Comparison of Application Effects of Various Ecological Restoration Technologies in Transmission Line Slope Treatment

QI ZHANG1,*, YA-FANG ZHAO2, OU ZHANG1, WEI-MAO XU1, XUE JIANG1
1, State Grid Liaoning Electric Power Company Limited Economic Research Institute
2, Electric Power Construction Technical and Economic Consulting Center, China Electricity Council, Beijing 100053, China
zhangq_jyy@ln.sgcc.com.cn

First author and corresponding author: QI ZHANG, zhangq_jyy@ln.sgcc.com.cn
Second author: YA-FANG ZHAO, 172564803@qq.com
The third author: OU ZHANG, zo_jyy@ln.sgcc.com.cn
Fourth author: WEI-MAO XU, xwm_jyy@ln.sgcc.com.cn
Fifth author: XUE JIANG, jx1_jyy@ln.sgcc.com.cn

Acknowledgement:
Study on Optimization of the Accounting Method for Environmental Protection and Water-Soil Conservation Expenses in Power Transmission and Transformation Projects.

Abstract
Transmission line slope instability poses significant challenges to infrastructure safety and environmental protection, necessitating ecological restoration approaches that balance engineering requirements with ecosystem functionality. This study conducted a comprehensive comparative evaluation of four ecological restoration technologies—plant slope protection, ecological bags, spray seeding greening, and comprehensive treatment—through 48-month field experiments in subtropical mountainous regions (28°15’N-28°45’N, 109°30’E-110°15’E). Employing randomized block design across three slope gradients (25-35°, 35-45°, 45-60°), the research integrated quantitative stability assessments with ecological performance indicators through multi-criteria decision analysis. Results demonstrated that comprehensive treatment achieved superior performance with highest safety factor (1.58±0.05), vegetation coverage (94±3%), and Shannon diversity index (2.85±0.22) at 48 months. Ecological bags provided immediate stabilization (FS=1.42±0.06 at 24 months) but limited biodiversity development, while plant protection exhibited gradual improvement with excellent long-term ecological outcomes. Spray seeding achieved rapid initial coverage (65% at 6 months) but required intensive maintenance. Economic analysis revealed comprehensive treatment yielded highest net present value ($68.50/m²) despite elevated initial costs ($22.60/m²). Environmental adaptability assessments showed differential responses to extreme events, with comprehensive treatment maintaining <5% soil loss during intense rainfall versus 35% in controls. The multi-criteria performance matrix and risk-based selection framework developed provide evidence-based guidelines for technology selection according to site-specific conditions. These findings advance slope restoration theory by quantifying synergistic effects of integrated approaches and establishing performance benchmarks for sustainable transmission line corridor management.
Keywords: ecological restoration; slope stability; transmission line; multi-criteria analysis; vegetation establishment; erosion control
1 Introduction
Transmission line corridors design and their operation are of considerable geotechnical issue, especially in hilly and mountainous regions where the stability of slopes is crucial while ensuring the safety and environment protection of the infrastructure[1]. The traditional slope stabilization measures, such as shotcrete, retaining walls, and anchorage system, etc., have a good performance in the prevention of slope failure[2], but they usually cause serious destruction to the ecological environment and landscape fragmentation. It has been reported from recent research: for the first five years of theconstruction 60% of the transmission line slopes are experiencing erosion and instability of various degree, result of this is very high costs of maintenance, as well as considerable effects on the landscape[3]. Ecological restoration technology as well as the demands of engineering stability has become a trend in the development of modern infrastructure, which can simultaneously meet the technical performance and environmental protection requirements[4].
The environmental influence of traditional slope protection measures are not limited to visual nuisance, also including habitat elimination, increase of the surface runoff, temperature enhancement in the soil and interception to natural hydrological flows[5]. These negative impacts have compelled regulatory authorities around the world to require ecological remediation for infrastructure projects, especially in cases where they are built in ecologically fragile areas[6]. The development of green slope concepts has completely altered our traditional approach to slope engineering design and has led to new approaches that consider both structural stability and environmental performance as two parallel targets[7]. Recently, research findings have shown that appropriately applied ecological restoration techniques may yield similar slope stability factors to those generated by engineering approaches and also provide other ecosystem services such as carbon sequestration, biodiversity conservation, and microclimate regulation[8].
Slope protection technology of vegetation planting is one of the earlier and most widely used ecological restoration methodologies as described in the literature, this method relies on the role that the roots of the plant play in increasing soil cohesion and reducing surface erosion[9]. Resistance of plant roots as a result of mechanical reinforcement occurs through various pathways, such as an increase in soil shear strength, better hydraulic conductivity, and improved aggregate stability[10]. Deep-rooted shrubs and grasses have also been found to show more effective in shallow landside prevention in field investigations[11]. Nevertheless, establishment time for vegetation becoming established and species adaptation to environmental conditions are still major limiting factors influencing success in their implementation[12].
