Table of Contents
Natural Resources from Land and Seas
Human societies depend on biological and geological resources from land and oceans. These resources can be grouped into:
- Renewable resources – replenish naturally within human time scales if used sustainably
- Wood, fodder, fish stocks, game, freshwater, fertile soil (to a degree), wild plants, biomass (e.g. algae), groundwater recharge
- Non‑renewable or very slowly renewable resources – form over geological time
- Fossil fuels, many mineral resources (phosphate rock, metals), some groundwater in deep aquifers
Whether a resource is “renewable” in practice depends on the rate of use vs. rate of regeneration. Overuse of even renewable resources leads to degradation, loss of productivity, or collapse of populations (e.g. overfished seas, overgrazed rangelands, deforested slopes).
The central question of this chapter is: how can we use land and seas in a way that meets human needs without destroying the ecological basis of life for future generations?
Land Use and Land Resources
Main Forms of Land Use
On land, humans use ecosystems primarily as:
- Cropland – for annual and perennial crops (grains, vegetables, fruits, oil crops, fiber plants)
- Grassland and rangeland – for grazing livestock (cattle, sheep, goats, etc.)
- Forests – for timber, fuelwood, non‑timber forest products, protection against erosion and floods
- Urban and industrial areas – settlements, roads, mining, infrastructure
- Protected and semi‑natural areas – national parks, reserves, traditional low‑intensity landscapes
Land use always alters natural habitats. The scale and intensity of these changes determine how strongly biodiversity, soil, water, and climate are affected.
Soils as a Critical Resource
Soil is not just “dirt” but a complex living system of minerals, organic matter, water, air, and organisms. It:
- Stores and filters water
- Supplies plants with nutrients
- Hosts a huge diversity of microorganisms and animals
- Stores large amounts of carbon
Soil formation from rock and organic matter is extremely slow. Many centimeters of fertile topsoil can be lost within a few years but need centuries to millennia to develop again. Therefore, soil is effectively non‑renewable on human time scales.
Soil Degradation
Unsustainable land use leads to:
- Erosion by water and wind (loss of topsoil)
- Compaction by heavy machinery or overgrazing (reduced porosity, poorer root growth)
- Salinization due to irrigation in dry regions (accumulation of salts in the root zone)
- Nutrient depletion by continuous cropping without sufficient nutrient return
- Pollution by pesticides, heavy metals, industrial emissions
Degraded soils produce lower yields, are more vulnerable to drought and heavy rain, and support fewer species.
Agriculture: Intensification and Its Consequences
To feed a growing population, agricultural production has been dramatically increased by:
- High‑yielding crop varieties
- Synthetic fertilizers
- Chemical pesticides and herbicides
- Mechanization
- Irrigation
- Concentrated animal feeding operations
These measures boost short‑term yields, but also bring ecological risks:
- Nutrient surpluses cause eutrophication of waters and greenhouse gas emissions (e.g. nitrous oxide).
- Pesticides can kill non‑target organisms (pollinators, natural enemies of pests) and contaminate food and water.
- Monocultures reduce habitat diversity and make agroecosystems more vulnerable to pests and climate extremes.
- High livestock densities lead to large amounts of manure, methane emissions, and often poor animal welfare.
The challenge is to balance food security with environmental protection.
Sustainable Land Management Approaches
Sustainable land management tries to maintain or improve productivity while conserving soil, water, and biodiversity. Important strategies include:
Soil and Water Conservation
- Contour farming and terracing – fields follow elevation lines; terraces reduce slope length and runoff velocity.
- Cover crops and mulching – living plants or plant residues protect the soil from erosion and increase organic matter.
- Reduced or no‑till agriculture – less plowing limits disturbance, decreases erosion, and can increase soil carbon.
- Windbreaks and hedgerows – trees/shrubs reduce wind speed, prevent erosion, and provide habitat.
More Ecological Crop Systems
- Crop rotation – alternating crops over years (e.g. cereals–legumes–root crops) breaks pest cycles and improves nutrient use.
- Intercropping and mixed cropping – growing multiple species together; can improve resource use and reduce pest pressure.
- Integration of legumes – plants that can fix atmospheric nitrogen (e.g. clover, beans) reduce the need for synthetic fertilizer.
- Agroforestry – combining trees with crops or livestock; trees stabilize soil, provide shade, wood, and habitat.
More Sustainable Use of Inputs
- Precision agriculture – applying fertilizers and pesticides only where and when needed, guided by data and sensors.
- Integrated pest management (IPM) – combining biological control, resistant varieties, and targeted pesticide use.
- Efficient irrigation – drip irrigation, scheduling according to crop needs, reducing evaporation and salinization.
Sustainable Grazing and Forest Management
- Rotational grazing – moving herds between paddocks to allow vegetation to recover.
- Adjusting stocking rates to the carrying capacity of the land.
- Avoiding grazing on very steep or sensitive areas.
- Close‑to‑nature forestry – selective logging, maintaining mixed‑species forests, preserving old trees and deadwood where appropriate.
- Reforestation and afforestation – planting trees on degraded land, considering native species and local ecological conditions.
Land Use Conflicts and Trade‑Offs
Different needs compete for limited land:
- Food and feed production
- Bioenergy and industrial raw materials (e.g. biofuels, bioplastics)
- Conservation of biodiversity
- Urban expansion and infrastructure
- Carbon storage (forests, peatlands, wetlands)
Decisions about land use involve trade‑offs: more land for bioenergy, for example, can mean less land for food or nature conservation. Planning and policy must weigh these conflicting goals and consider long‑term ecological consequences.
