Jia WANG1, Leijin LONG

1. Institute of Land Resources and Sustainable Development, Yunnan University of Finance and Economics, Kunming 650221, China; 2. Financial Office of Yunnan University of Finance and Economics, Kunming 650221, China

Abstract As one of the most fragile alpine plateau and canyon areas in China, the upper reaches of the Yangtze River are the key areas of ecological construction in China. It is also a key area for poverty alleviation in the country. Therefore, it is necessary to take into account the dual goals of poverty reduction and ecological environment construction, and explore a win-win road of ecological construction and poverty alleviation in line with the reality of the upper reaches of the Yangtze River. Taking Xueshan Township, Luquan Yi and Miao Autonomous County, Yunnan Province, which is located in the poor mountainous area of the upper reaches of the Yangtze River as an example, based on many field investigations and existing investigation and statistical data, this paper analyzes the current situation and main problems of land use in Xueshan Township, and then puts forward measures and suggestions for rational utilization of land resources in Xueshan Township. This can provide a necessary reference for the next implementation of rural revitalization strategy and ecological construction.

Key words Land resources, Rational utilization, Upper reaches of the Yangtze River, Poor mountainous areas, Xueshan Township, Luquan County

1 Introduction

Land resources are the most basic natural resources for human survival. Marx brilliantly pointed out: "Land is the source of any production and any existence"[1]. The rational development, utilization, protection, renovation and management of land resources are of great practical significance to the economic and social development of our country. It plays an important role in the implementation and realization of accurate poverty alleviation and poverty alleviation strategies and major policies in China[2]. The general requirements of "implementing the strategy of rural revitalization"[3]and "industrial prosperity, ecological livability, rural civilization, effective governance and affluence" put forward in the report of the 19th CPC National Congress are consistent with the goal of sustainable land use[4]. Therefore, the rational use of land resources has important practical significance to promoting the strategy of rural revitalization.

Rational use of land resources, referred to as rational land use, is in line with scientific principles (including ecological principles, economic principles, human sociological principles, ethics principles,etc.)[5]. The result of rational use of land resources must be the sustainable use of land resources, both of which have the same connotation and goal[6]. From the specific connotation of sustainable utilization of land resources in soil and water loss mountain areas, the prevention and control of soil erosion must be based on the rational use of land resources[7].

As one of the most fragile alpine plateau and canyon areas in China, the area in the upper reaches of the Yangtze River is an important ecological security barrier in China, which ensures the ecological security and sustainable development of the middle and lower reaches of the Yangtze River. However, for a long time, people often adopt the land use mode of "extensive management". There are many unreasonable development and utilization phenomena, such as deforestation and reclamation, steep slope reclamation, indiscriminate felling, overgrazing, and indiscriminate mining. This has caused serious degradation or even deterioration of the ecological environment, increasing soil erosion, land quality degradation, affecting the sustainable use of land resources. This is not conducive to solving the problems of agriculture, rural areas and farmers, and makes the phenomenon of "poverty" in the upper reaches of the Yangtze River very prominent. The severe flood in the Yangtze River Basin in 1998, which is characterized by "medium water volume, high water level and great disaster", is fundamentally caused by the serious ecological damage in the basin. This determines that the area in the upper reaches of the Yangtze River is not only an important area for soil erosion prevention and control in China and a key area for ecological construction, but also a national key area for accurate poverty alleviation and poverty alleviation in a wide range and a high degree. These two kinds of key areas are organically intertwined, which makes the two major tasks of ecological environment construction and poverty alleviation in the upper reaches of the Yangtze River overlap. Therefore, it is necessary to take into account the dual goals of poverty reduction and ecological environment construction, and explore a win-win road of ecological construction and poverty alleviation in line with the reality of the upper reaches of the Yangtze River. Taking Xueshan Township, Luquan Yi and Miao Autonomous County, Yunnan Province, which is located in the poor mountainous area of the upper reaches of the Yangtze River as an example, based on many field investigations and existing investigation and statistical data, this paper analyzes the current situation and main problems of land use in Xueshan Township, and then puts forward measures and suggestions for rational utilization of land resources in Xueshan Township. This can provide a necessary reference for the next implementation of rural revitalization strategy and ecological construction.

