Forestry

Summary

Forestry is the management of forests for human resource development, extraction, utilization, regeneration, and conservation. It relies heavily on various sciences, mathematics, engineering, and administrative procedures. Typical forest products are paper, joinery timbers, composite boards, cardboard, firewood, and carbon sequestration. The guiding principle is that both the trees and the supporting resources (such as soil nutrients and hydrology) should not be depleted but used so that they can persist in perpetuity.

Definition and Basic Principles

Forestry is the professional management of forests. It consists of several interlinked processes relying heavily on basic and interdisciplinary sciences such as soil science, forest ecology, entomology, remote sensing, geographic information systems (GIS), and statistics. It encompasses aspects of engineering (for example, road design and harvesting machinery), labor (stand inventory, tree felling, haulage, log grading, firefighting, and prescribed burning), budgeting and marketing, and product technologies (mill technology and wood processing chemistry). Forestry professionals are guided by government policies, laws, cultural mores, and advances in science.

The purpose of the forestry profession is to provide the long-term sustainability of forest-product yields and financial returns, in contrast to one-time plundering and gradual forest degradation. The sustainability of various forest attributes and products constitutes good planning in forest management. Timber, in some form, is the most common and marketable of forestry outputs, and forestry is closely linked to the timber industry. Timber yield and quality is, therefore, of primary concern to most foresters, with a consequent drive for maximization of timber yields (especially of the more valuable products) and for forecasting those yields.

Background and History

Forests have been used by humans for millennia. Forests have been converted to pasture for livestock, used to smelt ores, and to manufacture timber, tar, and other products. Trees have been turned into charcoal and removed from mountaintops to mine the ores below. Forestry originated in attempts to prevent the overuse of forests. For example, in the eleventh century, William the Conqueror established forest laws governing the usage of vegetation and wild game.

Until the eighteenth century, forest regeneration (reforestation) was accomplished through regrowth, replanting, or coppicing. In the early 1700s, several French scientists and naturalists, Jacques Roger, Henri-Louis Duhamel du Monceau, and René-Antoine Ferchault de Réaumur, as well as British naturalist John Turberville Needham, made scientific discoveries in the areas of tree breeding and cultivation, wood strength, and yields. Later that century, the German agriculturalist Georg Ludwig Hartig focused his research on sustained yield and founded the first German school of forestry.

During the nineteenth century, the first forest preservation programs in the United States were established. In 1887, the American Forestry Association created a movement to preserve the forests of the United States. In 1891, the Yellowstone Park Timberland Reserve was created by President William Henry Harrison. Seven years later, Cornell University became the first American college to offer college-level education in forestry. The Organic Administration Act of 1897 established the first national forests; however, they were to be working forests designed to improve water flows and to provide timber.

The US Forest Service (USFS), part of the US Department of Agriculture, was established in 1905 to ensure forests continued providing timber and water. Several national forests, most in the eastern United States, were created by the Weeks Law of 1911, designed to reforest areas that had been logged or cleared for farming. In the 1970s, after the start of the environmental movement, forestry began to expand its horizons and encompass environmental concerns. Ecological forestry, although lacking a standard definition, is generally used to refer to forestry that seeks to make use of forests sustainably, considering the whole ecosystem and the social and economic environments, as well as incorporating scientific research.

How It Works

Stock and Yield. Forecasting timber yields requires the measurement of existing stock (making an inventory of the forest) and estimating its growth. Growth is estimated either by repeated measurements over many years or by sampling different sites of similar productivity and different times since harvest. A common measure of productivity is the site index or the mean stand height at the age of fifty years. Yield tables are created, which cross-reference site index and time since harvest, to give harvestable timber volume.

Estimating the standing timber volume requires on-ground measurement of properties such as height and diameter at breast height. Such basic measurements are combined in allometric formulas to provide trunk taper, tree volume, or merchantable wood volume. A technology used at some locations is ground-based lidar (light distance and ranging), a scanning laser providing a map of the trunk surface and, therefore, the volume of several trees per scan. Statistics are taken, and estimates are made at several stages.

Stratification. For efficiency, rather than measuring the whole forest estate, inventory is taken of only portions, or stratums, often selected by their site index. This method relies on matching various environmental attributes such as slope and aspect, precipitation, fire history, soil nutrients, and soil depth. Good stratification provides more reliable interpolation between measured strata, improving overall stock and yield estimates.

