Understanding Ecological Succession

Ecological succession is the progressive change, in an ecosystem, of species composition over time. With the change in species composition comes a series of modifications in community structure and function. A classic example of succession involves the series of changes observed in an abandoned field in what is normally a forested area. Once the field is no longer grazed or mowed, the seeds of shrubs and trees will sprout and rapidly start growing. Before long, shrubs and tree saplings will be the dominant vegetation form. The tree species will then grow to the point of shading out the shrubs, eventually forming a complete canopy. The species composition in that young forest will continue to turn over until it is dominated by a stable, self-maintaining group of species called a climax community. Primary vs. Secondary Succession Ecological succession where there was no vegetation prior is called primary succession. We can observe primary succession on bulldozed sites, after an intense fire, or following a volcanic eruption, for example. The first plant species to show up have the ability to very quickly colonize and grow in these bare areas. Depending on the region, these pioneer species can be grasses, broadleaf plantain, Queen Anne’s lace, or trees like aspen, alder, or black locust. The pioneers set up the stage for the next phase of succession, improving soil chemistry and adding organic matter which provides nutrients, better soil structure, and greater water-holding capacity. Secondary succession occurs when a new set of organisms appears where there was an ecological set-back (for example a clear-cut logging operation) but where a cover of living plants was left behind. The abandoned agricultural field described above is a perfect example of secondary succession. Common plants during this stage are raspberries, asters, goldenrods, cherry trees, and paper birch. Climax Communities and Disturbance The last stage of succession is the climax community. In a forest, climax species are those that can grow in the shade of taller  trees – hence the name shade-tolerant species. The composition of climax communities varies geographically. In parts of the eastern United States, a climax forest will be made of sugar maples, eastern hemlock, and American beech. In Washington State’s Olympic National Park, the climax community may be dominated by western hemlock, Pacific silver fir, and western redcedar. A common misconception is that climax communities are permanent and frozen in time. In reality, the oldest trees eventually die and are replaced by other trees waiting under the canopy. This makes climax canopy part of a dynamic equilibrium, always changing but overall looking the same. Significant changes will occasionally be brought about by disturbances. Disturbances can be wind damage from a hurricane, a wildfire, an insect attack, or even logging. The type, size, and frequency of disturbances vary by region – some coastal, wet locations experience fires on average once every few thousand years, while eastern boreal forests may be subject to spruce budworm kills every few decades. These disturbances knock back the community into an earlier successional stage, restarting the process of ecological succession. The Value of Late Successional Habitat The dark shade and tall canopies of climax forests provide shelter for a number of specialized birds, mammals, and other organisms. The cerulean warbler, wood thrush, and red-cockaded woodpecker  are dwellers of old forests. The threatened spotted owl and Humboldt fisher both require large stands of late successional redwood and Douglas-fir forests. Many small flowering plants and ferns rely on the shady forest floor beneath old trees. The Value of Early Successional Habitat There is also considerable value in early successional habitat. These shrubland and young forests rely on recurring disturbances that set succession back. Unfortunately, in many places, these disturbances often turn forests into housing developments and other land uses that short-cut the ecological succession process. As a result, shrublands and young forests can become quite rare on the landscape. Many birds rely on early successional habitats, including the brown thrasher, golden-winged warbler, and prairie warbler. There are also mammals that need shrubby habitat, perhaps most notably the New England cottontail.

