APES Unit 5: Land and Water Use

4 Types of Forests

Tropical - hot year-round w/ high rainfall + most biodiverse

Boreal - found in high attitudes, dominated by conifers

Temperate - occur in places w/ distinct seasons, mix of deciduos and conifers

Subtropical - occur just N and S of the tropics, also a mix of trees

Provisioning Services of Forests

Lumber, paper, fuel

Cultural Services of Forests

Recreation (camping, hiking, ect), aesthetics, ecotourism.

Regulating Services of Forests

Storage of atmospheric carbon, purifies water + air, stabilize soil + reduce erosion, influences local/regional climate (provides shade + reflects light due to high albedo).

Supporting Services of Forests

Provides habitat, nutrient cycling, photosynthesis, water cycling.

Tragedy of the Commons

The tendency for a shared, limited resource to become depleted if it’s not regulated in some way.

Only applies to public commons.

Land or resource must become degraded or depleted.

Clear Cutting

Removing most or all trees from an area (can be combines w/ replanting so all the trees that regrow are the same age). Leads to deforestation, increases erosion from wind and water (esp. on slopes → higher change of landslides) which adds silt/sediment to nearby streams, increasing turbidity.

Tilling

Turns compacted soil to prepare for planting seeds.

Benefits: loosens soil allowing aeration and drainage, chops up existing weeds, helps mix compost + fertilizers into the soil.

Drawbacks: reveals bare soil → erosion, kills beneficial bacteria → reduced soil nutrients, releases stored CO₂, requires burning fossil fuels

Slash + Burn Agriculture

Occurs in developing countries w/ subsistence farming. Typically in tropical forests w/ low nutrient soil.

Drawbacks: unsustainable (ash nutrients only remain for a few years) → have to keep slash + burning new plots, releases CO₂ because combustion

Synthetic Fertilizers

Synthesized in large industrial plants (which requires fossil fuels).

Benefits: easy to transport + use, time released, customized for the soil’s specific needs

Drawbacks: production → CO_2, water soluble so enters runoff → eutrophication, often overused, does nothing for soil texture

Organic Fertilizers

Manure, compost, bone meal or fish emulsion.

Benefits: working into soil so stay put (less runoff concern), improve soil texture

Drawbacks: must be gathered (labor intensive process), nutrient levels unknown, harder to use (needs to be worked into soil)

Furrow Irrigation

Furrows (trenches) built on either side of crops + filled with water. Oldest technique.

Pros: high sediment water can be used, allows for some precision of aplication

Cons: not efficient w/ sandy soil because it just passed through, most inefficient method (33% lost to evaporation + runoff), soil erosion occurs, waterlogging + salinization

Flood Irrigation

Lake or stream diverted to agricultural field, entire field flooded + water soaks in evenly, levee needed to retain water.

Pros: easy + inexpensive

Cons: requires body of water, not for all crops (usually is for rice), land but be graded (sloped + leveled), levees needed, inefficient (20% lost to evaporation), waterlogging + salinization can occur

Spray Irrigation

Pumps are used to spray from a nozzle directly on crops.

Pros: precision application, can be efficient (5%-25% lost to evaporation), can be programmed to run at certain times of day

Cons: larger up-front cost, probably included machinery (CO₂ emissions), nozzles can clog, pivot systems can wear ruts into soil

Drip Irrigation

Uses piped w/ micropores that drip water onto crops.

Pros: very efficient (5% evaporation), reduced nutrient leaching, no land grading needed, good for sandy soil

Cons: very expensive, micropores can clog, ones pipes are put down they’re difficult to move + vulnerable to punctures

Waterlogging

Pore spaces in soil required for plant roots, pore spaces provide O₂ to roots for cellular respiration, waterlogging results in death of roots → kills plants.

To remediate, allow soil to dry out + add sand.

Salinization

Freshwater has trace salts, after irrigation water evaporates salts build up in soil, most crops have low salt tolerance so salt kills plants.

Most likely to occur w/ furrow irrigation in warm areas with lots of sunlight.

To remediate, flush soil w/ lots of water

Depleted Aquifers

Overuse of irrigation can lead to depleted aquifers.

