Land use practices must be improved for timber production, agriculture, housing, and infrastructure. We must improve the productivity of agricultural land, pasture, and tree plantations, and increase recycling efforts to lower the demand for raw materials and products from tropical forests. We also need to reduce urban sprawl, which eats up agricultural land and increases the pressure to convert forest land.
a. Eliminate incursions into pristine rainforests: This is more feasible in countries where population growth is low and where new facilities can be built on the sites of deteriorating ones without using any additional land. This will be considerably more difficult in countries where the population is rapidly growing, and will require considerable funding from richer countries. Even in countries with little population growth, consumerist and expansionist attitudes must change to reduce pressures on rainforests from consumer demand.
b. Utilize second-growth forests for timber production: Increasing interest is being given to using second-growth forests for timber production rather than invading virgin forests. These second-growth forests represent about two-thirds of the global forest cover. Since they are mainly reforested logged or agricultural land, they are frequently fragmented and close to roads, so that access to them is reasonably easy. Many of the tree species found in these forests are not as valuable in the marketplace as currently-utilized species, but are probably just as useful, and they will become more desirable as the supply of prime timber declines.
c. Reforestation: Much previously-forested land – probably hundreds of millions of hectares – can be reforested, although it would take many years before their biodiversity and complex ecological webs are recovered. Many other areas could regenerate naturally if they are left fallow and are not converted to other purposes.
Nevertheless, reforestation is not a simple proposition. Logging and other land use practices damage the soil and vegetation to a greater or lesser extent. In some cases, soil deterioration is so great that the soil turns to laterite (see Part I, Section L2). More often, the soil becomes so degraded through compaction or loss of nutrients and other factors that forest species cannot reestablish themselves, and the land becomes scrub or savannah.
Where logging has occurred and the land has not been converted for agricultural purposes, a forest can sometimes regenerate if the cut area is not too large. The most difficult areas to reforest are logging road tracks (and any other areas where topsoil is removed), which are highly compacted by the movement of heavy machinery and, in addition, are barren of topsoil and seeds. Compaction, still evident more than 10 years after logging, retards root growth and decreases nutrient availability to plants. Old logging roads can be identified since they tend to be dominated by a few light-demanding species, which compete with the normal forest colonizers. The former tend to be long-lived and may be dominant for decades. In many cases shrubby species invade the roads and interfere with colonization by trees. At the least, plant biodiversity is greatly reduced in compacted areas (Guariguata, 1997), which in turn affects the types and diversity of other species. Generalist bird species will generally be found in these areas, rather than the birds of mature forest.
The degree of logging activity is vital in determining whether forest can regenerate. In Kibale National Park, Uganda, uncut trees in heavily-logged areas suffered high mortality because they were often knocked over by falling trees. Twenty-five years later, tree growth rates in these areas were still reduced in comparison with unlogged areas, and the density of all size classes of trees was reduced. There were many gaps which had not been filled by new tree growth. In this forest there are few light-loving species which can colonize large gaps. This feature may partially explain why gaps in heavily-logged areas come to be dominated by herbs and shrubs, which inhibit the germination and development of tree seedlings. In more lightly-logged areas, tree growth rates for small trees were similar to unlogged areas, but larger trees had elevated growth rates, for unknown reasons. Small gaps still remained from logging activities, but there were many fewer changes in the condition of the forest than in heavily-logged plots (Chapman and Chapman, 1997).
Land which has been converted to agriculture, if abandoned, can also sometimes revert to forest. In Puerto Rico, abandoned shade coffee plantations, sugarcane fields and pastureland were able to reforest relatively quickly, with high biomass and biodiversity within 30 to 50 years. Abandoned coffee lands and pastures had approximately equivalent degrees of biodiversity. On former agricultural land, the type of crop, frequency of plowing and other factors influenced the biological heterogeneity of the recovering forest. For example, regenerating forests which grow on former coffee plantations have similar species, despite differences in altitude, soil type, and other features (Zimmerman, 2001). In Puerto Rico, reforestation has occurred because so many people have migrated elsewhere, and much food is imported, conditions not found in most other tropical countries.