The ecological bag technology has emerged as an innovative option that provides immediate structural reinforcement, as well as long-term establishment of vegetative cover[13]. These engineered structures are usually made up of biodegradable or synthetic geotextile bags filled with growth medium and seeds, offer immediate erosion control and are convenient for colonizing plants [14]. Recent developments in material science have led to the development of ecological bags with increased strength, water holding and nutrient release properties, which have resulted in higher vegetation establishment rates than those of the traditional methods[15]. Field applications within different climatic regions have shown the adaptability of ecological bag systems, but performance differences related to the degradation of materials and composition of filling material must be optimized for the site[16].
Spray seeding greening technology (SSGT), namely, hydroseeding or hydraulic mulch seeding, is able to have large-area rapid construction, especially in steep and hard-approaching slope areas of transmission line corridors[17]. This technology is to progress by hydraulically applying a mixture of seeds, mulch, fertilisers and binding materials for a protective cover to enhance germination and restrict erosion[18]. Recent advances in the substrate formulations which include the applied use of bioengineering materials, slow-release nutrients, and water gel absorbents have resulted in improved establishment success rates and long term vegetation performance[19]. Key parameters affecting the efficiency of spray seeding include the properties of the mixture adhesion, the viability of the seed in various climatic sets, and the selection of the thickness of the substrate according to different slope angles[20].
Integrated restoration methods including various ecological restoration technologies have been developed to tackle the complicated demands of transmission line slope restoration[21]. These combined systems would interact in a synergy manner between their various composition forms, i.e., as an integration of the stratifications: as buffers such as eco-bags for instantaneous stability coupled with slurry seeding for quick coverage and deep rooted plants for long-term reinforcing [22]. Technology synthesis optimizes on a spatial layout, a temporal sequence, and complementary functional characteristics to enhance both engineering performance and ecological services[23]. Economic evaluations of full treatment systems show more initial capital expenses, however long-term cost efficiency with reduced maintenance and enhanced ecosystem services[24].
The evaluation of the restoration technology with respect to quantitative measure of their desired ecological outcome requires comprehensive frameworks that consider both engineering stability metrics and ecological performance related indicators[25]. Recent advancements in methods for monitoring slope restoration, such as remote sensing, automatic monitoring, and bioengineering indexes, can be used for accurate quantification of restoration effectiveness from multiple scales of space and time[26]. There is a paucity of existing comparative research on restoration technologies than can function under controlled conditions, with respect to long-term performance trajectories and responses to extreme weather conditions.[27] There is an urgent need for the establishment of common evaluation procedures and best practice benchmarks in order to facilitate evidence-based selection of the technology and implementation policy[28].
Climate change factors complicate planning for ecological restoration, including changing precipitation patterns and extremes, as well as more intense storms that influence slope stability and the biosecurity of establishing vegetation[29]. Adaptive management systems which include the selection of climate-resilient species, the development of drought-tolerant substrate mixes and flexible implementation timing have been established as key to the success of restoration programs [30]. The combination of predictive models and field monitoring data allows the real-time adaptation of restoration strategies to the evolving environmental conditions[31]. In addition, the ability to sequester carbon on these vegetated slopes has bearing on objectives to mitigate climate change, and thus provides another reason to invest in ecological restoration of transmission infrastructure[32].
The purposes of this study are to provide a quantitative comparison of the 4 main ecological restoration technologies of plant, ecological bag, spray seeding greening, and comprehensive treatment measures for transmission line slope, respectively. The main goal is the thorough comparative analysis of performance of individual technologies, in terms of encouraging slope stability and concurrent ecological restoration, under different site conditions. Secondary aims include evaluation of cost-effectiveness relationships, analysis of long-term sustainability opportunities and generation of clinical guidelines for evidence-based selection of technology. The study fills important gaps in our knowledge of comparative performance criteria, optimal application conditions, and synergistical effects of integrated approaches. This research aims to promote theoretical guidance and practical application of ecological restoration technologies in the management of transmission line corridors based on intensive field experiments and multi-criteria analysis. Results will help in creating formal standards for selection of technology, protocol for implementation and method for evaluation of performance. The novelty of the present work stems from its rigorous comparative approach and the collaboration of engineering and ecological evaluation tools towards decision support tools for technology selection at specific sites.
2 Methodology
2.1 Study Area Selection
The study area encompasses three transmission line corridors located in subtropical mountainous regions (28°15’N-28°45’N, 109°30’E-110°15’E) with elevations ranging from 450-1,200 m above sea level. The regional climate exhibits distinct seasonal variations with mean annual precipitation of 1,450±120 mm, predominantly concentrated during May-September, and mean annual temperature of 16.8±0.5°C. Soil analysis revealed predominantly yellow-brown earth (Haplic Luvisols) with texture composition following the relationship

