A Postfire Chronosequence of Cone, Follicle and Seed Production in Banksia ornata

1986 ◽  
Vol 34 (4) ◽  
pp. 425 ◽  
Author(s):  
AM Gill ◽  
A Mcmahon

The fire-sensitive shrub Banksia ornata relies on seed stored in serotinous 'cones' for its regeneration. Seed release takes place largely as a result of fire but a very small percentage of fruits may open spontaneously. In a chronosequence studied in heaths of the Little Desert of north-western Victoria, we found no seedling establishment in the absence of fire except in the oldest stand, dated at 50+ years since fire. Seed quantity was low in stands 6-7 years old but rose to a peak in the 38-year-old stand. The decline of seed quantity in the 50+ year-old stand was due to dieback and death of bushes. There was no evidence for an increase in the proportion of seeds predated with age of stand. An average of about 70% of the seed was regarded as 'intact' (no sign of damage) and about 80% of these seeds germinated under ideal laboratory conditions. It was estimated that the amount of seed available for regeneration increased with stand age up to 38 years but declined by 50+ years. It was suggested that a period of 16 years without fire could be needed to achieve stand replacement of populations of this species. The age at which full replacement can be achieved will vary, however, according to fire intensity and seasonal weather conditions. Further quantitative research is needed.

1965 ◽  
Vol 5 (19) ◽  
pp. 500
Author(s):  
DJ Connor

Amsinckia is a serious weed in the wheat growing areas of north-western Victoria. It is successful in the inter-crop pastures, based upon barrel medic, because it grows faster than barrel medic in the cooler months of May to August. In addition, the rapid growth in height associated with the change from rosette to elongating phases ensures a height advantage over the pasture species when the flush of pasture growth does commence. Seed production by each Amsinckia plant is very high, and for this reason any competitive restriction obtained in one year is not necessarily reflected in the establishment phase of the next. Subterranean clover c.v. Clare is more competitive than barrel medic and was able to eliminate Amsinckia from the sward in two years. However it has only limited application in the pastures of north-western Victoria. A mowing treatment was carried out at the commencement of Amsinckia flowering, for this coincides with the beginning of rapid pasture growth. Regrowth produced a reversal of height relationships within the pasture and enabled barrel medic to shade Amsinckia BJ this treatment growth and seed production of Amsinckia were reduced by 99 per cent within the one season.


1965 ◽  
Vol 5 (19) ◽  
pp. 495 ◽  
Author(s):  
DJ Connor

Amsinckia hispida is a serious annual weed of cereal culture in north-western Victoria. Individual plants produce seed for up to two months in the spring and this provides a range of seed maturity that is reflected by a gradual build-up of germinability in the following autumn. In addition the seed has an optimum constant temperature for germination of 13�C (48�F) and responds markedly to a period of cold treatment. These three features act together to produce the series of Amsinckia populations which are characteristic of its autumn germination behaviour in north-west Victoria. Seeds which germinate early are responsible for infestations in the pasture phase and those which germinate later are not controlled by pre-sowing cultivation and remain to germinate within crops. The response of Amsinckia to environmental factors is such that these plants which germinate late within wheat crops have an extended rosette period and are highly competitive.


2015 ◽  
Vol 37 (3) ◽  
pp. 249 ◽  
Author(s):  
Judith M. Bean ◽  
Gavin J. Melville ◽  
Ronald B. Hacker ◽  
Stephen P. Clipperton