2 General situation of the research area

Luquan Yi and Miao Autonomous County (Luquan County for short) (102°14′ E-102°56′ E, 25°25′ N-26°22′ N) is located in the north-central part of Yunnan Province. It is the typical mountain poverty county in the upper reaches of the Yangtze River, and it is a county with the integration of "mountain area, nationality, old area, agriculture and poverty"[8]. The topography of the county is high in the northeast and low in the southwest, slowly descending from the northeast to the southwest. Mazongling, the main peak of Wumeng Mountain, 4 247 m above sea level, is the highest point in the country. The small estuary at the confluence of the Pudu River and the Jinsha River is 746 m above sea level, the lowest point in the country. The relative height difference is 3 501 m, and the three-dimensional climate is very obvious. According to the results of the second national land survey of the dam area of Yunnan Province[9], of the total land area of 423 400 ha in Luquan County, the dam area was only 12 000 ha, and the proportion of the dam area was only 2.83%. The mountain area reached 411 400 ha, and the mountain area proportion reached 97.17%, which was significantly higher than the average mountain area proportion of Yunnan Province (93.60%) and Kunming City (83.89%). According to the calculation of the Office of Yunnan Agricultural Zoning Commission (1987)[10], the proportion of land with topographic slope of greater than 15° in Luquan County was 76.97%, of which the proportion of steep land with topographic slope of greater than 25° was 37.43%, showing a significant situation of high mountains and steep slopes. It is precisely because Luquan County has the characteristics of a typical mountain county with high mountains and deep valleys that it shows another kind of mountain characteristics-three-dimensional climate. According to the calculation of the Office of Yunnan Agricultural Zoning Commission (1987)[10], Yunnan Province was divided into seven climatic zones, namely, north tropical zone, south subtropical zone, middle subtropical zone, north subtropical zone, warm temperate zone, temperate zone and cold temperate zone. Luquan County can be divided into six climatic zones (namely, south subtropical zone, mid-subtropical zone, north subtropical zone, warm temperate zone, temperate zone and cold temperate zone). Among them, the proportion of the south subtropical zone is 1.64%; the proportion of the mid-subtropical zone is 4.88%; the proportion of the north subtropical zone is 13.66%; the proportion of the warm temperate zone is 15.45%; the proportion of the temperate zone is 57.37%; the proportion of the cold temperate zone is 6.50%. This shows that the altitude of most areas in Luquan County is generally high and the climatic conditions are poor. At the end of 2017, the total population of the county was 487 300, of which the population of 23 ethnic minorities, including Yi, Miao and Lisu, was 159 300, accounting for 32.7%. In 2017, the per capita disposable income of rural permanent residents in Luquan County was 8 046 yuan, ranking 114th among 129 counties (cities and districts) in Yunnan Province. The county has been listed as one of the key counties of the national poverty alleviation and development work, with remarkable characteristics of a wide range of poverty, deep poverty, high incidence of poverty, heavy poverty alleviation tasks.

Xueshan Township is one of the 16 townships under the jurisdiction of Luquan County, located in the northeast of the county, 19.3 km away from county seat of Luquan, with a total land area of 13 313.98 ha. Xueshan Township has the typical geomorphological features of the poor mountain areas in the upper reaches of the Yangtze River, and its terrain is complex and diverse. The Pudu River flows from south to north and flows into the Jinsha River, which belongs to the Jinsha River system in the upper reaches of the Yangtze River. The highest elevation is 4 247 m, the lowest elevation is 794 m, and the elevation difference is 3 453 m. The whole territory is mountainous and lacks a flatbazi(commonly known as the basin). "High mountains, steep slopes, deep valleys, multiple bends and dangerous roads" are its basic topographic features. Due to the great disparity in altitude, extremely poor natural conditions and barren land, economic development is very backward and rural poverty is widespread.