where represents total texture index, is clay content (25-35%), is sand content (30-40%), and is silt content (30-35%).
Slope gradients were stratified into three categories based on the stability index

where represents slope angle in degrees and is the soil erodibility factor (0.28-0.35 t·ha·h·ha⁻¹·MJ⁻¹·mm⁻¹). Selected slopes exhibited gradients of 25-35° (gentle), 35-45° (moderate), and 45-60° (steep), representing typical conditions along 220 kV transmission corridors. Pre-existing vegetation consisted primarily of degraded secondary shrubland with coverage below 30%, dominated by pioneer species including Miscanthus sinensis and Artemisia argyi.
Table 1. Site characteristics and experimental design parameters
Parameter Gentle Slope Moderate Slope Steep Slope
Gradient range (°) 25-35 35-45 45-60
Plot dimensions (m) 10×20 10×20 10×20
Replicates 3 3 3
Soil depth (cm) 85±12 65±10 45±8
Bulk density (g/cm³) 1.32±0.08 1.38±0.10 1.45±0.12
As shown in Table 1, experimental plots followed a randomized complete block design with blocking based on slope position. Plot allocation employed the statistical model:

where represents the response variable, is the overall mean, is the treatment effect, is the slope gradient effect, is the interaction effect, and is the random error. Buffer zones of 2 m width separated adjacent plots to prevent edge effects and cross-contamination between treatments.
2.2 Evaluation Framework Development
The comprehensive evaluation framework integrates quantitative stability metrics with ecological performance indicators to assess restoration effectiveness. Slope stability assessment employs the limit equilibrium method calculating the safety factor as

where is effective cohesion (kPa), is slice base length (m), is slice weight (kN), is slice base inclination (°), is pore water pressure (kPa), and is effective friction angle (°). Displacement monitoring utilizes differential GPS technology with precision ±2 mm, while soil erosion rates follow the Universal Soil Loss Equation:

where is annual soil loss (t·ha⁻¹·yr⁻¹), is rainfall erosivity factor, is soil erodibility, is slope length-steepness factor, is cover management factor, and is support. practice factor.

