Renjie DU，Yuejun QU*，Hu JIN，Haibo JIANG，Yunchang DU，Dongyue ZHOU，Jing FU，Ping SHI

1.Mudanjiang Forestry Science Institute of Heilongjiang Province，Mudanjiang 157009，China；2.Hainan Forest Farm，Mudanjiang Forestry Bureau of Heilongjiang Province，Mudanjiang 157000，China

China's forestry development is changing rapidly and forest tending scale is increasing day by day.In the situation of implementing all-round prohibition of commercial logging，development direction，development method and development potential of forestry economy will play a decisive role in economic development of forest regions［1］.With gradual regulation of industrial structure of the forestry，the under-foresteconomy will replace traditional economic development and become new development direction and economic growth point.With social development and improvement of people's living conditions，green，organic and ecological foods and medicines under forest are gradually valued and promote advance in researches about under-forest cash crops.The establishment of under-foresteconomic plant cultivationmode can take advantage of resources under forest in a scientific and reasonable way［2］，so as to promote development of forestry economy.

1 Significance of under-forest Economic development

With gradual implementation of ecological construction，reasonable use and protection of forests are brought into schedule.Forest resources gradually become abundant，especially cultivation and large area extension of fast-growing timber forest and high yield forest，it is able to provide solid environmental space andmaterial foundation for developing under-forest economy.At present，the embryonic form of under-foresteconomy has taken shape and plays a positive role in development of forestry economy in some areas.On the basis of ensuring ecological stability and safety，reasonably developing and using under-forest resources，developing green and circular economy，and realizing maximum economic，ecological and social benefits can meet benefit demands of many parties and realize multiple win［3］.

1.1 Improving living environmentTraditional edible fungus cultivation is completed in rooms.Because spore powders will diffuse at the sporocarp maturity stage，traditional method will lead to excessively high concentration of spore powder in the room air.If inhaling too much，it will lead to discomfort of respiratory track or even lead to pneumonia.However，the under-forest cultivation has large space，fast air circulation，and low spore powder concentration，so it can avoid adverse effect due to excessive inhaling.

1.2 Stabilizing the biological chain of forestTree body in secondary forest land remains before closing，the biological community is simple，and the instability is high.At this time，sunshine，air，and water conditions of for est are basically the same as cultivated land area，so it is feasible to plant economic plants under forest.At the same time of managing cash crops，it can reach the purpose of weeding and water and fertilizer applying.When forest trees enter the rapid growth period and become closing，sunshine will become weak and humidity will become high under forest.In this situation，it is feasible to plant shade-requiring plant or edible fungus［3］.After having luxuriant foliage and spreading branches，treeswill also have a lot of fallen leaves，which can be used as nutrition source of edible fungus，but also can degrade cultivation waste and provide fertilizer for tree growth，so as to form ecological chain with mutual symbiosis［4］.

1.3 Increasing income of forest farmersTraditional forestry and new under-forest economy develop jointly and gradually weaken position of traditional forestry in the national economy of the forest area.It is required to strengthen scientific research and development of under-foresteconomy to form inter planting under-forest cultivation mode.Building forest into a green bank of farmers will play a positive role in increasing farmers'income and transforming industrial development structure.Development of the under forest economy can help farmers to grasp production skills through short period training.The investment scale is little，but the return is rapid.In the current period of economic construction，itmay stimulate famers'enthusiasm and promote sustainable development of forestry economy through bringing economic benefits to farmers［3］.

1.4 Shortening the production cycle to realize rapid effect

Traditional forestry has long production cycle，large input，slow effect，and high development difficulty.Some present forestry operating organizations are weak in development strength or even go bankrupt due to excessive input at the early stage but insufficient subsequent input.Through developing the under-forest economy and studying inter planting pattern，it is able to bring into full play functions of under-forest resources，invigorate economy of forest areas，realize return in short term，and so as to promote sustainable development of forest areas［3］.

2 Existing problems in the development of the under forest economy

2.1 Insufficient development of forest resourcesFor a long time，forestry always keeps the traditional operating mode and the use of forest resource is simple，i.e.production of timber［5］.For forestry byproducts，especially，the under-forest economy，it pays little attention.Asa result，forest resources are excessively developed，and forests are cut down excessively，timber resources are consumed excessively，leading to forestry economy has weak development strength in traditional pattern.

2.2 Excessive consumption of other forest resourcesFor a long time，predatory digging of medicinal plants and wild vegetables leads to excessive consumption of other forest resources.Restoration and operation mode fails to be established and domestic and foreign demands are greatly increasing.Therefore，it is necessary to establish relevant protection and development system，set up corresponding scientific research mechanism，increase research input，and develop traditional Chinese medicinal plants，edible fungus and wild vegetable cultivation mode.Besides，it is required to convert，extend and apply scientific research achievements，to change gradual exhaustion of available resources under forest.

2.3 Shortage of cultivated land resourcesIn China，the edible fungus，traditional Chinese medicinal plants and wild vegetables basically adopt fertile farmland.China is large in population but insufficient in available land.Especially，with the development of urbanization and construction of super cities，increasing overall yield relying on increasing cultivation area will be increasingly limited.Atpresent，wild vegetable，as health care food，has become indispensible thing for people's life；although its life rises all the time，the demand still keeps increasing［6］.Therefore，artificial cultivation is gradually valued.It not only can solve the problem of yield，but also can solve the problem of shortage of land resources.

