New Utilization Model of Karst Rocky Desertified Land in Southwest China: Ecological Planting of Dendrobium officinale Kimura et Migo on Bare Rocky Mountains

Mengyuan CHEN, Zisheng YANG

Institute of Land & Resources and Sustainable Development, Yunnan University of Finance and Economics, Kunming 650221, China

Abstract The Yunnan-Guangxi-Guizhou rocky desertified area in southwestern China is one of the contiguous extremely poor areas identified in the Outline of Poverty Alleviation and Development in the Rural Areas of China(2011-2020).In rocky desertified areas, due to long-term severe soil erosion, large areas of bedrock are exposed or gravels are accumulated.This bare rock and gravel-mulched land has become the main land type in the rocky mountains.Under normal circumstances, it cannot be directly used for agriculture, forestry, animal husbandry, and fishery production, and is classified as land that is difficult to be utilized.In recent years, in Debao County, Baise City, Guangxi Zhuang Autonomous Region, as a deeply impoverished county in the Yunnan-Guangxi-Guizhou rocky desertified area, a new land use model of karst rocky desertified land, that is, planting Dendrobium officinale Kimura et Migo on bare rocky ground, has emerged, and certain poverty alleviation benefits have been achieved initially.In this article, on the basis of analyzing the suitability of planting D.officinale Kimura et Migo on karst rocky desertified land, the practice of planning D.officinale Kimura et Migo on the rocky desertified land in Debao County was elucidated, and then suggestions for reasonable promotion of ecological planting of D.officinale Kimura et Migo in karst rocky desertified areas were put forward.

Key words Karst rocky desertified land, New utilization model, Dendrobium officinale Kimura et Migo, Poverty alleviation benefit

1 Introduction

The karst region in Yunnan, Guizhou and Guangxi located in southwestern China is the center of distribution of karst landform in East Asia, one of the world’s three major concentrated areas of karst landform, with an area of 320 000 km2.It accounts for more than 40% of the total land area of the three provinces(regions)[1].When going to these provinces(regions)to conduct field investigations on agricultural production reduction and poverty issues, we can often hear local people complaining: "The rocks in the ground have grown taller!" In fact, the rocks in the ground haven’t grown high, but due to long-term continuous soil erosion, the soil in the ground has continued to decrease or even disappear, so the rocks are exposed from the ground.This is the phenomenon of desertification of rocky land unique to China’s subtropical karst mountains.Rocky desertification is caused by long-term severe soil erosion that exposes a large area of bedrock or accumulates gravels, resulting in the decline or loss of land productivity and surface land degradation similar to a desert landscape.Rocky desertification is the top form of deterioration of the ecological environment in karst areas, and it is called "ecological cancer" by academia.According to the statistics, the area of rocky desertification in the karst mountainous areas of Yunnan, Guizhou and Guangxi has reached 70 000 km2, and the speed of rocky desertification is amazing[2].Lack of water, lack of soil, lack of forest and poverty are the basic products of rocky desertified environment[3].Therefore, the Yunnan-Guangxi-Guizhou rocky desertified area has become one of the contiguous extremely poor areas identified in theOutlineofPovertyAlleviationandDevelopmentintheRuralAreasofChina(2011-2020)[4].

In land use classification and survey, due to the large area of exposed bedrock or accumulation of gravels, the karst rocky desertified land is often classified as bare rock and gravel-mulched land.Bare rock and gravel-mulched land refers to the land which is mulched with rock or gravel on the surface layer and covers more than 50% of the land[5].Because of the large proportion of rock or gravel coverage, for agriculture, forestry, animal husbandry and fishery production, it cannot be used directly under the existing conditions.Therefore, it is generally classified as land that is difficult to be utilized[6].This is the root cause of the low land utilization rate in karst rocky desertified areas.In recent decades, the people in rocky desertified areas have been fighting against rocky desertification, and a lot of good rocky desertified land remediation and utilization models have been established.For example, the Dingtan model of Huajiang Gorge in Guizhou[7], the "splitting rocks to build field" model of Daguan Village, Luodian County, Guizhou[8], the "frying rocks to build platform" model of Muzhe Village, Xichou County, Yunnan[9],etc.have made remarkable achievements.

