsw.gov.au

The Rangeland Journal 39(2) 153-167 https://doi.org/10.1071/RJ16020
Submitted: 11 March 2016  Accepted: 19 December 2016   Published: 21 February 2017

Abstract

This study compared the effects of grazing management on soil organic carbon (OC) stocks in the semi-arid rangelands of New South Wales, Australia. A field survey was conducted at three locations (Brewarrina, Cobar–North and Cobar–South), with paired sites of long-term (>8 years) rotational grazing management and continuously grazed pastures (either set stocked or no stocking). At each location, soil OC, carbon (C) fractions, soil nitrogen (N) and microsite and site factors (including ground cover and woody vegetation) were measured. The control of total grazing pressure (TGP) through rotational grazing and exclusion fencing did not increase soil C stocks compared with continuous grazing for the majority of comparisons. However, in some parts of the landscape, higher soil C stock was found with TGP control, for example on the ridges (21.6 vs 13.3 t C ha–1 to 0.3 m). C stocks increased with litter and perennial ground cover and with close proximity to trees. At Brewarrina, C stocks were positively affected by perennial plant cover (P < 0.001) and litter (P < 0.05), whereas at Cobar–North and Cobar–South C stocks were positively affected by the presence of trees (P < 0.001), with higher C stocks in close proximity to trees, and with increasing litter cover (P  < 0.01). The present study demonstrates that natural resource benefits, such as increased perennial cover, can be achieved through controlling TGP in the rangelands but increases in soil C may be limited in certain parts of the landscape. These findings also highlight that interactions between managed and unmanaged TGP and microsite factors, such as ground cover and proximity to woody vegetation, need to be considered when evaluating the role of changed grazing management on soil C.

This study compared the effects of grazing management on soil organic carbon (OC) stocks in the semi-arid rangelands of New South Wales, Australia. A field survey was conducted at three locations (Brewarrina, Cobar–North and Cobar–South), with paired sites of long-term (>8 years) rotational grazing management and continuously grazed pastures (either set stocked or no stocking). At each location, soil OC, carbon (C) fractions, soil nitrogen (N) and microsite and site factors (including ground cover and woody vegetation) were measured. The control of total grazing pressure (TGP) through rotational grazing and exclusion fencing did not increase soil C stocks compared with continuous grazing for the majority of comparisons. However, in some parts of the landscape, higher soil C stock was found with TGP control, for example on the ridges (21.6 vs 13.3 t C ha–1 to 0.3 m). C stocks increased with litter and perennial ground cover and with close proximity to trees. At Brewarrina, C stocks were positively affected by perennial plant cover (P < 0.001) and litter (P < 0.05), whereas at Cobar–North and Cobar–South C stocks were positively affected by the presence of trees (P < 0.001), with higher C stocks in close proximity to trees, and with increasing litter cover (P  < 0.01). The present study demonstrates that natural resource benefits, such as increased perennial cover, can be achieved through controlling TGP in the rangelands but increases in soil C may be limited in certain parts of the landscape. These findings also highlight that interactions between managed and unmanaged TGP and microsite factors, such as ground cover and proximity to woody vegetation, need to be considered when evaluating the role of changed grazing management on soil C. This study compared the effects of grazing management on soil organic carbon (OC) stocks in the semi-arid rangelands of New South Wales, Australia. A field survey was conducted at three locations (Brewarrina, Cobar–North and Cobar–South), with paired sites of long-term (>8 years) rotational grazing management and continuously grazed pastures (either set stocked or no stocking). At each location, soil OC, carbon (C) fractions, soil nitrogen (N) and microsite and site factors (including ground cover and woody vegetation) were measured. The control of total grazing pressure (TGP) through rotational grazing and exclusion fencing did not increase soil C stocks compared with continuous grazing for the majority of comparisons. However, in some parts of the landscape, higher soil C stock was found with TGP control, for example on the ridges (21.6 vs 13.3 t C ha–1 to 0.3 m). C stocks increased with litter and perennial ground cover and with close proximity to trees. At Brewarrina, C stocks were positively affected by perennial plant cover (P < 0.001) and litter (P < 0.05), whereas at Cobar–North and Cobar–South C stocks were positively affected by the presence of trees (P < 0.001), with higher C stocks in close proximity to trees, and with increasing litter cover (P  < 0.01). The present study demonstrates that natural resource benefits, such as increased perennial cover, can be achieved through controlling TGP in the rangelands but increases in soil C may be limited in certain parts of the landscape. These findings also highlight that interactions between managed and unmanaged TGP and microsite factors, such as ground cover and proximity to woody vegetation, need to be considered when evaluating the role of changed grazing management on soil C.

