Forestry and Agriculture Concepts
Forestry Introduction
Key Sections: 5.2 & 5.17
Interactions Between Different Species and the Environment
Big Idea ENDURING UNDERSTANDING: When humans use natural resources, they alter natural systems.
Learning Objectives
Describe the effect of clear cutting.
Benefits of a Forest
Trees absorb pollutants.
Trees store carbon dioxide.
Trees produce oxygen.
Height of trees:
Example: 115m tall trees.
Inquiry: How can trees be so tall?
Clearcutting
Definition: A method of timber harvesting in which all trees in a forested area are removed in a single cutting.
Economic Advantage: Economically advantageous for timber harvesting.
Effects of Clear Cutting
Soil Erosion (Geosphere): Clearcutting leads to increased soil erosion.
Increased Soil and Stream Temperatures (Geosphere and Hydrosphere): Removal of trees affects local temperatures.
Flooding (Hydrosphere and possibly Biosphere): Changes to ecosystem lead to flooding risks.
Habitat Loss (Biosphere): Displacement of wildlife due to habitat destruction.
Release of Carbon Dioxide: Cutting and burning trees releases CO₂, contributing to climate change (Atmosphere).
Deforestation
Definition: The complete alteration of an area of forestry, replaced for other uses like agriculture or settlements.
Silviculture
Definition: The practice of manipulating forest vegetation to control establishment, composition, and growth to meet objectives of the forest owner.
Silviculture Treatments: Applied at the stand level to manage forests.
Forest Structure: A collection of stands administered as an integrated unit (compartments).
Silviculture System: A program of forest management for an entire rotation or rotation age of a stand, including harvest cutting, regeneration, and intermediate treatments.
Regeneration Methods: Concurrently harvest timber and establish tree reproduction (e.g., cut, site preparation, replant).
Forest Management: Planning and executing activities across a large area to satisfy multiple management goals such as wildlife management, recreation, and timber harvest.
Forestry Practices
Types of Forestry Practices:
Clear-cutting
Seed tree harvesting
Selective cutting
Shelterwood
Slash and burn agriculture
Strip cutting
Sustainability
Big Idea ENDURING UNDERSTANDING: Humans can mitigate their impact on land and water resources through sustainable use.
Learning Objectives
Describe methods for mitigating human impact on forests.
Mitigating Deforestation
Reforestation: Renewal of trees and other types of vegetation on land where trees have been removed.
Sustainable Forestry Techniques:
Selective Logging: Only harvesting certain trees instead of clear-cutting. Preserves forest balance and valuable resources.
Maturity: Longer time for young trees to mature increases long-term forest value.
Replanting: Planting new saplings after harvesting to restore forest.
Protecting Forests from Pathogens and Insects
IPM: Integrated Pest Management techniques to manage pests.
Methods of Control:
Removal of infected trees.
Awareness of tree diseases and destructive insects.
Prescribed/Controlled Burn
Importance: Controlled burns help manage forest fire risks.
Types of Fire:
Surface Fire
Crown Fire
Industrial Agriculture
Influence of the Green Revolution on agricultural practices.
Land Needed for a Growing Population
Population Changes: Calculate percent change in population size from 2009 to 2017.
Caloric Needs: Average person needs 2,450 kcal/day; average kcal/ha produced is 15,737,000 kcal/ha.
Calculation required for land needs to feed one person for one year.
Feeding the Population in 2017: Calculate necessary land for 2017 population.
Historical Context of Agriculture
Growth of agriculture parallels population changes over time.
Key historical milestones include the beginnings of agriculture in 10,000 BC, Industrial Revolution, etc.
Green Revolution
Shift in reliance from humans and animals to machinery.
Agricultural methods:
Polyculture and monoculture practices.
Fertilizer use vs. traditional methods.
Increased reliance on irrigation systems.
Increasing Profits in Agriculture
Mechanization enhances efficiency but increases fossil fuel reliance.
Tilling
Definition: Preparing land for raising crops through activities like plowing and harrowing.
