Protection, Development, and Restoration of Mountain Ecosystems: Taking the Wugong Mountain Meadow Ecosystem as a Study

Abstract

In this comprehensive chapter, we focus on the case study of a typical mountain meadow ecosystem within Wugong Mountain; and provide imperative aspects of protection, development, and restoration of such ecosystems. Firstly, the importance of protecting mountain meadow ecosystems was introduced. Mountain meadow ecosystems are an important component of global life support systems and ecosystems and are crucial to the global ecosystem. Secondly, the various challenges faced by mountain meadow ecosystems, including environmental degradation and disaster risks, were discussed, and special measures were also needed to adapt and mitigate climate change. Subsequently, a review was conducted on the research and protection of mountain meadow ecosystems, including research on vegetation biodiversity and the relationship between mountain soil and plant growth. In addition, the restoration of mountain meadow ecosystems was also discussed, including determining restoration goals, conducting comprehensive investigations of soil and environmental conditions, and determining vegetation planting methods. Finally, we explored the research on environmental carrying capacity in the process of sustainable development, including limiting development and developing sustainable tourism. In summary, we have systematically summarized the protection, development, and restoration of mountain meadow ecosystems, providing reference and inspiration for relevant research.

1. Introduction

Mountain ecosystems are characterized by rich biodiversity and unique geographical environments, which play a crucial role in preserving water, conserving soil and water, regulating climate, and protecting biodiversity [1]. Thus, safeguarding these ecosystems is of significant ecological, social, and economic importance [2]. In recent years, researchers have conducted extensive research on these aspects and proposed many protection strategies and measures, such as establishing natural reserves, ecological restoration, ecological sand fixation, vegetation restoration, and so forth [3, 4, 5]. The development of these ecosystems must adhere to the principles of sustainable development and focus on the unity of ecological, social, and economic benefits. The development direction mainly includes ecotourism, ecological agriculture, forestry, clean energy, etc. Throughout the development process, prioritizing ecological protection, judicious resource utilization, and industrial structure optimization is crucial. Scholars have further delved into the development of these ecosystems, examining various models, strategies, and policy suggestions [6, 7]. Ecosystem restoration involves actions like ecological and vegetation restoration, and soil enhancement to return the ecosystem to its near-natural state. Restoration efforts must concentrate on reviving species diversity, ecosystem function, and stability. Researchers have conducted extensive research on the restoration of mountain ecosystems and proposed many restoration technologies and methods, such as ecological sand fixation, vegetation restoration, and soil improvement. The intertwined processes of protecting, developing, and restoring these ecosystems are long term and complex, spanning multiple disciplines such as ecology, geography, and environmental science [8, 9].

The Earth’s three primary carbon reservoirs are its grasslands, forests, and oceans. Mountainous meadows are a larger form of terrestrial ecosystem with significant carbon storage capacity, they play a significant role in the global carbon cycle [10]. These meadows predominantly occupy flat terrains and are known for their rich organic matter and fertile soils. Recently, grassland research has emerged as a key area of interest to scientists. Exploring grassland mountain ecosystems represents an interdisciplinary research endeavor, encompassing fields such as ecology, botany, soil science, and meteorology [11]. In-depth exploration and comprehension of these ecosystems’ characteristics and principles can furnish the scientific foundation and theoretical guidance necessary for their protection and restoration.

Wugong Mountain in southern China has been widely known in recent years due to its beautiful alpine meadow landscape, and it also has rich historical and cultural connotations [12]. Wugong Mountain’s strategic location and orientation significantly influence the vegetation zoning across East China, serving as a natural demarcation for the central and northern subzones of evergreen broad-leaved forests in China’s humid subtropical east [13]. The mountain’s high elevation and steep terrain lead to a pronounced differentiation in the vertical zoning of both soil and vegetation, especially the widely distributed mountain meadows around the main peak, making it a rare natural museum of vegetation vertical zonality. Within Jiangxi, Wugong Mountain stands out as the only one with typical mountain meadow vegetation, unlike Lushan Mountain, Jinggang Mountain, and similar others [14]. Our colleagues have engaged in comprehensive studies here, including investigating and analyzing the occurrence conditions, nutrient characteristics, soil carbon, nitrogen, and soil microbial characteristics of mountain meadow soils at different elevations, to explore the nutrient characteristics, biological activity, and limiting factors of mountain meadow soils [15, 16, 17, 18]. Utilizing advanced international methods for soil nutrient analysis, they have conducted experiments on mountain meadow soil, determining nutrient limiting factors and spatial variability in different degradation stages and elevation meadow soil. They have uncovered the varying traits of nutrients, structure, morphology, microorganisms, and soil fertility in grassland soils across different times and spaces, along with the underlying mechanisms [19, 20]. These efforts foster environmental sustainability in grassland ecosystems, and aid in the restoration and enhancement of degraded grassland soils. They provide preliminary experience for the evaluation system and methods of the health status of grasslands in Wugong Mountain.

Hence, we utilize Wugong Mountain as a representative case study to examine research on the conservation, development, and restoration of mountain ecosystems, in order to provide a theoretical basis for the protection and sustainable development of mountain ecosystems.

2. Overview of the research area

2.1 Geographical location and location characteristics

Positioned in the northern part of the Luoxiao Mountains, Wugong Mountain marks the divide between the Xiang and Gan River systems (114°10′ ~ 114°17′ E, 27°25′ ~ 27°35′ N), encompassing around 260 km², it’s an average elevation exceeds 1500 m (Figure 1). Baihe Peak, also known as the Jinding, reaches the highest elevation of 1918.3 m [21]. The mountain experiences an annual average temperature of 14–16°C, with humidity levels ranging from 70 to 80%, and an annual rainfall of 1350–1570 mm. Wugong Mountain is predominantly formed of granite and gneiss. Wugong Mountain significantly influences the vegetation zoning across eastern China. Its steep, high-elevation terrain creates pronounced vertical zonation in climate, soil, and vegetation [22].

Figure 1.

The geographical location and scope of Wugong Mountain (within the yellow circle). A: Map of China, B: Map of Jiangxi Province, and C: Satellite map of Wugong Mountain area.