According to statistics, the total number of households in Xueshan Township at the end of 2016 was 3 422, with a total population of 12 527. Among them, the population of ethnic minorities (mainly Yi) was 1 842, accounting for 14.70%. There are 1 367 registered poor households and 5 311 poor people in the township. The incidence of poverty (here refers to the percentage of the registered poor population in the total agricultural population in 2014[12]) reached 45%, ranking first among the 16 townships in Luquan County. The seven villages of Hayi, Tuomuni, Shugu, Fengzu, Jiduo, Shicheng and Lewu are all poor villages, of which 5 villages are deeply poor villages[13]. According to statistics, a number of indicators in Xueshan Township ranked last among the 16 townships in the county in 2016. The total output value of agriculture, forestry, animal husbandry and fishing in the township was 68.81 million yuan; the total grain output was 3 880 tons; at the end of the year, there were 3 626 large animals on hand; the disposable income of rural residents in Xueshan Township was 3 915 yuan, which was much lower than that (7 301 yuan) of rural residents in Luquan County.

3 The present situation of land use

According to the results of the 2016 survey on the change of land use in Luquan County, of the total land area of 13 313.98 ha in Xueshan Township (divided into agricultural land, construction land and unused land), the area of agricultural land was 6 468.27 ha, accounting for 48.58%; the area of land for construction was 165.41 ha, accounting for 1.24%; the area of unused land was 6 680.30 ha, accounting for 50.18%. From each type of land area in the land use change survey, it is mainly dominated by cultivated land, woodland, grassland and bare land, while there are few other land types. A brief description is as follows.

The area of cultivated land is 696.58 ha, accounting for 5.23% of the total land area. And the area of paddy field is 36.96 ha, accounting for 5.31% of the cultivated land area; the area of dryland is 659.63 ha, accounting for 94.69% of the cultivated land. It lacks "irrigated land" in the land use classification system.

The area of woodland is 5 135.65 ha, accounting for 38.57% of the total land area. And there are 3 235.89 ha of woodland, accounting for 63.01% of the total forest land; there are 1 439.67 ha of shrub land, accounting for 28.03% of the total forest land; the area of other forest land is 460.09 ha, accounting for 8.96% of the total forest land.

There are 5 204.99 ha of grassland (Xueshan Township has only other grasslands in the land use classification system[14], that is, "wasteland" among unused lands in the previous classification system[15]), accounting for 39.09% of the total land area.

The area of bare land is 1 380.79 ha, accounting for 10.37% of the total land area. The current land use survey (including annual change survey) does not further divide it into bare land and bare rocky and gravel land.

The area of other types of land is relatively small, for example, the garden land area (only orchards in Xueshan Township) is 3.13 ha, accounting for 0.02% of the total land area; there are 588.64 ha of farmland belonging to other agricultural lands, accounting for 4.42% of the total land area, as well as 0.27 ha of facility agricultural land, 0.79 ha of ditches and 0.17 ha of pits and ponds; there are 70.46 ha of land for transportation, accounting for 0.53% of the total land area; there are 130.21 ha of land for water areas and water conservancy facilities, accounting for 0.98% of the total land area; the area of the village is 98.55 ha, accounting for 0.74% of the total land area; the area of mining land is 4.02 ha, and the area of scenic spots and special land is 0.69 ha, accounting for 0.30% and 0.005% of the total land area, respectively.

In addition, according to the current slope classification of cultivated land in China, the slope of cultivated land in Xueshan Township is high, especially the dryland which constitutes the main body of cultivated land (Table 1). The survey shows that in the 659.63 ha of dryland, the area of dryland with a slope of 6°-15° is 107.70 ha, accounting for 16.33%; the area of dryland with a slope of 15°-25° is 183.60 ha, accounting for 27.83%; the area of dryland with slope of greater than 25° is 368.33 ha, accounting for 55.84%.