Cesar Chavez Rhetorical Analysis - 1248 Words

Mexican-Americans and the Church: Rhetorical Analysis of Cesar Chavez Speech About 85% of churches are not fully active with their community. Statics have gotten higher throughout the years, about 40 years ago Mexicans were being treated unfairly due to poor working conditions. This unbarring situation led a fellow leader, Cesar Chavez to step up and build a firm foundation to lead his organization to success. He was the leader of the Mexican-American Community in Delano, Ca. Cesar went through a spiritual fasting, in which he did not eat due to the hazardous chemicals in field fruit. Chavez was a Catholic and used his morals for a nonviolent protest to better working conditions for field workers. Chavez had many helpers from different†¦show more content†¦He stated this matter at the Second Annual Conference in Sacramento, Ca. After his speech he gained over 6,000 people to join his fast. He could have not accomplished that without the help of an organization called Califor nia Migrant Ministry. This organization is a protestant group who helped Chavez succeed. Because their relationship grew, the ministry was right by Cesars side during the strikes. He later on explains how supportive the ministry was, â€Å" When 30 of the strikers were arrested for shouting Huelga, 11 ministers went to jail with them.† (Chavez). Although it might not be obvious, Chavez wanted the church to feel betrayed as well. He wanted them to begin to question why CMM was with them. Chavez also knew the Mexican-American Community was listening so he gives them facts about the Ministry, how supportive they are. As a result, Chavez’ purpose is to influence, the church to be open to change. The Mexican-American Organization, happily opened their arms to the California Migrant Ministry and it lead to an amazing outcome. Chavez wanted the church to adapt to society, he states, â€Å"We ask the church to sacrifice with the people for social change, for justice, and for love of brother. We dont ask for words. We ask for deeds. We dont ask for paternalism.† (Chavez). Chavez gets to the point of what him and the Mexican-American Community want. This is the purpose of the speech, the justification of what he expects from them. They dont need anything elseShow MoreRelatedRhetorical Analysis Of Cesar Chavez1082 Words   |  5 Pagesmigrant farm workers in America, a man named Cesar Chavez spoke out and instantly became a leader to these once defenseless people. Chavez devoted his life to improve conditions for farm workers, he began protests for better pay and conditions they went on â€Å"huelga† which means strike. Chavez united these farm workers and helped make their voices heard, creating a union to fight for their cause and the union was named the United Farm Workers Union. Chavez did not believe in violence so all of his protestsRead MoreRhetorical Analysis Of Cesar Chavez s Article1915 Words   |  8 Pages It’s hard to im agine that just ten short months ago I was sitting in a classroom building a spaghetti tower with no idea what a rhetorical analysis essay was or what the word anaphora meant. Now, just a couple of months later, I have read and analyzed six different novels, learned to write an argument, synthesis, and rhetorical analysis essay, expanded my lexicon of literary terms, and sat through a three hour AP exam. This class has not only given me the skills to master the AP exam, but it has

Leadership Style of Bill Gates †Free Samples to Students

Question: Discuss about the Leadership Style of Bill Gates. Answer: Introdcution: Bill Gates is the owner of Microsoft and describing his leadership style it can be accessed that he offers a more of a participative form of leadership. We can also refer the style of leadership as democratic style because it involves the input of values from the employees. Bill Gates believes in this theory and style and seeks for the success of an overall company. It is said that the success of Microsoft is due to the driving force of Bill Gates attitude along with his enthusiasm and hard work. He very well understands the business and the fluctuations that change the business environment and thus, Microsoft have been able to withstand all the difficulties to achieve success. Compared to the leadership style of Bill Gates, Steve Jobs offered a more of autocratic style of leadership. He was the only authoritarian of the company who did not bother to collect any input from his team members. Being the only person in charge he made all the decisions depending on the ideas that he conceives. This might seem to be harsh, but the style has given the great opportunity to Steve Jobs success. His key skill was Innovation and paying great respect and dedication for this innovation; Jobs has been able to make his company the most successful tech of the globe. He focused on the design of the computers that has benefited the company and the customers as well. Jobs prioritize the significance of taking a risk, and he is known as to be one of the biggest risk takers and leader of the world. Steve Jobs is reflective to his perspective and lunch from his mistakes easily. He is adaptable to changes in his self (Hill McShane, 2008). Bill Gates versus Steve Jobs Both the leaders are the enthusiast and much serious about their companies. However, considering the creativity level, Steve was more creative. On the other hand, if we considered the leadership styles would get is more efficient as a leader and management executive then Steve Jobs. He never thought of working alone and tried to develop the company with incorporating ideas of his team. To run an organisation, it will be advisable to use the management style and leadership style of Bill Gates along with the creativity and innovation of Steve Jobs. Both the leaders were great motivators. The team management system offered by Bill Gates was much more efficient than that of Steve Jobs. Bill Gates believes that working with the employees and taking an input of their ideas will lead to the development and success of the company. Whereas, Steve Jobs was many enthusiasts about his Innovation and ideas to develop the computer and operating systems for the customers and gain more popularity. According to the team management offered by Bill Gates, it is witnessed that he prioritises the feedback from his team members. This makes it easy for him to co-operate with the employees and bring out the maximum skills and talent his members are a position. On the other hand, Steve Jobs was less reluctant to hear from his team members, and that gradually led him to witness the downfall of his innovations. However, his talent and innovative ideas influence his team members in a positive way to work for his company. Steve Jobs is also concerned with the development which company. After t he launch of the iMac system, when there was the disruption in his relationship with the company and his partner, he faced great hardship and later on when he returned as an interim CEO of Apple, his ideologies had changed until then. This time he was a good leader who takes input from his team members to think more rationally and develop technical strategies for making Apple the biggest hub of computers (Carpenter, Bauer Erdogan, 2010). If you are in such an organization managing a team with huge expectation and leadership from their manager, identify what style of communication you would use to motivate your team Management and leadership qualities are interrelated with each other. A company which have high expectation from their performance needs a better guide and a management system. For being a good manager, it is necessary to exercise leadership styles properly on the employees of the company. The first and foremost thing to motivate the employees is to communicate with them. To motivate the employees through communication procedures, there are certain techniques which are as follows: Scheduled communication and oriented meetings once a week- arranging for scheduled meeting is necessary for both the management and the employees to communicate with each other. There might not be any valid purpose of the meeting but a platform of open communication. This will lead to hazard free and flexibility of the relationship. Asking questions to the Employees- it is necessary to go for random question answer rounds with the employees. They should be given the scope to speak up and communicate their problems to the management. This will help the management to build a better relationship with them and look for ways to solve their issues. Showing interest and concern for the employees- showing interest in the employee's behaviour and concerns make them feel taken care of, and that motivates them to stay dedicated to their work (Ramasamy, 2009). Offering solution to the Employees issues that frustrates them- for keeping the relationship positive it is important for the management to offer the proper solution to the Employees frustrations. It is not concerned with their personal issues but with the situations that they face within the company. Empathizing with the employees offers a better source of positivity. Keeping Communications positive- it is important to make positive communication with the employees that will influence and motivate them to work for the company. Instead of rebuking them for there for performance, management must give them opportunities and offer rewards for the improvement that make them feel galvanized (Daft, 2009). References Carpenter, M. A., Bauer, T., Erdogan, B. (2010).Principles of management. Daft, R. L. (2009).Principles of management. South-Western, Cengage Learning india Pvt. Limited. Hill, C. W., McShane, S. L. (2008).Principles of management(pp. 404-20). McGraw-Hill/Irwin. Ramasamy, T. (2009).Principles of management. Global Media.

