5/6Wetland Ecosystem Development and Succession in Ecology Save

What is succession in ecology?

Succession refers to predictable and orderly changes in the composition or structure of an ecological community.

What initiates ecological succession?

Succession may be initiated by the formation of new unoccupied habitat or by disturbances of an existing community.

What is primary succession?

Primary succession occurs in areas where no soil is initially present.

What is secondary succession?

Secondary succession begins in areas where soil is already present.

What is a sere in ecological terms?

A sere is a series of ecological communities formed in ecological succession.

Who enunciated the concept of autogenic succession?

The concept of autogenic succession was enunciated by Clements in 1916.

What are the three fundamentals of classical succession?

1. Vegetation occurs in recognizable communities. 2. Community change is dependent on biota. 3. Changes are directed toward a stable climax ecosystem.

What is the role of organic material in autogenic succession?

Organic material accumulation from plant production builds up the surface until it can support terrestrial forest species.

What does allogenic succession refer to?

Allogenic succession refers to changes in vegetation based on environmental conditions at a site.

What is the continuum concept in plant distribution?

The continuum concept holds that species distribution is governed by individual responses to the environment.

How do propagules affect wetland vegetation?

The chance distribution of propagules at a site affects the invasion/replacement sequence of species.

What are wetlands considered in ecological terms?

Wetlands are considered transitional ecotones between aquatic and terrestrial environments.

What is an example of a strong allogenic forcing function in wetlands?

Water levels can act as a strong allogenic forcing function

What are some historic names for different types of wetland communities?

Salt Marsh

What is the significance of zonation patterns in wetlands?

Zonation patterns may represent sharp environmental gradients that are ecologically steep.

How do abiotic factors influence wetland communities?

Abiotic factors often overwhelm biotic forces

What is pulsed equilibrium in salt marshes?

Pulsed equilibrium refers to the dynamic balance of salt marsh plants with overriding tidal forces.

What is the debate surrounding autogenic vs. allogenic processes in wetlands?

The debate centers on whether biota determine their future by changing their environment or if ecosystem development is a response to external conditions.

What is the classical view of wetland development?

The classical view considers wetlands as transient stages in the hydrarch development of a forested community.

What is the impact of drainage on organic soils in wetlands?

Once drained

What is the significance of the community concept in wetland literature?

The community concept emphasizes distinct vegetative associations based on particular plant species.

What do supporters of the continuum concept argue?

Supporters argue that individual species respond to subtle environmental cues rather than forming distinct communities.

What are allogenic processes in wetland ecosystems?

Processes determined by abiotic factors that influence plant species composition and distribution.

What is a seed bank?

A buried reserve of viable seeds that plays an important role in wetland succession.

What are two generalizations about present vegetation in some sites?

1. It has existed for several thousands of years. 2. Climatic change and glaciation had major impacts.

How do bogs respond to climatic changes?

Bogs expand during warm wet periods and constrict during cool dry periods.

What factors influence seed germination in wetlands?

Flooding

What is the Functional Guild Model?

A model that predicts plant community presence based on species traits and environmental filters.

What is the Environmental Sieve Model?

A model that describes how environmental factors determine species presence in a community.

What is the significance of moisture in wetland plant development?

Many wetland plants require moist but not saturated conditions for germination and establishment.

What is the relationship between P:R ratios in mature and immature ecosystems?

Mature systems exhibit P:R ratios around 1

What role do ecosystem engineers play in wetland ecosystems?

They significantly affect their environment and can influence hydrology and vegetation.

What are the characteristics of wetland ecosystems?

They exhibit high productivity

What is the impact of salinity on seed production in wetlands?

Saline zones produce few seeds as asexual reproduction dominates.

What is the effect of sediment depth on seed distribution?

Seed distribution decreases exponentially with depth of sediment.

What is the role of pre-emption in plant community development?

Chance plays a significant role in the development of plant communities

How do previous occupants of a site affect future colonization?

They determine what propagules are present for future colonization.

What are the three advantages of the Functional Guild Model over the community concept?

1. It simplifies species into manageable subsets. 2. It defines guilds by measurable functional properties. 3. It enables predictions of guild presence based on environmental conditions.

What is the significance of detrital-based systems in wetland ecosystems?

They are characteristic of mature systems and support complex food webs.

What are some factors that can insulate an ecosystem from its environment?

Genetic modifications at the individual level and peat production at the ecosystem level.

What does the term 'autogenic' refer to in wetland ecosystems?

Processes that are driven by the organisms within the ecosystem

What is the impact of flooding on seed banks?

Wetlands with draw-downs produce the greatest number of seeds.

What is the relationship between biomass production and ecosystem maturity?

Mature ecosystems exhibit balanced biomass production and respiration rates.

