environmental degradation and food security

The big 4

1. Deforestation

2. Soil depletion/erosion

3. Desertification

4. Wetland loss

Deforestation: benefits of rainforests

• Tremendous biomass

• Major oxygen producer and carbon sink

• Regulate water migration to oceans, prevent soil loss

• High biodiversity→greater resilience to climate change

• Deforestation causes

• Agriculture (slash and burn)

• Wildfires

• Invasive pets and pathogens

• Climate change

Deforestation: US context

• 80% of US forests degraded

• Many “recovered” forests are monocultures (low biodiversity)

Soil composition

• Sand + silt + clay (loam) + humus (decaying matter)

• Humus: retains moisture, insulates, bunds/releases nutrients

• Contains macronutrients (N, P, K, Ca), micronutrients (Zn, Mg, Se) and microorganisms (bacteria, fungi)

Soil horizons

• O: surface litter

• A: topsoil (organic-rich, takes 200+ years per inch, highly erodible)

• B: subsoil

• C: parent material

Causes of soil loss

• Poor farming practices, overgrazing, deforestation, acid rain

• Overgrazing →compaction, invasive species, species loss, poor water quality

• Urban construction, off road activity, logging, recreation

• Climate change impacts

• More intense rainfall → stronger erosion

• Loss of organic matter

• Melting permafrost= new erodible soils

Management strategies

• Terracing, contour farming, crop rotation

• Rotational grazing

• No till farming

• Desertification

• Land degradation in arid/semi-arid areas caused by human activity and climate variation

• End result: land no longer biologically productive

Desertification causes

Overgrazing

Drought and climate change

Desertification: The vicious circle

Political/economic stability

Large scale irrigation → salinization

Decline in productivity → poverty, migration

Climate change + drought worsen the cycle

Breaking the desertification cycle

Political stability, economic prosperity

Soil and water conservation, small scale irrigation

Science and technology integration

Desertification: case studies

China: >2.6 km² degraded; annual dust storms costing $40B. Reliance on grain imports (brazil)

American southwest: overgrazing, drought prone

What is a wetland?

Water-saturated area influencing soil and plant/animal communities

Types: marshes, swamps, bayous

High productivity; essential for fisheries

~90% of commercial fish/shellfish depend coastal wetlands

Ecosystem services

Habitat for waterfowl, fish, shellfish

Floodwater retention

Sediment and nutrient retention

Recreation and scenic beauty

U.S. context

1600s: >220M acres of wetlands in lower 48

Today: <50% remain

Loss due to farmland conversion, urbanization, roads, dams, logging, mining, dredging

Ongoing threats

Hydrological alterations (levees, channelization, diversion)

Groundwater withdrawal

Example: hurricane Katrina showed the dangers of lost coastal protection

Key takeaways

Deforestation: biodiversity loss, carbon cycle disruption.

Soil Erosion: threatens food security, worsens with climate change.

Desertification: poverty-driven, but reversible with sustainable practices.

Wetland Loss: reduces fisheries, storm protection, biodiversity.

Food Security is tied to healthy ecosystems; degradation undermines long-term human survival.