115 年 國立臺灣大學森林環境暨資源學系碩士班丁組《專業英文（E）》

Land use change, especially in the form of deforestation, is the second largest source of carbon dioxide emissions from human activities, after the burning of fossil fuels. Greenhouse gases are emitted from deforestation during the burning of forest biomass and decomposition of remaining plant material and soil carbon. Global models and national greenhouse gas inventories give similar results for deforestation emissions. Deforestation has many causes and drivers. Examples include agricultural clearcutting, livestock grazing, logging for timber, and wildfires. The relationship between deforestation and climate change is a positive climate feedback. The more trees that are removed equals larger effects of climate change which, in turn, results in the loss of more trees.

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In forestry, the tools to carry out on-the-ground management are found in the toolbox of silviculture, that is, the part of forestry that deals with the development and care of forests. This development and care can be all encompassing, including establishment, growth, composition, health, and quality of trees and stands to meet the diverse needs of society. The planned program of all these activities, spanning the entire life of a forest stand, is termed a silvicultural system. Ostensibly, such a definition for silviculture would seem to recognize most forests, outside of plantations, as natural ecosystems and that the tools to manage these ecosystems would be based on ecological principles. In reality, classical silviculture is largely based on principles of production agriculture, more so than the ecology of natural forests. The outcome of the long-term application of an agricultural model to managed forest is near global-wide simplification of structure and composition, as well as a reduced ability to adapt to unexpected and novel threats. An explicit goal of ecological silviculture and allied approaches is to manage forests in ways that reduce the disparity between natural forests and their managed counterparts in terms of composition, structure, and function.

Population genetics and silviculture are deeply interconnected, and their relationship extends into the ecological functioning of forests. Silvicultural practices such as thinning, selective harvesting, and regeneration cycles alter population density, age structure, and competition, which in turn influence natural selection on traits like vigor, growth rate, and reproductive success. From a genetic perspective, these interventions reshape allele frequencies and genetic variance across generations. Ecologically, silviculture acts not only as a tool for timber production but also as a regulator of evolutionary processes, shaping resilience and adaptability of tree populations. For example, non-selective thinning reduces competition intensity and viability selection, while selective thinning may reinforce or counteract natural selection depending on which trees are removed. These genetic consequences feed back into ecological outcomes such as forest productivity, regeneration success, and biodiversity maintenance. The ecological implications are critical in the era of global change. Forests provide ecosystem services including carbon sequestration, soil stabilization, water regulation, and habitat for diverse species. By influencing genetic diversity, silvicultural practices determine the adaptive capacity of forests to climate shifts, pests, and disturbances. High genetic variance enhances ecological resilience, while reduced genetic diversity may compromise regeneration, disease resistance, and ecosystem stability. Applications of this integrated perspective include conservation forestry, where thinning regimes maintain genetic diversity and ecological functions; restoration projects, where seed sources are chosen to maximize adaptability; and production forestry, where models predict both timber yield and ecological resilience. Ultimately, aligning silviculture with population genetics ensures forests remain dynamic, adaptive systems that sustain ecological services for both human societies and the natural world.

Forest-based biomaterials and bioenergy are important for sustainable development and carbon neutrality. Forests provide renewable lignocellulosic resources for producing energy, materials, and biocomposites. At the same time, forests can store carbon through proper forest management. By replacing part of fossil-based fuels and materials, forest-based products may help reduce greenhouse gas emissions and the use of non-renewable resources.

However, the environmental benefits of forest-based systems should not be assumed only because they are bio-based.
International climate policies and scientific studies emphasize that carbon neutrality must be evaluated from a life-cycle perspective. Feedstock sources, processing methods, energy efficiency, product durability, and end-of-life treatment all affect environmental performance. Therefore, combining forest-based biomaterials and environmental technologies with life cycle assessment is necessary to ensure that forest-based materials and energy truly contribute to climate change mitigation.

Climate change is making biodiversity conservation much harder. Habitats are being lost quickly, species are moving to new areas, and extinction risks are rising.

This is not only a loss of nature for its own sake. It also weakens ecosystem services that people depend on, such as clean water, food production, pollination, and protection from floods, droughts, and heat.

Even though global awareness is growing, conservation still faces major limits. Many biodiverse but poorer regions lack enough data, long-term monitoring, funding, and staff capacity. Climate adaptation is also not yet fully built into many conservation plans.

Biodiversity needs to be part of everyday decision-making in politics, the economy, and society. This includes aligning policies across sectors, using financial tools (green taxes, incentives, and payments), strengthening governance so biodiversity is considered in land-use and development decisions, and investing in education and community participation.

Looking ahead, new technology and cross-disciplinary work can help close knowledge and management gaps. We should link research more closely with policy, use citizen science and remote sensing to collect more data, and apply adaptive management with regular monitoring and review. Success will depend on global cooperation, strong local involvement, and a cultural shift that recognizes how closely human well-being is tied to biodiversity in a changing climate.