Phytophthora cinnamomi and Australia's biodiversity: impacts, predictions and progress towards control

2008 ◽  
Vol 56 (4) ◽  
pp. 279 ◽  
Author(s):  
David M. Cahill ◽  
James E. Rookes ◽  
Barbara A. Wilson ◽  
Lesley Gibson ◽  
Keith L. McDougall
Keyword(s):  
Management Practices ◽  
Phytophthora Cinnamomi ◽  
Species Abundance ◽  
Ecological Communities ◽  
Complete Control ◽  
Natural Systems ◽  
Limited Effectiveness ◽  
Federal Initiatives ◽  
Serious Disease ◽  
Made In

Phytophthora cinnamomi continues to cause devastating disease in Australian native vegetation and consequently the disease is listed by the Federal Government as a process that is threatening Australia’s biodiversity. Although several advances have been made in our understanding of how this soil-borne pathogen interacts with plants and of how we may tackle it in natural systems, our ability to control the disease is limited. The pathogen occurs widely across Australia but the severity of its impact is most evident within ecological communities of the south-west and south-east of the country. A regional impact summary for all states and territories shows the pathogen to be the cause of serious disease in numerous species, a significant number of which are rare and threatened. Many genera of endemic taxa have a high proportion of susceptible species including the iconic genera Banksia, Epacris and Xanthorrhoea. Long-term studies in Victoria have shown limited but probably unsustainable recovery of susceptible vegetation, given current management practices. Management of the disease in conservation reserves is reliant on hygiene, the use of chemicals and restriction of access, and has had only limited effectiveness and not provided complete control. The deleterious impacts of the disease on faunal habitat are reasonably well documented and demonstrate loss of individual animal species and changes in population structure and species abundance. Few plant species are known to be resistant to P. cinnamomi; however, investigations over several years have discovered the mechanisms by which some plants are able to survive infection, including the activation of defence-related genes and signalling pathways, the reinforcement of cell walls and accumulation of toxic metabolites. Manipulation of resistance and resistance-related mechanisms may provide avenues for protection against disease in otherwise susceptible species. Despite the advances made in Phytophthora research in Australia during the past 40 years, there is still much to be done to give land managers the resources to combat this disease. Recent State and Federal initiatives offer the prospect of a growing and broader awareness of the disease and its associated impacts. However, awareness must be translated into action as time is running out for the large number of susceptible, and potentially susceptible, species within vulnerable Australian ecological communities.

Narrow Band Random Fatigue Testing with Amsler Vibrophore Machines

1969 ◽  
Vol 11 (6) ◽  
pp. 598-604 ◽  
Author(s):  
D. J. White ◽  
J. Lewszuk
Keyword(s):  
Fatigue Testing ◽  
Narrow Band ◽  
Rayleigh Distribution ◽  
Fatigue Tests ◽  
Random Loading ◽  
Complete Control ◽  
Random Generator ◽  
Random Fatigue ◽  
Predetermined Time ◽  
Made In

A description is given of modifications made to Amsler Vibrophore machines to permit narrow band random fatigue tests to be made. In this mode of working, the machine electromagnet is excited by means of a random generator and a complete control loop is effected by connecting the output of the inductive transducer of the machine dynamometer to the automatic output regulator (compressor circuit) of the random generator. The dynamometer was strain-gauged and calibrated to read r.m.s. load. Under compressor circuit control, the stress peaks in a specimen followed the Rayleigh distribution at least up to four times the r.m.s. value. As in constant amplitude sinusoidal loading, these machines are capable of applying mean stress when working in random loading. Some practically occurring stress spectra may be synthesized by applying sequences consisting of a number of stepped r.m.s. loads, each step being applied for a predetermined time.

scholarly journals Inferring True Species Richness and Complete Abundance Distribution in Six Reef-fish Communities from Red-sea, Using the Numerical Extrapolation of Incomplete Samplings

2019 ◽  
pp. 1-21
Author(s):  
Jean Beguinot
Keyword(s):  
Reef Fish ◽  
Red Sea ◽  
Field Data ◽  
Full Range ◽  
Species Abundance ◽  
Fish Communities ◽  
Ecological Communities ◽  
Abundance Distribution ◽  
Internal Organization ◽  
Unrecorded Species

Even when ecological communities are incompletely sampled (which is most frequent in practice, at least for species-rich assemblages including many rare species), it remains possible to retrieve much more information than could be expected first, by applying numerical extrapolation to incomplete field data. Indeed, recently developed procedures of numerical extrapolation of partial samplings now allow to estimate, with fair accuracy, not only the number of the still unrecorded species but, moreover, the distribution of abundances of each of these unrecorded species, thereby making available the full range of the Species Abundance Distribution, despite dealing with incomplete data only. In turn, this allows to address a series of descriptive and functional aspects of the internal organization of species assemblages, which otherwise would have required disposing of truly exhaustive samplings. This approach is applied, here, to the previously reported partial samplings of six neighboring reef-fish communities from Tiran Island, Red Sea, with the goal of better understanding their internal organization in relation to their respective environments. In practice, the numerical completion contributes to avoid erroneous interpretations that would likely stem from considering only the incomplete field data. This point is especially relevant when studying reef-associated communities because accurate understanding of their organization will help guiding and refining at best the protective measures required by these particularly vulnerable communities.