Slash and Burn Agriculture
Definition: Felling and burning of forest vegetation, cropping for a few years, then allowing forest reinvasion.
Sahel Region Case Study
Livelihood strategies focus on crop growth and grazing animals.
Land management trends lead to desertification due to overgrazing and crop planting cycles.
Fertilizer
Definition: Substances that enhance soil fertility (e.g., manure, chemical mixtures).
Industrial Fertilizer Components: Nitrogen, Phosphorus, Potassium.
Use of Fresh Water
Distribution:
Public Supply: 15%
Agriculture: 76%
Types of Irrigation
Methods:
Flood irrigation
Drip irrigation
Spray irrigation
Furrow irrigation
Center pivot irrigation
Valley irrigation
Problems with Irrigation
Waterlogging: Excess water raises groundwater and limits oxygen absorption by plants.
Flood Irrigation: Loss of 20% of water from evaporation/runoff.
Furrow Irrigation: Inexpensive but entails about one-third loss of water.
Spray Irrigation: More efficient, with less than 25% lost but more costly; requires energy.
Drip Irrigation: Most efficient, only about 5% loss but expensive.
Salinization and Aquifer Depletion
Salinization Risk: Irrigated water can lead to toxic soil conditions. Examples: Australia, California, Arizona.
Aquifer Depletion: Overuse of aquifers, e.g., the Ogallala Aquifer, negatively affects water availability.
Case Study: Arizona
Agrarian challenges due to climate.
Irrigation reliance on Colorado River and groundwater.
Inquiry to compare irrigation methods: furrow vs. flood irrigation.
Dust Bowl
Historical context (1930-1939).
Relation to agricultural practices and climatic factors.
Weathering vs. Erosion
Definition: Distinctions between processes.
Pesticides and Pest Control
Types:
Herbicides
Fungicides
Rodenticides
Insecticides
Pesticide Treadmill: Economic model of increasing pesticide resistance and reliance.
GMOs (Genetically Modified Organisms)
Benefits: Increased resistance to pests/diseases.
Drawbacks: Risk to genetic diversity in crops.
Historical context and ethical concerns.
Delaney Clause
Definition: Provision of the Food, Drugs, and Cosmetic Act of 1938 prohibiting cancer-inducing chemicals in food.
Animal Farming
Overview of sustainable practices and ethical considerations.
Learning Objectives in Animal Farming
Various methods and implications for sustainability.
Meat Production Efficiency
Fact: Producing meat requires approximately 20 times the land for equivalent caloric yield compared to plants.
Methods of Meat Production
Types:
Free Range Grazing
CAFOS (Concentrated Animal Feeding Operations aka Feedlots)
Benefits & Drawbacks of Free Range Grazing
Benefits: Happier animals, cost-saving, healthier produce, reduced insects, better crop production.
Drawbacks: Supervision needs, potential for gardening damage, dust, hiding of eggs, manure issues, predation fears.
Concentrated Animal Feeding Operations (Feedlots)
Inquiry into singular advantages and disadvantages in meat production practices.
Overgrazing
Definition: Excessive feeding by livestock leading to vegetation loss and soil erosion.
Desertification
Definition: Process caused by overgrazing, degrading moist areas into arid conditions.
Environmental Impact of Reduced Meat Consumption
Less meat consumption can lower emissions (CO₂, methane, N₂O), conserve water, limit antibiotic use, and improve soil quality.
Overfishing
Issue of species scarcity impacting biodiversity and human livelihoods dependent on fishing.
Book recommendation: "Four Fish" by Paul Greenberg
Sustainable Agriculture
Overview of concepts encapsulating sustainability in agricultural and forested contexts.
Definition of Sustainability
Refers to resource use to avoid depletion for future generations.
Environmental Indicators: Biological diversity, food production rates, global temperature averages, CO₂, population sizes, and resource depletion trends.
Sustainable Yield
Definition: Amount of renewable resource extractable without reducing the available supply.
Natural Capital Degradation
Overview of environmental, health-related, and economic concerns stemming from unsustainable practices.
