Role of plant cover and stock trampling on runoff and soil-erosion from semi-arid wooded rangelands

Soil Research ◽  
1994 ◽  
Vol 32 (5) ◽  
pp. 953 ◽  
Author(s):  
RSB Greene ◽  
PIA Kinnell ◽  
JT Wood
Keyword(s):  
Plant Cover ◽  
Negative Relationship ◽  
Soil Surface ◽  
Sediment Concentration ◽  
Perennial Grasses ◽  
Stocking Rate ◽  
Eastern Australia ◽  
Local Water ◽  
Raindrop Energy ◽  
Semi Arid

Relationships between plant cover, runoff and erosion of a massive red earth were investigated for a runoff zone of an intergrove area in a semi-arid wooded rangeland in eastern Australia. The measurements were carried out in small experimental paddocks with different stocking rates of sheep and kangaroos. A trailer-mounted rainfall simulator was used to apply rainfall at a time averaged rate of 30 mm h-1 to obtain runoff rates and sediment concentrations. There was a significant negative relationship (r2 = 0.58; P < 0.01) between final runoff rate and plant cover. It is probable that the plants increase infiltration and decrease runoff by (i) funnelling water down their stems and (ii) providing macropores at the base of the plant through which water can rapidly enter the soil. However, there was no significant effect of plant cover on sediment concentration. Probable reasons for this are: (i) even though plant cover will absorb raindrop energy and decrease the erosive stress on the soil, the nature of the plants investigated is such that they may not be 100% effective in protecting the soil beneath them, and (ii) the distribution of contact cover provided by the base of the plants is highly patchy and thus relatively inefficient at reducing sediment concentration. At zero cover final runoff rates from paddocks with a high and low stocking rate were similar, i.e. 23.4 and 22.3 mm h-1 respectively. However, at zero cover, the sediment concentration from the high stocking rate paddock was significantly (P < 0.01) greater than that from the low stocking rate paddock. Greater hoof activity and lower organic matter (and hence lower structural stability) of the 0.20 mm layer in the high stocking rate paddock caused the soil surface to be more susceptible to erosion. These results show that grazing by removing perennial grasses and pulverizing the surface soil can have a major impact on local water balances and erosion rates respectively within the intergrove areas. The implications of these results for the long-term stability of semi-arid mulga woodlands is briefly discussed.

The Influence of Recent Grazing Pressure and Landscape Position on Grass Recruitment in a Semi-Arid Woodland of Eastern Australia.

1996 ◽  
Vol 18 (1) ◽  
pp. 3 ◽  
Author(s):  
VJ Anderson ◽  
KC Hodgkinson ◽  
AC Grice
Keyword(s):  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Run Off ◽  
Eastern Australia ◽  
Annual Grasses ◽  
History Of ◽  
Semi Arid

This study examined the effects of previous grazing pressure, position in the landscape and apparent seed trapping capability of soil surface micro-sites on recruitment of the perennial grass Monachather paradoxa (mulga oats) in a semi-arid woodland. Seedling emergence was counted on small plots which had been kept moist for one month. The plots were on bare ground, or at grass tussocks, or at log mounds, sited in the run-off, interception and run-on zones of paddocks that had been grazed for six years at 0.3 and 0.8 sheep equivalent/ha. Few naturally occurring perennial grass seedlings emerged on any of the sites. The level of previous grazing pressure influenced the recruitment of grasses from natural sources as well as from seed of M. paradoxa broadcast on the soil surface; significantly more grass seedlings recruited in paddocks stocked at 0.3 than at 0.8 sheep/ha. Emergence of the sown grass did not differ significantly between the three zones in the landscape, but trends in the data suggest the interception zone may have been the most favourable. Recruitment from in situ grass seed was highest in the mulga grove (run-on) zone. Most seedlings of the sown grass emerged around the bases of existing perennial grass tussocks, but recruitment of volunteer perennial and annual grasses was more evenly distributed between the mulga log-mounds and perennial grass tussocks. It is concluded that very low levels of readily germinable seed of perennial grasses remained in the soil at the end of the drought and that areas with a history of high grazing pressure have less probability of grass recruitment when suitable rain occurs.