However, what is even more surprising is that in April 2020, when we went to Debao County, Guangxi, one of the deeply impoverished counties in the Yunnan-Guangxi-Guizhou rocky desertified area, to investigate poverty issues, it was discovered that a new land use model of karst rocky desertified land, that is, planningDendrobiumofficinaleKimura et Migo on bare rocky ground, has emerged in this county and certain poverty alleviation benefits have been achieved.After investigation and research, it was concluded that this mode of utilization has certain promotion value.

2 Suitability analysis of karst rocky desertified land for planting D.officinale Kimura et Migo

D.officinaleKimura et Migo(Orchidaceae)is a perennial epiphytic herb, with high medicinal value.It is used as medicine with its stems, belonging to a yin-tonifying drug in tonic medicine.D.officinaleKimura et Migo has effects of benefiting the stomach, promoting fluid, nourishing yin and clearing away heat.It is called "resurrection herb" by Chinese medicine.The international medicinal plant community calls it the "panda of the medicine field".In China,D.officinaleKimura et Migo has always been an important species of medicinal Dendrobium.In theChinesePharmacopoeiaafter the 2010 edition,D.officinaleKimura et Migo is listed as a single species, and its identification, identification methods, testing standards and efficacy are introduced in detail.It suggests thatD.officinaleKimura et Migo has been recognized by China in terms of efficacy.

From the perspective of the growth environment,D.officinaleKimura et Migo is born on semi-damp rocks in the mountains, preferring a warm and humid climate, suitable for a cool, humid, unobstructed, semi-shaded and semi-sunny environment, generally able to withstand low temperature of-5 ℃[10].The karst area of southwest China has a humid climate and abundant rainfall, and it is suitable for the growth and planting ofD.officinaleKimura et Migo.WildD.officinaleKimura et Migo in the karst area of Southwest China usually grows in cracks in rocks and on parasitic trees.From the perspective of growth habits,D.officinaleKimura et Migo prefers a warm, humid semi-shaded and semi-sunny environment with an annual rainfall of more than 1 000 mm.In the subtropical remote forested mountains with the temperature in January higher than 8 ℃, it grows better.The suitable growth temperature is 15-28 ℃, and the suitable growth air humidity is above 60%.The requirements for soil and fertilizer are not very strict.D.officinaleKimura et Migo has an aerial root system, and it mainly requires good root permeability.The substrate used should be ventilated and air permeable to filter water.Under suitable temperature and humidity, it grows fast and has a very strong viability.In late spring and early summer, inflorescences are drawn from the upper nodes of biennial stems.After flowering, new buds grow from the stem base ofD.officinaleKimura et Migo to develop into stems.In autumn and winter, it enters the dormant period.

In terms of the selection of plots for artificially planting, according to growth habits,D.officinaleKimura et Migo should choose a semi-shaded and semi-sunny environment with air humidity above 80% and temperature in winter above 0 ℃.The environment that can be controlled manually is also suitable.From the perspective of planting practices in karst areas such as Guangxi and Guizhou, the bare rocky land selected in rocky desertified areas should generally be located in shady and humid areas, and there should be moss growth on the rock and a small amount of humus on the surface(Fig.1).