Stratification is facilitated by on-ground sampling, remote sensing, and geographic information systems (GIS). Relevant remote-sensing platforms include aerial photography, airborne lidar, and satellites. After stratification, the annual yields of the entire forest can be tallied from the yield tables.

Sustainability. Two main time frames are considered in sustainable forestry: harvesting cycles and the long term.

The primary considerations for each harvesting cycle include maintenance or regeneration of the ecosystem type (for native forests). For fauna, this most often refers to the landscape level, as local demographics often depend on the time since harvest. Another consideration at this level is the maintenance of near-optimum catchment-level water flows and water-table levels.

Long-term considerations include measures to ensure no downward trends in yields of primary forest products (notably timber), the financial returns from the forest estate, and the levels of vital nutrients, such as calcium and phosphorus. Such depletions can occur if successive harvests are too frequent—if they exceed the replacement time needed by nutrients—and site-dependent ecological processes. Another long-term consideration is the total carbon stock of the wider forest estate; the forest management activity must not constitute a net carbon emission. This consideration has come to the forefront with the rise of concerns over climate change and global warming; this requirement is readily met for plantations on old-field farmlands but is more difficult for native forests newly opened to logging and harvest cycles.

Harvesting Plans. Detailed harvest planning is part of legitimate forest management, entailing, for example, a local inventory, silviculture planning, mapping drag lines and buffer zones, yield expectations, and plan approval from government departments. It ensures that on-ground operations meet all prerequisites, such as applying appropriate engineering expertise in forest areas newly opened to industry and local environmental regulations. The plan also forms part of the site history record for future forestry operations.

Production Mechanisms. Silviculturalists grow forests by various techniques, such as collecting seed from local stock before harvest, coppicing, genetically engineering saplings, and prescribed burns, sometimes followed by aerial seeding. Follow-up treatment to promote growth may be unnecessary or include herbivore and weed control and stand thinning. Growth models, combined with mapped environmental variability, produce catchment-level forecasts of wood volume and carbon sequestration. Models help in forecasting responses to management efforts, such as spacing of plantings, pruning, commercial thinning, fertilizer addition, provenance selection, genetic improvement, clearfelling, prescribed burns, as well as less controllable aspects such as drought and wildfire. Linear programming is one method of optimizing finances, timber yields, sustainability, and carbon sequestration over multiple harvesting areas (coupes) within the forest estate. This allows for the development of harvesting plans and their approval several years before implementation, which, in turn, allows employment stability through prior assignment of logging teams and mill deliveries. Forest managers generally prefer error margins in yields to be less than 10 percent. Uncertainties are higher for previously unlogged native forests and mature stands because of buttressing and senescence but lower for more intensively managed forests and plantations.

Product Sourcing. Exotic species form much of the global plantation stock. For example, natural rubber comes from the Amazonian tree Hevea brasiliensis, which is cultivated extensively in Southeast Asian countries. Eucalyptus globulus from Australia is cultivated widely in southern Europe and South America. Pinus radiata from California is grown widely in Australia. This translocation reduces browsing by herbivores that evolved alongside the tree species, and some exotic plantation species can out-compete indigenous species, producing higher growth rates than they do in their place of origin. Such plantations form a major source of products consumed at a high rate, such as paper. In some regions, native forests are used unsustainably for such products. The more obvious environmental effects can be observed, and unsustainable use can be proven through the same fundamentals of forest sciences used in sustainable yield calculations.

Applications and Products

Internal Products. Some of forestry's outputs are consumed within the industry. These include computer software developed by foresters to aid in forestry operations and budgeting, harvesting machinery such as felling mechanisms, virtual reality harvesting simulators, stock valuation and carbon assessments, mill residues to fuel kiln drying of milled timber, and felled trees for construction of bridges on haulage roads.

External Sales. Volume quantities of wood and timber delivered from the forest can be converted directly to monetary values in terms of dollars per metric ton or cubic meter, depending on the type of product and its destination. Other outputs are not so easily converted to monetary equivalents. These include remediation of land through afforestation, unmonitored firewood collection, maintenance of biodiversity, water quality, salinity remediation, and reduced air pollution. Such calculations are, however, becoming more frequent in the scientific literature and even in government reports.

