What is Close-To-Nature Forestry (CNF)?
Close-to-nature forestry is about managing a forest in a way that imitates nature, yet benefits humans more than no management would. It is considered very low impact and low maintenance as it is making use of natural processes “working with nature, not against nature”. Close-to-nature forest management creates diverse, multi-functional and resilient forests. The idea originated from Germany, but is either entirely or in parts adapted throughout the world. Synonyms can be “natural forest management”, “integrated forest management” or “ecological forest management”.
CNF requires a forest manager to have a good and deep understanding of the forest. If research and historical data is lacking, it is often difficult to develop this kind of understanding. Furthermore forests managed this way are not having a growth rate as high as in traditional plantations – instead the provide many more ecosystem services. However, in many commercial plantations in the world production is the ultimate measure when choosing a management style.
Finally CNF, originating from Germany, is not a famous concept, yet. Many people simply haven’t heard of it.
Necessary Information for CNF
A forest manager should know the fundamentals of forest ecology, successional processes (for example if a forest naturally will be in an equilibrium stage), disturbance cycles, land use history, site conditions and the human influence on forests. It is, for example, important to know whether a forest is naturally simpler in structure (which can be induced by a lack of water) or whether the simplicity in structure derives from former degradation processes (when people collect fuelwood and with that natural regeneration of trees). While even in areas of the world where CNF has been practiced for a while science learns more and more about these factors and therefore can never give a complete answer, it is important to have a grasp of each of these aspects in order to judge a forest accurately.
An Example of CNF
You are the manager of a forest that based on research, natural disturbance cycles and undisturbed forests in reserves is determined to be an natural oak forest. Your most commercial species is pine but naturally only occurs in very small amounts. If there is no disturbance (which would be rather unnatural as your windthrow cycle is about every 120 years) the forest would change into a hemlock forest.
A traditional forester would…
…likely mostly or purely grow pines and regenerate them with a clear-cut. They bring the most money for their timber and are the fastest to grow.
A CNF manager would…
…recognize that, while pine brings the most money and hemlock is the “virgin forest” species, this forest ecosystem is dominated by disturbances and finds its semi-equilibrium in oak forests. He would try to keep a certain low percentage of pine, grow oak and optimize it’s quality through thinning techniques and also keep some hemlock as it would naturally occur in the forest as well. He may designate the commercial value to the pine and oak, though, and leave the hemlock only for ecosystem services like biodiversity.
Of course, management decisions are more complex than this example as they also have to take into account the political, socio-economic and local conditions. The example above was just including ecological and economical considerations.
So what is BFS exactly doing in Miyun?
The current condition
Nearly all of the forests in the Miyun watershed have either naturally established on degraded lands and are still in the process of recovery or have been planted in the 70s and 80s with the help of large state programs like the Grain for Green program. Back then barren mountains were a common picture and caused a lot of erosion issues affecting the reservoir which is why the government eventually intervened.
These plantations are for the most part mono-cultures that are not truly reflecting the natural vegetation which would provide more ecosystem services and be more resilient. Many of the planted forests today are too high in density, resulting in high h/d (height/diameter) ratios which make the forests prone to wind-throw and reduce the understory and general biodiversity. To the right you can find a description of the species used for afforestation back then.
These species were part of the original afforestation program in the Miyun reservoir in the 1970s and 80s. Most of the high forests you can see in the area are consisting of these species. They were usually planted in monoculture plantations.
Platycladus orientalis, commonly known as Oriental Thuja, is one of the two species most frequently used for afforestation on the project sites. It is fairly drought resistant and as a typical early successional well-adapted to withstand the harsh conditions bare mountains can bring. Historically it’s been planted around Buddhist temples.
Chinese Pine, or Pinus tabuliformis was the tree most frequently used for afforestation in the Miyun reservoir. It’s a native species that needs a lot of light but can withstand thin soils & harsh winds.
A variety of poplars and poplar hybrids are used in afforestation in lower elevations around Beijing. Some of the more frequently used ones are Populus cathayana, Populus davidiana and Populus simonii. Being an early succession species that is naturally wind-dispersed, it is easy for these species to establish in open environments.
The Prince Rupprecht Larch (Larix principis-ruprechtii) was often used for reforestation on high elevation sites around Beijing as it easily grows on rocky slopes. It needs a lot of light. Larches are one of the few deciduous conifers.
Not usually dominating forests, the Tree of Heaven (Ailanthus altissima) is an important native species, often used in afforestation to establish on the soil and protect it as it is a typical early successional species. It is fast-growing and rather short-lived, reaching a maximum age of 50 years. It’s timber is valuable, it prefers calcareous soils, growing naturally on slopes, roadsides and near villages. It is also used as a medicinal plant. It is also known as an invasive tree species in America.
It is our vision to restore the native vegetation while providing a maximum of ecosystem services to the villagers owning the forest and the people downstream depending on clean water. This means that we will not 100% replicate the natural forest but transform it in a way that brings humans and nature maximum benefits. This can for example mean that fruit trees or plant communities that favor the growth of medicinal plants will be favored.
Below you will find the current composition of the forests and an set of species that occur in natural forests.
Many different oak species are part of or dominating natural forests around Beijing. The most well-known might be the Mongolian Oak (Quercus mongolica) but also the Chinese Cork Oak (Quercus variabilis), the Daimyo Oak (Quercus dentata) and the Oriental White Oak (Quercus aliena). All of these oaks specialize in different site conditions but often also mix.
