Selecting sites for the establishment of planted forests requires the careful consideration of social and legal constraints – such as land tenure, the demand for productive agricultural land, and land accessibility. Landowners – public or private – who have made the decision to establish a plantation should have a clear plan for at least the first rotation from planting to harvesting.

Sites should have enough water, warmth, and soil to support a healthy tree crop; care should be taken to avoid planting trees for the production of goods in fragile ecosystems or systems with a high value for conservation, such as wetlands. If a primary management objective or economic consideration is the production of timber, sites should be close enough to a mill or aggregation centre that transportation costs are economic. Planting at scale is not practicable without road access, so all sites considered for planting forests must have road access or the forest manager must be prepared to put in roads. Poorly constructed or maintained roads are perhaps the major source of soil erosion and surface water pollution from planted forest, so roads must be professionally constructed and maintained for sustainable management of planted forest at scale (Dykstra and Heinrich, 1996).

Matching the right planting material to the right site conditions can be the difference between the success and failure of an investment in planted forest. Moreover, each species and provenance of the species has its own tolerances and growth conditions (Webb et al., 1984). As the global climate changes, in some cases managers are evaluating the use of provenances from warmer climate zones or mixtures of provenances to mitigate against climate change risks.

A wide range of factors, such as the purpose of the planted forest, the production goal (if applicable), the prevailing site conditions (e.g. terrain features, climate and soil), the availability of planting stock, and desired silvicultural and growth characteristics, will determine the choice of suitable species in a planted forest. Depending on the purpose, the selected species should yield marketable products such as lumber, fibre, wood fuel, foods, and medicines. Indigenous species may be preferred to introduced species for ecological or social reasons. On the other hand, the planting material from  introduced forestry species may have been improved through many generations of artificial selection for fast growth and specific timber properties or stem form. Whether indigenous or introduced, planting material should be evaluated for its risk to the planting environment due to invasiveness, and the risk to it of the planting environment due to pests and disease. The management plan should be able to adequately mitigate those risks if necessary.

Securing quality planting materials is one of the most important steps in establishing a planted forest. Managers must find a sufficient volume of viable planting material at a bearable costs to meet their management objectives, or else adjust those management objectives.

Whatever the preferred species or provenances for planting material, a vital consideration in planted forest management is the use of high-quality seeds or other propagation material (e.g. seedlings and cuttings) originating from healthy, well-formed parent trees. The use of high-quality propagation material reduces seedling mortality due to transplantation stress and the likelihood of having to replant. For large-scale afforestation/reforestation projects, therefore, it is advisable to produce forest seedlings in specialized forest nurseries, tree seed centres or project-run centralized or decentralized (community) nurseries. Containerized seedlings are preferred over bare-root stock because of the lower risk of dehydration and transplantation shock and increased likelihood of successful establishment (although see Forest pests for an argument for the use of bare-root seedlings). For tree species that fruit rarely or have seeds that are difficult to germinate, clonal planting stock can be produced from individuals that show desirable traits such as high growth rates, pest resistance and wood quality.

Ground and site preparation

Preparing a planting site so that it is conducive to the survival and rapid adaptation and growth of the planting stock is paramount to success. To reduce soil erosion and nutrient loss, the complete removal of ground-cover vegetation should be avoided. Mechanical site preparation should not be carried out when the soil water content is at field capacity as this may result in a significant soil compaction, associated with increased density and decreased macro-pore space. If no mechanized low-impact procedures are available, ground preparation should be carried out manually as far as possible to maintain soil texture and reduce nutrient losses. Buffers should be established and used to protect perennial streams and watercourses. Controlled burning may be used to clear larger areas of dense secondary undergrowth but requires expert knowledge to minimize environmental damage. Where the terrain has a 15 percent slope or greater, planting lines should follow the contour. Complete removal of weeds should be avoided during the tending process, to prevent soil erosion.

Tree planting

Successful tree-planting is not simple, and it is by no means the end of an afforestation/reforestation process. Unless weeds are controlled, fertilizer applied (where feasible), and fires prevented, the hard work of tree-planters and the effort expended in the nursery to grow seedlings may amount to little. Thus, afforestation and reforestation must be understood as a long-term process and not just a one-time tree-planting event. For planting to succeed, the following points should be considered a starting point, to be adapted and customized based on local conditions and best practices:

