A research team studying the impact of human land use on tropical ecosystems in Malaysia collected data over a 30-year monitoring period. They compared biod...

(a) The land use change that resulted in the greatest loss of species was conversion of forest to palm oil plantation, which lost 365 species (from 450 to 85). [1]

(b) Percentage of species lost when forest was converted to palm oil plantation: [2]

Species lost = 450 - 85 = 365 [1]

\[ \text{Percentage lost} = \frac{365}{450} \times 100 = \mathbf{81.1\%} \] [1]

Losing over 80% of species is a devastating ecological impact, reflecting the near-total replacement of a complex ecosystem with a monoculture.

(c) Why selective logging resulted in smaller species loss than palm oil conversion: [3]

• Selective logging only removes certain valuable tree species, leaving the majority of the forest structure intact. The canopy, understorey, leaf litter and root systems remain largely in place, continuing to provide habitat. [1]
• The remaining trees, shrubs and ground vegetation still provide food, shelter and nesting sites for a wide range of animals. Birds can still nest in the canopy, mammals can still forage on the forest floor, and insects can still find food plants. [1]
• The forest can regenerate over time as new trees grow in the gaps created by logging, allowing species to recover. In contrast, a palm oil plantation permanently replaces the entire forest ecosystem with rows of a single crop species, eliminating virtually all original niches. [1]

(d) What agroforestry is and why it is better for biodiversity than monoculture: [4]

• Agroforestry is a land management system where food crops, livestock or other agricultural products are grown alongside trees. The trees may provide fruit, timber, shade or nitrogen fixation, while crops grow in the spaces between them. [1]
• The trees provide habitat and food for many species that cannot survive in open farmland. Birds nest in the tree canopy, insects feed on tree flowers, and mammals use the trees for shelter, maintaining significant biodiversity alongside agricultural production. [1]
• Agroforestry maintains more structural diversity than a monoculture. Different canopy layers (tall trees, smaller trees, ground crops), shade variation, leaf litter and varying microclimates create many distinct niches that support a wider range of species. [1]
• It also preserves important ecosystem services such as soil stabilisation (tree roots prevent erosion), water regulation (trees intercept rainfall and reduce runoff) and nutrient cycling (leaf fall adds organic matter to soil). These services support both biodiversity and long-term agricultural productivity. [1]

(e) How a protected reserve can lead to an increase in species: [3]

• Protection removes human threats such as hunting, logging, land clearance and pollution. With these pressures eliminated, populations of threatened species can recover and increase in numbers. [1]
• Habitat quality improves over time as vegetation regenerates and matures. Young forest develops into more complex, multi-layered forest with greater structural diversity, dead wood, tree hollows and varied microhabitats, providing more niches for different species. [1]
• Species that had been displaced or locally extinct can recolonise the protected area from surrounding forests. As conditions improve, species from adjacent habitats move in, increasing the total species count beyond the original level (from 410 to 430 in this case). [1]

(f) Why large carnivores were lost from the agroforestry area: [2]

• Large carnivores (tigers, leopards) require very large territories to find enough prey. The agroforestry area covers only 400 km², which may be too small to support even a single viable population of a large predator species. [1]
• Human agricultural activity within the agroforestry area creates disturbance and fragmentation. The presence of people, livestock and farm machinery deters large carnivores, and the risk of human-wildlife conflict (predation on livestock) often leads to retaliatory killing. [1]