Ecology: Ecosystem Processes and Succession

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Questions and Answers

What key processes are involved in the operation of an ecosystem?

Pollination and seed dispersion

Only the influence of abiotic factors

Production, growth, and death of living components (correct)

Only the growth of living components

How do living components in an ecosystem influence abiotic factors?

By enhancing soil nutrients only

Only by storing energy in the food chain

Through their effects on habitat non-living elements (correct)

By reducing the temperature of the environment

Which statement accurately reflects the relationship between biotic and abiotic factors in an ecosystem?

Abiotic factors have no relation to living components

Biotic factors exclusively determine the abiotic conditions

Biotic and abiotic factors interact to shape ecosystems (correct)

Only abiotic factors are impacted by biological processes

What happens to the ecosystem when living components die?

It disrupts the production cycle Signup and view all the answers

Which of the following is NOT a principal step in the operation of ecosystems?

Growth of abiotic factors Signup and view all the answers

What does the term 'succession' specifically refer to in an ecological context?

The gradual change in species composition and community shape over time. Signup and view all the answers

Which of the following best describes the state of a community during succession?

It is in a continuous state of dynamic change. Signup and view all the answers

In relation to sample-plots, which statement is accurate?

Many lines can be present in sample-plots or study areas. Signup and view all the answers

What does the changing state of a community during succession imply?

The ecological roles of species within the community may change over time. Signup and view all the answers

Which factor is NOT likely to affect succession in ecological communities?

The historical migration patterns of animals. Signup and view all the answers

What distinguishes a terrestrial ecosystem from an aquatic ecosystem?

Terrestrial ecosystems operate on land. Signup and view all the answers

Which of the following is NOT a type of terrestrial ecosystem?

Oceanic ecosystem Signup and view all the answers

Which of these ecosystems is characterized by minimal rainfall and extreme temperatures?

Desert ecosystem Signup and view all the answers

How many types of terrestrial ecosystems are mentioned?

Three types Signup and view all the answers

Which type of ecosystem primarily consists of plants like grasses and few trees?

Grassland ecosystem Signup and view all the answers

What product is formed when calcium hydroxide reacts with carbon dioxide?

Calcium bicarbonate Signup and view all the answers

In the reaction 2KOH + CO2 → K2CO3 + H2O, what is the role of CO2?

It serves as a reactant. Signup and view all the answers

What is the likely outcome when acids are formed in the soil?

Nutrient availability decreases. Signup and view all the answers

What is produced alongside potassium carbonate in the reaction involving KOH and CO2?

Water Signup and view all the answers

Which of the following is true about the reaction Ca(OH)2 + 2CO2 → Ca(HCO3)2?

It forms a soluble product. Signup and view all the answers

What role do soil colloids play in water retention in the soil?

They hold water tightly in a thin film around soil particles. Signup and view all the answers

Which statement accurately describes the relationship between soil particles and water?

Soil particles are surrounded by a thin film of water due to soil colloids holding it tightly. Signup and view all the answers

How does the structure of soil colloids affect the retention of water?

They generate strong forces that effectively hold water molecules. Signup and view all the answers

What is the significance of the thin film of water around soil particles?

It facilitates the absorption of nutrients by roots from the soil. Signup and view all the answers

What forces are responsible for holding water so tightly around soil particles?

Chemical forces generated by soil colloids. Signup and view all the answers

What is the resultant size of a plant affected by repeated drying winds before maturity?

Subnormal size Signup and view all the answers

Which factor does NOT contribute to the deformation of a plant's shoot system?

Intermittent rain Signup and view all the answers

What effect does abrasion have on plant leaves?

It erodes the leaves Signup and view all the answers

What is a primary consequence of prolonged exposure to drying winds for a normal plant?

Decreased cell expansion Signup and view all the answers

How does erosion affect a plant's outer layer?

It removes the outer layer Signup and view all the answers

What condition leads to a plant retaining a dwarf form?

Constant exposure to strong winds Signup and view all the answers

What ultimately happens to a plant subjected to aerodynamic force from wind over time?

It may deform or erode Signup and view all the answers

What is a crucial early effect of wind acting as an abrasive force on plants?

