Effects of seed bed conditions on the germination of four Stylosanthes species in the Northern Territory

1976 ◽  
Vol 27 (6) ◽  
pp. 811 ◽  
Author(s):  
JJ Mott ◽  
GM McKeon ◽  
CJ Moore
Keyword(s):  
Management Practices ◽  
Surface Soil ◽  
Soil Surface ◽  
Northern Territory ◽  
Perennial Species ◽  
Wet Season ◽  
Native Grasslands ◽  
Grass Sward ◽  
Moisture Conditions ◽  
Potential Rate

Since the proposed use of low input management practices in the Northern Territory will require the establishment of Stylosanthes species in the native grasslands with the least possible disturbance, the effects of soil surface, soil type and seed treatments on the germination of four Stylosanthes species were studied. The species were the annual S. humilis, the facultative perennial S. hamara cv. Verano, and two obligate perennials, S. scabra CPI 40289 and S. viscosa CPI34904. The study was carried out on microplots in burnt and unburnt pasture near Katherine in the Northern Territory. Although all species germinated in both burnt and unburnt grassland, germination was much better under the grass sward. The two perennial species germinated much more slowly than either S. humilis or S. hamata, and the removal of grass cover caused low germination of these species, especially under the poor moisture conditions existing on the surface of sandy soils. Under the existing method of establishment with burning late in the dry season followed by sowing in the early wet season, the germination of the perennials S. scabra and S. viscosa will not attain the same levels as that of S. hamata and S. humilis. Our results suggest that field germination of the perennials could be enhanced by either pretreating the seed to improve its potential rate of germination, or by sowing later in the wet season to take advantage of the greater probability of prolonged moisture conditions.

Dormancy and Germination in Five Native Grass Species From Savannah Woodland Communities of the Northern Territory

1978 ◽  
Vol 26 (5) ◽  
pp. 621 ◽  
Author(s):  
JJ Mott
Keyword(s):  
Soil Surface ◽  
Moisture Stress ◽  
Northern Territory ◽  
Grass Species ◽  
Wet Season ◽  
Native Grass ◽  
Native Grasslands ◽  
Similar Range ◽  
Seed Fall ◽  
C 30

The dormancy and germination requirements of five native grass species (Themeda australis, Chrysopogon fallax, C. latifolius, Sorghum plumosum, S. stipoideum) from the savannah woodlands of the Northern Territory were studied under controlled conditions. Results were related to the ecology of these species in the native grasslands of the region. All species were dormant at seed fall, and dormancy was found to be broken by exposure to dry heat. Gibberellic acid was also found to have a stimulatory effect on germination of dormant seed but there was no effect on stratification. In the field, temperatures existent at the soil surface during the dry season ensure that dormancy was broken before the heavy rainfall of the following wet season. Seeds of all species studied germinated over a similar range of temperatures with optimum germination at high temperature (c. 30°C). Although seeds of all species were not adapted to germina- tion under moisture stress, the existence of sharply pointed calluses and hygroscopically active awns on the seeds ensured that they would be buried below the moisture extremes of the immediate soil surface.

Understorey vegetation drives surface runoff and soil loss in teak plantation-based system of Northern Laos

2020 ◽  
Author(s):  
Layheang Song ◽  
Laurie Boithias ◽  
Oloth Sengtaheuanghoung ◽  
Chantha Oeurng ◽  
Christian Valentin ◽  
...  
Keyword(s):  
Surface Runoff ◽  
Soil Loss ◽  
Management Practices ◽  
Soil Surface ◽  
Runoff Coefficient ◽  
Wet Season ◽  
Tree Plantation ◽  
Teak Tree ◽  
Runoff And Soil Loss ◽  
Soil Losses