What is the role of nutrients in seed bank dynamics?

Nutrients are crucial for seed germination and plant establishment in wetlands.

How do complex life cycles affect wetland consumers?

They typically have short life cycles but are intricately linked to the ecosystem's dynamics.

What evidence suggests that both allogenic and autogenic processes are at work in wetlands?

High productivity

What is the length of the Mississippi River?

Approximately 2

Which river is the chief tributary of the Mississippi River?

The Missouri River.

What is the combined length of the Missouri-Mississippi river system?

Approximately 3

How much area does the Mississippi River watershed drain?

About 1

How many states does the Mississippi River watershed cover?

All or part of 31 states.

What is the average discharge of the Mississippi River?

16

What is the primary productive resource yielded by the Mississippi River delta?

Large amounts of sulfur

What are the components of a delta?

Drainage Basin

What is the function of the drainage basin?

It indicates how much land drains into the delta.

What is an alluvial valley?

The edge of recent deposition areas resulting from overbank flows.

What does the delta plain include?

All geologically recently laid sediments

When does the highest river discharge into the Gulf of Mexico occur?

Between March and May.

What percentage of the Mississippi River's flow enters the Gulf of Mexico through the bird-foot delta?

Approximately 70%.

Where does the remaining 30% of the Mississippi River's flow discharge?

Into the Gulf of Mexico through the Atchafalaya River.

What is the receiving basin for the Mississippi River?

The Gulf of Mexico.

What is progradation in the context of a delta?

The growth of a delta seaward through the accumulation of sediments.

What materials accumulate first during delta progradation?

Sandy materials

What is necessary for a delta to continue prograding?

The sediment supply must exceed the rate of relative sea level rise.

What is the significance of the Mississippi River's sediment discharge?

It discharges over 200 million tons of sediment each year.

What happens to the sediments if the water flows through the Atchafalaya River?

They would flow into the Atchafalaya River instead of the Mississippi River.

What type of deposits are found in the Northern Gulf of Mexico?

Terrigenous

What is the slope of the Northern Gulf of Mexico?

Extremely gradual

What is the primary challenge for sub-aqueous sediments in the delta?

They are often unstable due to the speed at which they are deposited.

What is the delta cycle?

The process of sediment accumulation and delta growth over time.

What is the time frame for the Sale-Cypremort delta?

4500 years before present (yr bp)

What is the time frame for the Cocodrie delta?

4500-3500 years before present (yr bp)

What is the time frame for the Plaquemine delta?

750-500 years before present (yr bp)

What phase is characterized by fluvial dominance in delta growth?

Progressive Phase

What occurs during delta switching?

Marine dominance in delta growth

What are the main controls on delta growth?

Drainage and receiving basin conditions

What factors are vital for the vitality of a delta?

Soil type and amount of rainfall

How can human activities alter delta growth?

By changing climate

What is delta retrogradation?

The process where a delta begins to disappear due to insufficient sediment supply to offset sea level rise

What can cause retrogradation in a delta?

Fast sea level rise

What has accelerated land loss in the Mississippi Delta since the 20th century?

Human activities such as oil and gas production and flood control measures

What is the current rate of land loss in the Mississippi Delta?

Approximately 25 square miles per year

What impact do levees have on sediment supply to the Mississippi Delta?

They cut off sediment-laden overbank flow that nourishes wetlands

What is the average shoreline erosion rate in the Mississippi Delta?

10 meters per year

What is the primary problem facing the Mississippi River Delta Basin?

Sediment starvation

Why has the growth of an emergent delta nearly stopped?

The river deposits sediments into deep water

What are the consequences of pipeline and service canals in the delta?

They erode edges faster and increase saltwater incursion into wetlands

What happens to wetlands due to human activities in the Mississippi Delta?

They are starved of sediment and suffer from compaction and subsidence

What is the role of hurricanes in delta dynamics?

They are a natural process that affects delta stability and land loss

What is the significance of sediment supply in delta maintenance?

It counteracts subsidence and supports wetland health

What is the effect of climate change on delta growth?

It can alter sediment supply and growth rates of the delta

What does the term 'stream capture' refer to in delta dynamics?

The process where one stream captures the flow of another

What is meant by 'delta lobe degradation'?

The deterioration of delta lobes due to environmental changes or human impact

How does the Mississippi River's levee system impact its delta?

It prevents natural changes in the river's course and sediment deposition

What is the relationship between sediment compaction and wetland lifespan?

Compaction reduces the lifespan of emergent wetlands

What is a major consequence of reduced river flow in the delta?

It can lead to sediment supply declines and increased land loss

What is the significance of the term 'dewatering' in delta dynamics?

It refers to the removal of water from deposited sediment