Biosphere Resources: Soil Formation, Erosion, and Forest Management
Item 12. Resources of the Biosphere
1. Factors That Condition Soil Formation
Time is a nonrenewable resource because it takes a long time to regenerate. The factors influencing soil formation are: climate (conditional on the type of weathering of the bedrock, and of vital importance in their evolution), topography, the nature of the bedrock, biological activity, and time.
2. Soil Erosion and Desertification
Direct Methods for Detecting Erosion:
Physical Indicators:
- Grade 1: Sheet erosion – a more or less uniform removal of the surface soil horizon.
- Grade 2: Rill erosion – small grooves of a certain slope.
- Grade 3: Gully erosion – gullies and ravines, great grooves.
Biological Indicators:
- Degree zero: Dense vegetation and without exposed roots.
- Low grade: Cleared vegetation, some exposure of the roots and pedestals of erosion.
- Average grade: Cleared vegetation, exposed roots, and pedestals of erosion.
- High grade: Roots exposed.
- Very high grade: The presence of ravines and gullies, with no plants.
Control of Erosion on Cultivated Land:
The best way to control erosion is through planning. Methods include: firewalls, promoting the conservation of native forests, putting hedges or stone fences on the edges of crops, abandoning farming in marginal areas with excessive slope and little soil, reforestation, ensuring appropriate grazing levels (Daly Act), sewers, plowing along contour lines, buttress or retaining walls, and terracing of slope areas.
Desertification:
Causes of desertification:
- Chemical degradation: Loss of fertility by leaching of nutrients or poor soil toxicity due to contamination; salinization and alkalinization.
- Physical degradation: By trampling, which compacts the soil, making it less fluffy and productive.
- Biodegradation: Mineralization of humus.
- Water and wind erosion.
In general, anthropogenic soil desertification is the disappearance of vegetation, coupled with the existence of anticyclones, constant wind areas, and rock outcrops.
Erosion and desertification in Spain, natural causes:
The result is a landscape such as the Spanish one, which has steep slopes, a Mediterranean climate (irregular and sometimes torrential rainfall), hard clay soil with poor drainage, poor management of water resources, inadequate forest policy, and land use practices.
3. Forest Resources
The Causes of Deforestation:
The main causes are: extension of cultivation and grazing, introduction of new crops (for cosmetics, biofuels), illegal logging, timber and fuelwood collection, fire, and urban development.
Benefits of Forests:
Forests create soil and moderate climate, control floods, store water and prevent drought, reduce erosion, host and support the majority of living species, and take down CO2 (hence, lower the greenhouse effect) and provide fuel.
The Sustainable Use of Forests:
Appropriate measures to promote sustainable water use are:
- Increase the efficiency of industries.
- Improve transportation networks and eliminate waste wood.
- Reduce paper use and increase recycling.
- Increase energy efficiency of traditional wood fires.
- Increase forest planting on marginal lands.
- Find alternative employment related to forests.
- Promote forest plantations for carbon sequestration from the atmosphere commercially as set out in the Kyoto Protocol.