Sustainable Agriculture Goals
Aim to maximize soil quality while minimizing energy, water use, pesticide, and fertilizer reliance.
Organic farming fits within sustainable agriculture.
Soil Conservation Techniques
Techniques include contour plowing, windbreaks, perennial crops, terracing, and no-till agriculture.
Increasing Soil Fertility
Methods include crop rotation, use of green manure, and liming practices.
Rotational Grazing
Definition: Regular livestock rotation to prevent overgrazing in certain areas.
Aquaculture
Refers to the controlled cultivation of aquatic organisms for various purposes.
Benefits: High efficiency and low fuel dependence.
Drawbacks: Wastewater contamination, potential wild fish competition, and disease transmission risks.
Integrated Pest Management (IPM)
Definition: Environmentally sensitive pest management combining diverse strategies.
Core Concepts: Current info on pest life cycles and environmental interactions.
IPM and Pesticides
Clarification that IPM does not eliminate pesticide use but manages their applications based on damage thresholds.
Components of an IPM Program
Potential actions include: resistant varieties, beneficial insects, microbial pesticides, birth control methods, biochemical pesticides, cultivation practices, synthetic pesticides, and computer programs.
Resistant Varieties
Development of pest-resistant crops (e.g., Hessian fly resistant wheat).
Beneficial Insects
Use of organisms such as parasitic wasps and ladybugs to control pest populations.
Microbial Pesticides
Example organisms:
Nosema locustae (in grasshoppers).
Bacillus thuringiensis (B.t.) targeting specific caterpillars only.
Various Bacillus strains effective against different pests.
Birth Control Methods
Sterilizing males in pest populations to reduce future breeding.
Biochemical Pesticides
Use of pheromones to attract and trap insects.
Cultivation Practices
Various strategies to naturally deter pests through timing and plant management.
Use of Synthetic Pesticides
Example: SLAM bait for western corn rootworm.
Computer Programs in IPM
Program to determine pest life cycle stages for optimal timing of control actions.
Benefits and Drawbacks of IPM
Benefits: Reduces pesticide risks to health and environment.
Drawbacks: Complexity and potential costs involved in implementation.
Conclusion
Humans can significantly mitigate impacts on land and water use through adoption of sustainable practices in forestry, agriculture, and pest management.
Forestry Introduction
Key Sections: 5.2 (Forest Ecosystems and Resources) & 5.17 (Sustainable Land Management).
Interactions Between Different Species and the Environment
Big Idea ENDURING UNDERSTANDING: When humans use natural resources, they inevitably alter natural systems, often leading to complex and interconnected environmental changes.
Learning Objectives
Describe the effect of clearcutting on forest ecosystems and surrounding environments.
Benefits of a Forest
Trees absorb various air pollutants like ozone, nitrogen dioxide, and particulate matter through their leaves, improving air quality.
Trees store carbon dioxide (CO₂) from the atmosphere during photosynthesis, acting as significant carbon sinks and mitigating climate change.
Trees produce oxygen (O₂) as a byproduct of photosynthesis, essential for most life forms on Earth.
Height of trees:
Example: Some species, like Coast Redwoods, can reach over 115 ext{m} tall.
Inquiry: Trees can be so tall due to their efficient vascular systems (xylem and phloem) that transport water and nutrients against gravity, supported by strong woody stems.
Clearcutting
Definition: A method of timber harvesting in which all trees in a forested area are removed in a single cutting, regardless of size or species.
Economic Advantage: Economically advantageous for timber harvesting due to lower operational costs, faster harvest times, and maximized immediate timber yield. However, it can lead to long-term economic instability if not managed sustainably.
Effects of Clear Cutting
Soil Erosion (Geosphere): Clearcutting removes protective canopy cover and critical root systems, leading to increased exposure of soil to wind and rain, significantly increasing soil erosion rates.
Increased Soil and Stream Temperatures (Geosphere and Hydrosphere): The removal of tree canopy leads to more direct sunlight reaching the forest floor and streams, causing soil and water temperatures to rise, which can harm aquatic life and alter soil microbial activity.