Quercus mongolica forests are mainly distributed in mountainous areas on shady slopes at elevations of 500-1600m, but also sunny slopes and ridges. It often occures together with Acer truncatum.
Quercus variabilis forests are usually developing on mountain ridges but also some slopes. They are very light demanding.
Quercus dentata forests are common in the lower mountains of Beijing. Quercus aliena usually doesn’t dominate a forest but grows on sunny slopes.
Asian White Birch (Betula platyphylla) forests are mainly distributed in middle and higher mountains. It is an early successional type of forest that establishes after a larger disturbance. It can occur together with other birch, poplar or oak species. This species is rather light demanding.
Beakleaf Ash (Fraxinus rhynchophylla), although rarely occuring as the defining species in a forest, is an important component of the natural vegetation in the forests in mountainous areas around Beijing. It also occurs along rivers and on roadsides. The wood of this species if used for cabinet making.
The natural Prince Rupprecht Larch (Larix principis-ruprechtii) forests are mainly distributed in shady, rocky slopes at elevations of 1100-1700m. It is usually mixed with broad-leaf trees like Betula platyphylla, Populus davidiana, Quercus mongolica and Fraxinus rhynchophylla. Often also a shrub layer occurs. Keep in mind, though, that most of the Larch plantations encountered nowadays are plantations created during the afforestation efforts. Larch generally needs great amounts of light.
Basswood (Tilia) forests occur on shady slopes at elevations 500-1600m in the mountainous areas of Beijing. Due to serious deforestation and degradation these forests are rare and usually fragmented. Tilia forests are mainly composed of Tilia mandshurica and Tilia mongolica, they are often intermixes with other accompanying trees like Acer truncatum, Quercus mongolica etc. While a shrub layer is common, the herb layer is rather sparse.
Tilia mandshurica is a great source of timber and honey-nectar while Tilia mongolica‘s fibres are used as a substitute for hemp and yields good timber.
Manchurian Walnut (Juglans mandshurica) forests are very common in the Beijing area and are mainly found near brooks or on shady slopes at elevations 900-1600m. It often occurs together with Populus cathayana, Sorbus pohuashanensis and Phellodendron amurense but at some places it forms pure stands. Shurbs and herbs are abundant in this type of forest.
Juglans mandshurica is a very valuable species for local livelihoods as it’s not only providing valuable wood but more importantly producing walnuts which are locally sold and often present the main income of small communities, now often being planted in orchards.
The Goldenrain Tree (Koelreuteria paniculata) is a very common tree that is often found in the lower mountains and valleys of Beijing, though it is rarely dominating. It is easy to recognize as in the spring the whole tree is covered in yellow flowers (hence the reference to the “Golden Rain”). The flowers can be used as yellow dye. It prefers calcerous soils. The seeds are edible when roasted, but not commonly consumed. It is also a popular ornamental tree in other countries.
CNF turns plantations into natural forests. Research has shown that natural forests show greater resilience against many disturbances like wind-throw or pests through their multi-species, multi-age and multi-strata structure. Due to climate change the likelihood of more frequent and severe disturbances increases, making it more important to enhance the resilience of the local forests. If forests are severely damaged sediment flow and erosion can increase, decreasing the water quality. While this would also increase the overall quantity, it intensifies the flow variation, likely causing damages by flooding places during intense rain storms. Overall resilient natural forests secure a more modified, stable and high-quality supply of water.
The main method of transforming the plantations into natural forests BFS is using is thinning. Through thinning techniques BFS is carefully opening up the canopy and therefore reducing the competition to improve the quality of the remaining trees and reestablish the forest understory. The thinning technique being used is called “target tree thinning”. Target trees that promise to become high quality trees in the future, are selected and the closest immediate competitors are removed.
In some areas BFS is also doing shelterwood and selection cuttings in order to regenerate the forest and establish more tree species of the natural forest composition, for example the Mongolian oak (Quercus mongolica) or the Oriental white oak (Quercus aliena). Often natural seed sources for these trees are lacking, so that BFS often underplants the forests it is applying these cuts on.
While BFS forest experts are marking the trees and amount to be cut, the local villagers who own the forest are trained in managing the forest in the process, so that in the future they can manage their forest themselves.
To further improve the timber quality of the individual trees BFS also teaches local villages how to prune trees, especially the widely planted Chinese pine. Pruning is referring to the removal of the lower dead branches of a tree. There are many trees (often deciduous) that naturally self-prune, others have to be artificially pruned. Pruning trees improves the quality as there will be less knots in timber when the trees have matured which usually achieve higher timber prices. Pruning should be done when the tree is still young and only on the highest value segment of the tree.
The Logging Ban
The logging ban was instituted in 1992 in many forests designated as “Natural Protection Forests” and forbids the cutting of trees above a certain diameter. This was done to prevent large scale deforestation from happening in forests that are of special ecological importance. However, as shown earlier, especially planted monocultures can become too dense, reducing the light that reaches the understory and therefore reducing many important eco-functions. It is therefore important that such forests are managed. The local forest administration can give special cutting permissions, if it is proven to them that the actions are part of a forest management plan and not mere deforestation or forest degradation. As one of BFS’ goals is to enhance the eco-function of forests, it was possible to get such permits. BFS is now working on finding a way to get these permits to be more institutionalized so communities can manage forests that way on their own.