Persistent Pesticides

Remains in the environment for years or decades.

Problematic Pesticides

Can be transported through wind, runoff, and groundwater recharge. Can contaminate makes, streams, groundwater, and well water. Can result in killing of non-targeted species through bioaccumulation and biomagnification.

GMOs

Genetically Modified Organisms. Involve taking an adventurous gene from one organism and inserting it into the genome of another.

Ex: Bt corn that had a gene from a type of soil bacteria that naturally produces a toxin that kills insect larvae.

Meat Production lack of Efficency

Beef requires more than 80x as much land as wheat and 20x-30x more land than poultry or farmed fish.

Land requirements: land the animal occupies, land to provide food for animal to eat, land for disposal of waste

Meat Production Greenhouse Gases

CO₂ → mechanization

CH₄ - produced by cow’s digestive process + manure decomp

N₂O - produced from nitrification + denitrification of manure

CAFOs

Concentrated Animal Feeding Operations. Large indoor/outdoor structures designed for max occupancy of animals and max output of meat. Used for beef + dairy cows, hogs, + poultry. Animals have very little space.

Benefits: less land usage, feeding is more efficient, profits increased → fatter animals because less movement + fed high calories grains

Drawbacks: ethical concerns, high antibiotic use to curb outbreaks because they’re in a very concentrated space → antibiotic resistance, growth hormones, high water usage (cleaning + hydration), increased animal runoff + need for waste disposal

Manure Lagoon

Large human made pond lined w/ rubber to prevent leaking into groundwater. Used by large CAFOs, bacteria used to break down waste like sewage treatment plants, manure used as fertilizer.

Risks: produces a lot of N₂O, leaks in liner = groundwater contamination, can overflow into bodies of water, can lead to disease

Free Range Grazing

Allowing animals to graze outdoors on grass for most/all of life.

Benefits: more sustainable, less antibiotic use needed (animals more spread out), less fossil fuels used to make food cause animals eat the grass, waste is dispersed on it’s own, grazing can maintain grasslands

Drawbacks: uses more land, cost of meat is higher, overgrazing can occur if not managed correctly

Overgrazing

Excessive grazing in one area that can reduce or remove vegetation. Erodes + compacts soil. Arid environments w/ nutrient poor soils especially prone .

Desertification

Transformation of arable, productive, low precipitation land to desert-like unproductive land. Caused by climate change, overgrazing, + logging.

Nomadic Grazing

Sustainable solution to overgrazing. Farmers move herd of animals over long distances to seasonally productive feeding grounds.

Most sustainable way to graze animals, vegetation has time to regenerate, mimics natural grazing cycles of bison and wildebeests.

Rotational grazing

Cycling of livestock around a particular part of pasture to not overgraze an area.

Fishery

Commercially harvestable pop of fish w/in a particular ecological region.

Tragedy of the commons particularly applicable.

Fishery Collapse

When a fishery declines by 90% or more.

Commercial fishing methods

• Purse Seine Nets

• Bottom Trawling

• Gill Nets

• Long Line Fishing

• Pole + Line fishing

• Dredging

• Traps + Pots

Purse Seine Nets

Used to capture a school of fish often spotted w/ sonar or planes. Massive nets result in overfishing + bycatch.

Bottom Trawling

Nets are towed that drag across the seafloor to catch species that live on/near seafloor. Results in habitat destruction, esp in fragile ecosystems like grass meadows, sponge gardens, + coral reefs.

Sonar in Fishing

Pros: more efficient + profitable

Cons: overfishing + can interfere w/ behavior of marine species

Gill Nets

Set up to capture any fish that swim into them so result in a high amount of bycatch. Non-target species like turtles get caught.

Long Line Fishing

Lines can be over a mile long. Can result in overfishing.

Birds, turtles, + marine mammals also get caught on lines + hooks.

Pole + Line Fishing

The classing guy w/ fishing rod. Least environmental + ecological impact.

Dredging

Similar to trawling, but uses a rake to dig up burrowed shellfish, causes habitat destruction.