Flooding (Hydrosphere and possibly Biosphere): Forests act as natural sponges, absorbing rainfall and releasing it slowly. Clearcutting reduces the soil's capacity to absorb water, increasing surface runoff and the risk of flash floods downstream.
Habitat Loss (Biosphere): Displacement and destruction of wildlife habitats are immediate consequences, leading to reduced biodiversity, species migration, and potential extinctions as dependent flora and fauna lose their homes and food sources.
Release of Carbon Dioxide: Cutting and burning trees releases stored CO₂ back into the atmosphere. Furthermore, the decomposition of remaining organic matter also emits CO₂, contributing to climate change, and the loss of trees reduces the forest's capacity to absorb future CO₂.
Deforestation
Definition: The complete alteration of an area of forestry, replaced for other uses like agriculture (e.g., cattle ranching, soy, palm oil plantations), urban development, or infrastructure projects.
Silviculture
Definition: The practice of manipulating forest vegetation through various treatments to control establishment, composition, and growth to meet specific objectives of the forest owner, such as timber production, wildlife habitat, or recreation.
Silviculture Treatments: Applied at the stand level (a homogeneous unit of trees) to manage forests. Examples include thinning (removing some trees to promote growth of others), pruning, and site preparation.
Forest Structure: A collection of stands administered as an integrated unit, often referred to as compartments or management units, managed with a cohesive strategy.
Silviculture System: A comprehensive program of forest management for an entire rotation or rotation age of a stand, encompassing harvest cutting, methods for regeneration (replanting or natural seeding), and intermediate treatments (e.g., weeding, pest control) throughout the life cycle of the forest.
Regeneration Methods: Concurrently harvest timber and establish tree reproduction. This involves processes like cutting, site preparation (e.g., clearing debris, soil scarification to improve seedbed), and replanting (planting new saplings).
Forest Management: Planning and executing activities across a large area (often a landscape scale) to satisfy multiple management goals simultaneously, such as sustainable timber harvest, wildlife conservation, water quality protection, and recreational opportunities.
Forestry Practices
Types of Forestry Practices: These methods vary in intensity and environmental impact.
Clear-cutting: All trees removed.
Seed tree harvesting: Most trees removed, but a few strong, healthy trees are left as seed sources.
Selective cutting: Only mature or desired trees are harvested, leaving others to grow.
Shelterwood: Gradual removal of trees over a series of cuttings to provide shelter for regeneration.
Slash and burn agriculture: Traditional method involving felling and burning forests for temporary farmland.
Strip cutting: Harvesting trees in narrow strips, allowing natural regeneration from adjacent forest.
Sustainability
Big Idea ENDURING UNDERSTANDING: Humans can mitigate their impact on land and water resources through the intelligent design and implementation of sustainable use practices that consider long-term ecological health and resource availability.
Learning Objectives
Describe methods for mitigating human impact on forests, including sustainable practices and conservation efforts.
Mitigating Deforestation
Reforestation: The natural or intentional renewal of trees and other types of vegetation on land where trees have been removed, often through planting or seeding. This differs from afforestation, which is planting trees in an area that previously had no forest.
Sustainable Forestry Techniques: Practices designed to manage forests to meet the needs of the present without compromising the ability of future generations to meet their own needs.
Selective Logging: Only harvesting certain trees (e.g., mature, diseased, or damaged) instead of clear-cutting. This preserves the overall forest structure, maintains biodiversity, protects soil, and allows the remaining trees to continue providing ecosystem services.
Maturity: Allowing a longer time for young trees to mature before harvesting increases long-term forest value by producing higher quality timber, enhancing carbon sequestration, and supporting more complex ecosystems.
Replanting: Systematically planting new saplings after harvesting to restore the forest. It is crucial to plant diverse, native species suitable for the local ecosystem.
Protecting Forests from Pathogens and Insects
IPM: Integrated Pest Management techniques are applied not only in agriculture but also in forestry to manage pests in an environmentally sound manner, minimizing reliance on chemical pesticides.