Fig.1Comprehensive Evaluation Framework
Figure 1 Comprehensive evaluation framework integrating stability assessment and ecological effect indicators for slope restoration technologies
As shown in Figure 1, ecological indicators encompass vegetation dynamics and soil quality parameters. Plant diversity assessment employs Shannon-Wiener index

and Simpson’s index

where represents the proportional abundance of species and is total species number. Biomass accumulation rates are calculated as

where is biomass at time , is initial biomass, and is growth rate constant.
Table 2. Integrated evaluation indicators and measurement methods
Category Indicator Unit Method Frequency
Stability Displacement mm GPS monitoring Monthly
Stability Erosion rate t·ha⁻¹·yr⁻¹ Sediment collection Bi-weekly
Stability Shear strength kPa Direct shear test Quarterly
Ecological Vegetation cover % Quadrat survey Monthly
Ecological Soil organic matter g·kg⁻¹ Walkley-Black Quarterly
As shown in Table 2, monitoring frequency varies according to indicator response rates and seasonal dynamics.
2.3 Data Collection Methods
Field monitoring infrastructure comprised automated sensor networks integrated with manual sampling protocols. Displacement monitoring stations equipped with inclinometers and piezometers were installed at depths following the relationship

where is installation depth (m) and is slope height (m). Data acquisition followed exponential decay sampling intervals:

where is sampling frequency at time , is initial frequency (daily), and is decay constant (0.15). Quality assurance protocols incorporated duplicate measurements with acceptance criteria based on coefficient of variation

where is standard deviation and is mean value.
Laboratory analyses employed standardized methods for comprehensive soil characterization. Particle size distribution followed Stokes’ law:

where is settling velocity (m/s), is gravitational acceleration (9.81 m/s²), is particle radius (m), and are particle and fluid densities (kg/m³), and is fluid viscosity (Pa·s). Root architectural parameters were quantified using the fractal dimension:

where is number of root segments, is proportionality constant, is segment length, and is fractal dimension (1.4-1.8).
Table 3. Analytical methods and detection limits for key parameters
Parameter Method Detection Limit Precision (%) Standard
Soil organic carbon Combustion analyzer 0.01% ±2.5 ISO 10694
Total nitrogen Kjeldahl digestion 0.001% ±3.0 ISO 11261
Available phosphorus Olsen extraction 0.5 mg/kg ±4.0 ISO 11263
Root tensile strength Universal testing 0.1 MPa ±5.0 ISO 18134
Aggregate stability Wet sieving 0.1% ±3.5 ISO 10930
As shown in Table 3, analytical precision meets international standards for environmental monitoring applications.
2.4 Statistical Analysis Plan
Statistical analyses employed hierarchical approaches integrating univariate and multivariate techniques. Descriptive statistics characterized central tendency and dispersion using

where represents sample mean, denotes individual observations, is sample size, and indicates standard deviation. Two-way ANOVA examined treatment effects following the model:

where is the response variable, represents grand mean, denotes treatment effect, indicates slope gradient effect, represents interaction, and is random error.
Multiple regression analysis quantified relationships between stability factors and ecological indicators using:

where is dependent variable, is intercept, represents regression coefficients, denotes predictor variables, and is number of predictors. Multi-criteria decision analysis integrated normalized indicators through weighted linear combination:

where represents overall score for technology , denotes criterion weight ( ), and is normalized performance rating.
Table 4. Statistical methods and software implementation
Analysis Type Test Statistic Software Significance Level
Normality Shapiro-Wilk W R 4.3.0 α = 0.05
Homogeneity Levene’s test SPSS 28.0 α = 0.05
ANOVA F-statistic R 4.3.0 α = 0.05
Post-hoc Tukey HSD R 4.3.0 α = 0.05
Time series ARIMA(p,d,q) R forecast AIC criterion
As shown in Table 4, statistical significance was evaluated at α = 0.05 with Bonferroni corrections for multiple comparisons.
3 Experiment
3.1 Experimental Setup
Plant slope protection implementation commenced with systematic species selection based on ecological adaptability indices and root reinforcement potential. Native species prioritization followed the suitability score