Structural and Electronic Effects Acids and Bases Essay Example

Structural and Electronic Effects Acids and Bases Paper Lewis acid a substance that accepts an electron pair †¢ All BrOnsted-Lowry acids are also Lewis acids, but the reverse is not necessarily true. Any species that is electron deficient and capable of accepting an electron pair is also a Lewis acid. †¢ Common examples of Lewis acids (which are not BrOnstedLowry acids) include BF3 and AlCl3. These compounds contain elements in group 3A of the periodic table that can accept an electron pair because they do not have filled valence shells of electrons. †¢ Lewis base a substance that donates an electron pair 3 4 †¢ In a Lewis acid-base reaction, a Lewis base donates an electron pair to a Lewis acid. †¢ One bond is formed and no bonds are broken.This is illustrated in the reaction of BF3 with H2O. H2O donates an electron pair to BF3 to form a new bond. pKa’s AND ACID STRENGTH pKa An alternative to Ka to describe acid strength. (A concise way to state the strength of an acid. ) electron pair is not removed fr om the Lewis base. Instead, it is donated to an atom of the Lewis acid and one new covalent bond is formed. 5 1 Acid Strength and pKa †¢ Acid strength is the tendency of an acid to donate a proton. †¢ The more readily a compound donates a proton, the stronger an acid it is. †¢ Acidity is measured by an equilibrium constant. When a Bronsted-Lowry acid H—A is dissolved in water, an acid-base reaction occurs, and an equilibrium constant can be written for the reaction. Because the concentration of the solvent H2O is essentially constant, the equation can be rearranged and a new equilibrium constant, called the acidity constant, Ka, can be defined. It is generally more convenient when describing acid strength to use â€Å"pKa† values than Ka values. 7 8 COMPARISON OF pKa and Ka VALUES pKa = log Ka strong acids weak acids pKa -2 0 2 10-2 4 6 10-6 8 10 10-10 12 14 10-14 2 Ka 10 The smaller the value of the pKa the stronger the acid.We will use pKa to describe the strengths of acids. 10 EVALUATION OF ACID STRENGTH Commonly Used Bases in Organic Chemistry Common strong bases used in organic reactions are more varied in structure. HA + H2O H3O+ + A- In water, all acids form hydronium ion, the important factor of difference is the conjugate base. The difference between a strong acid and a weak acid is in the stability of the conjugate base. AA- E N E R G Y 11 WEAK ACID has strong conj. base (=higher energy) STRONG ACID has weak conj. base (=lower energy) HA ionization easier 2 EVALUATION OF ACID STRENGTH The weaker an acid, the stronger is its conjugate base; †¢ The stronger an acid, the weaker is its conjugate base. †¢ HCl is a very strong acid; it gives up its proton readily; its conjugate base, Cl-, has very little affinity for H+. It is a stable CB Factors that Determine Acid Strength †¢ †¢ Anything that stabilizes a conjugate base A:? makes the starting acid H—A more acidic. Four factors affect the acidity of H—A. These are: Element effects Inductive effects Resonance effects Hybridization effects †¢ No matter which factor is discussed, the same procedure is always followed.To compare the acidity of any two acids: o Always draw the conjugate bases. o Determine which conjugate base is more stable. o The more stable the conjugate base, the more acidic the acid. 14 †¢ CH3CO2H is a moderately weak acid; it gives up its proton somewhat reluctantly; its conjugate base, CH3CO2-, is weakly basic and has a modest affinity for H+. CB is relatively unstable 13 Element Effects—Trends in