Fig.1 Dendrobium officinale Kimura et Migo planted on bare rocks in Wangtun Village, Yantong Township, Debao County, Guangxi

From the perspective of poverty alleviation and future development in karst rocky desertified areas, the development of artificial cultivation ofD.officinaleKimura et Migo has great prospects.WildD.officinaleKimura et Migo originally grows in the crevices of rocks and on parasitic trees, and has low reproduction ability and slow growth.In the past, the collection of patented medicine usually involves uprooting one plant, and thus, the quantity ofD.officinaleKimura et Migo plants will become smaller and smaller.Since the 1960s, as market demand has increased, uncontrolled and unplanned gathering has devastated the resources of wildD.officinaleKimura et Migo.By the mid-1990s, China’s wildD.officinaleKimura et Migo production had declined severely, andD.officinaleKimura et Migo has become an endangered rare medicinal material.TheRegulationsontheProtectionandManagementofWildMedicinalResourcespromulgated by the State Council in 1987 listedD.officinaleKimura et Migo as a third-level protected species.In 1992, it was listed as an endangered plant in theChineseRareandEndangeredPlants.In order to meet market demand, in the 1980s, Chinese researchers began to explore the artificial cultivation technology ofD.officinaleKimura et Migo, including tissue culture and propagation of seedlings and wild cultivation, and significant progress has been made.In recent years,D.officinaleKimura et Migo has been artificially planted on karst rocky desertified lands in Guizhou, Yunnan, Guangxi and other regions, and preliminary results have been achieved.This has not only solved the problem of karst rocky desertification control, but also let the rocky barren hills become invaluable assets[11].Some poor farmers said that they used to worry about these rocks, but now these ‘dead resources’ have become living assets, and the "wealth-creating grass" is really planted on the rocky mountains!

3 Practice of planting D.officinale Kimura et Migo on rocky desertified land in Debao County

Debao County, a county under the jurisdiction of Baise City, Guangxi Zhuang Autonomous Region, China, is located in the southwest of Guangxi.The total land area is 2 575 km2, of which the rocky mountain area accounts for 70%.The total population is 368 000, and there are 9 ethnic groups including Zhuang, Han, Yao and Miao.Among them, the Zhuang population accounts for 98%.The county’s poverty coverage is large and deep.The task of poverty alleviation is arduous, and it is a key county in the national poverty alleviation and development work, and is one of the 20 deeply impoverished counties in Guangxi Zhuang Autonomous Region.One of the main reasons for poverty is poor natural conditions.The area of rocky mountains accounts for 70%.There are more mountains and less land, more people and less land.The per capita arable land area is only 0.052 ha.The quality of the soil is low overall.Karst rocky desertification restricts the organization and large-scale development of the industry.

In order to change the face of poverty and backwardness in karst rocky desertified areas and win the county’s poverty alleviation battle, after consideration by the local government that Debao County belongs to a subtropical monsoon climate zone with short cold winter, long summer and abundant rain(humidity is above 60% all year round), and has abundant rocky mountain resources and woodland resource and its unique natural environment is suitable for the growth ofD.officinaleKimura et Migo, planting ofD.officinaleKimura et Migo on rocks and under forests can be developed without occupying arable land.Thus, the industry ofD.officinaleKimura et Migo is introduced, and demonstration areas for poverty alleviation have been established and achieved good results.

The Demonstration Area for Poverty Alleviation by Imitating Wild Planting ofDendrobiumofficinaleKimura et Migo(Fig.2)in Debao County, Baise City is located in Jiaochatun and Longqintun, Xingwang Village, Yantong Township, Debao County, covering an area of 33.33 ha, including 30.00 ha of mountainous land and 3.33 ha of dry land.It is invested and constructed by Shanji Agricultural Development Co., Ltd.in Debao County, Guangxi.The headquarters of the demonstration zone has three one-floor buildings, including office building, living quarter, and warehouse.There is also a toilet, a comprehensive parking lot and fourD.officinaleKimura et Migo greenhouses.The demonstration base is based on the advantages of the local natural environment and integrates seedling domestication, imitating wild planting, processing, production technology training, planting promotion and marketing network construction ofD.officinaleKimura et Migo, in order to develop high-yield, high-efficiency and green Chinese herbal medicine industry.