where represents drought tolerance (0-10), indicates root depth ratio, denotes growth rate coefficient, and signifies temperature adaptability range. Selected species included Cynodon dactylon, Lespedeza bicolor, and Vitex negundo, planted in staggered patterns with densities of 25 plants/m² for grasses and 4 plants/m² for shrubs. Initial establishment involved soil preparation to 30 cm depth, incorporation of organic amendments at 2 kg/m², and installation of temporary irrigation systems delivering 5 mm/day during the first 60 days. Maintenance protocols encompassed biweekly monitoring, selective replanting of failed individuals maintaining 85% survival threshold, and quarterly fertilization using slow-release formulations (N:P:K = 15:15:15) at 30 g/m².
Ecological bag installation utilized double-layer polypropylene geotextile bags (tensile strength ≥15 kN/m, UV resistance >500 hours) measuring 40 cm × 80 cm when filled. Filling material comprised engineered growing medium with composition: 40% topsoil, 30% coconut coir, 20% expanded perlite, and 10% slow-release fertilizer, achieving bulk density of 0.85 g/cm³. Installation followed contour placement with 20 cm vertical overlap between rows and securing through biodegradable stakes (φ16 mm × 400 mm) at 1 m intervals. Quality control measures included compaction testing achieving 85% Proctor density, moisture content verification (25-30%), and photographic documentation of placement patterns. Integration with existing slopes required surface scarification to 5 cm depth ensuring adequate bag-soil contact and prevention of interface failure.
Spray seeding application employed hydraulic mulch formulations optimized through preliminary trials. The substrate mixture contained wood fiber mulch (1,500 kg/ha), tackifier (50 kg/ha), soil amendments (500 kg/ha), and hydrogel polymer (10 kg/ha), achieving application thickness of 3-5 mm. Seed mixture design incorporated functional group diversity: 40% fast-establishing grasses (Festuca arundinacea, Lolium perenne), 35% leguminous species (Medicago sativa, Trifolium repens), 20% native forbs, and 5% woody species for long-term succession. Application utilized hydroseeding equipment operating at 4.5 MPa pressure with fan-tip nozzles ensuring droplet size distribution D50 = 800-1,200 μm. Coverage uniformity assessment employed grid sampling (2 m × 2 m) measuring wet film thickness with coefficient of variation CV < 15% acceptance criterion.
Comprehensive treatment design integrated technologies through spatial and temporal optimization strategies. The implementation sequence followed: (1) ecological bag installation on slope toe and critical failure zones, (2) spray seeding application on middle sections achieving 70% coverage, and (3) strategic woody plant establishment on stable platforms. Spatial arrangement employed the optimization function