4 The problems in land use at present

4.1 The land use structure is unreasonable and the land utilization rate is lowAccording to the "three categories" stipulated in theLandManagementLawofthePeople’sRepublicofChina, the current area ratio of agricultural land, construction land and unused land in Xueshan Township is about 49∶1∶50. Compared with the ratio structure of the "three categories" in Luquan County at 79∶3∶18 (Table 3), it reflects that there are three obvious problems in Xueshan Township. The first is that the proportion of agricultural land is too low, the second is that the proportion of construction land is too low, and the third is that the proportion of unused land is too large. This shows that the level of overall development and utilization of land resources in Xueshan township is very low. At present, there are a large number of barren mountains and wastelands, which need to be developed and utilized reasonably according to the suitability of land and local conditions. In particular, other grasslands (that is, barren grasslands) (5 204.99 ha, 39.09% of the total land area) and bare land (1 380.79 ha, 10.37% of the total land area), are in urgent need of effective development, utilization and protection.

It is precisely because the proportion of unused land is too large that it means that the current land utilization rate in Xueshan Township is very low (Table 2). According to statistics, Xueshan Township has used land area of 6 633.68 ha (including agricultural land and construction land). Therefore, the land utilization rate (used land area/total land area×100%) is only 49.82%, which is far lower than the average land utilization rate of 81.8% in Luquan County. The land utilization rate of some village committees is less than 40%. For example, the land utilization rate of Shicheng Village and Jiduo village is only 32.94% and 35.90%, respectively.

4.2 The land is barren and the cultivation on steep slopes is seriousXueshan Township is a typical alpine and canyon area, where the mountain slope is steep, the soil layer is shallow, and the land is barren. The amount of existing cultivated land is not only small, but also its output rate and labor productivity are low. The ability to resist natural disasters such as drought and flood is weak. What is more worrying is that, according to the results of the survey, there is no gentle cultivated land of 0°-6° in Xueshan Township, and the slope of existing cultivated land is greater than 6°. Except for 36.96 ha of paddy fields (accounting for 5.31% of the total cultivated land in Xueshan Township), the existing 659.63 ha of dryland in Xueshan Township (accounting for 94.69% of the total cultivated land in Xueshan Township) are sloping farmland with prominent soil erosion. The area of sloping farmland of 6°-15° with obvious soil erosion is 107.70 ha, accounting for 15.46% of the total cultivated land in Xueshan Township; the area of sloping land of greater than 15° with soil erosion is 551.93 ha, accounting for 79.23% of the total cultivated land; the area of sloping land of greater than 25°with the most serious soil erosion reaches 368.33 ha, accounting for 52.88% of the total cultivated land, equivalent to 3.8 times the proportion of sloping land of greater than 25° in Luquan County (14.06%).

From the point of view of the proportion of gentle slope cultivated land (6°-25° dryland, excluding paddy field, the same below) and steep slope cultivated land (dryland of greater than 25°, excluding paddy field, the same below) to the total cultivated land, the difference is obvious (Table 1 and Table 3). The proportion of gentle slope cultivated land in Tuomuni Village, Shugu Village and Jiduo Village is about 50% to 58%. The proportion of gentle slope cultivated land in the other four village committees is all less than 50%, and the lowest is in Shicheng village, which is only 21.12%. The proportion of steep slope farmland in Hayi Village, Fengzu Village, Lewu Village and Shicheng Village is as high as 60%-66%. The proportion of steep slope farmland in the other three village committees is all less than 50%, but the lowest is 38.48% (Jiduo Village), which far exceeds the average of Luquan County (14.06%).

Sloping farmland is cultivated land reclaimed and planted along the slope. The whole process of crop management and planting (soil ploughing-soil preparation-sowing-soil loosening and weeding-fertilization-harvest) makes topsoil severely disturbed by man, which is very easy to cause soil erosion. Especially after harvest of dry crops and ploughing in flood season, due to frequent heavy rain, torrential rain and surface runoff erosion, the amount of soil and water loss is very large. In particular, the soil and water loss of sloping farmland above 15° is extremely serious, which makes sloping farmland become the type most seriously affected by soil and water loss in the upper reaches of the Yangtze River[16]. From our several field visits to Xueshan Township in recent years, we can also see that the result of excessive steep slope farming in Xueshan Township has led to increasingly serious soil and water loss. As the soil layer becomes thinner and thinner, a large number of soil nutrients are lost, the land quality is degraded, and the ecological environment is deteriorated. This is an unsustainable way of land use and needs to be changed urgently.

