A common way to restore a degraded forest is to plant seedlings and nurture these into full trees. Indeed, to most people restoration and tree-planting (with native species) are virtually synonymous. Planting and nurturing tree seedlings over a wide area, however, can be an expensive and labour-intensive affair. Not to mention the decades or even centuries it takes before seedlings grow into trees.
Another common path to restoration is to simply protect a degraded forest from further degradation, often by fencing it off. Over time, lost tree cover will return through natural regeneration. This option is a relatively inexpensive, but it can also take centuries to achieve full restoration and the environmental benefits it brings.