Role of Seed Reproduction in the Population Ecology of Sorghum halepense in Maize Crops

1988 ◽  
Vol 25 (3) ◽  
pp. 951 ◽  
Author(s):  
Ana L. Scopel ◽  
C. L. Ballare ◽  
C. M. Ghersa
Keyword(s):  
Population Ecology ◽  
Sorghum Halepense ◽  
Seed Reproduction

scholarly journals Key Aspects on the Biology, Ecology and Impacts of Johnsongrass [Sorghum halepense (L.) Pers] and the Role of Glyphosate and Non-Chemical Alternative Practices for the Management of This Weed in Europe

Agronomy ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 717 ◽  
Author(s):  
Travlos ◽  
Montull ◽  
Kukorelli ◽  
Malidza ◽  
Dogan ◽  
...  
Keyword(s):  
Weed Management ◽  
Control Plant ◽  
Field Trials ◽  
European Countries ◽  
Alternative Methods ◽  
Sorghum Halepense ◽  
Current Status ◽  
Integrated Weed Management ◽  
Alternative Practices

Sorghum halepense (L.) Pers is a common and noxious worldwide weed of increasing distribution in many European countries. In the present review, information on the biology, ecology, agricultural, economic and environmental impact of johnsongrass is given, and the current status of this weed in Europe is discussed. Furthermore, special attention is given to the important role of field trials using glyphosate to control weeds in arable and perennial crops in many European countries. Some of the factors which affect control efficacy and should be taken into account are also discussed. Finally, several non-chemical alternative methods (cultural, mechanical, thermal, biological, etc.) for johnsongrass management are also presented. The adoption of integrated weed management (IWM) techniques such as glyphosate use, crop rotation, and deep tillage is strongly recommended to control plant species that originate from both seed and rhizomes.

Advancing Terrestrial Salamander Population Ecology: The Central Role of Imperfect Detection

2015 ◽  
Vol 49 (4) ◽  
pp. 533-540 ◽  
Author(s):  
Katherine M. O'Donnell ◽  
Raymond D. Semlitsch
Keyword(s):  
Population Ecology ◽  
Imperfect Detection

scholarly journals Population dynamics of Cosmoclopius nigroannulatus Stal (Hemiptera, Reduviidae) in tobacco culture

2002 ◽  
Vol 62 (4b) ◽  
pp. 819-826 ◽  
Author(s):  
S. M. JAHNKE ◽  
L. R. REDAELLI ◽  
L. M. G. DIEFENBACH
Keyword(s):  
Population Dynamics ◽  
Population Ecology ◽  
Population Estimates ◽  
Daily Survival Rate ◽  
Porto Alegre ◽  
Individual Number ◽  
Mark Release Recapture ◽  
Culture Cycle ◽  
The Individual

The role of predators influencing populations of insects considered as pests is extremely important for agroecosystems. The population ecology of Cosmoclopius nigroannulatus, a predatory reduvid associated with the tobacco culture was investigated aiming to study the population dynamics of adults, along the culture cycle. In an experimental plot of approximately 300 m², in Porto Alegre (30°0'S; 51°13'W), RS, Brazil, 270 tobacco plants were grown; each plant identified by alphanumeric coordinates. Using the mark-release-recapture method, daily samplings were done from August to December 1999, and three times a week from this date until April 2000. The adults were captured by hand, marked, sexed and released on the same plant they were captured. The individual number and plant coordinate were registered. Population estimates were analyzed by the Fisher-Ford method. In 107 sampling occasions, 604 individuals were marked, 273 males and 331 females. Three generations of C. nigroannulatus were registered during the culture cycle. The colonizing generation was represented by 14 males and 15 females (a sex ratio of 0.48), the first by 109 males and 137 females (0.44) and the second by 150 males and 179 females (0.46). The estimated daily survival rate varied between generations decreasing from 98% in the colonizing generation to 87% in the second. The observed longevity or permanence time in the experimental area varied significantly among generations, being at about 40 days in the colonizing generation, 13 days in the first and 5 days in the second. It was observed that as the population increases, the survival and/or permanence time in the area decreases, suggesting a relation between this and a decline in the available resources probably with an associated increase in intra-specific competition.

Population Ecology (Organizational Ecology): An Experiential Exercise Demonstrating How Organizations in an Industry Are Born, Change, and Die

2017 ◽  
Vol 42 (3) ◽  
pp. 375-397
Author(s):  
Karen MacMillan ◽  
Jennifer Komar
Keyword(s):  
Environmental Factors ◽  
Decision Maker ◽  
Systems Thinking ◽  
Population Ecology ◽  
Organizational Ecology ◽  
Organizational Size ◽  
Present Evidence ◽  
Random Chance ◽  
Longitudinal Approach

This article describes a classroom exercise that is designed to help students understand the basic tenets of population ecology (also known as organizational ecology). The macro-level, longitudinal approach to understanding organizations can be difficult for students to conceptualize as it involves systems thinking. This exercise makes the theory come alive by asking students to put themselves directly into the role of an organizational decision maker in an evolving industry. Over the course of one class, students get to experience how organizational size/age, environmental factors, and even random chance can affect organizational success and the makeup of an industry. Simulating up to a decade or more, students learn that populations of organizations change in predictable ways. We have tested this exercise with hundreds of students and we present evidence that it is effective in teaching the principles of population ecology (postexercise testing average of 92%) and also engaging and enjoyable for students.