Managing competitive interactions to promote regeneration of native perennial grasses in semi-arid south-eastern Australia

2017 ◽  
Vol 39 (1) ◽  
pp. 59
Author(s):  
Ronald B. Hacker ◽  
Ian D. Toole ◽  
Gavin J. Melville ◽  
Yohannes Alemseged ◽  
Warren J. Smith
Keyword(s):  
Weed Control ◽  
Biomass Production ◽  
Soil Nitrogen ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Soil Nitrate ◽  
Nitrogen Reduction ◽  
Eastern Australia ◽  
Semi Arid ◽  
Native Perennial Grass

Treatments to reduce available soil nitrogen and achieve specified levels of weed control were evaluated for their capacity to promote regeneration of native perennial grasses in a degraded semi-arid woodland in central-western New South Wales. Treatments were factorial combinations of nitrogen-reduction levels and weed-control levels. The four levels of nitrogen reduction were no intervention, and oversowing of an unfertilised summer crop, an unfertilised winter crop or an unfertilised perennial grass. The three weed-control levels were defined by the outcome sought rather than the chemical applied and were nil, control of annual legumes and control of all annual species (AA). Regeneration of perennial grasses, predominantly Enteropogon acicularis, was promoted most rapidly by the AA level of weed control with no introduction of sown species. Sown species negated the benefits of weed control and limited but did not prevent the regeneration of native perennials. Sown species also contributed substantially to biomass production, which was otherwise severely limited under the AA level of weed control, and they were effective in reducing soil nitrogen availability. Sown species in combination with appropriate herbicide use can therefore maintain or increase available forage in the short–medium term, permit a low rate of native perennial grass recruitment, and condition the system (by reducing soil mineral nitrogen) for more rapid regeneration of native perennials should annual sowings be discontinued or a sown grass fail to persist. Soil nitrate was reduced roughly in proportion to biomass production. High levels of soil nitrate did not inhibit native perennial grass regeneration when biomass was suppressed by AA weed control, and may be beneficial for pastoral production, but could also render sites more susceptible to future invasion of exotic annuals. The need for astute grazing management of the restored grassland is thus emphasised. This study was conducted on a site that supported a remnant population of perennial grasses. Use of the nitrogen-reduction techniques described may not be appropriate on sites where very few perennial grass plants remain.

Changes in Grass Density in Australian Semi-Arid Woodlands.

1995 ◽  
Vol 17 (1) ◽  
pp. 26 ◽  
Author(s):  
AC Grice ◽  
I Barchia
Keyword(s):  
Perennial Grass ◽  
Perennial Grasses ◽  
Grass Species ◽  
European Settlement ◽  
Eastern Australia ◽  
Rate Of Response ◽  
Semi Arid

Changed grazing regimes since European settlement have been widely proposed as the cause of a decline of indigenous perennial grasses in the semi-arid woodlands of eastern Australia. A five year experiment using exclosures examined the effects of grazing on densities of perennial grasses. Short- lived Stipa spp. and Aristida spp. were dominant at most sites. Their densities fluctuated greatly with season and reached over 200 plants/m2 during climatically favourable periods. The long-lived Eragrostis eriopoda occurred at densities that were generally less than 5 plants/m2 and its populations were relatively stable. The response of Enneapogon avenaceus was distinctive. Though its density fluctuated considerably, successive peaks in density were higher and the species increased more in ungrazed areas than in destocked or unfenced areas. The differences between grazed and ungrazed populations became greater with successive peaks in density. Within the short periods that pastoralists are likely to be willing or able to apply such treatments, destocking or even removing all herbivores is unlikely to have a large effect on the density of many palatable perennial grass species. The rate of response to resting pastures will depend on seasonal conditions.

An Evaluation of Cover Type as a Predictor of Soil Surface Roughness in a Semi-Arid Grassland.