2.2 Natural resources

Wugong Mountain has beautiful scenery, with an elevation difference of 1600 m. Its main vein mainly runs in a southwest-northeast direction. The geological structure is mainly composed of granite core complex and peak cliff landforms, with an elevation generally exceeding 1000 m, and many mountain peaks reaching over 1500 m. It is a unique landscape of granite and mixed rock landforms, with the main types of landforms being middle and low mountains. Red soil, yellow soil, yellow-brown soil, and plateau meadow soil are distributed in a gradient pattern along the elevation [23].

Wugong Mountain belongs to a subtropical monsoon humid climate with distinct four seasons, mild climate, abundant rainfall, and large clouds and mist. The annual average temperature is 14–16°C, and the summer is cool and pleasant. At the same time, the temperature is lower than that of Mount Lushan and Mount Huangshan, which is a good place for summer vacation. The annual precipitation of Wugong Mountain is about 1700 mm, with abundant precipitation, forming numerous waterfalls, streams, and pools.

The zonal vegetation of Wugong Mountain belongs to the typical subtropical evergreen broad-leaved forest. The vegetation zone on the southern slope of the mountain range has strong tropical characteristics, while the northern slope has strong temperate characteristics. Vertical zonal vegetation types include mixed evergreen and deciduous broad-leaved forests, evergreen broad-leaved forests, coniferous forests, mountain dwarf forests, bamboo forests, and meadows. The forest coverage rate of Wugong Mountain reaches 88.1%, which is higher than the average level in China and even the world. There are 37 ancient trees and over 150 precious, rare, and endangered tree species preserved in Wugong Mountain [24]. In the current vegetation, there is a very rich variety of plant species. According to vascular plant statistics, there are 49 families, 114 genera, 403 species, 28 varieties, and 4 forms of ferns; 8 families, 22 genera, 29 species, and 2 varieties of gymnosperms (Table 1). There are more than 210 families and 1340 genera of angiosperms, accounting for about 60% of the total families and 38% of the total genera of angiosperms in China. Ginkgo biloba L is a relic plant from the Jurassic period of the Mesozoic era; Cryptomeria fortunei is a coniferous tree that continued from the Jurassic period to the present day. There is currently a species called Cryptomeria fortunei, which is distributed in primitive forests on Wugong Mountain. Glyphostrobus penilis, Cephalotaxaceae, and Taxaceae, which appeared as early as the Cretaceous 100 million years ago, have continued to this day and become a component of mixed coniferous and broad-leaved forests, or companion species in evergreen broad-leaved forests. Taxus chinensis, a shallow-rooted plant with an inconspicuous main root and well-developed lateral roots, is recognized as an endangered natural rare anti-cancer plant worldwide. It is an ancient tree species left over from the Quaternary glaciers and has a history of 2.5 million years on the Earth.

Type	Family	Genus	Species	Variety	Form
Ferns	49	114	403	28	4
Gymnosperms	8	22	29	2	—

Table 1.

Statistics on the number of vascular plants in Wugong Mountain.

2.3 Social humanities

Wugong Mountain has a long history and a rich cultural heritage. Since the Han (202–220 BC) and Jin (266–420 AD) dynasties, it has been chosen by both Taoism and Buddhism as a blessed place for self-cultivation. During the Song and Ming dynasties, when incense was at its peak, there were more than 30 nunneries of arhat halls, buddhist temples, and taoist temples built in the south and north of the mountain. To this day, there is a continuous stream of worshippers of good men and women, as well as famous scholars who appreciate mountaineering, recite poetry, and write poems, leaving countless precious ink marks. After Xu Xiake, a great Ming Dynasty traveler and geographer, visited Wugong Mountain, leaving behind the timeless quatrain of “Thousand peaks and towering jade hairpins, the five ridges are comparable to Wugong Mountain” [25]. According to research, more than a hundred ancient poems, plaques, and articles praising Wugong Mountain have been left behind. The altar community of southern China at the Jinding of Wugong Mountain, with a history of over 1700 years, is known as a unique feature of China; there are currently ten ancient pagodas in Jiulong Mountain, all of which were built in the Ming Dynasty and are considered the only group of ancient pagodas in the province. After restoration, they can recreate the scenery of the past.

3. Problems with mountain meadow ecosystems

Mountain meadows are a rare landscape type in the composition of mountainous tourist attractions. For a long time, Pingxiang City, Anfu County, and Yichun City around Wugong Mountain have all focused their attention on the unique resources of Wugong Mountain in the process of resource development and promoting rapid local socio-economic development [26]. In 1985, Wugong Mountain was approved by the People’s Government of Jiangxi Province as the first batch of provincial-level key scenic spots. In 2005, it was successfully declared as a national key scenic spot. With the completion of the high-speed railway from Shanghai to Ruili, the railway from Zhejiang to Jiangxi has increased in speed, and the expansion of the tourism road from Luxi to Wugong Mountain has been carried out, especially the construction of the road network in the scenic area and the opening of the two-level mountain climbing cableway, the range of tourist sources that come with admiration has significantly expanded. At present, the customer source market has expanded to the Nanchang, Changsha, and the border areas between Jiangxi and Hunan provinces. In the medium and long term, a tourism radiation area can be formed in the East China region centered around Shanghai, the Central China region centered around Wuhan, and the South China region centered around Guangzhou. Since 2004, the Wugong Mountain has received 450,000 visitors. Since 2008, the annual Wugong Mountain International Tent Festival has also attracted more and more tourists from all over the country to climb, explore, and camp [27]. It is worth noting that with the expansion of tourism scale and the extension of tourist travel range, the negative impact on various vegetation and special landscapes, including mountain meadows, is also increasing day by day. The arbitrary trampling by tourists and the discharge of waste have largely led to the degradation of meadow community composition and productivity, and the gradual fragmentation of about 4000 hm² of mountain meadows is becoming increasingly apparent [28].