Marine and Freshwater Resources
Marine Ecosystems as Resource Providers
Seas provide:
- Food – fish, shellfish, crustaceans, seaweed
- Raw materials – salt, sand and gravel, minerals (including in deep sea), fossil fuels (oil, gas)
- Space – for shipping routes, offshore wind farms, aquaculture, tourism
- Ecosystem services – climate regulation, oxygen production, nursery grounds for many species, cultural values
However, most of the ocean’s biological productivity is concentrated in coastal zones and upwelling areas, which are particularly vulnerable to human impact.
Fisheries and Overfishing
Wild fish stocks are a classic example of a common pool resource: they are rival (a fish caught by one person cannot be caught by another) but often difficult to exclude others from using.
Overfishing and By‑Catch
Overfishing occurs when catch exceeds the regeneration capacity of the fish population over the long term. Consequences:
- Decline or collapse of target species.
- Shifts in food webs (e.g. dominance of smaller, fast‑growing species).
- Loss of large, old individuals, which may produce more or higher quality offspring.
- By‑catch – non‑target species (juvenile fish, seabirds, turtles, marine mammals) are unintentionally caught and often die.
Technical innovations such as more efficient nets, sonar, and large trawlers have greatly increased fishing pressure, often beyond sustainable levels.
Aquaculture
Aquaculture is the farming of aquatic organisms (fish, shellfish, algae). It can:
- Reduce pressure on wild stocks.
- Provide food and income in coastal and inland communities.
However, intensive aquaculture can also:
- Produce waste that leads to local eutrophication.
- Require feed made from wild fish (fishmeal and oil).
- Lead to escape of farmed species or pathogens into the wild.
- Cause habitat damage (e.g. mangrove clearing for shrimp farms).
Sustainable aquaculture aims to:
- Improve feed efficiency and use plant‑based or by‑product feeds.
- Integrate different species (“integrated multi‑trophic aquaculture”) where waste from one species becomes resource for another.
- Minimize chemical use and disease outbreaks.
- Choose appropriate locations and farm designs.
Degradation of Coastal and Marine Habitats
Important habitats such as coral reefs, mangroves, seagrass meadows, and estuaries are under pressure from:
- Overfishing and destructive fishing methods (e.g. bottom trawling, dynamite fishing)
- Coastal construction and land reclamation
- Pollution from land (nutrients, plastics, industrial waste)
- Shipping (noise, collisions, invasive species through ballast water)
- Climate change (warming, ocean acidification, sea‑level rise)
These habitats often serve as nursery grounds, coastal protection (e.g. mangroves against storm surges), and carbon sinks (“blue carbon” in mangroves, seagrasses, salt marshes). Their loss reduces both biodiversity and human safety.
Freshwater as a Limiting Resource
Freshwater from rivers, lakes, and groundwater is essential for:
- Drinking water
- Irrigation
- Industry
- Energy production (hydropower)
Mismanagement leads to:
- Over‑extraction of rivers and aquifers (rivers running dry, sinking groundwater tables).
- Conflicts between upstream and downstream users.
- Loss of wetlands and riverine ecosystems due to damming and channelization.
- Declining water quality due to agricultural, industrial, and urban pollution.
Sustainable water management includes:
- Efficient use in agriculture (water‑saving irrigation, appropriate crops).
- Protection and restoration of wetlands and floodplains.
- Limiting pollution at the source (e.g. better wastewater treatment, reduced fertilizer use).
- Coordinated management of water resources across political boundaries (river basin management).
Sustainable Management and Governance
Common‑Pool Resources and the “Tragedy of the Commons”
Land, fish stocks, water, and clean air often function as common‑pool resources: many people use them, and it is difficult to exclude users. If every user follows only short‑term self‑interest, overuse and degradation occur (“tragedy of the commons”).
Avoiding this requires:
- Rules about who may use what and how much.
- Monitoring of compliance and resource status.
- Sanctions for violations.
- Participation of local users in decision‑making.
Effective management can be organized at different scales: from local community rules to national laws and international agreements.
Instruments for Sustainable Resource Use
To align human use with ecological limits, various instruments are used:
- Protected areas – e.g. nature reserves, national parks, marine protected areas, where use is restricted or prohibited.
- Quotas and licenses – limits on catches (in fisheries) or water abstraction.
- Spatial planning and zoning – designating areas for conservation, agriculture, industry, fishing, or tourism.
- Certification and eco‑labels – e.g. for sustainably managed forests or fisheries; provide market incentives.
- Economic instruments – taxes, subsidies, or payments for ecosystem services that reward sustainable behavior.
- Education and awareness – informing consumers and producers about the consequences of their choices.
The Role of Consumers and Technology
Individual and societal consumption patterns influence land and sea use:
- Diets rich in animal products require more land and feed than largely plant‑based diets.
- Demand for certain seafood species drives fishing pressure or aquaculture expansion.
- Use of bioenergy, cotton, palm oil, or soy affects global land use.
Technological innovations can both increase pressures (e.g. more efficient fishing gear) and support sustainability (e.g. better monitoring of illegal logging, improved irrigation technology). Their ecological impact depends on how they are embedded in rules and incentives.
Outlook: Balancing Human Needs and Ecosystem Integrity
The sustainable management of land and seas aims to:
- Secure food, water, and raw materials for a growing population.
- Maintain fertile soils, clean water, and productive ecosystems.
- Preserve biodiversity and ecosystem services.
- Limit contributions to climate change and adapt to its impacts.
This requires combining:
- Ecological knowledge (understanding limits and regeneration rates),
- Social and economic solutions (fair distribution, participation, incentives),
- International cooperation, since many resources (oceans, atmosphere, rivers) cross borders.
How humanity manages land and seas will largely determine the future state of the biosphere and the living conditions for future generations.