Table 1 Gentle slope cultivated land in Xueshan Township and Luquan County in 2016

Table 2 Land use structure of Xueshan Township and Luquan County in 2016

Table 3 Steep slope cultivated land in Xueshan Township and Luquan County in 2016

4.3 The forest coverage is low, which is not conducive to the protection and improvement of the ecological environment in the upper reaches of the Yangtze RiverForests often play a decisive role in maintaining the natural ecological environment, and at the same time have significant ecological, economic and social benefits. Forest coverage is the proportion of area of forest (equivalent to the secondary land category under "woodland" - "forest land" in the land use status investigation and classification system) to the total land area. It is usually one of the important indicators to measure the ecological environment of a country or region, especially in mountainous areas. Since the 1980s, China has implemented projects such as the construction of the Yangtze River shelterbelt system and returning farmland to forest in the upper reaches of the Yangtze River. However, the problems of "one-party governance, multi-party destruction", "point-based governance, surface destruction" and "governance can not catch up with destruction" are very serious, so that the scope of forest vegetation destruction in some places is expanding, the degree is increasing, and the harm is aggravating. From the perspective of Xueshan Township, the forest coverage rate of the whole township was only 24.30% at the end of 2016, about 2% of the average forest coverage in Luquan County. From the point of view of the village committees (Table 4), Shugu Village and Tuomuni Village have the highest forest coverage, which are 48.41% and 40.40%, respectively. The second is for Hayi Village, whose forest coverage is 36.13%. The forest coverage rates of the other four village committees are all less than 14%, of which the lowest is in Jiduo Village, whose forest coverage rate is only 4.27%. This is extremely incompatible with the strategic requirements of ensuring ecological environmental security and economic and social security in the lower reaches of the Yangtze River. China has promised the international community that forest coverage will be stable at more than 26% in 2050, so it is necessary to deal with the relationship between protecting cultivated land, returning farmland to forests and strengthening the construction of ecological civilization[17]. Especially in the alpine and canyon areas of the upper reaches of the Yangtze River such as Xueshan Township, it is necessary to scientifically implement the project of returning farmland to forests and the greening project of barren mountains and wasteland, so as to greatly increase forest coverage, effectively ensure the ecological security of the Yangtze River basin, and take the road of sustainable development.

Table 4 Forest coverage in Luquan County and Xueshan Township at the end of 2016

4.4 There are many barren mountains and wastelands, but there are also many difficulties in development and utilizationAt present, Xueshan Township has a large proportion of unused land, which is mainly manifested by a large number of barren mountains and wastelands, including two aspects.

First, there are many other grasslands. The "other grasslands" in the second national land survey, namely the "barren grasslands" in the first detailed land survey, refer to the unused lands with a canopy density of less than 10%, a surface layer of soil and weeds, which are the most important reserve land resources. At the end of 2016, the area of other grasslands (that is, barren grasslands) in Xueshan Township reached 5 204.99 ha, accounting for 39.09% of the total land area. Judging from the village committees (Table 5), the proportion of wasteland in Fengzu Village, Lewu Village, Shicheng Village and Jiduo Village has all exceeded 40%, of which the proportion of wasteland in Shicheng Village has reached 64.53%.

Second, there is a lot of bare land. The "bare land" in the second national land survey includes "bare land" in the first detailed land survey (that is, land with a surface of soil and basically no vegetation cover) and "bare rock and gravel land" (that is, land with a surface of rock or gravel, and cover area of more than 50%). At the end of 2016, the area of other grasslands (that is, barren grasslands) in Xueshan Township reached 1 380.79 ha, accounting for 10.37% of the total land area. According to the village committees, the proportion of bare land in Hayi Village, Tuomuni Village, Fengzu Village and Jiduo Village has all exceeded 10% (Table 6).