Overcultivation and overgrazing are some of the main causes of ecological and environmental problems in mountain meadows. Excessive cultivation can lead to intensified soil erosion, which in turn affects the safety of water sources. Overgrazing can lead to meadow vegetation degradation, and reduced biodiversity, and thus affect the stability of ecosystems. Therefore, limiting excessive cultivation and grazing is one of the important measures to protect the ecological environment of mountain meadows. Soil erosion is another important aspect of the ecological environmental problem in mountainous meadows. In addition, factors such as climate change may also lead to intensified soil erosion [29]. Therefore, taking measures to prevent soil erosion is one of the important measures to protect the ecological environment of mountain meadows. The reduction of biodiversity is another important aspect of the ecological environment of mountain meadows [30]. Besides to the above factors, other human disturbances also may lead to a gradual decrease in biodiversity, and some species may be endangered. Therefore, taking measures to protect biodiversity is one of the important measures to protect the ecological environment of mountain meadows.

4. Research on mountain meadow ecosystem

4.1 Research on plant biodiversity

Originating from the 1940s, biodiversity has become a crucial research domain within ecology and global change, presently commanding international ecological attention. Based on the hierarchy of life systems, different scholars divided biodiversity into four levels: genetic diversity, species diversity, ecosystem diversity, and landscape diversity [31].

The variation of biodiversity along environmental gradients is an important research topic in this field. Wang et al. [32] research shows that species diversity and evenness are highest in mid-elevation areas, and species evenness and diversity first increase and then decrease with increasing elevation. Among the currently rare diverse personality traits are: α diversity index increases with elevation, and there is no clear pattern in the species richness index of coastal gradient changes. Therefore, it is necessary to study the biodiversity of various important mountains in nature to accumulate a foundation for the pattern of mountain diversity.

Studying population spatial patterns has always been the most important research field in community ecology. Community pattern analysis is the process of studying the mosaic structure between small communities and small community gaps, or between community patches and community patch gaps. It is an important means of studying plant community structure. At present, common spatial distribution patterns include three types: random distribution, clustered distribution, and uniform distribution. Some scholars believe that spatial distribution patterns should be divided into four types: random distribution, clustered distribution, uniform distribution, and mosaic distribution [33]. The community environment is composed of biotic and abiotic factors. The spatial pattern often reflects the relationship between its dynamic environment and individual survival and growth, as well as indicates the ecological adaptation strategies of plants.

Based on the survey data of 115 sample plots in the distribution area of Wugong Mountain meadow, in previous studies, we analyzed the characteristics and distribution types of vascular plant flora, plant community diversity, spatial distribution patterns of small communities, and human interference effects in the meadow [34]. Through field investigations and specimen identification in the research area over the past 2 years, it was found that within the survey elevation range of 1500 to 1900 m, the meadow plant resources in Wugong Mountain are relatively abundant, including 44 families, 90 genera, and 108 species of ferns, gymnosperms, and angiosperms. Among them, there are 6 families, 6 genera, and 6 species of ferns; 1 family, 2 genera, and 2 species of gymnosperms; 37 families, 82 genera, and 100 species of angiosperms (31 families, 63 genera, and 81 species of dicotyledonous plants; 6 families, 19 genera, and 19 species of monocotyledonous plants). Through investigation and analysis of plant community species at different elevations and slopes in the Wugong Mountain meadow, it was found that Miscanthus occupies a dominant position in the entire plant community, followed by the wild ancient grass as a subdominant species. In addition, there are some accompanying species such as Hypericum ascyron and Selaginella.

We analyzed the spatial distribution pattern of the surveyed plant communities and found that Miscanthus, as the main community, has a relatively large distribution area, with 23 types of small communities. The dominant and constructive species in each small community are different, and they all exist as separate small areas in the surrounding large communities. These small communities are mostly distributed on both sides or near the main walkway, with small areas, and some are sporadically embedded in the large communities, a part of them is distributed in an island-like pattern on a mountain slope and is not universal. They are all unique to large communities. Similarly, in the vertical distribution pattern, it can be observed that there are more small communities distributed at elevations of 1650 and 1700 m compared to other elevations, with only one community found at an elevation of 1900 m. As the elevation gradient increases, the α diversity index changes in a wavy pattern (Table 2). Analyzing the changing trends of the five indices of the β diversity index shows that as elevation increases, all indices exhibit irregular jumping changes, which may be related to changes in factors such as temperature, water, soil, and light at elevation and changes in the degree of human interference.

Elevation(m)	Species number	Shannon-wiener index	Simpson index	Pielou index
1500	45	3.455	0.9577	0.8878
1550	34	3.085	0.9425	0.9162
1600	50	3.6028	0.962	0.9032
1650	46	3.8392	0.9714	0.9972
1700	40	3.6424	0.9674	0.9745
1750	45	3.6394	0.967	0.9934
1800	31	2.7586	0.9176	0.868
1850	25	2.5256	0.8911	0.8577
1900	26	3.2981	0.9527	0.8941

Table 2.

The changes of plant community diversity in different elevation gradient.

The main tourist trail and meadows on both sides of Wugong Mountain’s main peak (Jinding) have been deeply affected by tourism activities, especially the main peak, which has been seriously disturbed by human activities, and even several exposed plots have appeared. In response to these phenomena, a study was carried out on the effects of human interference on the meadow of Wugong Mountain. From the main peak of Wugong Mountain at 1900 to 1500 m (the lower limit of the meadow), sample plots were selected from the edge on the same side of the main trail that was most affected by tourism interference. A small sample plot of 1 m x 1 m was set up every 50 m above sea level, with each sample plot being 0 m, 4 m, 8 m, and 12 m away from the main track. Thus, four parallel transects were formed along the main track, totaling 36 small plots. During the investigation, record the plant name, abundance, coverage, frequency, and height of each small plot, as well as environmental factors such as longitude, latitude, and slope.

Tourism activities have had an impact on the community structure and species composition of the Wugong Mountain meadow to a certain extent. The farther away from the main walkway, the greater the total coverage of the transect, and the smaller the degree of tourism interference. In addition, the composition and structure of plant species in the meadow have also changed. Along the main trail, plants that were originally dominant in the meadow, such as Miscanthus and Arundinella hirta, have become companion species due to poor anti-interference ability. However, plants that were originally companion species, such as Gerbera delavayi Franch, Elsholtzia stachyodes (Link) C. Y. Wu, and Senecio latouchei J. F. Jeffrey, have become dominant species. These plants have strong competitiveness, wide adaptability, and certain anti-interference abilities under the interference of human tourism activities. This may be due to interference that can regulate the ratio of plant species and plant numbers between local and non-local species, thereby affecting the species composition of plant communities. With the vigorous development of the tourism industry, frequent human activities have had a certain impact on the vegetation growth and plant community structure of the Wugong Mountain meadow.

