IB ESS HL3.2 Human Impact on BiodiversityHL only~10 min read
Pressures on Biodiversity Hotspots
The places with the most biodiversity to lose are often the places with the least money to protect it. That is not a coincidence, and it is the central difficulty of hotspot conservation.
📘 What you need to know
Habitat destruction is the most significant threat to biodiversity hotspots.
Deforestation in tropical rainforests is a major cause of habitat loss.
Human causes of deforestation: agriculture (especially large-scale slash and burn), mining, hydroelectric power, logging, road building and settlements, and wildfires.
These activities cause fragmentation, making it harder for species to survive and reproduce.
Many hotspots are in developing countries, facing poverty, political instability and rapid population growth.
Conservation may conflict with economic development where people rely on natural resources for livelihoods.
Developing countries often have limited funding for conservation.
Habitat destruction
Habitat destruction is the most significant threat to biodiversity hotspots, and deforestation in tropical rainforests is a major cause. In the Amazon Rainforest, large areas are cleared for cattle ranching and soybean farming, threatening species such as the jaguar and the giant river otter.
Wildfires are typically natural, but people start them deliberately and human-induced climate change is increasing their frequency and severity.
Wildfires deserve a note of their own: although they are typically natural, people can intentionally start them, and human-induced climate change is associated with their increasing frequency and severity.
Why conservation is hardest here
Biodiversity is not evenly distributed across the globe, and many biodiversity hotspots are located in developing countries, particularly around the tropics.
Conservation here is not simply a question of will. It competes directly with how people feed their families.
Regional challenges
These regions often face poverty, political instability and rapid population growth, all of which make conservation efforts more difficult. Conservation strategies may conflict with economic development, because people in these regions rely on natural resources for their livelihoods. In Indonesia, efforts to conserve tropical forests have to balance the needs of local communities that depend on farming and palm oil production.
Lack of funding and resources
Developing countries often have limited funding for conservation, making it harder to implement effective strategies to protect hotspots. International organisations and governments sometimes provide support, but these efforts are often not enough to prevent habitat loss or species decline.
Be ready to explain the difficulties of conserving biodiversity in hotspots, especially in developing countries where environmental and economic needs conflict. Notice the link back to 1.3: this is environmental justice in practice. The countries asked to bear the cost of conservation are frequently not the ones that historically consumed the resources, and telling a subsistence farmer not to clear land is a very different proposition from telling a corporation not to.
Worked examples
WE 1
The main threat
Identify the most significant threat to biodiversity hotspots and explain its causes. (4 marks)
Step 1: the threatHabitat destruction is the most significant threat, with deforestation in tropical rainforests a major cause.
Step 2: the human causes
Agriculture, particularly large-scale slash and burn; mining; hydroelectric power; logging; and road building and settlements.
Step 3: wildfires
Wildfires are typically natural, but can be started intentionally by people, and human-induced climate change is increasing their frequency and severity.
Step 4: the consequence
These activities cause fragmentation of habitats, making it harder for species to survive and reproduce.
Six drivers of deforestation, all ending in fragmentationthe Amazon example — cattle ranching and soy, threatening jaguars and giant river otters — adds specificity
WE 2
Why location matters
Explain why conservation of biodiversity hotspots is particularly challenging. (4 marks)
Point 1: where hotspots are
Biodiversity is unevenly distributed, and many hotspots are in developing countries, particularly around the tropics.
Point 2: regional pressures
These regions often face poverty, political instability and rapid population growth, all of which make conservation harder.
Point 3: the economic conflict
Conservation strategies may conflict with economic development, because people rely on natural resources for their livelihoods. In Indonesia, forest conservation must balance the needs of communities dependent on farming and palm oil.
Point 4: funding
Developing countries often have limited funding, and although international organisations sometimes help, this support is often insufficient to prevent habitat loss.
The greatest biodiversity sits where the capacity to protect it is weakestnaming Indonesia turns a general argument into a specific one
WE 3
Fragmentation
Explain why habitat fragmentation is damaging to species. (3 marks)
Step 1: what fragmentation is
Activities such as logging, road building and agriculture break continuous habitat into isolated patches.
Step 2: the direct effect
Fragmentation makes it harder for species to survive and reproduce, because patches may be too small to supply the resources an individual or population needs.
Step 3: the genetic effect
Isolated populations cannot interbreed freely, which reduces gene flow and lowers genetic diversity, leaving them less able to adapt to further change.
Smaller patches, fewer resources, and populations cut off from one anotherthe gene flow point links this to reproductive isolation in 3.1
💡 Exam tips
State clearly that habitat destruction is the most significant threat.
Learn all six causes of deforestation, including the wildfire nuance.
Use the Amazon example with named species: jaguar and giant river otter.
Give all three regional challenges: poverty, political instability, rapid population growth.
Name Indonesia and palm oil for the conservation-versus-development conflict.
Mention that international support is often not enough.
⚠ Common mistakes
Naming climate change as the main hotspot threat. Habitat destruction is.
Calling all wildfires human-caused. They are typically natural but increasingly worsened by people.
Ignoring the economic conflict. Local livelihoods depend on these resources.
Blaming developing countries. The syllabus frames this as a resource and capacity problem.
Treating fragmentation as just habitat loss. Isolation of populations is a distinct harm.
Assuming international funding solves it. It is often insufficient.
Up next: Identifying Key Biodiversity Areas. Hotspots are one way of prioritising land for protection. KBAs are a second, using five scientific criteria — and unlike hotspots, they do not require the place to be damaged first.
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