Silviculture Methods Best Suited for Pine Tree Growth and Biodiversity in Boreal Forests of the World




"Silviculture, a discipline within forest science, offers a set of tools that make achievement of the forest management objectives possible. Sustainable forest management strives to maintain healthy ecosystems, improve the balance among alternative forest values and conserve biodiversity"(7).



Table of Contents

  1. Background Information

  2. Define Forest Type

  3. Biodiversity

  4. Methods for each

  5. Thinning

  6. Seven Conditions to Consider

  7. Scientific Journals

  8. Further Searching

  9. About the Author





1. Background Information:

Silviculture: The science and practice of caring for forests while maintaining human objectives in mind (6). This defines ways to cut down or fell trees, in order to improve stand quality or start over from scratch. "Sustainable silvicultural practices conserve biological diversity,water resources, soils, and landscapes to maintain ecological functions and ecosystem integrity" (1).


Boreal Forests: Boreal forests, or taiga, are circumpolar in extent and occupy a belt up to 1000 km wide in certain regions. Conifers occupying boreal forests include members of the genera Picea, Abies, Pinus, and Larix. These species have different life histories with varying levels of fire, insect, and disease resistance. More importantly, these species exhibit a wide range of shade tolerance and growth characteristics, and occupy different successional positions. In general, the firs and the spruces tend to be long-lived (typically 200 yr) species (4).


So, Why choose Silviculture? My research question is trying to find out which methods of silviculture and intermediate cuttings, work best for pine trees in boreal forests worldwide. Timber from pine trees is a major source of income and is of great use to loggers/forest owners worldwide. I want to see how differences in land use can impact our nation in the future. People mismanage their lands, which can lead to increased levels of deforestation and wasted land. Many people who own forest land or who are going to purchase some, are not aware of the effects of certain management services on their forests in the long run. Mismanagement leads to the loss of money, poor soil value, and decreased acreage of a forest in the long run. I believe that land owners and business owners will find my site helpful in order to determine what to do to their land, in order to make the most profit to save a large percentage of our biodiversity.


Example of a Boreal Forest





2. Define Forest Type:

In order to choose your Silviculture method, you must first decide whether your forest is even-aged, uneven aged, or two-aged.

*Even-Aged means the stand was planted within a couple of years of each other. They are from seeds which were planted and sprouted within 5 years of one another. These trees are usually the same height and width.

*Un-even aged means the stand has more than one age class of trees. They can range from about 10 or more years apart from one another. This can be due to thinning practices previously used on the land

*Two-Aged stands are those which hold only two age classes of different tree stands.









3. Biodiversity:

Many plant an animal species co-exist together in their natural habitats. In order to conserve these species, we must be sure to consider both when mantaining and managing a forest. Animals depend on different types of tree, shrubs, berries and niches, in order to make their nests and burrows. They also depend on trees as a food source, along with shelter and protection from predators and extreem weather conditions. Managing a forest stand not only helps to balance out the rate of growth, but also to create a balance between animals and their habitats. When cutting a forest, it is very important to consider the types of species on your land. If there are endangered species or animals that are protected under the Environmental Protection Agency, you may not be allowed to touch your stands.

In temperate and boreal regions, the forest understorey is typically much more diverse than the woody layers. In Canadian boreal forests, species diversity generally peaked at intermediate site treatments. In Japanese beech forests, the locations that sustained an intermediate frequency of disturbance had the highest species diversity . Similarly, in Himalayan oak forest the highest plant diversity was observed at the intermediate level of disturbance (3). This reveals to us that disturbances (thinning and cuttings) can be good for the biodiversity of a forest.



Wildlife in a Boreal Forest (LINK)





4. Methods of Silviculture for Stands of Pines

-For even-aged stands options include:

Clearcut Sudden and complete removal of all trees in a stand (9).
Seed Tree leaving 2-10 trees per acre to replenish the forest(9).
Shelterwood overstory is selectively removed in two or three operations separated by 10-20 year intervals (9) .
Perscribed Fire Prescribed burning promotes natural regeneration, and several rare and endangered species benefit from burning. Suitable areas for prescribed burning are moraine regeneration cutting areas, where soil is neither too fertile nor too barren, and where the size and shape of area allow safe burning (5).
Pesticides Herbicides are applied on a regular basis only within the afforestation of arable lands, whenever it is necessary to control the competing vegetation in order to ensure the survival of seedlings (5).




Seed tree




-For Un-even Aged forests (including two-aged) Options include (10):


Cutting down the poor quality trees and leaving high-grade trees

Single-Tree Selection Selecting trees to remove in a stand one by one
Group-Selection Small clear cuts in certain parts of a forest that allow for sun loving trees to emerge.


Single-tree Selection


Group-Tree Selection




5. Thinning Methods:

Sometimes a forest may not be ready for a complete cultivation, which is when thinning comes in. Thinning is a process where, "stands have reached sufficient size that trees to be removed have value as fuelwood/pulp or sawtimber.  These operations are often essentially weedings where the non-grade species are removed so that the better crop trees can grow.  A more intensive variant is called crop tree management, and it involves identifying the best trees in a stand and fully releasing them from competition"(8).