the Periodic Table. Factors that Determine Acid Strength: Across a row of the periodic table, the acidity of H—A increases as the electronegativity of A increases. Acids and BasesFactors that Determine Acid Strength—Inductive Effects †¢ An inductive effect is the pull of electron density through ? bonds caused by electronegativity differ-ences between atoms. †¢ In the example below, when we compare the acidities of ethanol and 2,2,2-trifluoroethanol, we note that the latter is more acidic than the former. Positive or negative charge is stabilized when it is spread over a larger volume. 15 16 †¢ When electron density is pulled away from the negative charge through ? bonds by very electronegative atoms, it is referred to as an electron withdrawing inductive effect. More electronegative atoms stabilize regions of high electron density by an electron withdrawing inductive effect. †¢ The more electronegative the atom and the closer it is to the site of the negative charge, the greater the effect. †¢ The acidity of H—A increases with the presence of electron withdrawing groups in A. TYPES OF INDUCTIVE EFFECTS ELECTRON WITHDRAWING GROUPS ELECTRON DONATING GROUPS ?Cl ?+ C ?+ CH3 ?C F, Cl, Br, N, O electronegative elements take electron density from cabon 17 R, CH3, B, Si alkyl groups and elements less electronegative than carbon don ate electron density to carbon INDUCTIVE EFFECTS HALOACIDS Chlorine helps to stabilize -CO2by withdrawing electrons Inductive effect in acids and bases O H H C H O C O H F H C H O C O H H3C H C H O C O H ?- ? + C Cl O C O O ?+ ?- ? + CH3-CO2 FCH2-CO2 CH3CH2-CO2CH3, electron donating ?Cl ?+ C ?- No substituent F, electron withdrawing C F makes O-H bond weak, easily broken – more acidic CH3 makes bond stronger, difficult to break – less acidic Strength of acids can also be determined by the stability of A:20 The effect diminishes with distance it carries for about 3 bonds.INDUCTIVE EFFECTS – 1 (EWG) increasing electronegativity INDUCTIVE EFFECTS – 2 (EDG) pKa Values H COOH CH3 CH3CH2 CH3CH2CH2 CH3 COOH COOH COOH pKa Values 3. 13 2. 87 2. 81 2. 66 CH3 COOH Cl CH2 COOH Cl Cl CH Cl Cl C COOH Cl COOH multiple substituents I Br Cl F CH2COOH CH2COOH CH2COOH CH2COOH 4. 75 2. 81 1. 29 0. 65 3. 75 4. 75 4. 87 4. 81 5. 02 CH3CH2CH2 COOH CH2CH2CH2 COOH Cl CH3 CH CH2 Cl CH3CH2 CH COOH Cl COOH 4. 8 4. 5 4. 0 2. 9 distance CH3 C COOH CH3 ELECTRONELECTRON-WITHDRAWING EFFECTS STRENGTHEN ACIDS O (-) R C OC OO (-) O OR S OOConversely †¦.. ELECTRONELECTRON-DONATING EFFECTS WEAKEN ACIDS O (-) R C OC OO (-) OOR S OO Any effect that â€Å"bleeds† electron density away from the negatively-charged end of the conjugate base will stabilize (lower the energy) of the conjugate base and therefore make the acid stronger. Any effect that â€Å"pushes† extra electron density toward the negatively-charged end of the conjugate base will destabilize (increase the energy) of the conjugate base and make the acid weaker. 4 Example 1: Compare the acids of H2O, HOCl and CH3OH Dissociation productsExample 2: Compare the acids of CH3OH, and (CH3)3COH Dissociation products H 2O HOCl CH3OH H OO O- H+ + OHH+ + ClOH+ + CH3O- CH3OH (CH3)3COH CH3 H+ + CH3OH+ + C(CH3)3O- NO EWG or EDG CH3 is EDG, therefore anion is unstable Cl is EWG, therefore anion is more st able Compare stability Compare stability CH3 Cl CH3 O- H3C C CH3 O- Both have EDGs which leads to anion instability 1 x CH3 3 x CH3, ClO gt; OH gt; CH3O most stable to least stable anion HOCl gt; H2O gt; CH3OH acid strengths 25 Therefore (CH3)3CO anion is less stable than CH3O- anion. (CH3)3COH weaker acid 26 5