scholarly journals Induced Resistance for Plant Disease Control: Maximizing the Efficacy of Resistance Elicitors

2005 ◽  
Vol 95 (12) ◽  
pp. 1368-1373 ◽  
Author(s):  
Dale Walters ◽  
David Walsh ◽  
Adrian Newton ◽  
Gary Lyon
Keyword(s):  
Disease Control ◽  
Induced Resistance ◽  
Management Practices ◽  
Control Strategies ◽  
Plant Growth Promoting Rhizobacteria ◽  
Complete Control ◽  
Plant Disease Control ◽  
Plant Growth Promoting ◽  
Significant Disease ◽  
Best Fit

Plants can be induced to develop enhanced resistance to pathogen infection by treatment with a variety of abiotic and biotic inducers. Biotic inducers include infection by necrotizing pathogens and plant-growth-promoting rhizobacteria, and treatment with nonpathogens or cell wall fragments. Abiotic inducers include chemicals which act at various points in the signaling pathways involved in disease resistance, as well as water stress, heat shock, and pH stress. Resistance induced by these agents (resistance elicitors) is broad spectrum and long lasting, but rarely provides complete control of infection, with many resistance elicitors providing between 20 and 85% disease control. There also are many reports of resistance elicitors providing no significant disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, and crop nutrition. Unfortunately, little information is available on the influence of these factors on expression of induced resistance. In order to maximize the efficacy of resistance elicitors, a greater understanding of these interactions is required. It also will be important to determine how induced resistance can best fit into disease control strategies because they are not, and should not be, deployed simply as “safe fungicides”. This, in turn, will require information on the interaction of resistance elicitors with crop management practices such as appropriate-dose fungicide use.

Agonistic Interventions in Wild Mountain Gorilla Groups

Behaviour ◽  
1997 ◽  
Vol 134 (1-2) ◽  
pp. 23-57 ◽  
Author(s):  
David P. Watts
Keyword(s):  
Study Groups ◽  
Female Mate Choice ◽  
Gorilla Gorilla ◽  
Female Aggression ◽  
Mountain Gorilla ◽  
Gorilla Gorilla Gorilla ◽  
Control Female ◽  
Limited Effectiveness ◽  
Gorilla Gorilla Beringei ◽  
Made In

AbstractData on a large sample of interventions that individuals in two mountain gorilla (Gorilla gorilla beringei) groups made in agonistic interactions between others corroborate and extend earlier analyses in several ways. Related females supported each other as often as those in some female-bonded primates and maintained alliances while they resided together. Most unrelated females rarely supported each other, but some developed alliances. Females mostly supported other females with whom they had affinitive relationships against those they often engaged in dyadic aggression. They showed reciprocity in support, and often intervened against individuals who, in turn, often intervened against them. But even female coalitions that outnumbered their opponents by more than two-to-one had limited effectiveness, largely because males intervened in many female contests to control aggression. By rendering coalitions ineffective, males contribute to a combination of factors (e.g. low potential to gain from cooperation in contest feeding competition) that limit the benefits of female philopatry. Male curtailment of female aggression may influence female mate choice. Co-resident mature males in the study groups competed to control female aggression. High-ranking males curtailed aggression to females by subordinates, although two males formed an alliance against two others in their group. Immature animals mostly received defensive support against larger individuals and did not receive support from adults that could lead to a nepotistic dominance system.

Community Ecology

Ecology ◽  
2012 ◽  
Author(s):  
Herman A. Verhoef
Keyword(s):  
Community Ecology ◽  
Evolutionary Biology ◽  
Environmental Gradients ◽  
Functional Integration ◽  
Species Abundance ◽  
Functional Trait ◽  
Individual Species ◽  
Global Changes ◽  
Ecological Communities ◽  
Early 21St Century