The barren mountains and wasteland composed of other grasslands (that is, barren grasslands) and bare land in Xueshan Township amount to 6 585.78 ha, accounting for 49.46% of the total land area. The barren mountain and wasteland in Xueshan Township accounts for about half of the total land area, indicating that the township is very rich in land reserve resources. However, on the whole, it is difficult to develop and utilize most of the barren mountains and wasteland. On the one hand, in such alpine and canyon areas, there are many difficulties in the development and utilization of barren mountains and wasteland because of high mountains and steep slopes, shallow soil layers, bad natural conditions, inconvenient transportation and poor water conservancy facilities. On the other hand, under the current policies and ideas of rural economic development, economic benefits are often given priority in local development and utilization, and ecological benefits and ecological environment protection are seldom considered. Especially in the deep poverty-stricken mountain areas, the current important task of governments at all levels is to win the battle against poverty and ensure that the poor people meet the national poverty alleviation standards by 2020, therefore, it is difficult to take into account the barren mountain and wasteland development and greening projects with the restoration of forest and grass vegetation as the main body.

Table 5 The barren grasslands in Xueshan Township and Luquan County in 2016

Table 6 The bare land in Xueshan Township and Luquan County in 2016

4.5 The proportion of land for construction is too low and land for infrastructure and public facilities is obviously insufficientAt present, the total area of construction land in Xueshan Township is only 165.41 ha, accounting for 1.24% of the total land area, of which, 98.55 ha are used for villages, 4.02 ha for mining, 27.43 ha for highways, 31.52 ha for reservoir (only distributed in Jiduo and Hayi villages), 3.20 ha for hydraulic construction, and 0.69 ha for scenic spots and special land.

Generally speaking, due to the significant small amount of land for highway, reservoir, hydraulic construction and ditches, there is a significant shortage of transportation, water conservancy facilities. This is not conducive to the comprehensive development and utilization of land resources and the healthy economic and social development in Xueshan Township.

From the perspective of village land, the per capita village land area in Xueshan Township was only 82.04 m2at the end of 2016, which was far lower than that in Luquan County (141.25 m2per person). From the point of view of the village committees, except that the per capita village land area of Jiduo Village obviously exceeds the upper limit of 150 m2per person stipulated in the Village and Town Planning Standard[18], the other six village committees have a small per capita area of village land. In particular, the per capita village land area in Shugu Village, Fengzu Village and Lewu Village is less than 72 m2(Table 7), and the lowest is in Lewu Village, whose per capita village land area is only 31.4 m2. Due to the obvious shortage of per capita village land, the public facilities of many villages and towns are obviously insufficient and the deficiency is prominent. This is not conducive to the comprehensive development of rural areas, and is not compatible with the implementation of the strategy of rural revitalization.

5 Measures for rational utilization of land resources in the future

5.1 Optimizing land use structure, promoting diversified land use and multi-functional agricultural models, and establishing a spatial pattern of land use with patch mosaic and ecological diversityIn view of the current unreasonable land use structure that the proportion of agricultural land and construction land is too low and the proportion of unused land is too large, it is necessary to increase the scale of agricultural land scientifically and reasonably in the rational use of land resources in the future. It is necessary to appropriately expand the scale of land for construction (especially for infrastructure and public facilities) and greatly reduce the scale of unused land. In other words, through the rational development and utilization of unused land, it is necessary to optimize the land use structure of the whole township. At the same time, all kinds of land should be reasonably distributed according to the characteristics of land and space suitability (or land suitability). This is the basic principle of land use on the whole.

Table 7 Per capita village land use in Xueshan Township and Luquan County in 2016

From the actual situation of Xueshan Township, which is located in the alpine canyon area in the upper reaches of the Yangtze River, it is suitable to adopt diversified land use and multi-function agricultural model for the future land use. Diversity is an important concept in contemporary ecology. From the perspective of land ecology, land ecological diversity actually refers to the diversity of land ecological subsystems (or land ecological types) in the regional land use pattern, which is characterized by heterogeneity in regional space. That is, the land ecological subsystems (farmland, woodland, grassland, towns, rural settlements, water areas,etc.) are unevenly distributed in the regional land ecosystem (general system or parent system). It is often composed of a variety of subsystems inlaid together in patches to form the spatial pattern of land use. This configuration improves its heterogeneity and enhances the ability of anti-interference. The patch mosaic of this diversified land ecological subsystem is a stable way on the scale of land ecosystem or landscape[19]. The construction of a certain mosaic model in the ecological design and allocation of land use can unify the prevention and control of soil and water loss, ecological protection and production of various industries[20]. This requires that when we carry out land use ecological planning and design, we must pay attention to maintaining and improving spatial heterogeneity and ecological diversity. Through the maintenance and development of land ecological diversity and spatial heterogeneity, we can not only promote the species diversity emphasized in ecology, but also reflect the principle of diversified economy in land use and large-scale agricultural production. In addition, key measures such as the combination of terrace agriculture and ridge economy and the combination of trees, shrubs and grasses should be emphasized in the planning of soil and water conservation measures, which can greatly promote the development of biodiversity and the comprehensive benefits of soil and water conservation.