Additional keywords: carbon sequestration, ground cover, nitrogen, particulate organic carbon, total grazing pressure.

 

Effects of grazing intensity on organic carbon stock characteristics in Stipa breviflora desert steppe vegetation soil systems

Heyun Wang A , Zhi Dong A B , Jianying Guo C D , Hongli Li A B D , Jinrong Li C , Guodong Han B and Xinchuang Chen A

A Forestry College of Shandong Agricultural University, Shandong Provincial Key Laboratory of Soil Erosion and Ecological Restoration, Taishan Mountain Forest Ecosystem Research Station, Tai’an 271018, PR China.

B College of Ecology and Environmental Science, Inner Mongolia Agricultural University, Hohhot 010019, PR China.

C State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, Institute of Water Resources for Pastoral Area, China Institute of Water Resources and Hydropower Research, Hohhot 010020, PR China.

D Corresponding authors. Emails: guojianying1980@163.com; lhl@sdau.edu.cn

The Rangeland Journal 39(2) 169-177 https://doi.org/10.1071/RJ16007
Submitted: 21 January 2016  Accepted: 15 February 2017   Published: 20 March 2017

Abstract

Grassland ecosystems, an important component of the terrestrial environment, play an essential role in the global carbon cycle and balance. We considered four different grazing intensities on a Stipa breviflora desert steppe: heavy grazing (HG), moderate grazing (MG), light grazing (LG), and an area fenced to exclude livestock grazing as the Control (CK). The analyses of the aboveground biomass, litter, belowground biomass, soil organic carbon and soil light fraction organic carbon were utilised to study the organic carbon stock characteristics in the S. breviflora desert steppe under different grazing intensities. This is important to reveal the mechanisms of grazing impact on carbon processes in the desert steppe, and can provide a theoretical basis for conservation and utilisation of grassland resources. Results showed that the carbon stock was 11.98–44.51 g m–2 in aboveground biomass, 10.43–36.12 g m–2 in plant litters, and 502.30–804.31 g m–2 in belowground biomass (0–40 cm). It was significantly higher in CK than in MG and HG. The carbon stock at 0–40-cm soil depth was 7817.43–9694.16 g m–2, and it was significantly higher in LG than in CK and HG. The total carbon stock in the vegetation-soil system was 8342.14–10494.80 g m–2 under different grazing intensities, with the largest value in LG, followed by MG, CK, and HG. About 90.54–93.71% of the total carbon in grassland ecosystem was reserved in soil. The LG and MG intensities were beneficial to the accumulation of soil organic carbon stock. The soil light fraction organic carbon stock was 484.20–654.62 g m–2 and was the highest under LG intensity. The LG and MG intensities were beneficial for soil nutrient accumulation in the desert steppe.

Additional keywords: biomass, degradation, grassland ecosystems, LFOC, plant community, SOC.

 

Pastureland transfer as a livelihood adaptation strategy for herdsmen: a case study of Xilingol, Inner Mongolia

Meiyan Zhang A B , Lizhong Zhang B E , Yaoqi Zhang C E , Yecheng Xu C and Jiquan Chen D

A Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, 010018, China.