At the beginning of the 20th century there was much debate about the “nature” of communities. The driving question was whether the community was a self-organized system of co-occurring species or simply a haphazard collection of populations with minimal functional integration. At that time, two extreme views dominated the discussion: one view considered a community as a superorganism, the member species of which were tightly bound together by interactions that contributed to repeatable patterns of species abundance in space and time. This concept led to the assumption that communities are fundamental entities, to be classified as the Linnaean taxonomy of species. Frederick E. Clements was one of the leading proponents of this approach, and his view became known as the organismic concept of communities. This assumes a common evolutionary history for the integrated species. The opposite view was the individualistic continuum concept, advocated by H. A. Gleason. His focus was on the traits of individual species that allow each to live within specific habitats or geographical ranges. In this view a community is an assemblage of populations of different species whose traits allow persisting in a prescribed area. The spatial boundaries are not sharp, and the species composition can change considerably. Consequently, it was discussed whether ecological communities were sufficiently coherent entities to be considered appropriate study objects. Later, consensus was reached: that properties of communities are of central interest in ecology, regardless of their integrity and coherence. From the 1950s and 1960s onward, the discussion was dominated by the deterministic outcome of local interactions between species and their environments and the building of this into models of communities. This approach, indicated as “traditional community ecology,” led to a morass of theoretical models, without being able to provide general principles about many-species communities. Early-21st-century approaches to bringing general patterns into community ecology concern (1) the metacommunity approach, (2) the functional trait approach, (3) evolutionary community ecology, and (4) the four fundamental processes. The metacommunity approach implicitly recognizes and studies the important role of spatiotemporal dynamics. In the functional trait approach, four themes are focused upon: traits, environmental gradients, the interaction milieu, and performance currencies. This functional, trait-focused approach should have a better prospect of understanding the effects of global changes. Evolutionary community ecology is an approach in which the combination of community ecology and evolutionary biology will lead to a better understanding of the complexity of communities and populations. The four fundamental processes are selection, drift, speciation, and dispersal. This approach concerns an organizational scheme for community ecology, based on these four processes to describe all existing specific models and frameworks, in order to make general statements about process–pattern connections.

scholarly journals Effects of logging and recruitment on community phylogenetic structure in 32 permanent forest plots of Kampong Thom, Cambodia

2015 ◽  
Vol 370 (1662) ◽  
pp. 20140008 ◽  
Author(s):  
Hironori Toyama ◽  
Tsuyoshi Kajisa ◽  
Shuichiro Tagane ◽  
Keiko Mase ◽  
Phourin Chhang ◽  
...  
Keyword(s):  
Phylogenetic Diversity ◽  
Tropical Rainforest ◽  
Deciduous Forests ◽  
Ecological Communities ◽  
Illegal Logging ◽  
Phylogenetic Structure ◽  
Evergreen Forests ◽  
Phylogenetic Community Structure ◽  
Β Diversity ◽  
Made In

Ecological communities including tropical rainforest are rapidly changing under various disturbances caused by increasing human activities. Recently in Cambodia, illegal logging and clear-felling for agriculture have been increasing. Here, we study the effects of logging, mortality and recruitment of plot trees on phylogenetic community structure in 32 plots in Kampong Thom, Cambodia. Each plot was 0.25 ha; 28 plots were established in primary evergreen forests and four were established in secondary dry deciduous forests. Measurements were made in 1998, 2000, 2004 and 2010, and logging, recruitment and mortality of each tree were recorded. We estimated phylogeny using rbcL and matK gene sequences and quantified phylogenetic α and β diversity. Within communities, logging decreased phylogenetic diversity, and increased overall phylogenetic clustering and terminal phylogenetic evenness. Between communities, logging increased phylogenetic similarity between evergreen and deciduous plots. On the other hand, recruitment had opposite effects both within and between communities. The observed patterns can be explained by environmental homogenization under logging. Logging is biased to particular species and larger diameter at breast height, and forest patrol has been effective in decreasing logging.

Rhizosphere interactions: root exudates, microbes, and microbial communities

Botany ◽  
2014 ◽  
Vol 92 (4) ◽  
pp. 267-275 ◽  
Author(s):  
Xing-Feng Huang ◽  
Jacqueline M. Chaparro ◽  
Kenneth F. Reardon ◽  
Ruifu Zhang ◽  
Qirong Shen ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Root Exudates ◽  
Root Exudate ◽  
Management Practices ◽  
Plant Root ◽  
Agricultural Practices ◽  
Rhizosphere Interactions ◽  
Broad Variety ◽  
Sustainable Agricultural Practices ◽  
Made In

The study of the interactions between plants and their microbial communities in the rhizosphere is important for developing sustainable management practices and agricultural products such as biofertilizers and biopesticides. Plant roots release a broad variety of chemical compounds to attract and select microorganisms in the rhizosphere. In turn, these plant-associated microorganisms, via different mechanisms, influence plant health and growth. In this review, we summarize recent progress made in unraveling the interactions between plants and rhizosphere microbes through plant root exudates, focusing on how root exudate compounds mediate rhizospheric interactions both at the plant–microbe and plant–microbiome levels. We also discuss the potential of root exudates for harnessing rhizospheric interactions with microbes that could lead to sustainable agricultural practices.