where represents overall effectiveness, denotes technology weighting factor, indicates coverage ratio, and represents position coefficient based on slope stability analysis. Synergy enhancement incorporated mycorrhizal inoculation (Glomus mosseae, 50 spores/g) in all planting substrates and installation of biodegradable erosion control blankets (coconut fiber, 400 g/m²) at technology interfaces.
Table 5. Summary of experimental treatment specifications and key parameters
Treatment Coverage Rate Material Cost ($/m²) Installation Time (h/100m²) Expected Establishment (%) Maintenance Frequency
Plant Protection 25 plants/m² (grass) 12.5 8.5 85 Biweekly
Ecological Bags 1.25 bags/m² 18.2 6.0 95 Monthly
Spray Seeding 3-5 mm thickness 8.8 2.5 75 Weekly (first month)
Comprehensive Variable 22.6 12.0 90 Biweekly
Control None 0 0 <10 None As shown in Table 5, comprehensive treatment required highest initial investment but projected superior establishment success through synergistic technology integration. 3.2 Monitoring Program Implementation The monitoring program implemented a comprehensive temporal framework designed to capture ecosystem development trajectories from initial establishment through maturation phases. Short-term monitoring during the first six months employed intensive protocols with weekly assessments documenting germination dynamics, seedling emergence patterns, and early mortality events. Field teams conducted standardized surveys using 1 m × 1 m quadrats systematically distributed across treatment plots, recording emergence timing, survival counts, and initial growth parameters. Erosion control effectiveness was evaluated through sediment collection following each significant rainfall event, with collectors positioned at 5 m intervals along plot boundaries. Digital photography from fixed points documented surface changes, while automated data loggers recorded soil moisture, temperature fluctuations, and initial displacement measurements at 30-minute intervals. Medium-term monitoring spanning months 6-24 transitioned to monthly assessment cycles focusing on vegetation structural development and community assembly processes. Plant height measurements, canopy dimensions, and coverage estimates followed standardized protocols using point-intercept methods along permanent 20 m transects. Root system development assessment employed quarterly soil coring campaigns extracting samples at 10 cm depth increments to 100 cm, analyzing root length density, biomass distribution, and architectural parameters. Slope stability monitoring integrated automated inclinometer data with seasonal topographic surveys using differential GPS technology achieving centimeter-level accuracy. Species composition changes were documented through complete floristic inventories identifying all vascular plants within treatment plots, tracking both planted species performance and natural colonization patterns. This phase revealed critical differences in development trajectories among treatments, with ecological bags supporting rapid establishment but limited diversity compared to comprehensive approaches. Long-term monitoring beyond 24 months emphasized ecosystem functionality, sustainability metrics, and self-maintenance capacity. Quarterly comprehensive assessments evaluated community structure through stratified sampling of vegetation layers, documenting height class distributions, life form compositions, and spatial heterogeneity patterns. Soil quality evolution was tracked through biannual sampling analyzing organic matter content, aggregate stability, nutrient availability, and microbial activity indicators. Performance degradation assessment systematically examined treatment component deterioration, including geotextile integrity loss in ecological bags, seed bank depletion in spray-seeded areas, and mortality patterns in planted zones. Ecosystem service provision was quantified through carbon sequestration measurements, runoff reduction capacity, and habitat quality indices based on faunal utilization observations. Table 6. Critical threshold values and performance benchmarks across monitoring phases Monitoring Phase Performance Indicator Minimum Acceptable Target Value Intervention Trigger Short-term (0-6 mo) Germination rate (%) 40 70 <40 Initial coverage (%) 30 60 <30 Erosion reduction (%) 25 50 <25 Survival rate (%) 60 85 <60 Medium-term (6-24 mo) Vegetation coverage (%) 50 80 <50 Root depth (cm) 30 60 <30 Species richness 8 15 <8 Slope factor of safety 1.2 1.5 <1.2 Long-term (>24 mo) Self-maintenance (%) 70 90 <70 Annual maintenance visits <8 <4 >8
Biodiversity index 1.5 2.5 <1.5
Carbon accumulation rate (kg/m²/yr) 0.5 1.2 <0.5
As shown in Table 6, performance benchmarks were established based on literature values and regional restoration standards, with intervention triggers indicating when adaptive management actions were required. These thresholds guided decision-making throughout the monitoring program, ensuring timely responses to underperforming treatments.
Monitoring data revealed distinct temporal patterns across restoration technologies. Figure 2 illustrates the contrasting development trajectories of vegetation coverage and erosion control effectiveness, demonstrating rapid initial responses in spray seeding and ecological bag treatments versus gradual but sustained improvements in plant protection approaches. The comprehensive treatment consistently achieved superior performance through synergistic effects, though requiring higher initial investment in monitoring infrastructure.

(a) Temporal Evolution of Vegetation Coverage (b) Erosion Reduction Performance
Fig.2 Comparative monitoring results of restoration treatments over 48 months
The monitoring program successfully captured critical performance differences among restoration technologies, revealing trade-offs between rapid establishment and long-term sustainability. Ecological bags demonstrated immediate erosion control benefits but limited vegetation diversity development, while plant protection methods showed slower initial progress but superior ecological outcomes over extended periods. Spray seeding achieved moderate performance across metrics but required frequent maintenance interventions. The comprehensive treatment consistently outperformed individual technologies, validating the synergistic integration approach for transmission line slope restoration. These findings informed adaptive management strategies and technology selection guidelines for varying site conditions and restoration objectives.
3.3 Results and Analysis
Comprehensive evaluation of restoration technologies revealed distinct performance patterns across stability, ecological, and economic dimensions. Quantitative stability assessments demonstrated significant variations in slope reinforcement effectiveness, with safety factors ranging from 1.05 ± 0.12 in control plots to 1.58 ± 0.05 in comprehensive treatment areas after 24 months. Temporal evolution of stability parameters followed technology-specific trajectories, with ecological bags providing immediate mechanical reinforcement achieving 85% of ultimate stability within three months, while plant-based methods exhibited progressive enhancement correlating with root system development over 12-18 month periods. Critical failure analysis identified shallow translational slides as the predominant failure mode in untreated slopes, occurring at depths of 0.5-1.2 m coinciding with the soil-weathered bedrock interface. Treatment technologies effectively mitigated these failures through different mechanisms: ecological bags through immediate surface armoring, plant protection via progressive root reinforcement, spray seeding through rapid surface stabilization, and comprehensive treatment combining multiple protective functions.
Figure 3 illustrates the temporal evolution of safety factors across all treatments, demonstrating the superior performance of integrated approaches and revealing critical stabilization thresholds achieved at different time intervals. The comprehensive treatment exceeded the minimum acceptable safety factor of 1.3 within six months, while spray seeding required 18 months to achieve comparable stability levels.