<p>Humid tropical mountainous area experiences serious soil erosion due to rapid changes in landuse, sometimes implying erosion prone management practices. In this study, we hypothesized that keeping understorey in teak tree plantation would protect soil and avoid soil erosion. We assessed the effects of 4 management practices in teak tree plantation area on water and soil losses using 6 replicated 1-m<sup>2</sup> microplots in four plantations situated in Northern Laos during the wet season of 2017. The landuses in the four plantations were teak without understorey (TNU), teak with low density of understorey (TLU), teak with high density of understorey (THU), and teak with broom grass, <em>Thysanolaena latifolia</em> (TBG). During the wet season of 2017, we monitored surface runoff and soil loss for 22 rainfall events. We also measured some of the teak tree and understorey characteristics (i.e. height and percentage of cover) and the percentage areas of soil surface features (i.e. litter, free aggregates, crusting, etc.). Relationships among these variables was estimated through multiple statistics and regression analyses. We found that runoff coefficient and soil loss were the smallest for THU and TBG: runoff coefficient was 23% for both treatments, and soil losses were 465 and 381 g m<sup>-2</sup>, respectively. Runoff coefficient and soil loss for TLU were 35% and 1115 g m<sup>-2</sup>, respectively. We observed the highest runoff coefficient and soil loss under TNU (60%, 5455 g m<sup>-2</sup>) associated to the highest crusting rate (82%). High runoff coefficient and soil loss under TNU was explained by the kinetic energy of rain drops falling from the broad leaves of the tall teak trees down to bare soil, devoid of plant residues, thus leading to severe soil surface crusting and detachment. Overall, promoting understorey such as broom grass in teak tree plantations would (1) limit surface runoff and improve soil infiltrability, thus increase the soil water stock available for both root absorption and groundwater recharge, and (2) mitigate soil loss and favour soil fertility conservation.</p>

Growth, Water use and nutrient uptake from the subsoil by grass swards

1967 ◽  
Vol 69 (1) ◽  
pp. 125-130 ◽  
Author(s):  
E. A. Garwood ◽  
T. B. Williams
Keyword(s):  
Perennial Ryegrass ◽  
Surface Soil ◽  
Soil Surface ◽  
Plant Nutrients ◽  
Soil Horizon ◽  
Soil Water Deficit ◽  
Moist Soil ◽  
Soil Horizons ◽  
Positive Interaction ◽  
Grass Sward

1. Plant nutrients, N, P and K, were applied to the soil surface or injected at a depth of 18 in. or 30 in. in perennial ryegrass swards, when the upper horizons of the soil profile were dry.2. When the surface soil was dry and a soil water deficit of 2 in. existed there was no response to surface applied N but injection of N into moist soil at a depth of 18 in. produced a marked increase of growth. At this depth of injection there was a significant positive interaction between N and PK.3. There was a substantial recovery in the herbage (59–80%) of the nitrogen applied to the subsoil, provided water was available in the soil horizon in which the nitrogen was applied.4. Failure of a grass sward to regrow after cutting when the water available to the plant has been removed from the uppermost soil horizons is largely due to a deficiency of plant nutrients in the subsoil. The major deficiency is that of nitrogen.

scholarly journals Evaluation of Image-Based Phenotyping Methods for Measuring Water Yam (Dioscorea alata L.) Growth and Nitrogen Nutritional Status under Greenhouse and Field Conditions

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 249
Author(s):  
Emmanuel Frossard ◽  
Frank Liebisch ◽  
Valérie Kouamé Hgaza ◽  
Delwendé Innocent Kiba ◽  
Norbert Kirchgessner ◽  
...  
Keyword(s):  
Management Practices ◽  
Leaf Surface ◽  
Plant Traits ◽  
Soil Surface ◽  
Shoot Biomass ◽  
N Content ◽  
Total Leaf ◽  
Image Pixels ◽  
Leaf N Content ◽  
Yield Formation

New management practices must be developed to improve yam productivity. By allowing non-destructive analyses of important plant traits, image-based phenotyping techniques could help developing such practices. Our objective was to determine the potential of image-based phenotyping methods to assess traits relevant for tuber yield formation in yam grown in the glasshouse and in the field. We took plant and leaf pictures with consumer cameras. We used the numbers of image pixels to derive the shoot biomass and the total leaf surface and calculated the ‘triangular greenness index’ (TGI) which is an indicator of the leaf chlorophyll content. Under glasshouse conditions, the number of pixels obtained from nadir view (view from the top) was positively correlated to shoot biomass, and total leaf surface, while the TGI was negatively correlated to the SPAD values and nitrogen (N) content of diagnostic leaves. Pictures taken from nadir view in the field showed an increase in soil surface cover and a decrease in TGI with time. TGI was negatively correlated to SPAD values measured on diagnostic leaves but was not correlated to leaf N content. In conclusion, these phenotyping techniques deliver relevant results but need to be further developed and validated for application in yam.

Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

1992 ◽  
Vol 43 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Mott ◽  
MM Ludlow ◽  
JH Richards ◽  
AD Parsons
Keyword(s):  
Growing Season ◽  
Close Correlation ◽  
Dry Season ◽  
Carbon Gain ◽  
Panicum Maximum ◽  
Wet Season ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Moisture Conditions ◽  
Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

Projecting demands for renal replacement therapy in the Northern Territory: a stochastic Markov model

2018 ◽  
Vol 42 (4) ◽  
pp. 380 ◽  
Author(s):  
Jiqiong You ◽  
Yuejen Zhao ◽  
Paul Lawton ◽  
Steven Guthridge ◽  
Stephen P. McDonald ◽  
...  
Keyword(s):  
Renal Replacement Therapy ◽  
Markov Model ◽  
Replacement Therapy ◽  
Management Practices ◽  
Markov Models ◽  
Self Care ◽  
Potential Effect ◽  
Northern Territory ◽  
Baseline Scenario ◽  
On Demand

Objective The aim of the present study was to evaluate the potential effects of different health intervention strategies on demand for renal replacement therapy (RRT) services in the Northern Territory (NT). Methods A Markov chain simulation model was developed to estimate demand for haemodialysis (HD) and kidney transplantation (Tx) over the next 10 years, based on RRT registry data between 2002 and 2013. Four policy-relevant scenarios were evaluated: (1) increased Tx; (2) increased self-care dialysis; (3) reduced incidence of end-stage kidney disease (ESKD); and (4) reduced mortality. Results There were 957 new cases of ESKD during the study period, with most patients being Indigenous people (85%). The median age was 50 years at onset and 57 years at death, 12 and 13 years younger respectively than Australian medians. The prevalence of RRT increased 5.6% annually, 20% higher than the national rate (4.7%). If current trends continue (baseline scenario), the demand for facility-based HD (FHD) would approach 100 000 treatments (95% confidence interval 75 000–121 000) in 2023, a 5% annual increase. Increasing Tx (0.3%), increasing self-care (5%) and reducing incidence (5%) each attenuate demand for FHD to ~70 000 annually by 2023. Conclusions The present study demonstrates the effects of changing service patterns to increase Tx, self-care and prevention, all of which will substantially attenuate the growth in FHD requirements in the NT. What is known about the topic? The burden of ESKD is projected to increase in the NT, with demand for FHD doubling every 15 years. Little is known about the potential effect of changes in health policy and clinical practice on demand. What does this paper add? This study assessed the usefulness of a stochastic Markov model to evaluate the effects of potential policy changes on FHD demand. What are the implications for practitioners? The scenarios simulated by the stochastic Markov models suggest that changes in current ESKD management practices would have a large effect on future demand for FHD.

Soil seed bank and vegetation dynamics in Sahelian fallows; the impact of past cropping and current grazing treatments

2004 ◽  
Vol 20 (6) ◽  
pp. 683-691 ◽  
Author(s):  
Bruno Hérault ◽  
Pierre Hiernaux
Keyword(s):  
Seed Bank ◽  
Management Practices ◽  
Soil Seed Bank ◽  
Residual Effects ◽  
Ex Situ ◽  
Phosphorus Fertilizer ◽  
Wet Season ◽  
Seed Extraction ◽  
The Impact

The soil seed bank in a 5-y-old Sahelian fallow was studied through seed extraction and compared with germinations recorded either in controlled conditions, ex situ in a glasshouse, or in the field. The influence of phosphorus fertilizer and mulch application during the preceding crop period, and that of seasonal grazing regimes applied the last 2 y of fallowing, were assessed on the composition of the seed stock. Ctenium elegans, Fimbristylis hispidula, Merremia pinnata and Phyllanthus pentandrus accounted together for 75% of extracted seeds, 72% of ex situ, and 62% of in situ seedlings. Mulch treatment was correlated with the first axis of the canonical correspondence analyses performed on the seedling datasets. Mulch and phosphorus fertilizer treatments held similar responses, as they both favoured the seed bank of erect dicotyledons such as P. pentandrus and Cassia mimosoides. On the whole, the effects of grazing remained modest compared with the residual effects of past crop management practices. However, seedling densities increased as a result of dry-season grazing, while the soil seed bank decreased with wet-season grazing. Grazing also reduced the spatial heterogeneity of the seed bank rather than the overall number of species.

scholarly journals Trace Metal Distribution and Mobility in Soils after Silvicultural Thinning and Burning

2017 ◽  
Vol 9 (5) ◽  
pp. 83
Author(s):  
Ngowari Jaja ◽  
Monday Mbila ◽  
Yong Wang
Keyword(s):  
Trace Metal ◽  
Management Practices ◽  
Soil Depth ◽  
Anthropogenic Activities ◽  
Block Design ◽  
Forest Health ◽  
Soil Surface ◽  
Parent Material ◽  
Design Experiment ◽  
Randomized Block Design