Erosion of the outer layer Signup and view all the answers

Study Notes

Plant Ecology

Plant ecology is the scientific study of the relationship between plants and their environment.
It's related to other branches of botany and science.
Ecology derives from the Greek words: oikos (house) and logos (study of), denoting the study of relationships between organisms and their surroundings.
Plant ecology has two main types:
- Autoecology: studying specific plants in their natural habitats to understand how environmental factors influence them.
- Synecology (Phytosociology): studying plant communities in an area to understand their structures, origins, development, distribution, and how factors like environmental conditions affect these communities.

Branches of Plant Ecology

Autoecology, focusing on individual plants and their responses to the environment.
Synecology (Phytosociology), focusing on plant communities and their interactions.

Relationship Between Plant Ecology and Other Branches of Botany

Plant ecology is closely related to other branches of botany and science.
Morphology and Anatomy: plant structure is often linked to environmental adaptations.
Physiology: plant functions, like transpiration and osmotic pressure, are affected by ecological factors.
Taxonomy: plant classification is crucial for understanding plant communities.
Meteorology: accurate data on climate factors such as temperature, precipitation and wind are essential for understanding communities.
Pedology: the study of soil properties is vital for understanding plant growth as roots need minerals and nutrients from soil.
Hydrology: the study of water properties, like depth and currents, is crucial in ecosystems with aquatic plants.
Geography: distribution pattersn of plants and their classification into groups.
Geology: study of earth layers is needed for the study of old plants and evolution.

Definition of Environment and Habit

Environment includes all factors that affect a plant's growth, reproduction, etc.
Habitat or habit refers to the location where a plant lives.

Environmental Factors

Environmental factors are classified into: climatic factors, edaphic factors, physiographic factors, and biotic factors.

Climatic Factors

Climatic factors influence plant life directly and indirectly. Including:
- Light: affects chlorophyll formation and number of chloroplasts
- Temperature: crucial for all metabolic processes like germination, growth, reproduction, transpiration.
- Wind
- Humidity
- Evaporation

Light

Light affects the number and position of chloroplasts, and the formation of chlorophyll.
Plants are divided into sun plants (growing directly under sunlight) and shade plants (growing indirectly under sunlight)

Temperature

Plant temperature follows its medium. Shoot system is affected more by air temperature; root system is affected more by soil temperature
All metabolic processes increase with increasing temperature (germination, growth, reproduction, transpiration).
Each plant has a specific temperature range for growth, between a minimum and maximum temperature.

Temperature and Transpiration

There are two main types of transpiration:
- Stomatal transpiration: water vapor exits through plant stomata.
- Cuticular transpiration: occurs at high temperatures where stomata are closed. This is more prevalent than stomatal transpiration.

Humidity

Absolute humidity: the actual amount of water vapor in the air.
Relative humidity: the proportion of water vapor in the air compared to the maximum amount it can hold at the given temperature.
Factors affecting humidity: temperature, and wind

Evaporation and Wind

Evaporation is water movement from any surface.
Wind is air in motion that has both positive and negative effects on plants.
Negative effects (harmful):
- Desiccation
- Dwarfing
- Deformation
- Abrasion
- Erosion and deposition

Edafic Factors

Edafic factors include all physical and chemical soil properties affecting plant growth, including soil texture, profile, moisture, organic matter, soil reactions, and mineral content.
Plants heavily affected by edaphic factors are referred to as "Edaphic plant communities".

Importance of Soil

Fixation: Plants are fixed in soil through their roots.
Supplying plants with water and minerals.
The source of organic matter (humus).
Medium for root respiration and aeration

Origin of Soil

Two main types of soil:
- Residual soil: comes from the disintegration of local rocks.
- Transported soil: moved from another location.

Soil Formation

Soil forms from the outer layer of Earth's crust.
Disintegration occurs through (mechanical processes) and physical factors:
- Temperature change: heating and cooling causes mineral expansion and contraction, leading to disintegration.
- Water influence: water absorption in porous rocks causes swelling and splitting, resulting in disintegration.
- Wind and volcanoes: Wind carries soil particles; volcanoes erupt and deposit material.

Chemical Processes of Soil Formation

Chemical processes change the chemical composition of soil materials, also known as weathering. This includes oxidation, reduction, hydration, and hydrolysis.
Carbonation occurs from CO2 combining with soil bases to create carbonates and bicarbonates.
Solution: acids formed in soil are more effective at decomposing rocks and minerals.