(a) Temporal Evolution of Slope Stability (b) Slope Displacement Patterns
Fig.3 Comparative stability performance of restoration technologies
Ecological restoration effectiveness varied substantially among technologies in both magnitude and temporal patterns of ecosystem recovery. Vegetation coverage development followed distinct trajectories, with spray seeding achieving rapid initial coverage (65% by month 6) but plateauing at moderate levels (75% by month 24), while plant protection demonstrated slower establishment but continued improvement reaching 84% coverage by month 48. Biodiversity indices revealed contrasting patterns, with comprehensive treatment supporting highest Shannon-Wiener diversity (H’ = 2.48 ± 0.20) through provision of multiple microhabitat niches, compared to relatively homogeneous spray-seeded communities (H’ = 1.65 ± 0.12). Soil quality improvements correlated strongly with vegetation establishment duration and root biomass accumulation, with organic matter content increasing from baseline 1.2% to maximum values of 3.8% in comprehensive treatment plots versus 2.1% in spray-seeded areas after 48 months.
Table 7. Comparative ecological performance metrics at 24 and 48 months post-treatment
Treatment Type Vegetation Coverage (%) Shannon Diversity Index Soil Organic Matter (%) Root Biomass (kg/m²) Ecosystem Services Score
24 months
Plant Protection 80 ± 6 1.82 ± 0.15 2.4 ± 0.3 1.8 ± 0.2 6.2 ± 0.5
Ecological Bags 88 ± 5 2.15 ± 0.18 2.1 ± 0.2 1.2 ± 0.2 6.8 ± 0.4
Spray Seeding 75 ± 8 1.65 ± 0.12 1.8 ± 0.2 0.8 ± 0.1 5.5 ± 0.6
Comprehensive 92 ± 4 2.48 ± 0.20 2.8 ± 0.3 2.2 ± 0.3 8.2 ± 0.5
Control 22 ± 7 0.85 ± 0.10 1.3 ± 0.1 0.3 ± 0.1 2.1 ± 0.3
48 months
Plant Protection 84 ± 5 2.12 ± 0.16 3.2 ± 0.4 2.8 ± 0.3 7.8 ± 0.6
Ecological Bags 90 ± 4 2.35 ± 0.19 2.8 ± 0.3 1.8 ± 0.2 7.5 ± 0.5
Spray Seeding 79 ± 7 1.78 ± 0.14 2.1 ± 0.3 1.2 ± 0.2 6.2 ± 0.5
Comprehensive 94 ± 3 2.85 ± 0.22 3.8 ± 0.4 3.5 ± 0.4 9.2 ± 0.4
Control 25 ± 6 0.92 ± 0.11 1.4 ± 0.2 0.4 ± 0.1 2.3 ± 0.3
As shown in Table 7, ecological performance metrics demonstrated progressive improvement across all treatments, with comprehensive approach achieving superior outcomes in all measured parameters. The ecosystem services score, integrating multiple functional attributes, highlighted the synergistic benefits of technology integration.
Cost-benefit analysis revealed complex trade-offs between initial investment requirements and long-term economic returns. Initial implementation costs varied from $8.80/m² for spray seeding to $22.60/m² for comprehensive treatment, with ecological bags ($18.20/m²) and plant protection ($12.50/m²) representing intermediate options. However, maintenance cost trajectories diverged significantly over time, with spray seeding requiring frequent interventions totaling $42.50/m² over 48 months compared to $18.60/m² for comprehensive treatment. Long-term economic benefits incorporated avoided slope failure costs, reduced sediment management expenses, and ecosystem service values including carbon sequestration ($0.85/m²/year for comprehensive treatment) and biodiversity conservation ($1.20/m²/year). Net present value calculations using 5% discount rate over 20-year project lifetime indicated comprehensive treatment achieved highest returns ($68.50/m²) despite elevated initial costs.
Figure 4 presents the cumulative cost trajectories and benefit-cost ratios across treatments, demonstrating the economic crossover points where initially expensive technologies become cost-effective through reduced maintenance requirements and enhanced ecosystem service provision.