The implementation of diversified land use and the establishment of multi-functional agriculture are important ideas for sustainable land use in the world. In fact, it is the principle of diversified economy emphasized by our country since 1978. Diversified land use patterns are meaningful for ecological, economic and social sustainability[21]. This utilization model can protect and develop biodiversity (especially ecosystem diversity and species diversity). At the same time, the complexity of regional land use pattern, diversity of use types and fragmentation of land plots caused by this model can promote the stability of regional scale ecosystem and land ecological diversity. In this regard, the utilization model is basically consistent with or very similar to the basic principles of the DLU model[22]put forward by the famous German ecologist Professor Haber (1990). In poor and backward mountainous areas with soil and water loss, it is of special significance and value for soil and water conservation and ecological construction, sustainable land use, poverty alleviation and rural revitalization strategy to carry out diversified land use patterns and establish multi-functional agriculture according to local conditions.

5.2 Earnestly carrying out the utilization and comprehensive improvement of sloping farmland with emphasis on the terracing of sloping land and the establishment of terraced agriculture and ridge economyXueshan Township has an area of 36.96 ha of paddy fields (all terraced fields), and the land ecology is basically safe. It is necessary to keep the existing use unchanged, pay attention to strengthening the construction of irrigation and water conservancy, improve the degree of intensive management and utilization, and develop characteristic intercropping, mixed cropping, interplanting and multiple cropping in accordance with local conditions, so as to improve agricultural biodiversity and yield.

There are different degrees of soil erosion in 291.30 ha of gentle slope dryland (6°-25°). The amount of soil loss is greater than the allowable amount of soil loss, and the land ecology is in an unsafe state. In the long run, this kind of land use is not sustainable. In order to ensure the basic demand for food, except for some 6°-25° slope dryland with serious soil erosion and thin soil layer at present, most of the slope dryland of greater than 25° basically keeps the use of cultivated land. However, effective ecological construction measures (mainly changing sloping land into terraced fields) must be gradually implemented. The sloping dryland with soil, water and fertilizer loss must be transformed into horizontal terraces with soil conservation, water conservation and fertilizer conservation. The amount of soil loss should be less than the allowable amount of soil loss. On this basis, efforts should be made to improve soil fertility, carry out irrigation and water conservancy construction, and develop intercropping and interplanting according to local conditions, so as to improve the land output rate[23].

At the same time, in order to further improve the economic output rate of gently sloping cultivated land, it is necessary to maximize the precision poverty alleviation, and make a reasonable industrial layout at high, middle and low elevations according to the three-dimensional climate characteristics of alpine and canyon areas. In the cold mountain areas at elevations of higher than 2 400 m above sea level, we should focus on plantingCodonopsispilosula,Angelicasinensisand other cold-resistant Chinese herbal medicines in turn. In the middle altitude zone of 1 500-2 400 m above sea level, we should mainly grow medicinal papaya, safflower pepper and other cash crops. In the river valleys and mountain areas with an elevation of less than 1 500 m, we should focus on planting green pepper, sorghum and bergamot, and try to grow tropical fruits[13], so as to increase people’s income and achieve better social, economic and ecological benefits.