1991 ◽  
Vol 13 (1) ◽  
pp. 61 ◽  
Author(s):  
DJ Eldridge
Keyword(s):  
Surface Roughness ◽  
Storage Capacity ◽  
Water Storage ◽  
Soil Surface ◽  
Perennial Grasses ◽  
Biologically Active ◽  
Water Storage Capacity ◽  
Cover Type ◽  
Soil Surface Roughness ◽  
Semi Arid

Sites dominated by perennial grasses were significantly rougher than sites dominated by ephemerals and the the character of the surface cover did not explain the variation in surface roughness at most sites. Rougher sites dominated by grasses have a greater water storage capacity, enhanced and are probably more biologically active than sites dominated by ephemerals.

Effects of nitrogen and phosphorus on vegetation dynamics of a degraded native grassland in semi-arid south-eastern Australia

2011 ◽  
Vol 33 (1) ◽  
pp. 87 ◽  
Author(s):  
R. B. Hacker ◽  
I. D. Toole ◽  
G. J. Melville
Keyword(s):  
Vegetation Dynamics ◽  
Plant Density ◽  
Perennial Grass ◽  
Ground Cover ◽  
Perennial Grasses ◽  
Grass Species ◽  
Nitrogen And Phosphorus ◽  
Mineral N ◽  
Eastern Australia ◽  
Semi Arid

The roles of nitrogen (N) and phosphorus (P) in controlling vegetation transitions in a degraded semi-arid grassland were investigated in a factorial experiment that combined two initial levels of perennial plant density (low and high), three levels of N (N+, N0 and N–) and two levels of P (P+ and P0). Increased levels of both N and P were achieved by fertiliser addition while sucrose was used to reduce the level of N. Vegetation dynamics were driven primarily by soil N rather than P. Addition of sucrose, which was inferred to result in the immobilisation of mineral N, reduced the growth of annual species and facilitated the establishment and growth of native perennial grasses. Addition of P generally had no significant effect on dry matter production, either in total or for species grouped as forbs, annual grasses and perennial grasses, or on recruitment and mortality of perennial grasses. However, at some times of observation addition of P increased ground cover and/or the basal circumference of some perennial grass species. Basal circumference for Enteropogon acicularis was also increased by addition of N. Soil biological activity, measured by decomposition of cotton strips, was increased by addition of N, which maintained vegetation in an annual-dominated condition, and was not affected by addition of P. Carbon addition has the potential to assist restoration of this grassland. However, the capacity of some native grass species to respond to increased fertility suggests that once restoration is achieved some increase in fertility may be beneficial for pastoral production.

Run-Off and Sediment Yield From a Semi-Arid Woodland in Eastern Australia. Ii. Variation in Some Soil Hydrological Properties Along a Gradient in Soil Surface Condition.

1993 ◽  
Vol 15 (2) ◽  
pp. 234 ◽  
Author(s):  
DJ Eldridge ◽  
TB Koen
Keyword(s):  
Vegetation Cover ◽  
Surface Condition ◽  
Soil Surface ◽  
Perennial Grasses ◽  
Sediment Removal ◽  
South Wales ◽  
Run Off ◽  
Physico Chemical ◽  
Eastern Australia ◽  
Red Earth

Three sites on red earth soils were examined at Yathong Nature Reserve and 'Coan Downs' in central- western New South Wales. The sites represented a gradient in soil surface condition from a stable, uneroded and productive site, supporting moderately dense perennial grasses (site 1) to a moderately unstable and degraded site with few perennials and evidence of erosion (site 3). The hydrological characteristics of the three sites were measured using a rainfall simulator on plots with varying vegetation cover. Water ponded earlier at the degraded site, and run-off and sediment removal increased as the soil surface became more degraded. Associated with this was an increase in the importance of vegetation cover, and a decrease in the importance of soil physico-chemical variables as descriptors of soil hydrological properties. The results are consistent with the notion that vegetation plays a more important role in maintaining soil hydrological processes as the soil surface becomes more degraded.

The Effects of Perennial Grasses, Stocking Rate and Rainfall on Sheep Production in a Semi-Arid Woodland of Eastern Australia.