Methods of Control: Effective strategies include:
Removal of infected trees: This prevents the spread of diseases (e.g., Dutch elm disease) or insect infestations (e.g., emerald ash borer).
Awareness of tree diseases and destructive insects: Early detection and monitoring are crucial for prompt intervention and preventing widespread damage.
Prescribed/Controlled Burn
Importance: Controlled burns are intentionally set fires under specific weather conditions to remove excess fuel (leaf litter, dead wood), reduce the risk of catastrophic wildfires, promote new growth, and maintain ecosystem health that depends on fire.
Types of Fire: Understanding fire behavior is key.
Surface Fire: Burns only surface litter, undergrowth, and small trees.
Crown Fire: Ignites the canopy and spreads from treetop to treetop, often very destructive and difficult to control.
Industrial Agriculture
Influence of the Green Revolution, starting in the mid-20th century, profoundly reshaped agricultural practices globally, leading to significant increases in food production.
Land Needed for a Growing Population
Population Changes: To calculate percent change in population size from 2009 to 2017, one would use the formula: (( ext{Population in 2017} - ext{Population in 2009}) / ext{Population in 2009}) imes 100.
Caloric Needs: Average person needs 2,450 ext{ kcal/day}; average kcal/ha produced is 15,737,000 ext{ kcal/ha}.
Calculation required for land needs to feed one person for one year:
Annual caloric need per person: 2,450 ext{ kcal/day} imes 365 ext{ days/year} = 894,250 ext{ kcal/person/year}.
Land needed per person per year: 894,250 ext{ kcal/person/year} / 15,737,000 ext{ kcal/ha} ext{ (average yield)}
ewline hickapprox 0.05682 ext{ ha/person/year}.
Feeding the Population in 2017: This calculation would then be multiplied by the total population in 2017 to determine total land requirements.
Historical Context of Agriculture
Growth of agriculture parallels population changes over time, with major innovations driving population booms and vice versa.
Key historical milestones include the beginnings of organized agriculture around 10,000 ext{ BC} (Neolithic Revolution), the agricultural improvements during the Industrial Revolution (e.g., mechanization, scientific breeding), and the later Green Revolution, all dramatically increasing food production capacity.
Green Revolution
Shift in reliance from human and animal labor to machinery (tractors, harvesters), allowing for cultivation of larger areas more efficiently.
Agricultural methods:
Polyculture: Growing multiple crops in the same area. It enhances biodiversity and reduces pest outbreaks.
Monoculture: Growing a single crop over a large area, which can increase yields but also increases vulnerability to pests and diseases.
Increased use of synthetic fertilizers (nitrogen, phosphorus, potassium) vs. traditional methods like manure and crop rotation.
Increased reliance on modern irrigation systems to provide water to crops, especially in arid or semi-arid regions.
Increasing Profits in Agriculture
Mechanization enhances efficiency, reduces labor costs, and increases output but significantly increases fossil fuel reliance for machinery operation and manufacturing, contributing to greenhouse gas emissions.
Tilling
Definition: Preparing land for raising crops through various activities such as plowing, harrowing, and cultivating, which churns and aerates the soil, controls weeds, and incorporates crop residues.
Slash and Burn Agriculture
Definition: A traditional method involving the felling and burning of forest vegetation, clearing the land for cultivation. The ash provides temporary nutrients to the soil, allowing for cropping for a few years before soil fertility declines, and the land is then left to allow forest reinvasion (fallow period).
Sahel Region Case Study
Livelihood strategies in the Sahel region often focus on crop growth and grazing animals, which are highly sensitive to climatic variations.
Land management trends, including overgrazing by livestock and unsustainable crop planting cycles without adequate fallow periods, lead to significant desertification due due to loss of vegetation, soil compaction, and increased erosion.
Fertilizer
Definition: Substances added to soil or plants to enhance soil fertility by providing essential plant nutrients (e.g., manure, compost, or chemical mixtures).