The species richness index of Wugong Mountain meadow shows a decreasing trend with the decrease of tourism disturbance. Research has shown that a significant decrease in species richness index can be observed from the first parallel transect to the second, indicating that tourism interference causes changes in the internal composition structure of plant communities. However, there is no significant change in the richness indexes in the second parallel transect to the fourth, and the intensity of tourism interference does not have a substantial impact on the structure of plant communities. The first parallel is located at the edge of the main trail, which is most disturbed by tourism activities. Human activities have led to the invasion of some companion plants, damaging the original plant community and increasing the species richness index at the edge of the main trail.

The higher the elevation areas, the lower the coverage and the greater the degree of grazing disturbance. The species richness index shows an increasing trend with the degree of interference, and both the diversity index and evenness index show a trend of “first increasing, then decreasing, and then increasing”. The evenness index is highest for mild interference and lowest for moderate interference; the diversity index of undisturbed plants is the lowest, while the diversity index of heavily disturbed plants is the highest, indicating that the strength of grazing disturbance has a certain degree of impact on plant community diversity.

4.2 Research on soil characteristics of mountain meadows

Soil is an important component of the Earth’s biosphere and the material foundation on which humans and other animals and plants rely for survival. Soil permeability is one of the important factors affecting soil erosion and an important indicator reflecting the function of soil water conservation and regulation. As a sensitive indicator for stabilizing ecosystems and monitoring changes in soil quality, the diversity of soil microorganisms has played a huge role in evaluating ecosystems and maintaining ecological balance. Therefore, more and more scholars are turning their attention to the research and protection of soil microbial diversity. Soil microorganisms are not only an important component of soil, but also the main drivers of soil nutrient cycling. Changes in soil microbial communities can to some extent reflect the trend of soil quality changes [35]. Among soil microorganisms, bacteria and fungi have the most types and quantities. Bacteria and fungi play an extremely important role in soil nutrient cycling, organic matter formation and decomposition, soil structural composition formation, ecological environment improvement, plant growth and development, and crop pest control [36]. Therefore, research on the characteristics of microorganisms dominated by bacteria and fungi has received widespread attention. Soil nutrients are essential nutrients for plant growth provided by the soil. Soil available nitrogen (AN), available phosphorus (AP), and available potassium (AK) nutrients are the direct sources of the three essential basic elements for crop growth and development [37, 38, 39]. Elevation is an important ecological factor that affects crop layout and growth and development, and also has a significant impact on the content of various nutrients in the soil [40, 41]. Natural meadow vegetation is the largest green vegetation layer on the Earth’s land surface and an important component of terrestrial ecosystems [42, 43].

The Wugong Mountain meadow in Jiangxi province is a typical representative of subtropical mountain meadows, which have typicality and specificity in the vertical vegetation spectrum of east China due to its wide area and low distribution benchmark elevation. Due to the sharp increase in the number of tourists, the meadow ecosystem has undergone varying degrees of degradation due to human trampling, plant populations have evolved, age structures have changed, biodiversity has decreased, and productivity has declined. Meadow plants exhibit characteristics such as dwarfism, inferiority, and sparsity, some of which even become exposed to the surface, leading to a decrease in fragile ecosystem functions and a weakened ability to recover. Li et al. [44] studied the hyperspectral characteristics of several vegetation in the region and found that the spectral reflectance of the vegetation was as follows: Carex chinensis > Arundinella anomala>Miscanthus sinensis > Sinarinaria nitida > Fimbristylis wukunnshanensis; Zhao et al. [21] research showed that the total amount of inorganic phosphorus in meadow soil significantly increased with increasing elevation; Deng et al. [45] believe that as the elevation increases, there is no significant change in the content of available Fe, Cu, Zn, B, and other elements in the meadow soil. However, as the degree of degradation increases, the content of available Cu shows an enrichment phenomenon; Yuan et al. [46] found that the alkaline nitrogen content in the 0–20 cm soil layer of the meadow in the region was higher than that in the 20–40 cm soil layer.

We also found that there is variation in the soil water conservation function of meadows at different elevations in Wugong Mountain, but the variation characteristics are not completely consistent with the changes in elevation [47]. The best water conservation capacity is observed within a range of 1600 m, followed by 1800 and 1700 m, while the water conservation capacity is weak within a range of 1900 m. The soil permeability ranges from 1600 to 1800 m and gradually decreases with increasing elevation, while it increases again in the high-elevation range of 1900 m. As meadow degradation intensifies, soil permeability gradually decreases. The universal empirical model can better fit the soil infiltration process in this study area. The variation characteristics of soil pH show an increase with elevation, an increase in soil activity with the degree of meadow degradation, and a decrease in pH value; soil organic matter remains consistent across varying elevations and degraded meadows; soil potassium concentration rises with elevation, whereas both total phosphate and available phosphate quantities augment with meadow degradation; available sulfur diminishes with elevation ascent and goes up with meadow degeneration; available manganese quantity exhibits a drop with elevation and degradation increment.

At different elevation ranges, the variation characteristics of soil microbial distribution mainly come from the 1900 or 1800 m range of high-elevation areas, while the variation characteristics of soil microbial distribution in mountain meadows with different degrees of degradation mainly come from areas with severe meadow degradation. As the elevation increases and the degree of meadow degradation intensifies, the biomass per unit area of meadows generally shows a decreasing trend. There is a significant positive correlation between bacterial diversity index and leaf biomass, while the number of bacterial OUTs (Operational Taxonomic Units) is positively and negatively correlated with leaf biomass ratio and root biomass ratio, respectively. There is a certain negative correlation between Cyanobacteria, Archaea, Nitrifying spirochetes, and biomass. The Saccharomycota is positively correlated with total vegetation biomass, while the Chlamydomonas is negatively correlated with aboveground vegetation biomass. Soil catalase is positively correlated with both underground and total biomass of vegetation, while sucrase is negatively correlated with aboveground biomass. There is a negative correlation between total potassium and available phosphorus in soil and aboveground biomass of vegetation [18].