1999 ◽  
Vol 21 (2) ◽  
pp. 199 ◽  
Author(s):  
D Freudenberger ◽  
A Wilson ◽  
R Palmer
Keyword(s):  
Weight Gain ◽  
Live Weight ◽  
Perennial Grasses ◽  
Green Leaf ◽  
Stocking Rate ◽  
Live Weight Gain ◽  
Wool Growth ◽  
Sheep Production ◽  
Stocking Rates ◽  
Semi Arid

A grazing study was conducted in a semi-arid mulga (Acacia aneura) woodland to determine the relative importance of variables controlling sheep production in this environment. The study was based on six sheep stocking rates (0.3-0.8 sheeplha) with the exclusion of other large herbivores including kangaroos and feral goats. The availability of forage and its components, together with the wool growth and live weight of the sheep were measured every three months for seven years from October 1986. Annual rainfall accounted for 60% of the annual variation in live weight gain per head and 79% of the variation in wool growth per head. Stocking rate accounted for an additional 10% of the variation. Rainfall accounted for this large proportion of variation by its strong influence on the yield of green leaf which accounted for 78% of the variation in live weight gain and 66% of the variation in wool growth. Green leaf was a determinant of sheep production because of its superior crude protein content and digestibility compared to dry leaf and stem. The species comprising this green leaf had an influence on sheep production only during drier years when the presence of palatable perennial grasses became important to sheep production. The frequency and yield of perennial grasses were greatly diminished at high stocking rates. This change in forage composition caused a decline in sheep productivity as detected by a loss of linearity in the relationship between stocking rate and live weight gainlhead. We conclude that adjusting stocking rates is required in this environment for maintenance of long-term sheep productivity and landscape function. The loss of palatable perennial C, grasses over much of the region has reduced livestock productivity and increased the variability in forage availability. Stock numbers should be adjusted at critical times to avoid losing perennial grasses that are important for sheep production in drier years. New grazing strategies are required to restore these grasses to the region.

The effects of fire on the soil in a degraded semiarid woodland .II. Susceptibility of the soil to erosion by shallow rain impacted flow

Soil Research ◽  
1990 ◽  
Vol 28 (5) ◽  
pp. 779 ◽  
Author(s):  
PIA Kinnell ◽  
CJ Chartres ◽  
CL Watson
Keyword(s):  
Soil Surface ◽  
Sediment Concentration ◽  
Fire Frequency ◽  
Uniform Size ◽  
Degree Of Protection ◽  
Material Surfaces ◽  
High Degree ◽  
Semi Arid ◽  
Experimental Plots ◽  
Cryptogamic Crusts

Small (500 by 250 by 100 mm) soil monoliths collected from experimental plots subjected to various fire frequencies in a semi-arid woodland near Coolabah, N.S.W., were tested for their susceptibility to erosion by rain-impacted flows under laboratory conditions. In the tests, the erosive stress applied to the soil surfaces was controlled by using drops of uniform size (2.7 mm) falling 11.2 m onto flows whose depths were controlled between 1 and 2.7 drop diameters. Experimental data and thin-section observations showed that cryptogams provide a high degree of protection against erosion. Sediment concentration (measured in g L-1) from cryptogam-covered plots was considerably less than that from both bare-crusted surfaces and surfaces dominated by depositional material. Surfaces with cryptogamic crusts were generally free of debris, but showed only minor signs of erosion, whereas bare-crusted and depositionary surfaces suffered pronounced lowering and tended to disintegrate. Because increasing fire frequency reduces the spatial distribution of the cryptogamic cover on the soil surface in the semi-arid woodlands, increasing fire frequency must increase the erosion hazard.

