reading quiz mod 26, 28, 34 agriculture impacts, meat/overfishing, aquaculture, sustainable forestry

how do density-independent events and plowing affect succession of soil differently?

storms aren’t regular, but plowing is common and unnatural, fragmenting habitats and lowering biodiversity

plowing

digging deep into the soil and turning it over (usually turning A horizon)

describe the process of plowing 3

• breaks up soil structure, exposes buried material

• brings nutrients from B horizon, buries weeds

• done on current agricultural land and not previously used land before planting

tilling

preparation of soil through a variety of activities including plowing, stirring, digging, and cultivating, especially burying undesired crops and done any time (esp end f harvest)

what 3 benefits does plowing and tilling have in common

• exposes nutrients and rock material to weathering → increase nutrient availability

• organic matter surface → soil

• increased cation exchange capacity and base saturation → higher crop yield

consequences of plowing and tilling 4

• organic matter exposed to wind and water erosion, reducing CEC and nutrient content

• increase particles in air and in waterways → cloudiness, oxygen intake of fish

• soil compaction → interferes w root penetration and water infiltration

• repeated trampling reduces soil poor space → human-created plow layer in A horizon (Ap horizon)

slash and burn agriculture

agricultural method in which land is cleared and farmed for only a few years until the soil is depleted of nutrients

whats wrong w slash and burn today 3

• land overused and not enough recovery time

• soil compaction → less productivity, only suitable for grazing

• piles from clearing → compaction, exposes organic matter to erosion

how does slash and burn affect the atmosphere 3

• oxidizes carbon

• second largest human contributor to atmospheric carbon dioxide concentration increases

• net destruction/clearing of forest → net increase in atmospheric CO2

difference between organic and synthetic fertilizer (5)

synthetic:

• concentrated, readily available, rapid fertilization

• runoff into waterways

• much more emissions r released during production

organic:

• low concentration, slow

• do more to change cation exchange capacity bc more organic matter

why is meat production less efficient than crop production

requires much more land than anything for the same caloric input and more fossil fuel energy per calorie of food

CAFOs

A large indoor or outdoor structure designed for maximum occupancy of animals and maximum output of meat

manure lagoon

Human-made pond lined with rubber built to handle large quantities of manure produced by livestock, where bacteria break down into nutrients for fertilizing fields

risks of manure lagoons 3

• leaking into groundwater

• diseases

• anaerobic decompositions releases emissions

free range grazing

Allowing animals to graze outdoors on grass for most or all of their lifecycle

nomadic grazing

feeding of herds of animals by moving them to seasonally productive feeding grounds, often over long distances

overgrazing

Excessive grazing that can reduce or remove vegetation and erode and compact the soil

desertification

Transformation of arable, productive low-precipitation land to desert or unproductive land due to climate change or destructive land use such as overgrazing and logging

2 trends of fish stuff

decrease in wild fish caught, increase in aquaculture

fishery

A commercially harvestable population of fish within a particular ecological region

overfishing

The decline of a fish population by 90 percent or more

bycatch

The unintentional catch of nontarget species while fishing

explain Northwestern Atlantic fisheries and overfishing 2

• overfishing led to fish stock depletion

• fisheries closed, recovery seen in some areas, but many still remain closed and less fish removal

Sustainable Fisheries Act 3

• restore depleted fish stocks and respond to fishery collapse

• shifted focus to species conservation

• mandates protection of critical marine habitats and no fishing for endangered species until recovery

Alaska's commercial salmon fishery management 3

• commercial salmon populations declined rapidly between 1940 and 1970

• overfishing during limiting seasons

• introduced quota system → increase

Maine lobster fishery management 2

• by local communities rather than federal government

• follows Elinor Ostrom's model to avoid the tragedy of the commons

how to meet global demand for fish increases even as wild caught fish decreases

new ways to increase seafood production in aquaculture → stock organisms, feed them, protect from disease, manage waste

describe open-net pens floating offshore 4

• water flows freely through enclosure carrying food meds and waste solutions

• antibiotics sometimes used depending on fish density

• waste removal systems prevent harmful buildup

• submerged net pens similar but fully underwater

describe recirculating above ground tanks that can be placed almost anywhere with water supply 4

• more energy efficient than wild capture since no long fishing trips

• systems use far less area than wild fishing and reduce pressure on wild stocks

• lower risk of disease transfer to wild fish

• tanks also reduce risk fish escaping and affecting wild genetics

environmental criticisms of aquaculture

• wastewater can contain feces uneaten food antibiotics and pathogens

• escaped farmed fish can compete with wild fish and alter their gene pool

• escaped fish may spread diseases and parasites to wild species

above ground tank aquaculture and its sustainability benefits 4

• tanks work like swimming pools with pumps filters and climate control

• systems need water energy and waste disposal so innovations aim to reduce impact

• some systems reuse fish waste to fertilize plants and grow algae fed back to fish

• aquaculture can relieve pressure on overfished wild stocks and provide protein for undernourished people

reforestation

natural or intentional restocking of trees after clear-cutting to repopulate the forest reduce erosion, and begin the process of removing carbon dioxide from the atmosphere

sustainable forestry

methodology for managing forests to provide wood and also clean water, maximum biodiversity, and maximum carbon sequestration in both trees and soil

explain sustainable forestry programs 4

• reducing and reusing wood helps lower demand for newly harvested timber

• certification organizations verify sustainable harvesting and chain of custody, costing more to support practices

• demand for certified wood could encourage more sustainably managed forests

• some vendors falsely label nonsustainable wood as certified to charge higher prices

prescribed burns

When a fire is deliberately set under controlled conditions, thereby decreasing the accumulation of dead biomass on the forest, reducing risk of uncontrolled and giving benefits of ash

ecological outcomes of wildfires 3

• fires created nutrient-rich habitat for early successional plants

• new growth attracted elk and other herbivores

• decades later, much of the burned area shows strong ecological recovery