5.3 Vigorously promoting the utilization and transformation of woodland and steep slope farmland focusing on the combination of trees, shrubs and grasses and multi-layer allocation

There are 368.33 ha of sloping dryland of greater than 25°and some sloping dryland of 15°-25°with serious soil erosion and thin soil layer at present. As the soil erosion is very serious and the land ecology is significantly unsafe, this mode of utilization must be changed as soon as possible, and the basic measure is to return farmland to forest (grass). In the process of returning farmland to forest, we must adhere to the effective management model focusing on the combination of trees, shrubs and grasses and multi-layer allocation, greatly increase the surface vegetation coverage and effectively control soil erosion. We should not blindly pay attention to the construction of pure economic forest, because it will make the ground bare and soil erosion out of control. Many practices, experiences and lessons have proved that the methods of forest, shrub and grass combination and economic forest multi-layer cultivation are effective greening measures to increase surface vegetation coverage and conserve soil and water[24-25]. It can not only achieve the ecological benefits of controlling soil erosion, beautifying the ecological environment, maintaining and developing biodiversity, but also achieve the goal of developing diversified economy, increasing people’s economic income, and gradually getting rid of poverty and becoming rich.

At present, 3 235.89 ha of woodlands mostly suffer slight soil and water loss, but some woodlands (especially man-made pure forest land) face a certain degree of soil and water loss because of low or even lack of surface coverage. This part of the woodland should be properly reformed, the coverage of herbaceous plants under the forest should be increased, or the man-made economic woodland should be transformed into terraced fields, so as to greatly control the amount of soil loss.

For other woodlands, most of the sparse woodlands, newly built young woodlands and some shrubs with low coverage have different degrees of soil erosion, forming the so-called phenomenon of "looking at the green mountains from afar, but finding that it is soil and water loss after approaching". The land ecology is not safe, so it is necessary to take measures such as mountain closure for forest cultivation and aerial sowing recommendation to improve the surface vegetation coverage as soon as possible in order to effectively control soil loss and promote the development of biodiversity.

5.4 Focusing on the development and utilization of barren mountains and wasteland for greening and reasonably improving the utilization rate of landAt present, the barren mountains and wastelands (including barren grasslands and bare land) in Xueshan Township have occupied about half of the land for a long time. This is the reason why the land use structure of the township is significantly unreasonable and the land utilization rate is low. The soil and water loss of most barren mountains and wasteland is serious, it is ecologically unsafe, and the ecological function is low. Reasonable utilization methods must be adopted to make effective use of the land so as to improve the overall utilization rate and output rate of land. At the same time, it is necessary to adopt appropriate ecological construction measures to effectively control soil and water loss. Specifically, it is mainly as follows: for the barren mountains and wasteland suitable for reclamation, the measures of "terracing" must be taken in the development and utilization, the terraces with soil and water conservation must be built, and attention should be paid to supporting water conservancy facilities and improving soil fertility; for the barren mountains and wasteland which are suitable for garden and woodland, effective soil and water conservation measures such as terracing, tree, shrub and grass multi-layer vegetation configuration and multi-layer cultivation must be taken in the development and utilization. Generally speaking, forest and grass greening is mainly suitable for most of the barren mountains and wasteland in Xueshan Township. Therefore, in the future, efforts should be made to improve the coverage of forest and grass vegetation in barren mountains and wasteland, and to protect and improve the ecological environment in alpine and canyon areas.

5.5 Scientifically planning to appropriately expand the scale of construction landIn accordance with the requirements of the beautiful rural construction and the implementation of the rural revitalization strategy in the new era, it is necessary to scientifically and rationally measure the demand for all kinds of construction land in the next 10-20 years, highlight the key points, coordinate various parties, and appropriately expand the scale of construction land. It is necessary to scientifically work out the "General Land use Plan of Xueshan Township" and the optimal layout of all kinds of construction land. In the planning and layout of construction land, we should focus on three aspects: first, it is necessary to appropriately increase the scale of land used by the site where the township government is located; second, it is necessary to increase the scale of village construction land (including small market towns) in Hayi Village, Tuomuni Village, Shugu Village, Fengzu Village, Lewu Village and Shicheng Village, improve the living environment in rural areas, and appropriately increase the land for public services and facilities; third, it is necessary to appropriately increase the scale of land for transportation, water conservancy and other basic facilities, improve traffic conditions and water conservancy facilities, and promote the smooth implementation of the strategy of beautiful rural construction and rural revitalization.