Chapter 17

Question 1

Succession

Answer 1

change in species composition of communities over time

Question 2

Disturbances

Answer 2

abiotic events that physically injure or kills some individuals and creates oppurtunities for other individiuals to grow and reproduce

Question 3

Abiotic Factors

Answer 3

Wave, currents, wind, water supply, chemical composition, temperature, volcanic activity

Question 4

Biotic factors

Answer 4

Negative interactions: competition, predation, herbivory, disease, parasitism, trampling, digging

Question 5

When does stress occur?

Answer 5

when abiotic factors reduce growth, reproduction, or survival of individuals and creates opportunities for others

Question 6

Succession

Answer 6

The process by which species composition of a community changes over time.
Involves colonization and extinction by abiotic and biotic factors

Question 7

Climax stage

Answer 7

a stable end point that experiences little change until an intense disturbance sends community back to an earlier stage

Question 8

Primary succession

Answer 8

involves colonization of habitats devoid of life, potentially due to a catastrophic disturbance (such as on pumice plain at mount st. helens) or since they are newly made habitats such as volcanic rock.

Question 9

Secondary succession

Answer 9

involves reestablishment of a community in which most, not all, of the organisms or organic constituents have been destroyed

Question 10

Henry Chandler Cowles

Answer 10

studied successional sequence of vegetation in sand dunes on the shore of lake Michigan.
Cowles found a successional pattern by assuming plant assemblages farthest from lakes edge were oldest and ones nearest lakes are the youngest

Question 11

Space for time substitution

Answer 11

used frequently to study communities over time scales that exceed life spans of ecologists, assumes that main factor of change is time, and unique conditions in specific locations are inconsequential

Question 12

What did Clements and Gleason believe

Answer 12

Clements believed plant communities are like superorganisms that work together for some deterministic end and Gleason viewed individual species response to prevailing conditions as significant

Question 13

Examples of how animals influence successional patterns

Answer 13

Eating
Dispersing
Trampling
And destroying

Question 14

Facilitation model (inspired by clements)

Answer 14

early colonizers modify environments to benefit future species while limiting their own dominance, with the progression leading to a climax community where species no longer facilitate others and are displaced by disturbances.

Question 15

Tolerance Model

Answer 15

earliest colonizers modify the environment neutrally, with early species reproducing and growing quickly, while later species persist through slow growth, few offspring, and long life, allowing them to tolerate stresses hindering early successional species.

Question 16

Inhibition model

Answer 16

early successional species modify the environment to hinder later successional species by monopolizing resources, and this inhibition is broken when stress or disturbance reduces the abundance of the inhibitory species, enabling the persistence of later species through tolerance of environmental or biological stresses.

Question 17

Glacial Retreat in Alaska (Cooper)

Answer 17

The melting glaciers initiated a prolonged sequence of community change, spanning centuries and progressing through pioneer, dryas, alder, and spruce stages, as evidenced by permanent plots tracking plant species richness and composition, with soil analysis highlighting notable increases in organic matter and soil moisture.

Question 18

Facilitation and Inhibition Experiments in Alaska (Chapin)

Answer 18

Manipulative experiments involving spruce seeds across various successional stages revealed changing patterns of facilitative and inhibitory effects on spruce seedlings, with low germination in pioneer and dryas stages, a net positive effect in the alder stage, and predominantly negative effects in the spruce stage due to competition.

Question 19

Salt Marsh Secondary Succession in New England (Mark Bertness and Scott Shumway)

Answer 19

The study on salt marsh secondary succession examined facilitative and inhibitory interactions, where disturbance in the form of wrack created bare patches; cordgrass inhibited distichlis in low intertidal zones, while black rush could colonize in the middle zone under specific conditions of distichlis presence or watering, with salt stress influencing the outcomes.

Question 20

Sousa’s experiments in SoCal

Answer 20

Disturbances caused by waves and low tides initiate colonization and succession, as demonstrated by Sousa’s Southern California boulder field experiments, where algae domination, particularly Ulva lactuca and Gigartina canaliculata, indicated inhibition as the primary mechanism, with the transition to mid-successional algal species influenced by grazing crabs.

Question 21

Terence Farrell study in Oregon

Answer 21

challenged the prevailing view by revealing context-dependent inhibition in sessile-dominated communities, where Chthamalus dalli, Balanus glandula, and three macroalgal species displayed a succession pattern, with Balanus facilitating macroalgal colonization and supporting the facilitation model.

Question 22

Alternative scenarios and Stable States

Answer 22

Numerous experimental studies indicate that communities undergo succession driven by a combination of facilitation, inhibition, and tolerance mechanisms, with pioneer stages experiencing physical stressors and facilitative interactions being more prominent in early succession, leading to the dominance of slow-growing, long-lived species as succession progresses.

Question 23

John Sutherland Study

Answer 23

Communities can exhibit stability, characterized by a return to the original structure and function after disturbance, with stability dependent on spatial and temporal scales; John Sutherland’s study on marine fouling communities identified alternative stable states, where sessile species like Styela and Schizoporella demonstrated stability influenced by fish predation.

Question 24

Shifts caused by Human Activities

Answer 24

Human activities, including habitat destruction, species introductions, and overharvesting, have the potential to induce shifts in communities to alternative states, and these shifts may be irreversible (hysteresis); however, excluding ecosystem engineers in models can introduce spatial state issues, exemplified by tiles lacking a high spatial state.

Question 25

Hysteresis

Answer 25

inability to shift back to original community type even when original conditions are restored