Mill Products. Two main mill products from logged timber are pulpwood and sawlogs, sometimes from the same forest tree or stand (integrated harvesting) or from entirely separate forests. The proportion of the original tree volume that becomes cut lumber is usually no more than 55 percent and often lower. Consequently, optimization of sawmilling is financially crucial. Taper formulas, which model tree shapes, indicate not only total wood volumes but also volumes of different mill products. Computer-automated milling to optimize the cutting pattern within individual logs can reduce wastage. Final product yields are fed back to aid future revenue forecasting. Woodchip and pulp mills are coarser processors, with throughput of up to 400 metric tons of woodchips per hour, equivalent to one fully laden log truck every two and one-half minutes. These rates are driven by the global market developed for paper products.

Product Variety. In terms of volume, the material products of forestry are dominated by lumber and paper, but other products such as firewood, charcoal, cork, sandalwood oil, cinnamon, and palm oil can be regionally significant. Some outputs, such as firewood, although measurable, can be from forestry harvests or simply collected from forests without forest management, but both come under the heading of forest products in national accounts. Broader-scale outputs of nontraditional forestry include salinity remediation, regeneration of semiarid landscape functionality, amelioration of urban air pollution, and attempts to address climate change. Reducing the emissions from deforestation and forest degradation is an area of increasing investment and requires adaptation of traditional forest sciences to different forest components (such as nonmerchantable tree components, woody debris, and soil) and to a greater range of time scales.

Natural Resins and Gums. These products, such as myrrh, frankincense, and gum arabic to name a few, fall under the non-timber forest products and have a sizable share in the forest-based product trade. They have varied applications in industries such as pharmaceutical, food, and cosmetics. There is a growing need to apply proper forest management techniques to manage and monitor the natural resins and gums market.

Careers and Course Work

Trained foresters are in demand for forestry management of both native and plantation forests. The two main drivers are the production of wood products and the conservation of the environment. Aspirants can work as natural resource specialists, horticulturists, and soil conservationists. The traditional route for those interested in pursuing a career as a forester or conservation scientist has been to gain a bachelor's degree at a special forestry school or university department, often focusing on wood production. Often, these studies are combined with environmental sciences or geography as part of a more general environmental science degree. Nevertheless, dedicated forestry departments are still part of many universities, especially those in major capital cities or those where the forest products industry has a regional presence and a substantial stake in the workforce. Some universities link with others to provide more comprehensive training.

Students who wish to pursue forestry in college should take science classes and at least one mathematics class while in high school. A forestry degree can be combined with biology, botany, accounting, economics, geography, or resource management. A forestry degree will often include at least one class in forest ecology. For more advanced studies in forestry, statistics is necessary at the undergraduate level. Universities such as the University of Montana and Michigan Technological University offer degree courses in forestry.

Social Context and Future Prospects

The sustainability of key environmental attributes remains problematic, even with rigorous protocols and planning, because advances in forest science must be comprehensively proven and written into policy before integration with demands for productivity. For example, evidence and modeling suggest that in many forests, heat stress from higher summer temperatures and droughts will outweigh the carbon dioxide fertilization and longer growing seasons accompanying climate change, requiring recalculation of harvesting quotas.

A question remains as to where and how forestry should be implemented. Many plantations, such as rubber and palm oil plantations in Southeast Asia, required clearing of the original forest and have since been reforested. Afforestation can have environmental benefits, such as providing a reprieve for native forests, land rehabilitation, and climate change mitigation. In 2010, although progress had been made toward recycling paper and curtailing illegal logging, the paper industry and some forestry professionals participated in an initiative designed to get people to print more emails. They argued that paper is a natural and eco-friendly product, and the number of trees being felled for pulp extraction for the paper industry is being replenished by the growing afforestation globally due to the implementation of proper forestry management practices. Moreover, they claimed that forest cover is increasing globally with the adoption of natural gas in household uses, thereby replacing firewood.

The application of forestry knowledge is increasingly sought in newer, nontraditional industries, such as mine-site and rangeland rehabilitation and urban forestry. Forestry principles are also used in climate change mitigation efforts, such as carbon budgeting practices and calculating emission offsets. The Global Forest Goals Report 2021, released by the United Nations, highlighted the economic impact of the COVID-19 pandemic in 2020-2021 on forests. The report found the pandemic created stress on forests in combination with natural and other socio-economic factors. The pandemic also interfered with forestry's production, trade, and supply-train aspects. The field of forestry continued to advance technologically as the 2020s progressed, incorporating artificial intelligence and data analytics. Forestry also remained a critical field in the fight against global climate change, and its impact on economies, social conditions, and education continued to be felt. 

Bibliography

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