Two experimental sites were selected in the semiarid rangelands of north-west New South Wales, Australia. The sites had contrasting soil types and vegetation communities, but were similar in the existence of topographically high areas occupied by populations of perennial grasses. Adjacent slopes had very low numbers of perennial grass plants, indicating a moderate level of degradation. Shrubs, including Eremophila sturtii R.Br. (turpentine), were present but had not thickened to cause severe degradation. The topographically high areas were fenced as seed production areas. Replicates of a control and two cultural treatments: (1) piles of fine branches of turpentine placed along the topographic contour and (2) pits dug by a revolving metal drum, were established on the adjacent slopes. Maximum regeneration of perennial grasses took place, during favourable seasonal weather conditions, under the piles of branches on the site characterised by long gentle slopes of relatively impervious hard-setting red earths. Seed availability was not a limiting factor and a significant amount of seed was apparently sourced from the seed production areas. The piles of branches were very effective in promoting germination and survival of the perennial grasses, Monachather paradoxus Steud. and Aristida jerichoensis (Domin) Henrad, and species with large seed-retaining inflorescences, but not Thyridolepis mitchelliana (Nees) S.T. Blake. The piles of branches increased capture of seed, developed an improved seedbed and established a more mesic micro-environment and were, therefore, effective in enhancing natural landscape processes. At the site characterised by a medium-textured lithosol, even during favourable seasonal weather conditions, numbers of new plants were much lower. Pits were obliterated during the first heavy rains and the piles of branches had a negative impact on the survival of the second cohort of T. mitchelliana. At both sites, levels of germination and survival needed for regeneration of perennial grasses only occurred where a treatment effective in enhancing natural landscape processes had been established prior to favourable seasonal conditions. Pits were not effective in doing this at either site, nor for any of the perennial grass species.


2014 ◽  
Vol 25 (3-4) ◽  
pp. 69-76
Author(s):  
G. A. Mustafayeva

Scales (Hemiptera, Diaspididae) are the dangerous crop and park-ornamental plant pests. They reproduce very quickly and cause great harm to plants, sometimes even lead to their complete destruction. Scales suck juices from plants, cause premature drying, dying and falling off leaves, dry branches, deformation of leaves, fruits and shoots, reducing annual growth of plants. Therefore the fight with these pests is rather topical in the agriculture. In this connection in this work the analysis of bioecological peculiarities of oleander scale on the territory of Azerbaijan, and also the detection of species content of parasites and predators, which regulate their number is conducted. We will mark that oleander scales in the wild there are the entomophages are vermin and predators that reduce their quantity. For realization of biological fight against people we studied the bioenvironmental features of wreckers, and also educed specific composition of vermin and predators that regulate their quantity. In a biological fight against these wreckers, one of basic questions is study of specific composition of these entomophages. The faunistic material on entomophages of this pest was collected from different biocenosis; the researched works were conducted in the laboratory and field conditions in Azerbaijan. The advanced and research studies that we conducted gave an opportunity to educe entomophages oleander scale that inflicts an enormous damage to the agricultural cultures and park-decorative plants. The method of breeding of effective types of entomophages is studied in laboratory terms. Firstly the biology of oleander scale on Apsheron peninsula and in Guba Khachmazskii area was studied. The results of long-term studies showed that oleander scale, having distributed on Apsheron peninsula, on olive trees gives 3 generations. Only adult female animals and maggots of I and II age spend winter. Awakening of the scales on olives takes place in March-April. In II and III decade of April the male animals begin their flight. In Guba Khachmazskii area the biology of this scale, dwelling on oleander bush was studied. On this plant the scale gives 3 generations. Young female animals, and also maggots of I and II age winter. As a result of the works conducted the following entomophages of oleander scale were detected: predator Rhyzobius lophanthae Blaisd, Chilocorus bipustulatus L., Chilocorus renupustulatus L; parasites: Aphytis chilensis Howаrd, Aspidiotiphagus citrinus Graw, Encarsia aurantii (Howard). The habitat of Rhyzobius lophanthae is Australia. At the end of the last century of this predatory beetle left to California, from there left to Italy and in other Mediterranean countries. In 1947 by chance was left to Georgia (Abkhazia). Maybe these useful predators in Azerbaijan were from Georgia. For diluting the entomophages from the local indigenous fauna the potato tubers were used, on which firstly the oleander scales, and then road-beetles Rhyzobius lophanthae, Chilocorus bipustulatus reproduced themselves. In the laboratory conditions the methods of diluting of these Coccinellidae was developed. Thus, firstly the way of diluting parasites of oleander scale was studied and developed – Aphytis chilensis Howard, Aspidiotiphagus citrinus Graw и Encarsia antantii (Howard). It was detected that predatory entomophage-chilocor in the natural conditions is ineffective, as their maggots and chrysalises are affected by other local parasites. In the laboratory conditions this beetle produce itself very well on the potato tubers, infected by oleander scale. However, we should note that among entomophage parasites Aphytis chilensis plays the huge role in destruction of scales. In dependence on the weather conditions this macrophage in the nature can give 3–4 generations. Also it was proved that beetle Rhyzobius lophanthae in the biological fight can be applied against all round scales. This predator is effective entomophage of oleander, olive scale, black pine-leaf scale, white peach scale, European fruit scale and cactus scale. In connection with this, Rhyzobius lophanthae can be applied in the biological fight against oleander scale and presently is irreplaceable and perspective entomophage. 


