C.4 Extreme environments’ futures

The scenario describes continuous cropping without fallow periods and removal of crop residues. These are both characteristic of unsustainable farming practices, one of the three principal human drivers of desertification.

Without fallow periods, soil has no recovery time to replenish organic matter and nutrients. Removing crop residues strips organic material that would otherwise decompose and rebuild soil structure, leaving the soil increasingly infertile and structurally weak.

The correct option describes the nutrient exhaustion and structural breakdown caused by continuous cropping — the direct mechanism at work. Salinization requires irrigation-related evaporation, which is not described. Wind erosion and deforestation are separate drivers not triggered by this farming practice alone.

Continuous cropping without rest exhausts soil nutrients and breaks down soil structure is the mechanism that directly explains the fertility decline described, making this the correct answer.

The question asks which process most directly explains soil fertility decline caused by the specific practices of removing crop residues and not allowing fallow periods.

'Wind erosion strips the exposed topsoil during dry seasons' involves a physical removal mechanism driven by exposure. While unsustainable farming can contribute to this, the question asks about the direct cause of fertility loss from the stated practices — nutrient depletion, not physical erosion, is the primary effect here.

'Salinization draws salts to the surface as floodwaters evaporate' requires irrigation and high evaporation in irrigated fields — the scenario describes rain-fed cropping without irrigation. 'Deforestation removes tree canopy' is a separate driver not involved in the described practices of crop residue removal and absent fallow.

'Continuous cropping without rest exhausts soil nutrients and breaks down soil structure' is the only option that directly matches the mechanism: removing residues and skipping fallow periods deplete organic matter and nutrients, which is the stated cause of fertility decline.

The government passes a law that limits livestock numbers in fragile zones with legal penalties. This is a zoning law — a legal instrument that designates how land may be used and restricts certain human activities.

Policy-based strategies target human behaviour and institutional structures through regulation, law, or education. This law regulates land use; it does not directly plant trees, build soil conservation structures, or install irrigation systems — it changes what people are allowed to do, not the physical state of the land itself.

A physical strategy would directly intervene on the land (e.g. reforestation, terracing). A scientific strategy implies research methodology. A technological strategy implies specific technology like GPS or sensors — none of which are described as the mechanism of this law.

Policy-based strategy is the correct classification because the measure works through legal regulation of human land use, which is the defining feature of zoning laws as opposed to physical restoration techniques.

The question asks how to classify a law limiting livestock numbers in fragile zones — the focus is on what type of desertification strategy this represents.

'A physical strategy, because it directly changes the physical condition of the soil through reduced livestock compaction' misclassifies the measure. While fewer livestock may eventually reduce compaction, the law itself is a regulatory instrument, not a direct physical intervention on the land — the physical change is an indirect consequence, not the mechanism.

'A scientific strategy relying on remote sensing data' and 'a technological strategy using GPS tracking' both introduce technologies not described in the scenario. The measure described is a legal restriction, not a data-collection or monitoring tool.

'A policy-based strategy, because it regulates human behaviour through a legal instrument rather than directly restoring the land' is the correct classification — zoning laws are the canonical example of a policy-based approach to combating desertification.

The question asks about the most significant difference between militia extraction and TNC extraction. The key distinction lies in their legal basis, method of control, and use of revenue.

Militia groups seize extraction sites by force, operate outside legal and regulatory frameworks, and use revenue to purchase weapons and sustain armed conflict. Environmental regulations and community consultation do not apply, as militias have no accountability to legal authorities.

TNCs obtain government licences for extraction, operate under national and international regulatory oversight, and are accountable to shareholders and (at least nominally) to environmental and social standards — even when these are imperfectly enforced.

The correct option — illegal force-based control funding armed conflict vs legal concessions under regulatory frameworks — captures the fundamental distinction examiners expect between militia and TNC resource exploitation.

The question asks how militia control most differs from TNC operations — looking for the fundamental distinction in legal status, methods, and outcomes.

'Militias extract resources more sustainably using traditional methods' is incorrect — militias have no incentive to follow sustainable practices and often cause severe unregulated environmental damage. 'Militias invest more in local infrastructure and employment' is also incorrect — resource revenue funds armed conflict, not development.

'Militias focus on minerals while TNCs focus exclusively on oil and gas' is false — TNCs operate across oil, gas, mining, and other sectors, and militias exploit whatever high-value resource is available, including timber, wildlife products, and oil, not only minerals.

'Militias operate through illegal, force-based control that directly funds armed conflict, while TNCs operate under legal concessions and regulatory frameworks' identifies the essential distinction: legal status and the destination of resource revenue.