3 Artificial establishment of inter planting pattern for under-forest Economic plants

Building edible fungus，medicinal plants and wild vegetable production base using under-forest space and excellent resources not only can satisfy demands of enterprise processing and increase added value of under-forest by-products，but also can protect reasonable use of wild resources，avoid extinction of endangered species due to pursuit for benefits.Thus，developing forest resource is of great significance.According to selected economic plants，it is feasible to make scientific matching，cultivate economic plants under secondary forest，and establish cultivation mode areas for under-forest medicinal plants and wild vegetables.At the same time of fostering forest，it is able to promote increase of utilization efficiency of under-forest resources，protect surface soil and prevent loss of water and soil.Bringing into play productivity of under-forest economic plants can help obtain economic benefits.In the selection of economic plants，it is recommended to select varieties with small competitiveness against forest，high economic benefits，rapid growth，and excellent endurance［7］.

3.1 Major modes of development of under-forest Economic plantsAt present，in the under-forest development，the forest is mainly secondary forest，trees are mainly poplars，willows and birches，and hardwood trees，and economic species are mainly Chinese Magnoliavine Fruit，monkey leg like mushroom，honeysuckle，root of herbaceous peony，Pteridium aquilinum var.latiusculum，matt euccia struhiopteris，andauricularia auriculajudae，etc.

3.1.1 Forest and edible fungus compound mode.At present，there are many varieties of edible fungus suitable for planting under forest.The mell ea armillaria sporophore is a widely distributed edible and medical fungus.It grows in root，trunk and base of broad leaf trees，stumps and felled trees，as well as roots crossing in soil and rhizomes in mixed broadleaf-conifer forest and forest with a lot of dry branches and fallen leaves.The mellea armillaria sporophore is delicacy unique to northeast forest areas.On the precondition of protecting wild resources，artificially increasing yield of mellea armillaria sporophore is of great significance for realizing semi-artificial cultivation of mellea armillaria sporophore under forest.Generally，it is recommended to select Mongolian oak as semi-artificial cultivation base of mellea armillaria sporophore.

The umbellate pore fungus is a traditional perennialmedicinal fungus.Its sporocarp isedible and has extremely high nutritive value and it tastes delicious.Besides，its sclerotium can be used asmedicine.Atpresent，nearly allwild umbellate pore fungushas been damaged.Thus，cultivation of umbellate pore fungus under forest has broad prospect.It is recommended to select Mongolian oak as semi-artificial cultivation base of umbellate pore fungus.

We propose taking the marketas orientation and high science and technology asguidance，making breakthrough in technical difficulties in artificial cultivation，energetically developing semi-artificial cultivation of mellea armillaria sporophore and umbellate pore fungus，to realize large-scale and industrialized operation.

3.1.2 Forest and vegetable compound mode.It is recommended to select scientific and reasonable cultivation management mode，select forest land with proper closing，and cultivate suitable plants（for example，crucifer）.But it should design reasonable spacing in the rows，clean up fallen leaves，properly turn up the soil，water the land and apply fertilizer［7］.For example，it is feasible to plant Pteridium aquilinum var.latiusculum，matteuccia struhiopteris，Aralia elata Seem，and Osmunda through opening ditches，or cultivate these species through drilling holes to shorten the production cycle.

3.1.3 Forest and medicinal plant compound mode.Establishing under-forest medicinal plant compound mode can protect rare and scarce medicinal plant resources，consolidate development of isatis root，root of membranous milk vetch，codonopsis pilosula，and atractylodes japonica planting industries with local characteristics and distinctive advantages，speed up construction and certification of standardized planting base，and promote sustainable development of medicinal plant industry.Medicinal plants suitable for under-forest are generally shade plants，such as Ginseng under forest，Oenothera biennis，nippon yam rhizome，Saposhnikovia divaricata，Codonopsis lanceolata，and isatis root.

3.2 Management and protection principle for optimizing interplanting patterns for under-forest Economic plants

3.2.1 Weakening cultivation strength and reducing cultivation cycle，to realize vertical fostering of under-foresteconomic plants.The inter planting patterns for under-forest economic plants need high self fertility，shortgrowth cycle，and low cultivation strength.It is recommended to take scientific and reasonable management means，reduce disturbance against forest，make effort to increase economic benefits of cultivation plants，reduce movement of cultivation plants，and minimize influence on forest［8］.

3.2.2 Reducing time of economic benefits and maximizing economic benefits.Scientific interpl anting pattern can realize maximum use of space under forest and maximize economic benefits.Economic plants have short growth period and rapid speed of return［7］，increase forest closing，increase carbon cycle and circulation speed of other nutrition elements，and prevent loss of water and soil，which is of great significance to keep ecological balance of forest.

4 Conclusions

The prohibition of commercial logging provides great development space for development of under-forest industry.It is recommended to turn focus of cutting down timber to developing forest by-products，and forest management should change development ideas，explore potential of the under-forest industry，increase scientific research input，study and develop suitable inter planting patterns，pay close attention to conversion of scientific research achievements，and foster forest by-products production and processing［9］.Besides，it is recommended to take ecological civilization construction as the direction and＂beautiful China construction＂as objective，regulate industrial structure，change the excessive dependence on timber cutting，fully develop under-forest resources，guide in-depth development of forestry，and push social economy of forest regions to higher development stage.

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