Selective Logging: Methods, Specifics, And Impacts

What Is Selective Cutting?

Selective logging (or cutting) is a timber-harvesting method to fell the chosen trees. The method implies removing only the best timber and leaving the rest in the stand, this is why selective cutting has higher productivity. Typically, the choice is based on their diameter, height, species, and other parameters contributing to their merchant value.

Selective cutting in forestry is rather an economic strategy than a forest-management practice. The best timber is logged for the highest profit (aka high-grading ^{Sanford S. Smith. Thinking of Selling Your Timber? Beware of High Grading. 2020. College of Agricultural Science. The Pennsylvania State University}), and aging or weak ones remain in the forest since they present low economic value. Nonetheless, the method leaves poor material for forest regeneration by cutting the best species before they produce saplings or seeds and decreasing timber quality in the future. Taking these factors into consideration, selective cut logging should and can be implemented in a more sustainable way.

Selective Wood Cutting Vs. Other Forest Management Practices

The two fundamental aspects of forest management are timber harvesting and reforestation, so a sustainable approach strongly relies on forest regeneration after logging. There are four basic timber harvesting practices: selective logging, seed-free, shelterwood, clear-cutting.

Selective Logging vs. Clear-Cutting

Clear-cutting is the removal of all or nearly all trees in the stand. In selective harvest logging, most trees remain.

What’s More Environmentally Friendly Selective Logging Or Clear-Cutting?

Some experts believe that selective cuts support forest regeneration ^{Bjorn Norden, Per Kristian Rørstad, Jakob Magnér, Frank Götmark & Magnus Löf. The economy of selective cutting in recent mixed stands during restoration of temperate deciduous forest. 2019. doi.org/10.1080/02827581.2019.1679876↑} because younger trees get more sunlight to grow, and pathogens get more sunlight to be destroyed. Regeneration after clear-cuts starts either naturally or by replanting in a couple of years. However, the next timber harvesting after clear-cuts will be possible on average after sixty years.

Why Is Selective Logging Better Than Clear-Cutting?

Clear-cutting allows logging many trees at once, which saves operation time, so it is good for time-management reasons. However, selective logging is still better than completely or mostly empty areas after clear-cuts because it leaves some wood to harvest for the nearest years.

Difference between Shelterwood, Seed-Tree, And Selective Cutting

As the name suggests, the seed-tree method leaves mature trees to produce seeds for new stand development. Seed trees are cut once the saplings properly establish. Shelterwood practice provides some shadow protection for the sun-intolerant species, and then mature trees are cut after 5 to 10 years. All these methods are selective in their nature, but the difference between them is the timber choice. Seed-tree and shelterwood practices promote forest revival, while selective cutting harvests the most expensive timber.

Selective Cutting Methods

Compared to clear-cutting, selective logging is a way more difficult to implement and its methods have a number of steps to complete:

• marking the trees;
• calculating the timber volumes;
• areas covered;
• equipment used;
• timber transportation options;
• protection of the remaining stand.

The last point implies herbicide applications and saplings’ competition with the older trees.

Considering the above-mentioned aspects, selective logging is performed either by cutting single trees or their groups.

Selective Cutting Of Single Trees

According to this method, foresters remove the chosen trees individually. Such logging mimics the natural ecosystem process, when the trees die naturally, and ensures continuous harvesting. On the other hand, single-tree logging applies only to shade-tolerant species regeneration due to the limited sunlight penetration and ensures frequent harvesting thanks to the availability of mature valuable trees.

Group Selective Cutting

This logging type commonly cuts groups of older trees. It still ensures profitable timber production but makes wider gaps in the forest stand. It is similar to the ones occurring due to strong winds, floods and landslides, or tree diseases. However, the logging method is different from natural processes because it chooses only the most valuable timber (often of nearly the same age). Monitoring from the space, group cuts are easier to track in comparison to single-tree logging.

Combination Of Group And Single-Tree Selective Cutting

The logging methods are often combined, and economically valuable mature trees are felled either individually or in groups. All chosen trees that meet the required criteria are cut down along the entire perimeter of the forest area and transported with designated logging machinery.

Advantages Of Selective Cutting

Even though the practice removes the strongest trees in the forest, there are certain benefits of such a practice. First, it leaves behind some important species. Second, forests are less subject to tree diseases. Third, this method promotes carbon sequestration ^{Tropical Forest CO2 and energy exchange. Goulden Lab Department of Earth System Science.}, as proved by a study of Brazilian tropical forests by the University of California.

Among other benefits, selective logging also:

• Provides more light that kills fungi and is necessary for shade-intolerant species.
• Boosts seed growth in the cleared-up areas.
• Leaves some valuable trees for future logging.
• Prevents forest wildfires.
• Produces no smoke and air pollution issues compared to prescribed burning.

Selective Cutting Negative Impact

This logging system has a number of negative consequences because all or most of the economically viable trees are cut in one season. Let’s consider the most essential ones.

Financial Impact

Even though the logging method chooses the most expensive trees providing the highest profit, this effect is only temporal. Mature tree cutting eventually spoils the timber quality and volumes, so forest owners should not expect a stable income over time. Selective logging doesn’t apply when it comes to forest sustainability, and this method cannot ensure continuous profit in the long run.

