3 ideas
Evelyn argues that England's security depends on its navy, and its navy depends on a steady supply of mature oak for hulls and knees. Iron smelting, glassworks, expanding tillage, and Civil War-era felling have used up woods faster than they regrow, so the shortage is a strategic weakness and not just an economic problem. The remedy he proposes is deliberate replanting by private landowners, backed by the Crown.
Oak takes a century or more to reach ship-timber size, so the person who plants it will not harvest it. Evelyn presents tree-planting as a patriotic and moral obligation that landowners owe to posterity and the state, rather than a personal investment judged on returns within one lifetime. On this view, stewardship becomes a question of honour and inheritance, not of profit horizons.
The book organises its practical guidance tree by tree: oak, elm, beech, ash, chestnut, walnut, and others. For each species it covers seed collection and sowing, nursery raising, transplanting, soil and site suitability, pruning, protection from cattle, and uses of the wood. Matching the species and method to the land and the intended end use turns forestry from opportunistic cutting into a repeatable, managed cultivation practice.