• Several suitable tree species may be planted on a given site. For logistical reasons, in plantations it may be easier to keep the number of species small in a given site and vary species across the landscape.
• Seedlings may be positioned randomly across a site at an average distance between adjacent trees of 2–3 m, or they can be planted in lines or clusters.
• The planting pit for the seedling should be at least 25 cm deep and 25 cm wide (deeper for dry forest areas; see (Chidumayo and Gumbo, 2010, Chapter 9))
• The combined density of planted plus naturally regenerated seedlings is usually in the range of 625 stems per ha (average spacing of 4 m x 4 m) but can go as high as 10 000 (1 m x 1 m) for certain broadleaved species. The planting density should be sufficient to establish a forest stand capable of meeting the objectives while minimizing the cost of seedlings and labour.
• The optimal height of seedlings for planting is generally considered to be in the range of 25–50 cm. When planting into existing vegetation, such as during enrichment planting, seedling height of 50–75 cm may be required because taller plants are more likely to compete successfully with existing vegetation. The higher cost of producing larger plants in the nursery is likely to be offset by lower mortality rates and reduced weeding costs.
• The best time to plant trees is during a period in which the soil is moist and temperatures are moderate (e.g. at the start of the rainy season, and/or in the late spring season). Locally appropriate planting dates can be determined from local meteorological data. Plant early in the morning to reduce heat stress on workers and saplings.
• The logistics of the operation from the nursery to the planting site and into the ground need careful planning to minimize transportation time and exposure of the planting material to desiccating wind and sun.
• In temperate climates, a ground survey should be conducted 3–6 months after the initial planting to assess the establishment rate. Dead seedlings should be replaced at the beginning of the planting season, ideally with seedlings of a similar size to those surviving nearby. In tropical climates or in plantations of fast-growing trees, the survey of establishment and replacement of failed seedlings should be conducted within the same planting season. Using good practice in planting, the forest owner can expect to replace ten to fifteen percent of the seedlings planted.

Protection of seedlings

Tree seedlings, whether natural or planted, need to be protected after establishment against competition from weeds for light, moisture and nutrients; wildfire; and browsing by wild or domestic animals. Planted forests usually fail if seedlings are planted and then abandoned. Dense weed growth will retard the growth of both natural regeneration and planted seedlings – and can cause their death – as a result of competition for moisture, nutrients and light. Weed control helps newly established trees to survive and grow by minimize the damaging effect of other plants on the desired trees. If chemical weeding is deemed necessary for economic reasons, it should only be done by properly trained personnel using the necessary equipment and applying the herbicides according to the manufacturer’s instructions and the guidance, regulations and laws of the relevant authorities. Protection of planted tree seedlings against pests and diseases is key for their survival; for more information see (Duryea and Dougherty, 1991; M. Kenis et al., 2019).

Tending, thinning and pruning

Tending and thinning in planted forests are silvicultural operations to improve stand quality by eliminating or suppressing undesirable vegetation, including climbers and vines, and by removing poorly formed, damaged or diseased trees. The objective is to increase the crown development and diameter growth of the trees, to concentrate future increment on the best-formed trees, and to increase the stability of the stand by giving more growing space to the roots of the potential final crop. Canopy closure or the death of the lowest tree branches are indicators for the forest manager that it is time to thin the stand. Tending and thinning operations are significant factors in the achievement of production goals (e.g. high-quality saw logs) in as short a time as possible. Not thinning is usually not appropriate for the production of general utility timber or good-quality saw or veneer logs, but may be suitable for the production of pulpwood or wood fuel.

Pruning is the removal of live or dead side branches, close to or flush with the stem, and of multiple leaders, from a standing tree with the aim of improving the quality of the tree’s timber. Pruning is costly and should only be implemented in stands that are expected to yield good-quality saw logs or veneer logs. Many species grown in planted forests self-prune, reducing the need for active pruning of the stand. Where it is necessary, pruning should only be carried out after the first thinning operation, and it should be confined to the potentially good (a.k.a. crop) trees.

Roles, responsibilities and a schedule of work should be developed to implement planted forest projects. It is a common mistake to underestimate the time required for implementation. Reconnaissance surveys of the project site should start two or three years prior to planting. It is usually better to plant relatively small areas annually over several years than to plant a large area in a single season and have large numbers of planted trees die because of a lack of tending. The table presents an example of a work schedule for a medium-to-large-scale planted-forest project aimed at producing saw logs or veneer logs.

Table 1 An Indicative Work Schedule for Planted Forest Investment in a Seasonally dry Environment

Planted forests are long-term investments, with costs associated with, for example, the selection of germplasm, nursery production, site preparation, establishment, tending, weeding and other silvicultural operations, protection and harvesting. Some indicative costs, which will vary greatly depending on local conditions, are given below. For more information, see the SFM Toolbox Module on Forest Finance. The total costs of a successful planted-forest project in the tropics, including seedling production and all materials and labour for planting, maintenance and monitoring over three years, is likely to be in the range of US$1000–3,000 per ha (Evans and Turnbull, 2004, table 6.1; FAO and UNCCD, 2015, table 2; Hitimana, 2019, personal communication). Planted forests are considerable investments, therefore, and their long-term protection is essential.