B College of Economics and Management, Beijing Forestry University, Beijing, 100083, China.

C School of Forestry and Wildlife Sciences, Auburn University, AL 36849, USA.

D Centre for Global Change and Earth Observations, Department of Geography, Michigan State University, East Lansing, MI 48824, USA.

E Corresponding authors. Emails: zhangy3@auburn.edu; myz_2002@eyou.com

The Rangeland Journal 39(2) 179-187 https://doi.org/10.1071/RJ15121
Submitted: 12 December 2015  Accepted: 15 February 2017   Published: 27 March 2017

Abstract

The grassland is the most important resource for the herdsmen in Inner Mongolia, China. In the 1980s, pastureland was administratively allocated based on household size. The subsequent changes in socioeconomic and new household characteristics suggest that adjustment is needed for more efficient land use. This study reviewed the recent progress of the rental market and investigated the herdsmen’s behaviours regarding grassland market transactions in Xilingol League, Inner Mongolia. The economic assumption is that there exists a variation in values by household for each given parcel of land, which drives land transfer to users who can generate higher values. Each household is characterised by its initial pasture landholding, herding facilities and demographics. But the gain from the transfer must be deducted from the transaction costs, and cooperative membership can significantly reduce the transaction costs. An econometric model is developed and tested with data collected from household surveys in the Xilingol League. The results indicate that household size is the most significant variable for land transfer in the long run. Herdsmen have been dynamically adjusting herding equipment and pasture landholdings, allocating labour between herding and non-herding activities in response to these changes in society. Cooperative organisation was found to be significant in facilitating land transfer due to its role in reducing transaction costs. Higher quality land with higher rent is also found to be more likely to transfer since the percentage of the transaction cost is lower than lower quality land.

(No additional keywords)

 

Pastoralist adaptation practices under non-governmental development interventions in Southern Ethiopia

Chuan Liao A C and Ding Fei B

A University of Michigan, Natural Resources and Environment, Ann Arbor, Michigan 48109, USA.

B University of Minnesota Twin Cities, Geography, Environment, Minneapolis, MN 55455, USA.

C Corresponding author. Email: lchuan@umich.edu

The Rangeland Journal 39(2) 189-200 https://doi.org/10.1071/RJ16015
Submitted: 29 February 2016  Accepted: 10 March 2017   Published: 6 April 2017

Abstract

Non-governmental organisations (NGOs) have been playing important roles in facilitating pastoralist adaptation; however, focussed studies have yet to examine whether and how NGO interventions generate viable opportunities for adaptation and development in pastoral communities. This paper analyses how Boran pastoralists cope with various socio-environmental risks under NGO interventions in southern Ethiopia. We find that pastoralist adaptation practices under NGO development interventions enhanced diversification, communal pooling, storage, and market access, but compromised mobility. Changes in pastoralists’ pursuit of livelihoods facilitated alternative adaptation, but such changes risked exacerbating rangeland degradation, reinforcing dependence on external aid, and weakening indigenous institutions. We thus conclude by arguing for more conscious interventions that can mitigate risks without negatively influencing the wellbeing of human subjects and ecosystems.

Additional keywords: adaptation, Ethiopia, intervention, NGO, pastoralists.

 

Disturbance-dependent invasion of the woody weed, Calotropis procera, in Australian rangelands

Enock O. Menge A C , Sean M. Bellairs A and Michael J. Lawes B

A Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, NT 0909, Australia.

B Department of Geography, McGill University, 805 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada.