Traps + Pots

Used for crabs + lobsters. Bycatch + habitat destruction are not concerns, but gear can get swept away + entangle organisms like whales.

CITES

The Convention on International Trade in Endangered Species of Wild Flora and Fauna.

Protects species from overexploitation from international wildlife trade.

ESA

Endangered Species Act. All 7 species of marine turtle protected.

Aquaculture

Farming of fish, shellfish, or aquatic plants w/ intent to sell. Can occur in both marine + freshwater. China is worldwide leader.

Benefits: as global pop increases → need for food increases = can meet need for more protein, wild harvests been flat or decreasing since 90s, less dangerous than open-water fishing, more efficient + requires less fossil fuels

Drawbacks: disease concern bc of concentration → controlled by meds which can contaminate + disease can be spread to wild pops, waste can cause eutrophication, uneaten food can pollute, farmed organisms can escape + breed w/ or outcompete wild pops

Ecological Footprint

Measure of how much resources a person uses expressed in an area of land (hectacres) = How much land required to maintain your lifestyle?

Five variables:

Carbon footprint - energy usage

Built-up land - settlements

Forests - timber + paper

Croplant + pasture - food + fibers

Fisheries - seafood

Urbanization

Shift away from rural areas w/ agricultural jobs to non-agri jobs in areas w/ high pop density.

Benefits: reduces fossil fuel use for transport, less residential space per capita/more efficient use of land

Drawbacks: lotta solid waste, pollution, + greenhouse gas emissions, more water usage, requires water diversion like dams

Saltwater Intrustion

Greater demand for water → more aquifer use. Rapid pumping of wells in aquifers reduced water table → water pressure decrease → saltwater fills the vacum.

Heat Island Effect

Impermeable surfaces have lower albedo + absorb more heat → cities have higher temps than rural areas

Methods to reduce Urban Runoff

• permeable pavement

• planting trees

• smart city design + public transit (less roads + cars w/ motor oil)

• sidewalk planners

• electric vehicles

Sustainability

Ability to use a resource w/out depleting that resource for future generations.

Max Sustainable Yield (MSY)

Largest quantity of a renewable resource that can be harvested indefinitely.

Harvesting at MSY keeps resource around ½ of carrying capacity. Applies to renewable resources like fish, wild game, gathered plants, timber, agricultural products. Does not apply to non-renewable + mineral resources.

Sustainable Agriculture

Uses practices centered around soil conservation to prevent erosion, increase topsoil depth, increase nutrient.

Often requires more labor. More expensive because more labor, but long term productivity can make cost worthwhile.

Intercropping

Growing trees w/ crops. Allows vegetation of different heights to act like windbreakers to prevent soil erosion.

Strip Cropping

Planting crops w/ different spacing and rooting characteristics in alternating rows. Prevents soil erosion.

Contour Plowing

Plowing and harvesting parallel to the topographic contours of the land. Helps prevent erosion by water while allowing the practical advantages of plowing.

Terracing

Shaping sloping land into step-like terraces that are flat. Prevents erosion → if there is erosion the soil will move to the next terrace below.

Perennial Plants

A more sustainable farming technique. Reduces erosion by eliminating the need to plow, till, or disturb the soil. Plant researches trying to selectively breed plants to convert them from annual to perennial.

No-till Agriculture

Used in fields of annual crops where farmers do not till or plow between seasons. Reduces soil erosion + degradation + CO₂ emissions (because stored CO₂ in the soil isn’t released). However herbicides are usually applied so other plants don’t outcompete.

Green Manure

Plant material deliberately grown in a field with the intention of plowing it under at the end of the season. Adds nutrients and organic matter to the soil, like compost or animal manure. Improves soil fertility with no risk of nutrient run-off.

Integrated Pest Management

Pest control method that uses multiple strategies To more sustainably curb pests.

Includes:

• physical control - physical barriers to stop pests

• biological control - using natural methods to control pests (like ladybugs)

• crop rotation - can reduce # of pests

• intercropping - can reduce # of pests

• chemical control - last resort

Prescribed Burns

Can improve forest health by clearing out dead brush which often houses pests + reducing dead matter to catch on fire in a wildfire.