Deforestation is destroying mixed dipterocarp forests because trees are removed faster than the ecosystem can regenerate, while cleared land is often permanently converted to agriculture. Logging, roads, fragmentation and fire also disrupt ecological processes throughout the remaining forest.
Mixed dipterocarp forests are tropical forests dominated by several tree species from the family Dipterocarpaceae. They support high biodiversity, including many species specialized for conditions beneath or within the forest canopy.
| Human pressure | Mechanism of ecosystem loss |
|---|---|
| Commercial logging | Valuable mature dipterocarp trees are removed. Falling trees and machinery also damage surrounding vegetation and compact soil. |
| Agricultural conversion | Forest is cleared for plantations, crops or livestock, replacing a diverse community with a simplified agricultural ecosystem. |
| Road construction | Roads remove habitat, divide populations and give people access to previously remote areas for further logging and settlement. |
| Fragmentation | Smaller forest patches have stronger edge effects, including higher temperatures, lower humidity and greater exposure to wind and fire. |
| Burning | Fire kills organisms and seedlings; repeated fires can prevent normal forest regeneration. |
Tree removal reduces habitat and food resources, causing population decline. Fragmented populations may become isolated, reducing gene flow and increasing the risk of local extinction.
Deforestation also disrupts nutrient cycling. With less canopy cover, rainfall reaches soil more directly, increasing erosion and nutrient loss. Reduced root systems decrease soil stability, while declining transpiration can alter local moisture conditions. If cleared land remains under agriculture, ecological succession cannot restore the original forest community.
A common misconception is that selective logging leaves the ecosystem largely intact because some trees remain. In reality, removing large canopy trees and constructing logging roads can cause extensive indirect damage and make later clearance more likely.
Exam technique: This case study is required at both SL and HL under A4.2 Conservation of biodiversity. For an “explain” question, link each anthropogenic cause to a biological consequence-for example, road construction → fragmentation → reduced gene flow → increased extinction risk-rather than merely listing causes.