C Corresponding author. Email: Enockondeyo.Menge@cdu.edu.au

The Rangeland Journal 39(2) 201-211 https://doi.org/10.1071/RJ16120
Submitted: 9 November 2016  Accepted: 31 March 2017   Published: 26 April 2017

Abstract

Plant invasions are threats to biodiversity and ecosystem processes that have far reaching ecological and economic impacts. Understanding the mechanisms of invasion essentially helps in developing effective management strategies. Rubber bush (Calotropis procera) is an introduced milkweed that invades Australian beef production rangelands. Its establishment is often associated with disturbances caused by pastoral management practices. We examined whether or not rubber bush (1) outcompetes native grasses, (2) can invade intact rangeland, and (3) if disturbance facilitates rubber bush establishment and spread in grassy rangelands. We measured the competitive response of different densities of Mitchell grass (Astrebla pectinata) individuals and the competitive effects of associate rubber bush seedlings in an additive common garden experiment. Replicated field exclosure experiments, under grass-dominated and tropical savanna woodland conditions examined the effect of increasing levels of disturbance on rubber bush seedling emergence. The dominant native Mitchell grass was a stronger competitor than rubber bush when grown together under greenhouse conditions, whereby root and shoot biomass yields were more restricted in rubber bush compared with Mitchell grass. This finding was corroborated in the field exclosure experiments at both sites, where seedling emergence increased 5-fold in seeded and highly disturbed plots where superficial soils were turned over by treatments simulating heavy grazing and trampling by cattle or machinery. Emergence of rubber bush seedlings in seeded plots that were undisturbed, clipped and grazed was minimal and rubber bush seedlings did not survive the seedling stage in these plots. These results demonstrate that disturbance to the superficial soil stratum affects the ability of rubber bush seeds to successfully establish in a microsite, and high levels of soil disturbance substantially increase establishment. Thus, rubber bush is a poor competitor of Mitchell grass and does not invade intact grassland. Consequently, rubber bush invasion is disturbance-dependent in the vast Australian rangelands. The spread of this weed may be arrested by management practices that minimise disturbances to grass cover.

Additional keywords: barley Mitchell grass, competition, exclosure experiment, grazing, invasion dynamics, rangeland management, rubber bush.

 

A survey of swainsonine content in Swainsona species

Daniel Cook A C , Dale R. Gardner A , Kevin D. Welch A and Jeremy G. Allen B

A USDA/ARS Poisonous Plant Research Laboratory, 1150 East 1400 North, Logan, UT 84341, USA.

B DAFWA Diagnostic Laboratory Services, Department of Agriculture and Food, 3 Baron-Hay Court, South Perth, WA 6151, Australia.

C Corresponding author. Email: daniel.cook@ars.usda.gov

The Rangeland Journal 39(2) 213-218 https://doi.org/10.1071/RJ16088
Submitted: 27 August 2016  Accepted: 18 January 2017   Published: 25 February 2017

Abstract

The indolizidine alkaloid swainsonine is an inhibitor of α-mannosidase and mannosidase II that causes lysosomal storage disease and alters glycoprotein processing. Several plant species worldwide contain swainsonine, grazing these plants may cause severe toxicosis in livestock, leading to a chronic disease characterised by altered behaviour, depression, weight loss, decreased libido, infertility and death. Swainsona is a large genus of the Fabaceae family with all species but one being endemic to Australia. Swainsonine has previously been reported to be, or expected to be, present in 26 Swainsona species in Australia. Methods of detection in these 26 species were a jack bean α-mannosidase inhibition assay, gas chromatography, or gas or liquid chromatography coupled with mass spectrometry. Seven of these 26 Swainsona species are reported to be toxic, and for three of these no chemical assay for swainsonine has been undertaken. Only 1 of the 26 species has been analysed for swainsonine using modern instrumentation such as gas or liquid chromatography coupled with mass spectrometry. Using both liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry, 248 specimens representing 41 Swainsona species were screened in the present study for swainsonine. Swainsonine was detected in 9 of the 41 Swainsona species, eight of which had not been determined to contain swainsonine previously using modern instrumentation. The list of swainsonine-containing taxa reported here will serve as a reference for diagnostic purposes and risk assessment.

Additional keywords: herbarium specimens, poison pea.