4.3 Response of mountain meadow ecosystem to climate change

Climate change is one of the important issues facing the world today, among which rising atmospheric CO₂ concentration and temperature are the main characteristics of future climate change. These changes have a significant impact on the soil nitrogen mineralization process, which in turn affects crop growth and soil quality. After crop residues enter the soil, the content of available nitrogen in the soil is influenced by the dynamic changes of microbial fixation and organic nitrogen mineralization. On the one hand, under high atmospheric CO₂ concentration, the C/N content of crop residues is higher. Soil microorganisms not only obtain rich carbon sources but also increase the fixation of inorganic nitrogen in the soil. Although microorganisms may promote the mineralization of soil organic nitrogen to utilize more inorganic nitrogen, it is manifested overall as a net biological fixation of mineral nitrogen, resulting in a decrease in effective nitrogen content in the soil. On the other hand, C/N in soil decreases with organic decomposition and CO₂ release, and the rate of nitrogen fixation by microorganisms gradually decreases compared to the mineralization rate of organic nitrogen, resulting in net mineralization of organic nitrogen. Therefore, under the condition of elevated CO₂, although crop residues strengthen microbial nitrogen fixation in the short term, they may ultimately promote soil organic nitrogen mineralization, increase the available nitrogen content in the soil, and facilitate crop absorption and utilization. Climate change has a significant impact on soil nitrogen mineralization, mainly manifested in the increase of atmospheric CO₂ concentration and temperature, as well as the impact of crop residues on soil nitrogen mineralization [48].

Nitrogen is an important nutrient element in living organisms, one of the main components of proteins, and a key factor in regulating the production, structure, and function of terrestrial ecosystems. It can limit the primary and secondary productivity of communities. The disruption of the balance of nitrogen cycling will inevitably affect the ecological balance of other important physical, chemical, and biological properties, leading to changes in the global environment. The core problem of meadow degradation is soil degradation, which has a certain buffering and complexity. Nitrogen is the most abundant element in the atmosphere and an essential element for plant growth and development. It is crucial in the global carbon and nitrogen cycle. The nitrogen absorbed by plant growth and development mainly comes from the soil; therefore, the chemical form and transformation of soil nitrogen restrict the absorption and utilization of nitrogen by plants. The detection of soil nitrogen usually selects total nitrogen (TN), alkaline nitrogen (AN), nitrate nitrogen (NO3−N), and ammonium nitrogen (NH4 + −N).

Our research starts with the response of the soil nitrogen pool in the Wugong Mountain meadow to ecosystem degradation and simulated warming, exploring the changes in soil physicochemical properties with meadow degradation, as well as the impact of climate change on meadows. With nitrogen as the breakthrough point, we accurately grasp the impact of meadow degradation on soil nutrients. There are many reasons that can cause meadow degradation, such as overgrazing, climate change, outbreaks of herbivorous small mammal populations, and interference from tourism behavior. The degradation of meadows leads to soil degradation, and the two are mutually causal and cyclical. The mountainous meadow ecosystem has important ecological functions such as improving soil, regulating climate, purifying air, and conserving water sources and its nitrogen storage is enormous. However, due to excessive tourism development, the degradation of Wugong Mountain meadow is becoming increasingly serious. This not only leads to the destruction of soil structure, soil fertility, and vegetation diversity in the meadow ecosystem but also causes significant changes in the composition and structure of its meadow vegetation; the regional ecological environment is facing severe challenges. Therefore, maintaining the stability of meadow ecosystems is of great significance for the development of the regional ecological environment and nitrogen balance. A study on nitrogen mineralization in the meadow soil of Wugong Mountain found that under the same temperature cultivation, as degradation intensifies, the net nitrogen mineralization rate will gradually increase. Under the same elevation and degree of degradation, the net nitrogen mineralization rate of soil will significantly increase from 15 to 25°C (P < 0.05), and slightly decrease from 25 to 35°C, with an overall performance of 25°C > 35°C > 15°C. Therefore, it is predicted that the peak of soil net mineralization in Wugong Mountain meadow may occur between 25 and 30°C [22, 48].

5. Research on the protection and restoration of mountain ecosystems

The protection of mountain ecosystems mainly relies on legal, policy, scientific research, and educational means to reduce the damage of human activities to the ecosystem, promote the restoration of the ecosystem, and protect biodiversity. Governments of various countries protect mountain ecosystems by formulating relevant laws and regulations. For example, regulations such as the Regulations on Nature Reserves of the People’s Republic of China and the Wildlife Protection Law of the People’s Republic of China have played an important role in protecting mountain ecosystems and wildlife. The government protects mountain ecosystems by formulating various policies and plans. The Chinese Government has implemented policies such as natural forest protection projects and land conversion projects to protect mountain forest ecosystems. Chinese scientists want to understand the ecological processes and biodiversity of mountain ecosystems through scientific research, they have discovered many unique plant and animal species on the Qinghai Tibet Plateau, which provided a scientific basis for protecting these species. The Chinese government want to enhance public awareness and awareness of mountain ecosystem protection through educational and promotional activities, some education departments has added content related to nature conservation in primary and secondary school textbooks to enhance young people’s awareness of nature conservation.

The restoration of mountain ecosystems is mainly promoted through vegetation restoration, soil restoration, and water resource management to promote the restoration of ecosystems and improve the ecological environment. Through measures such as aforestation and returning farmland to forests, the vegetation of mountain ecosystems can be restored, and the biodiversity and stability of the ecosystem can be improved. China’s Grain for Green project improves the stability and disaster resistance of mountain ecosystems by gradually restoring steep slope farmland to forest vegetation. By taking physical, chemical, and biological measures to repair damaged soil, the quality and productivity of the soil can be improved. Some regions in China have adopted measures such as returning straw to the field and applying organic fertilizers to improve soil structure and enhance soil fertility. By rational allocation and effective management of water resources, we can ensure the normal operation of mountain ecosystems and the full play of ecological service functions. Other regions in China have adopted measures such as rainwater collection and water-saving irrigation to improve the efficiency and management level of water resources.