scholarly journals Seed ingestion and germination in rattlesnakes: overlooked agents of rescue and secondary dispersal

2018 ◽  
Vol 285 (1872) ◽  
pp. 20172755 ◽  
Author(s):  
Randall S. Reiserer ◽  
Gordon W. Schuett ◽  
Harry W. Greene
Keyword(s):  
Seed Dispersal ◽  
Population Ecology ◽  
Empirical Studies ◽  
Evolutionary Process ◽  
Terrestrial Plants ◽  
Frugivorous Birds ◽  
Secondary Dispersal ◽  
Cheek Pouches ◽  
Primary Dispersal

Seed dispersal is a key evolutionary process and a central theme in the population ecology of terrestrial plants. The primary producers of most land-based ecosystems are propagated by and maintained through various mechanisms of seed dispersal that involve both abiotic and biotic modes of transportation. By far the most common biotic seed transport mechanism is zoochory, whereby seeds, or fruits containing them, are dispersed through the activities of animals. Rodents are one group of mammals that commonly prey on seeds (granivores) and play a critical, often destructive, role in primary dispersal and the dynamics of plant communities. In North America, geomyid, heteromyid and some sciurid rodents have specialized cheek pouches for transporting seeds from plant source to larder, where they are often eliminated from the pool of plant propagules by consumption. These seed-laden rodents are commonly consumed by snakes as they forage, but unlike raptors, coyotes, bobcats, and other endothermic predators which eat rodents and are known or implicated to be secondary seed dispersers, the role of snakes in seed dispersal remains unexplored. Here, using museum-preserved specimens, we show that in nature three desert-dwelling rattlesnake species consumed heteromyids with seeds in their cheek pouches. By examining the entire gut we discovered, furthermore, that secondarily ingested seeds can germinate in rattlesnake colons. In terms of secondary dispersal, rattlesnakes are best described as diplochorous. Because seed rescue and secondary dispersal in snakes has yet to be investigated, and because numerous other snake species consume granivorous and frugivorous birds and mammals, our observations offer direction for further empirical studies of this unusual but potentially important channel for seed dispersal.

Translocation of Assimilates and Dalapon in Established Johnsongrass

Weed Science ◽  
1969 ◽  
Vol 17 (3) ◽  
pp. 314-320 ◽  
Author(s):  
Richard J. Hull
Keyword(s):  
Life Cycle ◽  
Sorghum Halepense ◽  
Flowering Stage ◽  
Rhizome Growth ◽  
And Storage ◽  
Rhizome System

The influence of repeated clipping of the shoots on the translocation of 14C-assimilates and 2,2-dichloropropionic acid 2-14C (dalapon) into the rhizome system of established johnsongrass (Sorghum halepense (L.) Pers.) was studied when regrowth was in the preboot, boot, and flowering stages. Radioautography and radio-assay procedures were used to follow the distribution of label within the plants. Plants defoliated three times prior to treatment showed no increase in basipetal translocation over plants defoliated once. As plants matured to the flowering stage, assimilate translocation into rhizomes increased. This increase was closely related to the degree of secondary rhizome growth occurring at time of label application. During preboot, assimilate movement was restricted to rhizome apices with very little retention in intervening tissue. Labeled dalapon followed a similar translocation pattern to that of assimilates. The role of assimilate translocation and storage as correlated with life cycle changes in carbohydrate nutrition of established johnsongrass is discussed.

The feeding and consequent role of Eulalia viridis (O. F. Müller) (Polychaeta) in intertidal communities

1977 ◽  
Vol 57 (1) ◽  
pp. 93-96 ◽  
Author(s):  
R. H. Emson
Keyword(s):  
Population Ecology ◽  
Feeding Behaviour ◽  
Soft Tissues ◽  
Feeding Habits ◽  
The Other ◽  
Sufficient Evidence ◽  
Intertidal Communities ◽  
Other Hand

The intertidal phyllodocid polychaete Eulalia viridis (O. F. Müller) is widely regarded as a predator as stated, for example, by Newell (1970). This assertion is based on statements made by several authors, e.g. Moore & Kitching (1939), Glynne-Williams & Hobart (1952), Connell (1961), and Kensler (1964, 1967), who have reported E. viridis foraging over rocky substrates at low tide in daylight and in some cases have observed the insertion of the proboscis between the opercular plates of a barnacle and the subsequent ingestion of the soft tissues. The capture of a large chironomid by E. viridis has been recorded by Connell (1961). This was considered sufficient evidence for stating that E. viridis is a predator attacking living barnacles and other intertidal animals. Moore & Kitching (1939) further suggested that E. viridis might be as important a predator on barnacles as Thais lapillus (L). On the other hand Michel (1970) regarded E. viridis as a scavenger feeding on dead and decaying animals. There is evident disagreement about the feeding habits of E. viridis and consequently of its role in the population ecology of the community of which it forms a part. Examination of its feeding behaviour has been undertaken to clarify the situation.

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