Fig.2 Dendrobium officinale Kimura et Migo cultivation demonstration base in Wangtun Village, Yantong Township, Debao County

D.officinaleKimura et Migo seedlings are cultivated in the greenhouses of the headquarters of the demonstration zone.Electricity, water and passages are provided in the nursery greenhouse, and the roof is covered with plastic.In the greenhouses, elevated beds with an overhead bottom are prepared, and wooden strips or square strips are used as the frame of planting beds.Plastic plate with aperture of 0.3-0.5 cm is laid as the supporting surface of the cultivation substrate.A sprayer is used to apply water.The purpose of constructing elevated planting beds is to make it easy to control moisture and ventilation, so as to provide the best moisture for the growth of tissue culture seedlings, ensure ventilation and synchronize application of fertilizer and drug, so that the survival rate of transplanting is high.Under the condition of large-scale transplanting, labor will be saved greatly.In the greenhouses, bark and wooden blocks are laid evenly according to local conditions.Part of the seedlings will grow in the greenhouses, and part of the tissue culture seedlings will be transplanted to the demonstration area.Before transplanting, the bottle seedlings need to be moved to the seedling hardening room for 2-3 weeks to let the bottle seedlings transition from a closed and stable environment to an open and changing environment and slowly adapt to the natural environment to ensure that the bottle seedlings grow robust and have normal leaf colors.In the demonstration zone of Debao County, it can be cultivated except the coldest January to February and the hottest July to August.When transplantingD.officinaleKimura et Migo, a lot of labor is required to make holes in the rocks.The seedlings should be taken out with tweezers carefully and then transplanted to rocks.Because the ecological environment such as humidity, air and water quality in this area is very in line with the living conditions ofD.officinaleKimura et Migo, the production ofD.officinaleKimura et Migo is stable throughout the year, significantly promoting the development of the local rural economy.

At theD.officinaleKimura et Migo demonstration base in Wangtun Village, Yantong Village, the Wangtun Village Party Branch adheres to the work idea of "party building+poverty alleviation", actively explores ways to develop the collective economy of the village and implement theD.officinaleKimura et Migo planting industry project in Wangtun Village.The project promotes the development model of "party organization+cooperative+company+base+farmer".It is jointly funded and constructed by the villagers’ cooperative and Guangxi Shanji Agriculture Co., Ltd.The total investment of the first phase is 1 million yuan, including 490 000 yuan from the villagers’ cooperative and 510 000 yuan from Guangxi Shanji Agriculture Co., Ltd.A total of 3.33 ha ofD.officinaleKimura et Migo is cultivated, and 200 000 clusters of seedlings are invested.D.officinaleKimura et Migo is a labor-intensive industry.TheD.officinaleKimura et Migo planting industrial base integrates seedling domestication, imitating wild planting in rocky mountains, processing, production technology training, planting promotion and marketing network construction to provide long-term industrial support for 100 poor households in Wangtun Village.Only the item of going out to work will enable the poor household workers to earn 1 500-2 000 yuan per month, with significant poverty alleviation benefits and great local promotion value.

4 Suggestions for the reasonable promotion of planting D.officinale Kimura et Migo in karst rocky desertified areas

4.1 Making full use of the bare rock resources in the rocky desertification areas to turn waste into treasure and develop ecological planting patterns on limestone surfaces in karst areasKarst areas such as Yunnan-Guangxi-Guizhou are one of the origins ofD.officinaleKimura et Migo.These areas have fresh air and clean water sources, and most of them have no industrial pollution.This is an advantageous condition for the development of ecological planting ofD.officinaleKimura et Migo in karst rocky desertified areas.The good natural ecological conditions should be fully utilized to develop the ecological planting ofD.officinaleKimura et Migo, and artificially cultivated seedlings are transplanted on the rocks in the original ecological environment.The human intervention is minimized to let them grow naturally and ensure that product quality can meet or approach wild standards.In recent years, as product safety and quality issues become more prominent, and the planting model of returning to the original place of origin and returning to the original ecology has gradually emerged and has been widely recognized.Although the output of ecological planting is much lower than that of greenhouse planting, and is even not one-tenth of the output of artificial facilities, its product quality is recognized by consumers, and its price is more than 10 times that of greenhouse-grown products.Therefore, in the southwestern karst rocky desertified area, a large number of bare rock resources should be fully utilized to turn waste into treasure, and the ecological planting model ofD.officinaleKimura et Migo on the surface of limestone in karst areas should be developed actively according to local conditions to plant more "wealth-creating grass" on the rocky mountains and add new forces to the industry for poverty alleviation, thereby promoting poverty alleviation and sustainable development in impoverished rocky desertified mountainous areas.