The Wugong Mountain Meadow in Jiangxi Province is a typical representative of subtropical mountain meadows. Currently, human interference and excessive tourism development have led to serious degradation and fragmentation of the fragile meadow ecosystem in the region. It is urgent to carry out reasonable vegetation restoration to prevent further deterioration of the ecological environment [49]. Bai et al. [50] summarized the theoretical and practical work of early degraded ecosystem restoration and reconstruction, and believed that plant measures are the primary step and preferred solution in restoration measures. Yang et al. [51] used ryegrass (Lolium perenne L.), Poa annua L., and creeping purple fescue (Festuca rubra L.) as sowing grass seeds, plant paper, and non-woven fabric as auxiliary materials, and conducted fertilization treatment experiments. It was found that non-woven fabric and plant paper have similar auxiliary effects on vegetation growth, and an increase in fertilization will actually reduce the emergence rate. Ge et al. [52] restored the degraded areas of alpine meadows in Maqu County, Gansu Province through measures such as fertilization, supplementary sowing, and soil plowing, and believed that several measures were effective. Yang et al. [53] conducted a study on the vegetation restoration of the slopes of the Yuexi to Wuhan expressway in the western Anhui region and found that using plant fiber blankets as auxiliary materials has better effects.

The research team led by the author has currently conducted research on soil nutrient distribution [17, 20], vegetation hyperspectral characteristics [44], and mountain meadow tourism marketing [54] in the Wugong Mountain meadow, enriching the scientific research achievements of the vegetation ecosystem in the region. The degradation of meadows can generally be attributed to two major factors: natural and human factors [43]. The vegetation degradation of Wugong Mountain meadows is mainly caused by tourism development and human trampling. How to adapt to the environmental requirements of the region and have good tolerance to the trampling behavior of tourists, while quickly repairing the current ecological degradation situation, is an important issue faced by scientific research and business planning personnel. We take the severely degraded area of Wugong Mountain meadow as the research object and analyze the vegetation growth effect and adaptability characteristics under different treatment methods by sowing different grass species, covering different auxiliary materials, and conducting turf transplantation and enclosure. We explore excellent measures suitable for vegetation restoration in the area, providing theoretical guidance for the ecological restoration of degraded meadows, providing a reference basis for the management planning and sustainable development of subtropical mountain meadows. Among several vegetation restoration measures, direct sowing of awns has the best growth effect, followed by dogtooth root, tall fescue, ryegrass, thrush grass, and enclosed vegetation have poor growth effects. Covering non-woven fabric as an auxiliary measure has a better vegetation growth effect than covering grass curtains and non-covering measures. Grass transplantation has the best growth effect among all vegetation restoration measures, and the grass transplantation effect of local grass species such as Miscanthus, Carex chinensis, and Fimbristylis wukungshanensis is better than that of imported grass species such as Cynodon dactylon. In the process of vegetation restoration, it is recommended to use measures such as grass transplantation based on the premise that it does not cause significant damage to the original vegetation environment; in addition, it is recommended to use Miscanthus as the main grass species for restoration, Cynodon dactylon as an auxiliary grass species, and cover it with non-woven fabric for vegetation restoration [55].

6. Development and utilization of sustainable mountain ecosystems

The development of mountain ecosystems mainly utilizes resources through sustainable ecotourism, agriculture, and forestry to promote economic development and reduce poverty [56]. Some local governments and tourism companies utilize the natural landscapes and cultural heritage resources of mountainous ecosystems to develop the ecotourism industry and provide support for local economic development. China’s Jiuzhaigou Valley Scenic and Historic Interest Area, Zhangjiajie, and other tourist attractions have attracted a large number of tourists to come for sightseeing and vacation by using their unique natural landscape and cultural heritage resources. There are also some local governments and business operators utilize the agricultural resources of mountainous ecosystems to develop characteristic agriculture and improve the income and living standards of farmers. The province of Guizhou and Yunnan in China have utilized their abundant agricultural resources to develop characteristic agricultural industries such as tea and flowers. If there are mountains within the administrative area, government departments and tourism enterprises Utilize the forestry resources of mountainous ecosystems to develop the forestry industry and provide support for local economic development. China’s Changbai Mountain and Huang Mountain have used their rich forestry resources to develop forestry industries such as wood processing and undergrowth economy [57].

The tourism industry is affected by the environment. In a certain sense, it can be said that tourism is developed based on the environment. Only a beautiful environment can make people feel relaxed and happy, leaving them lingering and immersed in the beautiful atmosphere. At the same time, it can cultivate sentiments, stimulate enthusiasm, achieve spiritual satisfaction, and discover, enjoy, and spread beauty in the beautiful scenery. On the contrary, if there is no high-quality environment or the environment is damaged, it cannot attract tourists to travel. Protecting the environment is the fundamental guarantee for the sustainable development of tourism, and it is the most basic condition for the sustainable development of a country or region’s tourism industry. At the same time, good tourism development can also promote the protection of the tourism environment and provide local environmental investment, which complement each other [54].

However, in recent years, with the rapid development of the tourism industry and the arrival of the era of mass tourism, a large number of tourists have flooded into tourist destinations, putting enormous pressure on the sustainable development of tourist destinations. Some problems such as resource destruction, declining landscape quality, and environmental pollution are becoming increasingly serious, mainly manifested in (1) endogenous destruction, which is the damage caused by tourism activities themselves, there are mainly constructive damages to tourist attractions and pollution of the tourism environment caused by household waste. (2) Exogenous damage, namely the damage caused by economic activities in the surrounding areas, mainly includes pollution of the tourism environment caused by waste gases and water, and unreasonable layout of infrastructure, which damages the tourism environment. However, the traditional tourism environment management in our country still remains at a low level due to the emergence of diverse policies and chaotic management. (3) Without new breakthroughs, the sustainable development of scenic spots is greatly threatened. Based on this, tourist attractions must seek more suitable sustainable development strategies and scenic area tourism environment management methods. Experts in the tourism and natural ecology fields are also actively considering how to protect tourism resources, prevent environmental pollution and damage, and achieve an organic unity of economic, social, and environmental benefits [58].