Soil Organic Matter (Humus)

An essential difference between fertile soil and infertile soil is whether the former contains organic matter.
Soil humus is the end product of organic matter decomposition from plant and animal organic matter.
Humus is dark-colored, and resistant to decomposition. It is composed of long-branched chains,.
Importance of humus:
- Source of nitrogen (N) from proteins
- Increases water holding capacity (from colloid content)
- Increases soil aeration (from aggregate formation).

Soil Texture

Soil properties heavily depend on particle size which can be determined using sieve methods.
Based on particle size, soil can be classified into coarse particles (gravel,sand), intermediate particles (silt), and fine particles (clay).
Important groupings of soils based on their characteristics include:
- Sandy Soil
- Loamy Soil
- Mud Soil

Effect of Soil Texture on Soil Features

Water holding capacity: high ratio of fine particles can absorb large quantities of water compared with coarser particles.
Infiltration of water: Sandy soil absorbs water easily, while clay soil absorbs slowly.
Fertility: A high proportion of fine particles usually correlates with higher fertility.
Mechanical resistance to root penetration: Heavy clay soils are harder for roots to penetrate compared with lighter sandy soils.
Rate of water movement: Water movement is fastest through sands and slowest through clays.
Aeration: Sandy soil has good aeration; whereas, clay soil has poor aeration.

Soil Profile

Soil profile is a vertical section of soil that shows different layers with different characteristics. Layers are called horizons.
Horizons of soil profile include:
- A-horizon: upper, surface layer.
- B-horizon: lower layer, concentration of minerals.
- C-horizon: consists of weathered parent material.
- D-horizon: original rocks.

Water Content of Soil

Water is vital for living organisms.
Types of soil water:
- Gravitational water
- Capillary water
- Hygroscopic water
- Combined water

Topographic Factors (Physiographic Factors)

Controlled by landforms (altitude, slope, exposure).
They influence local climates and factors like wind and rainfall.
Important for plant distribution, density, and the type of plants in a particular habitat.

Biotic Factors

Green plants are influenced by other living organisms.
Plants influence each other by factors like shading.
Other biotic factors: grazing (animals eating plants), pollination (animals aiding in reproduction), dissemination (seeds dispersal by animals).

Ecosystems

Ecosystems consist of two basic components:
- Autotrophic (produces its own food): green plants
- Heterotrophic (depends on other organisms for food): animals, fungi
Components of ecosystem based on its structure:
- Abiotic components: non-living (soil, water, air).
- Biotic components: living (producers, consumers, decomposers).

Food Chains and Food Webs

Food chain: a sequence of organisms where each eats the one before it.
Food web: the network of interconnected food chains. Food web demonstrates interdependence among organism in an ecosystem.
Types of food chains:
- Predator chain: starts with a plant to a predator eating a larger animal.
- Parasitic chain: starts with a larger organism to a smaller parasite.
- Saprophytic chain: starts with dead matter to microorganisms.

Vegetation

Vegetation is the sum total of plants in an area.
Basic units of vegetation are plant communities.

Plant Communities

A plant community is a group of plants found in the same habitat with growth controlled by similar environmental conditions.
Plant community orders:
- Plant formations (based on life form, like forest, grassland, etc)
- Associations (groups of related plant types)
- Consociations (one dominant species)
- Societies (highly organized communities)

Methods of Vegetation Analysis

Quadrate method: using plots (quadrates) to determine species, frequency, density, and distribution. Different types of quadrats include list, count, cover.
Transect method: using a line or strip to sample plants (belt transect, line transect)

Succession

Succession is the gradual change of plant communities in an area over time.
Two main types of succession:
- Hydrosere (starts in water)
- Xerosere (starts on dry land)

Stages of Hydrosere

Submerged stage: pioneer plants like Elodea and Ceratophyllum are completely submerged.
Floating stage: plants like Eichhornia and Nymphaea develop, with leaves floating on the water surface.
Reed-swamp stage: the ecosystem is now filled with reeds and other emergent vegetation.
Sedge-meadow stage: grasses and herbs dominate.
Woodland stage: trees begin to appear and shade-loving herbs die back.
Climax forest: a mature forest develops and the dynamics of the ecosystem stabilize.

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Description

This quiz explores key processes involved in ecosystem operation, focusing on the interactions between biotic and abiotic factors. You'll learn about the concept of succession in ecology and how changes within a community can influence the ecosystem. Test your understanding of these critical ecological principles!