Seedling recruitment of native perennial grasses within existing swards

2011 ◽  
Vol 62 (7) ◽  
pp. 591 ◽  
Author(s):  
R. Thapa ◽  
D. R. Kemp ◽  
D. L. Michalk ◽  
W. B. Badgery ◽  
A. T. Simmons
Keyword(s):  
Plant Material ◽  
Field Experiments ◽  
Seedling Recruitment ◽  
Plant Cover ◽  
Perennial Grass ◽  
Soil Surface ◽  
Soil Disturbance ◽  
Perennial Grasses ◽  
Control Treatment ◽  
Bare Ground

Two field experiments, one each on Austrodanthonia spp. and Bothriochloa macra, investigated the effects of biomass manipulation, seed level modification, site preparation and pasture composition on the recruitment of native perennial grass seedlings. The experiments coincided with drier than average years and although successful emergence of seedlings occurred, survival was extremely low. In the Austrodanthonia experiment, control treatments resulted in the emergence of only 1 seedling/m2, whereas there were 130/m2 in the best treatment which had biomass cut with plant material removed, seed added, and the soil surface scarified. Insecticide treatments increased emergence as seed-harvesting ants are common in these systems, but the benefits were small. Similarly, B. macra had no emergence in the control treatment compared with 73 seedlings/m2 in the best treatment, which was pasture cropped, and had seed added and herbicide applied. Availability of microsites may be a major constraint to B. macra emergence, as soil disturbance through pasture cropping substantially increased seedling numbers (279/m2). The effects of herbicide on emergence were small with the largest being related to bare ground and litter biomass. Austrodanthonia seedling numbers at emergence were related to bare ground, litter and green biomass. Survival of young Austrodanthonia plants 24 weeks after emergence was negatively related to plant cover, but only in treatments where plant material was cut and removed. The success of survival was determined at 52 weeks after emergence and the number of young plants that survived in both experiments seemed to have been influenced by the presence of competitive biomass of existing plants.

Alpine and Subalpine Wetland Vegetation on the Bogong High Plains, South-eastern Australia

1999 ◽  
Vol 47 (2) ◽  
pp. 165 ◽  
Author(s):  
C.-H. Wahren ◽  
R. J. Williams ◽  
W. A. Papst
Keyword(s):  
Soil Depth ◽  
Vegetation Type ◽  
Soil Surface ◽  
Wetland Vegetation ◽  
High Plains ◽  
Composition And Structure ◽  
Eastern Australia ◽  
Drainage Channels ◽  
Floristic Variation ◽  
Steep Slopes

The botanical composition and structure of wetland vegetation from seven sites in the alpine and subalpine tracts of the Bogong High Plains was sampled in 1995 and 1996. Sites were in the vicinity of Mts Nelse, Cope and Fainter. Sampling was based on contiguous 1-m2 quadrats along transects 20−70 m long across each wetland. Samples were ordinated using non-metric multidimensional scaling (NMDS). Floristic variation was assessed both within selected individual wetlands, and between wetlands from different regions. The relationship between the ordinations and environmental variables such as soil surface texture, soil depth and the amount of bare ground was tested by fitting vectors. Three dominant vegetation assemblages were identified. Closed heath, of hygrophyllous, scleromorphic shrubs such as Richea continentis and Baeckea gunniana, the rush Empodisma minus and the moss Sphagnum cristatum occurred on the deeper peats. Low open heath of Epacris glacialis and Danthonia nivicola occurred on shallow peats. Herbfields of Caltha introloba and Oreobolus pumilio occurred on stony pavements in two different physiographic situations&horbar;on relatively steep slopes (10−20°) at the head of wetlands, and on flat ground (slope < 2°), below the head of wetlands. The pavements on the steeper sites appeared to be associated with periglacial features such as solifluction lobes and terraces. Those on the flatter ground appeared to have been derived more recently. Wetlands in the Mt Cope region consisted of closed heath, low open heath and pavement herbfield in various proportions. Wetlands on Mt Fainter, which are subject to heavy trampling by cattle, were in a degraded condition, with a low cover of major hygrophyllous mosses and shrubs, and a high cover of introduced species. Long-ungrazed wetlands in a 50-year exclosure at Rocky Valley had high cover of closed heath, no pavements, numerous ponds and virtually no entrenched drainage channels or exposed peat. The Caltha herbfields are significant features nationally, both floristically and geomorphologically. Alpine and subalpine wetlands have been listed under the Victorian Flora and Fauna Guarantee Act 1988, and continued grazing by cattle is not compatible with the conservation objectives for this alpine vegetation type.

Sign in / Sign up

Export Citation Format

Share Document