(a) Total Cost Evolution Over Project Lifetime (b) Economic Efficiency Evolution
Fig.4 Economic analysis of restoration technologies over 20-year project lifetime
Environmental adaptability assessments revealed technology-specific responses to varying climatic conditions and extreme events. Performance monitoring during drought periods (rainfall <60% of normal) indicated ecological bags maintained 78% vegetation survival through water retention properties, while spray-seeded areas experienced 45% mortality requiring extensive replanting. Extreme rainfall events (>100 mm/24h) generated differential erosion responses, with comprehensive treatment maintaining <5% soil loss compared to 18% in spray-seeded plots and 35% in control areas. Temperature fluctuation tolerance varied significantly, with plant protection demonstrating superior resilience through deep-rooted species capable of accessing stable soil moisture reserves. Site-specific effectiveness factors included slope aspect influences, with north-facing slopes supporting 15-20% higher vegetation coverage across all treatments due to reduced evapotranspiration stress. Table 8. Environmental adaptability performance under extreme conditions Treatment Type Drought Survival (%) Heavy Rain Erosion (t/ha) Freeze-Thaw Cycles Heat Stress Recovery Overall Resilience Score Plant Protection 72 ± 8 2.8 ± 0.5 Moderate High 7.2 ± 0.6 Ecological Bags 78 ± 6 1.5 ± 0.3 High Moderate 7.8 ± 0.5 Spray Seeding 45 ± 12 5.2 ± 0.8 Low Low 4.5 ± 0.8 Comprehensive 85 ± 5 0.8 ± 0.2 High High 8.9 ± 0.4 Control 18 ± 8 12.5 ± 2.1 Very Low Very Low 1.8 ± 0.5 As demonstrated in Table 8, comprehensive treatment exhibited superior resilience across all stress conditions, while spray seeding showed particular vulnerability to environmental extremes. These findings emphasize the importance of technology selection based on site-specific climate variability and extreme event probability assessments. 3.4 Comparative Analysis Multi-criteria performance evaluation integrated stability and ecological indicators through a comprehensive assessment framework accommodating diverse stakeholder priorities and site-specific objectives. The weighted scoring system incorporated eight primary criteria: slope stability (weight 0.20), erosion control (0.15), vegetation coverage (0.15), biodiversity development (0.10), implementation cost (0.10), maintenance requirements (0.10), environmental resilience (0.10), and ecosystem services provision (0.10). Performance scores were normalized using min-max scaling to ensure comparability across disparate metrics, with values ranging from 0 (poorest performance) to 10 (optimal performance). Technology rankings varied substantially under different weighting scenarios, reflecting the inherent trade-offs between engineering stability and ecological restoration objectives. Sensitivity analysis revealed that comprehensive treatment maintained superior rankings across 85% of weighting combinations, demonstrating robust performance regardless of prioritization schemes. Plant protection technologies excelled under ecological-focused weightings (biodiversity weight >0.25), while ecological bags dominated stability-prioritized scenarios (stability weight >0.35). Spray seeding demonstrated competitive performance only under cost-minimization objectives, suggesting limited applicability for projects emphasizing long-term sustainability. The analysis identified threshold weight values triggering technology preference shifts: ecological bags superseded plant protection when stability weighting exceeded 0.30, while comprehensive treatment remained optimal unless cost weighting surpassed 0.40.