Wugong Mountain is a mountainous scenic area with natural scenery as its main feature. The mountainous meadows are a rare landscape type in the composition of mountainous tourist attractions. By comprehensive and systematic investigation, analysis, and evaluation of the tourism resources, a survey and analysis were conducted on the recreational behavior of tourists; previous researchers conducted an analysis and evaluation of various recreational activities’ impact on the tourism environment factors of Wugong Mountain’s scenic area. We considered tourist experience and resource conservation aspects to construct a range of mountain grassland recreation opportunities, calculate the tourism environmental carrying capacity, and offer pertinent suggestions for environment management, including national park establishment, waste management, greenway development, and ancient tree cultural restoration [57, 59, 60, 61].

6.1 Analysis and evaluation of tourism resources

The Wugong Mountain Scenic Area has a wide variety of tourism resources with complex structures and abundant individual resources. The overall evaluation score for tourism resources is 80 points, including 9 fifth-level tourism resources. The score for typical landscapes (mountain meadow landscapes, celestial wonders, and ancient tree landscapes) is 85 points, indicating a high score and high overall development value.

6.2 Analysis of recreational behavior characteristics of tourists

Based on first-hand data obtained from questionnaire surveys and in-depth interviews, this study focuses on mountain tourists and analyzes the general characteristics of the Wugong Mountain recreational market and tourist recreational behavior. The results indicate that the recreational behavior of tourists in Wugong Mountain has the following obvious characteristics:

1. In terms of demographic characteristics, the gender structure is dominated by male tourists, with middle-aged and young tourists as the main group. Among them, the proportion of male and female tourists is 60.7 and 39.3%, and tourists between the ages of 18 and 40 account for 89.3%. In terms of occupation and education, student tourists account for 38.2%. In addition, company employees and enterprises and institutions account for 17.1 and 13.2%, respectively, with a higher proportion. From the perspective of educational background, tourists have the characteristic of high education, with 70.4% having a bachelor’s degree and 5.3% having a graduate degree. Therefore, young students also as the main group, with high educational qualifications. However, the proportion of high-end outdoor recreational tourists is relatively small.

2. In terms of the spatial structure of the customer source market, the market structure is mainly characterized by short-range customers, supplemented by remote customers, and a combination of short-range and remote customers.

3. In terms of general recreational behavior characteristics, there is an inherent consistency between tourist motivation and activity preferences, and they exhibit a preference for recreational activities in mountain meadows and backpacking characteristics.

4. In terms of recreational experience evaluation, tourists have higher satisfaction and willingness to revisit, and there is also an inherent consistency between the two, but their satisfaction with the meadow tourism environment is relatively low. Tourist satisfaction is an important indicator of experience evaluation, which can reflect their perceptions and evaluation opinions on tourism products and services. The Likert scale was used to analyze visitor satisfaction in Wugong Mountain’s recreational environment. Five attitudes, namely very dissatisfied, dissatisfied, basically satisfied, satisfied, and very satisfied, are expressed in the form of 1–5 points. After statistical analysis, the overall satisfaction of tourists with the recreational environment of Wugong Mountain is 3.45, indicating that tourists are generally satisfied with the recreational environment of Wugong Mountain at present. This is basically in line with the recreational expectations of tourists. 38.6% of tourists believe that the recreational experience of Wugong Mountain is “mostly what I expected” and 37.3% of tourists feel that the recreational experience is “good, but I hope there are still some aspects that can be done better”. Generally speaking, tourists’ satisfaction directly affects their rate of revisiting and their willingness to revisit. 80.5% of first-time tourists come to Wugong Mountain, of which 62.3 and 19.7% are first-time tourists who make “possible” and “certain” choices to participate in outdoor recreation in Wugong Mountain again. The inherent consistency between tourist satisfaction and willingness to revisit indicates that the recreational environment and projects provided by Wugong Mountain Scenic Area are generally recognized by tourists, but 18% of tourists choose “unlikely” to revisit.

6.3 Analysis of the impact of the recreational behavior of tourists in Wugong Mountain on tourism environment

The impact of recreational behavior of tourists in Wugong Mountain on the meadow environment was analyzed from the aspects of trampling behavior, camping activities, tourism waste, and hiking, mainly using on-site experiments and investigations. The results indicate that:

1. In the experimental state, the height, coverage, number of plant clusters, and dominant species of the meadow near the Wugong Mountain plot all increased with the increase of distance from the main road, while the number of accompanying species did not change significantly. As the intensity of trampling interference increases, the average height and coverage of the meadow plant community decrease, and the horizontal structure of the community undergoes significant changes. However, with the passage of time after trampling, both the community coverage and height show a trend of recovery, almost approaching the pre-trampling standard (except for 700 trampling intensities). Under the interference of trampling experiments, as the intensity of trampling interference increases, the number of dominant and associated species also increases. Under high-intensity trampling, there were significant changes in the combination of dominant and associated species compared to the control group, but the combination of dominant and associated species tended to stabilize; the impact of over 200 trampling intensities on meadow vegetation diversity still exists 2 months after the end. Moreover, the meadow plant community exhibits response characteristics (resistance and recovery) under trampling interference. When the trampling intensity reaches 1325 times, the relative coverage decreases by nearly 50%. The required trampling intensity for every 50% increase in relative coverage should continue to increase, and there is a non-linear relationship between trampling intensity and flat coverage. Under trampling interference, there are two response thresholds for vegetation coverage (89.7 ± 1.2% ~ 78.3 ± 0.7%, 78.3 ± 0.7% ~ 62.1 ~ 0.9%), corresponding to trampling intensity of 313 and 683 times, respectively. When the trampling intensity is below 313 times, the decrease in vegetation coverage is relatively slow; when the trampling intensity is between 313 and 683 times, the vegetation coverage decreases at a relatively stable rate; when it exceeds 683 times, the vegetation coverage decreases at a faster rate. Based on the decrease in meadow community coverage after 1 week of trampling, the meadow community coverage recovered by 29.7, 58.96, and 78.5% after 2 weeks, 1 month, and 2 months of trampling, respectively.

