Sustainability and Change · Paper 2 — Free Biology SL Practice Questions

A researcher studies the effect of sustainable agricultural practices on soil biodiversity in a grassland ecosystem. She compares two adjacent fields over 5 years: Field A is managed with conventional tillage and synthetic pesticides; Field B uses no-till farming, cover cropping, and integrated pest management (IPM). The Shannon-Wiener diversity index ($H$) for soil invertebrates is measured each year. A higher $H$ value indicates greater biodiversity. Year — Field A ($H$) — Field B ($H$) 1 — $1.2$ — $1.8$ 3 — $0.9$ — $2.3$ 5 — $0.7$ — $2.5$

A field study was conducted in a temperate deciduous forest to evaluate the sustainability of harvesting wood for biofuel. Two $1\,\text{ha}$ plots were established: Plot A (unharvested control) and Plot B (selective logging of $30\%$ of tree biomass every 5 years). Data collected after 20 years are shown below. Parameter — Plot A — Plot B Total woody biomass — $450\,\text{t}$ — $320\,\text{t}$ Simpson's Diversity Index ($D$) — $0.87$ — $0.72$ Soil organic carbon — $120\,\text{t}$ — $95\,\text{t}$ Annual NPP — $12.5\,\text{t}\,\text{ha}^{-1}\,\text{yr}^{-1}$ — $10.8\,\text{t}\,\text{ha}^{-1}\,\text{yr}^{-1}$ - Harvested wood from Plot B over 20 years: $210\,\text{t}$ - Energy content of dry wood: $18.5\,\text{MJ}\,\text{kg}^{-1}$ $$D = 1 - \frac{\sum n_i(n_i - 1)}{N(N-1)} \qquad \text{Percentage change} = \frac{\text{new} - \text{original}}{\text{original}} \times 100\%$$

A coastal community is evaluating the installation of a tidal barrage for renewable electricity generation. The barrage would enclose a $5.0\,\text{km}^2$ estuary. Environmental impact assessments collected the following baseline