CONSERVATION AGRICULTURE IN THE INDOGANGETIC PLAINS OF INDIA: PAST, PRESENT AND FUTURE

2017 ◽  
Vol 55 (2) ◽  
pp. 339-357 ◽  
Author(s):  
PETER HOBBS ◽  
RAJ GUPTA ◽  
RAJ KUMAR JAT ◽  
R. K. MALIK
Keyword(s):  
Management Practices ◽  
New Technology ◽  
Conservation Agriculture ◽  
Gangetic Plains ◽  
Farmer Adoption ◽  
Key Factor ◽  
Complex Technology ◽  
Use Efficiency ◽  
On Farm ◽  
Made In

SUMMARYThis paper follows the progress made in India for research and farmer adoption of conservation agriculture (CA) since the publication of Erenstein (2012), who contested the idea that zero-till (ZT) establishment of wheat in rice–wheat systems could be further developed into full CA systems. Data presented in this paper show that research has successfully found solutions for both the wheat and rice phases of the rice–wheat systems of the Indo-Gangetic Plains (IGP) in the past 8 years. It shows that by finding solutions in both the rice and wheat phases, yields, water use efficiency and profits increased, while labour needs reduced. Indian scientists have also confirmed these benefits in participatory on-farm research in various locations, both east and west regions of the IGP. Farmers see for themselves through experimentation that they get higher yields with less cost and with more efficient use of inputs and water. A key factor has been the development of improved seed drills with the help of Indian private sector manufacturers of agricultural equipment. Indian scientists have also successfully conducted CA research on several other crops and in other regions besides the IGP. The paper shows that it is better to introduce parts of the CA management practices in a step-wise fashion first, rather than introducing the entire package at once since farmers first have to test and evaluate a new technology to understand how it benefits them personally before they will adopt it. The paper concludes that in the rice–wheat systems of South Asia, adoption of CA is indeed possible to achieve although it is still a work in progress. CA is a complex technology package and it takes time to overcome all of the contested issues mentioned in Erenstein (2012).

scholarly journals Evolving Role of the Information Center: Challenges and Directions

2009 ◽  
Vol 10 ◽  
pp. 1-35
Author(s):  
Sajjad ur Rehman
Keyword(s):  
Knowledge Management ◽  
Best Practices ◽  
Management Practices ◽  
Review Of Literature ◽  
Information Center ◽  
It Applications ◽  
Developed Nations ◽  
Made In ◽  
Information And Knowledge Management

The paper provides a critical review of the development of information center through different phases, transformation of the information center in response to the inter-disciplinary imperatives of information and knowledge management, IT imperatives, trends in the areas of content, services, management, and personnel, and future possibilities and prospects. An extensive review of literature was made in order to discern trends and analyze the current situation in pertinent areas focused in this paper. It was noted that the information center has changed through different phases. Information and knowledge management have made a distinct impact on the dynamics of the center. Changes in resources and services, IT applications, user community, and management practices are most evident. These factors have been critical in shaping the identity and substance of the information centers. Based on this analysis, challenges facing the information centers have been elaborated. Best practices in specific areas in the developed nations have been highlighted. Future of the information center is projected to be dynamic, enterprising, and challenging. This review is useful for taking strategic cues for planning and managing the information centers.

scholarly journals Postharvest Management Practices of Grains in the Eastern Region of Kenya

2019 ◽  
Vol 11 (3) ◽  
pp. 33 ◽  
Author(s):  
Anastasia W. Njoroge ◽  
Ibrahim Baoua ◽  
Dieudonne Baributsa
Keyword(s):  
Management Practices ◽  
Production Systems ◽  
Eastern Region ◽  
Stored Grain ◽  
Primary Methods ◽  
Postharvest Management ◽  
Seed Crops ◽  
Storage Technologies ◽  
Semi Arid ◽  
Made In

Cereals and legumes play a major role in the production systems and diets of farmers in the semi-arid eastern region of Kenya. Efficient postharvest management can tremendously contribute to food security in these regions. A study was carried out in three counties in eastern Kenya to assess pre and postharvest management practices among farmers. Data was collected using semi-structured questionnaires designed and administered using Kobo Toolbox via android tablets. Results showed that farmers cultivated three main crops: maize (98%), beans 66%), and pigeon peas (28%). The most saved seed crops were beans (80%) and pigeon peas (50%). Majority of the farmers (80%) experienced pre-drying losses due to insects (48%), rodents (40%) and birds (39%). Farmers stored grain for consumption (80%) and for sale (19%). About 48% of farmers stored the grain for more than 9 months. Challenges during grain storage were insects (57%) and rodents (43%). Primary methods of grain preservation included hermetic methods (61%) followed by insecticides (33%). While progress is being made in addressing storage challenges, there still a need to continue building awareness about improved storage technologies and find solutions for pest infestations in the field and drying after harvest.

Sign in / Sign up

Export Citation Format

Share Document