Low Thinning

Removes Immediate and Supressed Trees that are located near the canopy of the forest
Crown Thinning Removes dominant and co-dominant trees that are located at or above the canopy (very large trees)
Mechanical Thinning This is done in some sort of mathematical or geometric way. The harvester will either cut down every other tree, every 3rd row, 5th row, etc. This thinning is done by physical location.

Selection Thinning

Removing only the dominant trees
Free Thinning a combination of both low and crown thinning


Frequent commercial thinnings were regarded as an important means to improve growth and value and to reduce natural mortality among pine and spruce trees in Nordic boreal forests. However, research and experience have shown that, in managed stands, foresters can decide within wide limits the amount of wood they want to harvest in the form of thinnings or final harvest. The choice of stand treatment programmes therefore depends more on economic factors, such as the price of wood assortments produced and harvesting costs (2).


*KEY REMINDER: IT IS VERY IMPORTANT IN THINNING TO MAKE SURE THAT YOU MARK THE TREES TO BE THINNED WITH PAINT AT BREAST HEIGHT AND AT THE BOTTOM OF THE STUMP! This is because some loggers will cut down the wrong trees, but if they are marked at the stump, you will be sure to keep track of whether or not your loggers are doing the job correctly.




6. Seven Conditions to Consider for Cutting Down any Tree (9).

When Are conditions right to consider a clear-cut?

  1. When regenerating tree species that need full sunlight to stimulate seed sprouting and seedling growth.
  2. When dealing with sparse or exposed or shallow-rooted trees that are in danger of being damaged by wind.
  3. When trying to produce an even-aged stand.
  4. When regenerating stands of tree species that are dependent on wind blown seed, root suckers or cones that need fire to drop seed.
  5. When faced with salvaging over-mature stands and/or stands killed by insects, disease or fire.
  6. When converting to another tree species by planting or seeding.
  7. To provide habitat for wildlife species that require "high-density, even-aged stands".






7. Scientific Journals


Name Reference Description
1. Different Methods of Clearcutting R.J. Mitchell, J.K. Hiers, J.J. O’Brien, S.B. Jack, and R.T. Engstrom. Silviculture that sustains: the nexus between silviculture, frequent prescribed fire, and conservation of biodiversity in longleaf pine forests of the southeastern United States. NRC Canada 2006. study done in order further investigate the longleaf pine and ways to preserve it in America.  Different silviculture methods are examined such as prescribed fire.
2.Silviculture in Boreal Forests Hagner, S. Unasylva: Silviculture in Boreal Forests. Food and Agriculture Organization of United Nations. 1995. Journal article mentions a brief history of boreal forests and how forestry is changing in order to acomplish safe biological results.
3. Threatened Species Reier, Ülle; Tuvi, Eva-Liis; Pärtel, Meelis; Kalamees, Rein; Zobel, Martin.  Threatened herbaceous species dependent on moderate forest disturbances: A neglected target for ecosystem-based silviculture.  Taylor and Fransis 2005. Methods of thinning and prescribed fires have helped to enhance biodiversity in certain parts of forests. 

4. Silviculture's Role in Boreal Forests

Graham, R. T. and T. B. Jain. 1998. Silviculture's role in managing boreal forests. Ecological Society of America to the Resilience Alliance. January 1, 2000. Introduces what a Boreal forest is and where they are usually found. Also explains the importance of them and ways to go about using proper Silviculture to use the forests efficiently.
5. Biodiversity and Forests in Europe Mielikäinen, Kari, and Jari Hynynen. "Silvicultural management in maintaining biodiversity and resistance of forests in Europe–boreal zone: case Finland." Journal of Environmental Management 67.1 (2003): 47. Academic Search Premier. EBSCO. Web. 26 Apr. 2010. Provides a journal on Silviculture practices that impact boreal forests, such as regeneration methods and thinning. Also Discusses economical and ecological impacts.





8. Further Searching




6.Glossary Of Silviculture Terms Website priovdes definitions one may need to know when considering any method of Silviculture. This site also has pictures along with the definitions to help someone who may not be familiar with any terms. LINK
7.Silviculture of Southern Pine Forests This site provides different methods used in order to better manage pine tree stands. It also explains what yellow pines are and different ways for improvement and fertilization. LINK
8. Silviculture Systems focuses on projects of high grading and cuttings in the Americas. Methods of silviculture are displayed such as, intermediate cuts, regeneration cuts, even and uneven aged cuts and other various systems LINK
9. World Boreal Forests Explains the definition of forestry, along with more methods of Silviculture. It has put together different techniques that can be used, including a list of conditions for cutting down every tree. LINK
10. Even/Uneven Aged Pictures of Silviculture used in Even and uneven aged stands of pine trees. LINK






9. Author:

Site Created by Amanda Bolin for World Forestry 414 in order to find out the best methods of Silviculture for pine trees and biodiversity in Boreal Forests. Created April, 2010.