2. In natural conditions, tourist camping activities have a significant impact on the average height and number of plants in the meadow, both showing a decreasing trend with activity intensity. The height increased from 31 to 5 cm, and the number of plants increased from 252 to 94. The numerical variation of the impact on soil bulk density is more significant, and the soil is more compact, which affects the extension and growth of meadow roots and the permeability of water. However, there is not much change in pH value after the holiday, and camping has no significant impact on soil acidity and alkalinity. The numerical changes in the impact on soil bulk density are also more significant, and the soil is more compact, affecting the extension and growth of meadow roots and water permeability.

3. In the natural state, in the survey of tourists’ preferences for existing road choices, 67.77% of the upward trend and 46.28% of the downward trend choose bare land. The maximum and minimum values of road width among the 5 abnormal path widths have increased, indicating that the abnormal paths have been widened due to the trampling of tourists. The meadow vegetation and soil near the road are significantly affected by the trampling of tourists. The height of the meadow vegetation on both sides of the road increases gradually from 1 to 5 m, and the types and associated species of meadow vegetation at 1 m are more affected by human activities than at 5 m.

4. The tourism waste in Wugong Mountain Scenic Area presents a large amount, wide coverage, and concentrated types, while the existing disposal methods are still simple and crude, which has a significant negative impact on the environment, image, and tourist satisfaction of the scenic area.

6.4 Research on the carrying capacity of tourism environment

Twenty evaluation indicators were selected from three aspects: elasticity, support, and resistance, and a bearing capacity evaluation index system for the recreational environment of Wugong Mountain meadow was constructed. The threshold range of each indicator and bearing capacity index was determined, and a corresponding bearing capacity index model was constructed.

The comprehensive index (LO) of the carrying capacity of the recreational environment in the Wugong mountain meadow during peak season is 0.4263, and it presents a carrying pattern of “high elasticity-low support-low resistance”. The elasticity index (LA), support index (LB), and resistance index (LC) are 0.0644, 0.2066, and 0.1553, respectively. In the off-season, its comprehensive bearing capacity index (LO) is 0.5661, showing a bearing pattern of “high elasticity full support high resistance”. The elasticity index (LA), support index (LB), and resistance index (LC) are 0.0656, 0.2513, and 0.2492, respectively.

From a single indicator perspective, the recreational environment of the Wugong Mountain meadow is significantly overloaded during peak season, with 65% of indicators in an overloaded state, 25% in a fully loaded state, and only 10% in a low-loaded state. During the off-season, the indicator carrying capacity is diverse, with 35% in the “overloaded” and 35% in the “fully loaded” states, and 30% in the “low-loaded” state.

6.5 A tourism environment management strategy for Wugong Mountain based on tourist recreation behavior

Based on the laws and characteristics of tourist recreational behavior, this study attempts to strengthen and improve the management of the tourism environment in Wugong Mountain through strategies such as introducing national park management system pilot construction, constructing recreational opportunity spectrum, garbage management, greenway construction, and ancient tree culture production.

1. Pilot construction of national park management system.

   Wugong Mountain stretches for 120 km with a total area of over 260 km². It is a complete ecosystem that integrates cultural and natural landscapes, fully in compliance with the national park standards recognized by the International Union for Conservation of Natural Resources (IUCN). Given the current situation of the management committees for one mountain and three scenic spots, and against the backdrop of the country actively promoting the pilot construction of national parks, it is necessary and appropriate for Wugong Mountain to promote the pilot construction of the national park management system.

2. Building a recreation opportunity spectrum for Wugong Mountain.

   Based on the characteristics of the recreational environment of the Wugong Mountain meadow and the comprehensive consideration of the environmental recreational possibilities of the mountain meadow tourist area, and based on the questionnaire survey of the recreational activities and experiences expected by tourists in three different environmental types, and the analysis of the importance and preference of the comprehensive recreational environmental factors, a mountain meadow ecological recreational opportunity spectrum is determined based on three aspects: environmental type, recreational activities, and recreational experiences.

3. Wugong Mountain tourism garbage management model.

   The reason for the problem of tourism waste is the result of the joint action of relevant stakeholders, and the existing governance methods mainly rely on technical and management level governance led by a single entity, which has not been effective. Stakeholder theory should be introduced to construct a tourism waste management model for mountainous scenic areas, which involves a collaborative approach of multiple stakeholders to implement full process management from source control before tourism waste generation to maintenance after cleaning, achieving effective management of tourism waste in mountainous scenic areas.

4. Wugong Mountain Greenway construction.

   The Wugong Mountain Greenway, also known as the Wugong Mountain Ecological Trail or Scenic Trail, has important practical significance for achieving sustainable development of the Wugong Mountain meadow. It helps to improve the ecological system, increase cultural charm, improve reception facilities, and enhance safety management. The construction of greenways in the Wugong Mountain meadow should choose ecological, cultural, humane, and safe approaches.

5. The production mechanism of ancient tree culture in Wugong Mountain.

   There are over 100 ancient trees and 37 varieties, which are relatively concentrated. Firstly, in the inheritance and protection of ancient tree culture, we should actively maintain the individuality of ancient trees and selectively inherit and utilize ancient tree culture; secondly, efforts should be made to shape the image of ancient trees and reconstruct their landscapes, striving to amplify the cultural value of the trees themselves and expand the cultural space for their survival; thirdly, cultural transplantation should be carried out on unnamed and storyless ancient trees, borrowing foreign cultural resources to make them important tourism resources.

7. Conclusion

The Wugong Mountain meadow ecosystem is a typical alpine meadow in southern China, with important ecological value and unique tourism resources. The core of protecting and restoring the meadow ecosystem of Wugong Mountain lies in establishing and implementing strict management systems. In the process of protecting and restoring the meadow ecosystem of Wugong Mountain, we need to pay attention to the balance between ecological protection, resource utilization, and economic development. Only through scientific management and protection measures can the sustainable utilization and development of mountain meadow ecosystems be achieved.

Protecting, developing, and restoring mountain ecosystems are a long-term and arduous task that requires the joint efforts of the government, enterprises, and the public. In recent years, researchers have achieved rich research results in this field. However, further research is still needed in this field, including improving protection measures, development models, restoration technologies, and policy regulations, in order to better achieve sustainable development of mountain ecosystems. In addition, it is necessary to strengthen scientific research and technical support to provide a theoretical basis for the protection, development, and restoration of mountain ecosystems.

Conflict of interest

The authors declare no conflict of interest.