Future Management Options

High-grade logging provides the highest profit only during the first cut. However, removing the best timber will reduce the timber quality in the future. The second harvesting will be possible when valuable timber restores, yet the subsequent high-grade logging will be limited. Due to the poor economic value of the remaining trees, foresters have to refresh the stand to increase their profit. In this case, forest regeneration includes two options:

• cutting the whole stand and planting better species;
• letting the forest revive naturally until the trees are mature enough for harvesting.

Selective Logging And Deforestation

At first glance, selective logging is sparing because the stand is not felled completely but only thinned. However, there are certain drawbacks. First of all, felling can cover huge forest areas and remove thousands of cubic meters of productive forest. Secondly, selective cutting requires activities to collect and transport the harvested timber, which negatively affects the remaining trees. The movement of logging machinery disturbs the forest floor and topsoil, and transportation passages get wider with time, contributing to deforestation.

Environmental Effect Of Selective Cutting

By harvesting the best timber, selective logging promotes the growth of weeds and poor-quality trees like red maple, beech, and hemlock, negatively affecting biodiversity and reducing carbon sequestration. The method also impacts the stand symmetry and proportion as logging may cover larger areas in one forest part and smaller in the other.

Selective Timber Cutting For Wildlife

Logging the trees that produce a lot of masts negatively impacts wildlife because it decreases the availability of food sources. For example, red oak or black cherry provides food for deer, squirrels, bears, turkeys, and other birds, while the fruit of chestnut, beech, or oak is eaten by wild pigs. So when wildlife diversity matters, forest fauna should get favorable living conditions, suitable for each species. The density of the vegetation canopy is also important, so poor crowns won’t provide enough food for wildlife and its specific habitat.

Satellite Technologies For Selective Cutting Implementation

Compared to clear-cutting, selective logging is much more difficult to monitor since it does not imply large-scale deforestation of big forest areas.

EOSDA Forest Monitoring relies on satellite imagery to detect illegal logging, warn about wildfire risks, and report on forest health in general. The NDVI index on the platform shows if the selected AOIs re-grow sufficiently after selective cutting.

EOSDA Forest Monitoring offers the possibility to create customized solutions, which our team can implement specifically for your forestlands, and which can be actively used in the forest and selective logging.

Deforestation Feature To Detect Forest Logging

One of the methods of selective logging is group cutting. Thanks to satellite images and their processing by our system, our product shows the cut areas in the forest. There are also additional features to implement. Custom solutions are based on higher accuracy of data processing, taking into account the properties specific to your forest: tree species, vegetation density, historical data from the area, and more. Extended forest data can be used to evaluate the effectiveness of forest management contractors. For example, foresters have marked the area for logging. After tree-felling operations are complete, they will see whether the contractors have cut more trees than planned and will be able to detect illegal selective logging.

Thermal Anomalies Feature To Prevent Wildfires

Selective logging means exposing the forest floor to sunlight by cutting down a few rows of densely foliaged trees.

Under this type of logging, forests are more susceptible to forest fires because sunlight penetrates the sparse canopy, drying out and heating up the forest floor, which makes it much more vulnerable to fire. High temperatures increase the chance of spontaneous combustion of the remaining trees. It is important to monitor territories with a high risk of fire, either seasonal or on extremely hot days. There is a Weather section in EOSDA Forest Monitoring for this purpose; it gives access to historical weather data alongside temperature and precipitation forecasts.

A separate layer in the Thermal Anomalies monitoring allows seeing a map of abnormal temperatures, which frequently signals a fire. By adding forest stands to EOSDA Forest Monitoring, our users will also receive an automatic alert if an abnormal temperature is detected in any part of the forest, allowing responding to fires more quickly and minimizing losses.

Forest Productivity To Detect Mature Trees

Selective cutting removes healthy and mature trees, and the Forest Productivity feature on our platform helps detect them by dividing forestland into zones based on their productivity. NDVI maps show green productive zones suitable for harvesting. Single trees that meet the criteria can also be found in less productive zones, too. However, productive zones are richer in valuable timber. Also, the advantage of high-grade cutting in a highly-productive area is that partial felling will not have a significant impact on the overall productivity of the zone. However, cutting off mature, healthy trees in zones with medium productivity may permanently lead to a decline in productivity in that area of the forest.

Forest Productivity To Track Vegetation Changes

Thinning can affect forest productivity. The Forest Productivity Feature allows users to track changes in productivity and estimate the thinning effects. Forest harvesting suggests different methods that vary in logging intensity. Therefore, it is important to assess logging effects on the stand. Aggressive thinning can lead to forest decay caused either by logging itself or timber transportation. The impacts are not always clearly visible but may reveal with time. By analyzing a productivity map, users can see the productivity of a forest area at different dates (e.g., before and after cutting) and understand its impact on the forest. This way, foresters can decide if this approach is rational, or if they need to consider another and more sustainable one.

Contact our sales team and get an expert consultation for the rest of the EOSDA Forest Monitoring features at sales@eosda.com.