Fire Ecology ◽  
2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Valerie S. Densmore ◽  
Emma S. Clingan

Abstract Background Prescribed burning is used to reduce fire hazard in highly flammable vegetation types, including Banksia L.f. woodland that occurs on the Swan Coastal Plain (SCP), Western Australia, Australia. The 2016 census recorded well over 1.9 million people living on the SCP, which also encompasses Perth, the fourth largest city in Australia. Banksia woodland is prone to frequent ignitions that can cause extensive bushfires that consume canopy-stored banksia seeds, a critical food resource for an endangered bird, the Carnaby’s cockatoo (Calyptorynchus latirostris, Carnaby 1948). The time needed for banksias to reach maturity and maximum seed production is several years longer than the typical interval between prescribed burns. We compared prescribed burns to bushfires and unburned sites at three locations in banksia woodland to determine whether low-intensity prescribed burns affect the number of adult banksias and their seed production. Study sites were matched to the same vegetation complex, fire regime, and time-since-fire to isolate fire intensity as a variable. Results Headfire rates of spread and differenced normalized burn ratios indicated that prescribed burning was generally of a much lower intensity than bushfire. The percentage survival of adult banksias and their production of cones and follicles (seeds) did not decrease during the first three years following a prescribed burn. However, survival and seed production were significantly diminished followed high-intensity bushfire. Thus, carrying capacity for Carnaby’s cockatoo was unchanged by prescribed burning but decreased markedly following bushfire in banksia woodland. Conclusions These results suggest that prescribed burning is markedly different from bushfire when considering appropriate fire intervals to conserve canopy habitats in fire-resilient vegetation communities. Therefore, low-intensity prescribed burning represents a viable management tool to reduce the frequency and extent of bushfire impacts on banksia woodland and Carnaby’s cockatoo.


1994 ◽  
Vol 70 (4) ◽  
pp. 468-472
Author(s):  
M. Martin Dupuis

For millenia, fire and insects have played an important role in forested land evolution. Understanding the roles they play can be important in helping us not only to control them, but to use them as an ecological tool. Also, we notice some important interactions between these two agents. As insects affect fire, fire may control insect pests. Controlled burning may provide excellent results, but allows a very slight margin for possible errors. Fire use as an insect mangement tool, requires a very precise and wide knowledge of weather conditions, fire intensity, insect's life cycle, available fuels, and type of ecosystem involved.After a long run of experiences and research, we notice that fire has been and will always be an important factor in equilibrium of some ecosystems. Since wild fire prevention campaigns and the emergence of insecticides, some forests have become excessively vulnerable to insect pests. Proper knowledge, and use of fire control, rather than immediate suppression of forest fires, would allow us to conserve various ecosystems in a healthy balance.


2007 ◽  
Vol 26 (4) ◽  
pp. 1075-1080 ◽  
Author(s):  
CLAUDIA FARFÁN ◽  
MIGUEL ROBLES MUNGARAY ◽  
SAÚL JAIME SERRANO-GUZMÁN

1963 ◽  
Vol 14 (6) ◽  
pp. 778 ◽  
Author(s):  
DE Harrison

During the late winter and early spring of 1960, and again to a lesser extent in 1961 and 1962, many lettuce crops in the Murray Valley area of north-western Victoria were seriously affected by a disease characterized by blackening, dry rotting, and collapse of the affected leaves. The incidence of disease varied from about 10% up to practically complete destruction of some plantings. A yellow bacterium was consistently isolated from affected plants and proved to be pathogenic to lettuce. Laboratory studies have shown that the organism agrees closely with the recorded description of Xanthomonas vitians (Brown) Dowson, which has not, apparently, been previously studied in Australia.


Sign in / Sign up

Export Citation Format

Share Document