After a plantation is established, tending will depend not only on the skill of the forest manager and their luck with unplanned natural disturbances (fire, windstorms, pests and diseases) but also on economics. Plantations are often managed for the goods they can produce and revenues that can be generated from their products; costs are incurred throughout a rotation but only recuperated with the harvest of timber or ingresses from payment for ecosystem services, hunting permits, or similar. In the period between incurring costs and selling trees to pay those costs (the investments maturation), the owner’s accounting reflects the cost of his capital, comprising (Zhang and Pearse, 2012):

• the prevailing interest rate (the opportunity cost of his investment)
• inflation, as if it is positive a unit of currency is less valuable tomorrow than today
• risk, usually based on known and quantifiable risk to the standing timber or price
• uncertainty, things that the owner cannot predict or know but reflect a personal or cultural perception of a likely future

Thus species that grow quickly, shorter rotations, and forgoing precommercial thinning and pruning may be more attractive as a business proposition if the cost of capital is high. In economically, politically, or socially unstable situations a landowner may rationally invest less and harvest earlier in his planted forest, regardless of the silvicultural merits of tending. For the landowner running a plantation business, his investment should at least make the same return as the long-alternative risk-adjusted rate of return from other viable investments.

Financial benefits, such as those created by employment, the harvesting of forest products, ecotourism, and environmental services, are the most obvious and measurable sources of motivation for stakeholders to participate in tree-planting projects. Additionally, neighbours of planted forests often regard less tangible benefits, such as improving the environment (e.g. soil and water resources) and village infrastructure (e.g. the renovation of school buildings), maintaining cultural traditions, and political gain (e.g. the strengthening of land-tenure rights), as equally – or more – important reasons to plant trees and reforest landscapes.

Climate change adaptation

The higher intensity, quantity and frequency of biotic and abiotic hazards (e.g. extreme weather events) projected as a consequence of climate change could increase the vulnerability of planted forests and have serious impacts on forest productivity and the provision of environmental services. FAO’s Climate change guidelines for forest managers set out specific interventions to reduce the risk to planted forests posed by climate change.

Biotechnology

The application of biotechnologies in planted forests is seen by many as an opportunity to provide new tree varieties and reproductive materials adapted to changing environmental, social and economic conditions. Genetic engineering, for example, has the potential to increase the productivity of planted forests and to generate planting material that is more resilient to pests, water scarcity and the impacts of climate change (FAO, 2014, Chapter 8). However, there are also serious concerns about the potential environmental risks posed by genetically modified organisms. They include the possibility of developing aggressive, invasive species, and the loss of biodiversity due to the displacement of traditional cultivars by a small number of genetically modified organisms.

Forest Certification

Forest Certification is a tool for promoting social, environmental and economic sustainability of forest management. It is an important market mechanism for promoting sustainable forest management that provides a proof-point that forests are being managed in a responsible manner. A certification label on a forest product informs potential buyers that the product was produced in a well-managed forest in accordance with a given set of standards. For more information, see the SFM Toolbox Module on Forest Certification.

Natural and planted forests

Globally, demand for forest products such as lumber, wood fibre, woodfuel and non-wood forest products is increasing, driven by demographic changes, economic growth, policies that favour the use of renewable energy, and worldwide campaigns advancing the value of wood as an environmentally friendly material. At the same time, the area and quality of natural forests is declining, and remaining natural forests are increasingly being designated for the protection of soil and water, biodiversity conservation and other purposes that preclude or limit wood production (FAO, 2020). Thus, the role of planted forests in meeting the growing demand for forest products is increasing (Carle and Holmgren, 2008; Jürgensen, Kollert and Lebedys, 2014; Payn et al., 2015). To achieve positive outcomes it is important that planted forest not supplant remaining healthy natural forest and that best practices are implemented and  monitored by the global community (FAO, 2006).

Planted forests and biodiversity

Biodiversity underpins the functions that forests provide to people and the environment. Biodiversity in forests is primarily conserved through wild populations of trees and the organisms that occur with them; this biodiversity can be seen both as having inherent value (e.g. for cultural or spiritual reasons) as well as having value for utilitarian purposes, as a toolbox and template of options that helps improve resilience. Natural forest ecosystems conserve the majority of terrestrial biodiversity; the importance of the maintenance of biodiversity in forest ecosystems has therefore been emphasized in various international conventions and agreements.

While planted forests can complement natural forests in biodiversity conservation, they do not substitute for the functions of natural forests as a reservoir of biodiversity. Planted forests can be seen as a specialized use of a narrow portion of the biodiversity conserved in natural forest. When managers wish to increase the diversity of goods and services from planted forest, or increase resilience of the forest to disturbance or change, it then becomes desirable to increase biodiversity in the planted forest as well. This may be done at the genetic, species, compartment, or landscape level; and may also be done through the rotation of the crop over time in the same place (Carnus et al., 2006).