4.2 Further carrying out trials and demonstrations of cultivation and planting ofD.officinaleKimura et Migo to radiate and drive its large-scale planting in karst rocky desertified landTo implement a planting model that returns to the original ecology, it is necessary to choose suitable environmental conditions.This is the key to the success of ecological planting ofD.officinaleKimura et Migo.In view of this, it is recommended to further carry out experiments on imitating wild cultivation ofD.officinaleKimura et Migo based on the existing planting practices in recent years and layout planting tests according to different environmental conditions(including altitude, aspect, slope, canopy closure, vegetation characteristics, topography, ventilation conditions,etc.)to screen out the environmental conditions suitable for the ecological planting ofD.officinaleKimura et Migo.On the basis of successful experiments, demonstration and promotion should also be strengthened to drive large-scale planting in karst bare rocky mountains and gradually expand the scale of the industry to form a scale effect.

4.3 Strengthening the in-depth development of theD.officinaleKimura et Migo industry to make it an important industry for farmers in karst rocky desertified areas to get rid of poverty and become richAmong the many characteristic medicinal materials in the southwestern karst area,D.officinaleKimura et Migo is the main species urgently awaiting further development, and it has certain basic and resource advantages in the research, development and production of Chinese patent medicines and "big health" related products, which has laid a good foundation for the development ofD.officinaleKimura et Migo industry in karst areas.However, judging from the current development ofD.officinaleKimura et Migo in the southwestern karst area, there are still many problems.For example, theD.officinaleKimura et Migo industry is developing fast, but there is still a lack of planning as a whole; enterprises are growing disorderly and technological innovation is weak; there are many forms of planting and preliminary processing products, but a unified quality standard is lacked; there are many planting enterprises and farmers, but there are few deep processing and leading enterprises.These problems have greatly affected and restricted the pace of farmers in karst rocky desertified areas to get rid of poverty and become rich.It is recommended that the national and local governments actively strengthen scientific and technological support for the development ofD.officinaleKimura et Migo industry, promote germplasm resource bank construction, variety breeding, market demand research, beverage development and industry-university-research cooperation ofD.officinaleKimura et Migo to let it make new contributions to poverty alleviation in the Yunnan-Guangxi-Guizhou contiguous impoverished rocky desertified area.

In terms of plantingD.officinaleKimura et Migo and increasing the income of poor households, the "123" model of targeted poverty alleviation developed by Xicheng Xiushu Agriculture and Forestry Co., Ltd.in Anlong County, Guizhou Province[11]is worth learning."1" is a guarantee, allowing poor farmers to enter enterprises for employment.Thus, their monthly income will be more than 2 000 yuan, and the family’s economy is guaranteed."2" means two dividends.The first is capital preservation and dividends, with a minimum annual income of 1 200 yuan per household.The second is reverse rent through inverse contract.Poor households invest in the company with provincial-level financial modern agricultural characteristic competitive industry development funds, and the extra production increase ofD.officinaleKimura et Migo will be divided according to the ratio of 5∶5."3" is the "three-change" reform, that is, turning resources into equity, turning funds into equity funds and turning farmers into shareholders, in order to maximize the use of financial poverty alleviation funds and drive poor households to get rid of poverty and become rich.