Industrial Fertilizer Components: Primarily Nitrogen (N), Phosphorus (P), and Potassium (K), often referred to as NPK. Nitrogen promotes leaf growth, phosphorus aids root and flower development, and potassium supports overall plant health and disease resistance.
Use of Fresh Water
Distribution (approximate global averages):
Public and Domestic Supply: 15 ext{%}
Agriculture: 76 ext{%} (the largest consumer of freshwater globally)
Types of Irrigation
Methods:
Flood irrigation: Entire field is flooded with water.
Drip irrigation: Water delivered slowly and directly to the plant roots through emitters.
Spray irrigation: Water sprayed through high-pressure nozzles from a central pivot or moving lateral lines.
Furrow irrigation: Water flows through small channels (furrows) dug between rows of crops.
Center pivot irrigation: Water delivered via sprinklers on a central pivot, forming crop circles.
Valley irrigation: Similar to center pivot but covers a rectangular area.
Problems with Irrigation
Waterlogging: Excess water in the soil raises the groundwater table and saturates the root zone, limiting oxygen absorption by plant roots and leading to root rot and nutrient deficiencies.
Flood Irrigation: Relatively inefficient, with up to 20 ext{%} of water lost from evaporation, runoff, or deep percolation.
Furrow Irrigation: Inexpensive and simple but generally entails about one-third water loss to evaporation and runoff.
Spray Irrigation: More efficient than flood or furrow, with less than 25 ext{%} water lost, but more costly and requires significant energy to run pumps.
Drip Irrigation: Most efficient method, with only about 5 ext{%} (or less) water loss, as it delivers water directly to roots; however, it is the most expensive to install and maintain.
Salinization and Aquifer Depletion
Salinization Risk: Irrigated water, especially in arid regions, contains dissolved salts. When the water evaporates, these salts are left behind in the topsoil, leading to a buildup that can make the soil toxic for most crops. Examples: Major issues in agricultural areas of Australia, California, and Arizona.
Aquifer Depletion: Overuse and unsustainable withdrawal of groundwater from aquifers for irrigation can lead to significant drops in water tables, making water more expensive to pump, causing land subsidence, and reducing water availability for future generations or other uses. E.g., the Ogallala Aquifer in the U.S. Great Plains is being depleted faster than it can recharge.
Case Study: Arizona
Agrarian challenges due to its arid climate and limited natural water resources.
Irrigation reliance heavily on the Colorado River (via canals like the Central Arizona Project) and non-renewable groundwater sources.
Inquiry to compare irrigation methods: Furrow vs. flood irrigation in Arizona, considering water loss, cost, and suitability for different crops in a desert environment.
Dust Bowl
Historical context (1930-1939): A severe drought combined with decades of unsustainable dryland farming practices (e.g., extensive deep plowing that removed native prairie grasses) caused massive soil erosion in the Great Plains, leading to dust storms and economic devastation.
Relation to agricultural practices and climatic factors: A classic example of human interaction with climate leading to environmental disaster.
Weathering vs. Erosion
Definition: Weathering is the process by which rocks and soil are broken down gradually by physical, chemical, or biological agents (e.g., freeze-thaw cycles, acid rain, roots). Erosion is the process by which weathered rock and soil materials are transported from one location to another by agents like wind, water, or ice.
Pesticides and Pest Control
Types: Chemical substances used to kill or control pests.
Herbicides: Target weeds.
Fungicides: Target fungi.
Rodenticides: Target rodents.
Insecticides: Target insects.
Pesticide Treadmill: An economic and ecological model describing the cycle where farmers must continuously increase the dose or frequency of pesticides, or switch to new, more potent pesticides, because pests rapidly evolve resistance to existing chemicals. This increases costs and environmental risks.
GMOs (Genetically Modified Organisms)
Benefits: Organisms whose genetic material has been altered using genetic engineering techniques. Benefits include increased resistance to pests/diseases (e.g., Bt corn), enhanced nutritional value, tolerance to herbicides, and increased yields.
Drawbacks: Risks to genetic diversity in crops (monocultures of GMOs can be vulnerable to new diseases), potential for