Forestry
Forestry and its Benefits
Humans benefit in a wide variety of ways from forests. They provide timber, release oxygen which is required for cellular respiration, provide habitats for a multitude of species, and can provide food. They have a variety of other services they provide as well: they can filter the air by taking in pollutants, their roots hold the soil in place and help to prevent erosion, and can sequester CO2. As we continue to rely on forests and the demand for their resources increases, the need to manage them grows. Forestry focuses on the management and conservation of our forests, ideally (but unfortunately not always) striking a balance between ecological and human benefits.
While this is not the case for all forests that are managed for timber, a very large portion of the timber industry focuses on tree plantations. These are also known as tree farms, and they essentially work the same way as monoculture farming - there are areas where the same species of fast-growing tree will be planted and then harvested at the same time. These trees are even-aged, meaning they are all the same age. This lowers the biodiversity of the ecosystem, therefore lowering its resilience.
Timber Harvesting
There are a variety of ways that can be used to harvest timber from forests. The simplest, and often most cost-effective way, is clearcutting. This is, simply put, cutting down all of the trees in an area at once.
There are significant ecological issues with clearcutting. The lack of roots results in more frequent erosion, which causes soil to degrade and lose its nutrients and water. The lack of shade and lower albedo of soil leads to an increased temperature in the soil, which increases risks of desiccation. As erosion becomes more frequent, soil can enter sources of water more frequently, increasing turbidity and water temperature. All of this happens, on top of completely changing a community through the removal of multiple habitats.
Sustainable Forestry
While clearcutting is currently the most widely used method for harvesting timber, alarms have been rung about the ecological damage that it can cause. As such, a variety of more sustainable methods have been developed so that trees can be managed in ways that do not degrade the resource or cause as much ecological damage.
Here in the United States, the National Forest Management Act was passed, requiring national forests to develop plans centered around the concepts of maximum sustainable yield and multiple use, which was the idea that they would be managed for multiple uses including recreation, wildlife, ecosystem integrity, and resource extraction.
A lot of harvesting methods aim to maintain uneven-aged trees, which means the trees are not all the same age. Having trees that are a variety of ages allows for a larger number of potential habitats for other organisms and provides a wider variety of ecosystem services. For a similar reason, they also often aim to include multiple species of trees as well.
Selection systems are a type of forestry management in which some trees in an area are cut at a time, rather than all of them. There are two major types: single-tree selection and group selection. Single-tree selection, also known as selective cutting, is when trees that are widely spaced out from each other are cut one at a time. Group selection, also known as strip cutting, is when all of the trees in a small section are cut. These methods are not perfect. They still disturb the soil, increase the amount of runoff, increase the risk of flooding and landslides, increase erosion and worsen water quality, and disturb forest composition. However, they do so to a significantly lower extent than clearcutting does. The forest's structural diversity remains mostly intact. However, while they are more ecologically friendly, these methods are more expensive than clearcutting and are not always used.
The use of any machines for timbering can compact the soil (resulting in a loss of water-holding capacity and an increase in erosion) and disturb the forest floor ecosystem. One way to forest more sustainably is by using fewer machines. Using increased human and animal labor reduces soil compaction and degradation.
When trees are cut down and new ones planted, it is also important that the same species of native trees are planted. Different species provide different ecological services, provide a habitat for different species, and fall into different parts of the food web for the ecosystem. By planting the same species, the changes to the ecosystem as a whole are minimized. Likewise, in areas where deforestation has occurred, reforestation can be done to replant native trees and restore a previously destroyed forest.
Another way that forests can be managed more sustainably is by decreasing the need to cut down trees for timber. This can be done by recycling and reusing wood.
Fire in Forests
When someone thinks about fires within a forest, they typically imagine it as being a problem. Maybe it's thanks to Smokey the Bear and all of his warnings, but we are pretty good at associating forest fire with "really bad." In fact, for a long period of time, whenever there was a forest fire, it was the position of agencies such as the US Forest Service that the fire should be put out as soon as possible wherever it appeared.
However, and this may seem counterintuitive, fires can be good for forests. There are ecosystems that have evolved to depend on natural forest fires. Some species of plant have evolved seeds that do not begin to germinate until a fire has happened, allowing them to repopulate a thinned-out forest. When forest fires naturally occur, nutrients are returned to the soil due to the burning.
By suppressing forest fires, communities have been altered and animal and plant diversity have changed. As an example, areas like grasslands, which frequently have natural fires, will have more shrubs growing in the absence of the fires. In addition, with the build-up of dry biomass on forest floors, there is significantly more fuel for fires, resulting in the potential for much more severe fires, which have become far more common recently.
We have learned that monitoring the low-intensity and natural fires is a better course of action than active fire suppression. However, all of the kindling that has built up over the years results in extreme fires, devastation to ecosystems, destruction to homes and property, and injury and death. Prescribed fires have been being used to help address and solve this issue. Land management agencies have been working to intentionally use small, controlled fires to burn away the built-up biomass, return nutrients to the soil, improve the health of ecosystems, and reduce the risks of severe fires. This controlled burning can greatly help an ecosystem, but they take a large amount of time to do so carefully. That, coupled with the fact that many people (including politicians in charge of decision-making) do not understand the process and have yet to come to the understanding that fires are not intrinsically bad for forests, this method is grossly underused, leaving many US forests still at risk of severe and dangerous fires.