Silvicultural thinning and burning are common management practices that are widely used to address ecosystem problems such as tree stocking and general forest health. However, high-severity fire has variable effects on soils, resulting in damages which are directly or indirectly reflected on the trace metal chemistry of the soil. This study was conducted to evaluate the trace metal variation at the Bankhead National Forest in Northern Alabama following the silvicultural thinning and burning. The experimental site had treatments consisting of two burning patterns and three levels of thinning as part of an overall treatment of three burning patterns and three levels of thinning applied to nine treatment plots to fit a completely randomized block design experiment. Four treatments sites were used for this study and samples were collected from soil profile pits excavated at representative plots within each treatment. The samples were analyzed for trace metals-As, Cu, Ni, Zn and Pb-using Perkin Elmer 2100 ICP-OES. Post treatment samples indicated that the trace metal concentrations generally decreased with soil depth. Copper, Ni, and Zn at the Pre-burn site gradually increased with depth to a maximum concentration at about 50 cm below the soil surface. Arsenic in the surface horizons increased by 156% in the burn-only sites, 54% in the thin-only treatment, 30% for the burn and thin treatments. Such differences were unlikely due to differences in the geochemistry of the parent material, but likely due to anthropogenic activities and possibly the forest management practices in question.

Problem crocodiles, Crocodylus porosus, at Nhulunbuy, Northern Territory: an assessment of relocation as a mangaement strategy

1993 ◽  
Vol 20 (1) ◽  
pp. 127 ◽  
Author(s):  
B Walsh ◽  
PJ Whitehead
Keyword(s):  
Carrying Capacity ◽  
Northern Territory ◽  
Effective Strategy ◽  
Wet Season ◽  
Rates Of Return ◽  
Saltwater Crocodile ◽  
Crocodylus Porosus ◽  
Remote Sites ◽  
Total Capture ◽  
Capture Rates

Since 1986 the Conservation Commission of the Northern Territory has operated a programme to remove 'problem' saltwater crocodiles from waters in and adjoining the township of Nhulunbuy. Over a period of five years, 52 different saltwater crocodiles (44 male) were captured. Most (48) were released at remote sites designated by the traditional Aboriginal owners of the surrounding lands. Release distances from the township varied from 17 to 282 km (by coastline). Many crocodiles (47.9%), including those released at the most distant sites, returned to, and were subsequently recaptured at, the township. Total capture rates (initial captures and recaptures pooled) varied seasonally, with fewer crocodiles being caught in the cooler dry season. During the wet season capture rates remained high, but relatively fewer 'new' crocodiles were caught. Probability of recapture could not be related to distance and direction of release from the township, nor size and sex of the released crocodile. Frequency of capture of individual crocodiles (1-8 times) was also unrelated to these variables. The high rates of return indicate that relocation is unlikely to be an effective strategy for managing humancrocodile interactions, at least in areas where potential release sites already support saltwater crocodile populations near carrying capacity.

Thinking honeyeater: nectar maps for the Northern Territory, Australia

2000 ◽  
Vol 6 (1) ◽  
pp. 61 ◽  
Author(s):  
John C. Z. Woinarski ◽  
Greg Connors ◽  
Don C. Franklin
Keyword(s):  
Northern Territory ◽  
Dry Season ◽  
Spatial And Temporal Variation ◽  
Wet Season ◽  
Nectar Production ◽  
The World ◽  
Eucalypt Forests ◽  
The Times ◽  
Species Specific ◽  
Nectar Availability

We create monthly maps of nectar availability for the 1.4 x 106 km2 jurisdiction of the Northern Territory, Australia. These are based on a combination of vegetation mapping and a series of indices of plant species specific nectar scoring. The maps reveal complex spatial and temporal variation in nectar availability, but most notably a greater nectar resource in the monsoon-influenced north than in the arid south, and a peak in nectar availability in the dry season. The latter is associated with the extensive tropical eucalypt forests (especially those co-dominated by Eucalyptus miniata and E. tetrodonta). In contrast, wet season nectar availability in these forests is limited, but riparian and swampland forests, typically dominated by Melaleuca species, provide rich but spatially restricted nectar resources. The extensive and rich nectar resources available in eucalypt forests in the dry season supplement the diets of many species which are not primarily nectarivorous. This resource helps shape the singularity of northern Australian eucalypt forests relative to other extensive forests elsewhere in the world. Nectarivores remain in the system through a combination of movements across a number of scales, habitat shifting, and diet shifting. The latter is aided by the peaking of invertebrate and fruit resources at the times of minimum nectar production; a shuffling in resource availability brought about by the extreme climatic seasonality.

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