Life Support Systems Food and Soil As populations

Life Support Systems

Food and Soil �As populations grow, the need for increased food production is greater �On a global scale we produce enough food to adequately feed all of the world’s population �Tens of millions continue to suffer from starvation and undernourishment each day minimum critical diet 9900 J = approx 2200 cal �See Figure 3 Page 715

�There are two forms of malnutrition �under nourishment �over nourishment

World Hunger �Causes of world hunger are complex �some regions of world have fertile soils and favourable climates �others have poor soil conditions �drought �flooding �and other harsh conditions that limit the ability to grow food �poverty �See Figure 4 Page 715

Food Sources �Humans depend on. . . �grain products �livestock �ocean fisheries �It is estimated by the Worldwatch Institute that yield thresholds are being met.

Our Oceans. . . �Within the oceans, over fishing has depleted stocks beyond estimated sustainable yields Populations may not recover If significant reductions are not met globally, can cause a severe prolonged collapse of stocks

Livestock � 10 billion animals used for livestock! �Livestock ranching has led to forest degradation 36% of world’s grain goes to feed livestock wastes are implicated in the pollution of waterways ▪ proliferation of toxic algal blooms ▪ loss of fish species ▪ water loss (to livestock, and to fresh water supplies)

Agricultural Land Being converted to non-agricultural uses. . ▪ Housing, industry soil degradation ▪ deforestation exposes soil ▪ loss of roots of living plants that would retrieve nutrients from deeper layers of soil disrupt nutrient cycles ▪ salinization ▪ accumulation of excess of salts in soil that restricts water and essential nutrients that plants can withdraw from the soil

Energy Pyramids �Ecologists often use energy pyramids to visualize transfer of food energy from one trophic level to the next through a food chain �Much of the energy is lost at each trophic level and this energy cannot be recaptured �Approximately only 10% of energy in one organism is transferred to an organism in the next trophic level �Top consumers receive a small fraction of available energy from the producers

Efficient Energy Distribution

Go Veggie? �Humans can obtain more energy from consuming producers directly than from other consumers � Read P. 720. . . �Discuss. . . Take a stand on Biotechnology

Water and Air �Urban Sprawl Growth of low density development on the edges of cities and towns �Aquifers Porous, water-saturated layers of sand, gravel, or bedrock that can store and yield significant volumes of water Precipitation and runoff enter recharge zones and percolate gradually down to an aquifer

Oak Ridges Moraine

�Despite it’s recognized ecological importance to southern Ontario, the moraine is at risk from having to accommodate housing developments

Water Resources �supply is not limitless that 1% of Earth’s water is fresh water �human activities negatively affect the supply that does exist livestock operations have been introduced into rural Canada contamination from livestock wastes and poor regulation of monitoring procedures and chlorination equipment has led to tragedies (Walkerton)

water supplies polluted by fertilization of cropland, pesticides, acid precipitation, and runoff from storm water off of soiled pavement, industrial wastes (most of which are toxic), mine tailings, household waste water, and raw sewage all lead to critical health concerns regarding the scarcity of clean water for drinking and irrigation.

Cellular respiration of bacterial populations increases, depleting oxygen from the water. This harms other aquatic organisms

Phosphates and nitrates from fertilizers and sulfates from laundry detergent support cellular respiration of some algae and plants, (algal bloom) further depleting oxygen sources for other organisms Heat produced by power plants and other industrial processes also reduces the amount of dissolved oxygen that can exist in water

Threats to the Atmosphere

Air Pollution

Acid Precipitation (aka) Acid deposition A mixture of Sulfur dioxide and nitrogen oxide pollutants that can reach earth’s surface in the form of rain, gas, or solid particles.

The Greenhouse Effect

Global Warming �Take a look at this video. . . It will make you think! �http: //www. youtube. com/watch? v=z. ORv 8 w wiad. Q&feature=player_embedded#