Vegetation Ecology Research Articles

Soil Physicochemical Properties and Carbon Storage Reserve Distribution Characteristics of Plantation Restoration in a Coal Mining Area

The Bulianta Coal Mine is among the problematic coal mining areas in China that is still creating environmental damage, especially associated with soil destruction. Therefore, a scientific investigation was conducted to establish a scientific basis for evaluating the impact of planted forest on soil physical and chemical properties, as well as the ecological benefits following 15 years of vegetation restoration in the area. The soil physicochemical characteristics and distribution of organic carbon storage in the 0–80 cm layer soils of Pinus sylvestris forests, Prunus sibirica forests, and Hippophae rhamnoides forests restored after 5, 10, and 15 years were investigated. The immersion method was used to determine soil porosity and density followed by the determination of soil indicators, and a statistical ANOVA test was applied to examine the differential effects of different vegetation types and restoration years on soil properties. The results clearly demonstrated the following: (1) The recovery of vegetation was achieved after a period of 15 years, with the average bulk density of the 0–80 cm soil layer as follows: P. sylvestris forest (1.513 g·cm−3) > P. sibirica forest (1.272 g·cm−3) > H. rhamnoides forest (1.224 g·cm−3), and the differences among different forest types were statistically significant (p < 0.05). (2) In planted forests, soil nutrients were predominantly concentrated in the 0–20 cm layer, while soil carbon storage exhibited a decline with an increasing soil depth. (3) The soil carbon storage across the three forest types was as follows: P. sylvestris forest (45.42 t·hm−2) > P. sibirica forest (44.56 t·hm−2) > H. rhamnoides forest (41.87 t·hm−2). In summary, during the ecological vegetation restoration process in the Bulianta Core Mine, both P. sylvestris forest and P. sibirica forest exhibit superior carbon storage capacities compared to H. rhamnoides forest, as well as more effective soil improvement outcomes.

Effects of groundwater level changes on soil characteristics and vegetation response in arid and semiarid coal mining areas.

Coal mining in arid and semiarid regions often leads to numerous ecological and environmental problems, such as aquifer depletion, lake shrinkage, vegetation degradation, and surface desertification. The drainage from coal mining activities is a major driving force in the evolution of the groundwater-soil-vegetation system. In order to explore the effect of groundwater level fluctuation on soil properties and the response mechanism of surface vegetation in coal mining areas, this study is based on hydrogeological and ecological vegetation investigations in the Bojianghaizi Basin, and soil and vegetation samples are collected in the areas with different groundwater levels, and soil and vegetation indexes are analyzed with the aid of methods such as numerical statistics, linear regression, and correlation analysis with the aid of the Origin software. The results show that there is a significant negative correlation between groundwater table (GWT) and soil water content (SWC), soil conductivity, soil organic matter (SOM), soil available nitrogen (SAN), and soil available potassium (SAK). Mining activities have led to the destruction of the soil structure, greatly reducing its ability to retain water and fertilizer. The contents of SWC, SOM, and SAN in the mining area are significantly reduced, which are at least 49.73%, 47.56% and 59.90% lower than those around the mining area. On the northern and southern sides of the lake, serious soil salinization exists in the lakeshore zone where the depth to the water table is <0.5m, and the water required for the growth of vegetation here mainly comes from the groundwater, so there are only a few water-loving and saline-resistant plants; when the depth to the water table is 0.5-7m, the growth of surface vegetation is influenced by the double impacts of the water table and atmospheric precipitation with a high degree of species richness; when the depth to the water table is >7m, the surface vegetation is only dependent on the limited atmospheric precipitation for water. When the depth of groundwater is >7m, the surface vegetation only relies on limited atmospheric precipitation for water, and drought-tolerant plants mainly grow in these areas. This study not only provides a scientific basis for the sustainable development and environmental protection of similar mines in the world, but also has important significance in guiding the ecological management and rational utilization of water resources in coal mine areas. What is more, This study provides valuable insights into sustainable water resource management in arid and semi-arid regions, crucial for mitigating the ecological impacts of coal mining activities.

The neglected giant Tchen-Ngo Liou:The enlightenment of his dynamic geobotany theory to current studies in vegetation ecology and biodiversity.

Prof. Tchen-Ngo Liou is one of the founders of China's botany, geobotany, and forest ecology. Theory of dynamic geobotany, established by Prof. Liou, can track back from his doctoral work in Alps in France, and was developed based on his long-term field works in northeast, southeast, north, northeast parts of China, India, North Korea and other regions. In the short course on dynamics geobotany in 1962, he gave a series of lectures which formed a synthesized system. The key elements of this theory are the comprehensive review and critical thinking on climax theory of vegetation science and community succession. Prof. Liou has applied this theory into the establishment of artificial vegetation, the improvement of natural vegetation, forest harvesting and regeneration, and the prevent and control of desertification in China. Here, we gave a short summary about this theory, and discussed its potential influence on important topics in vegetation ecology and biodiversity science, including mountain biodiversity, natural forest conservation, forest management, global change, and vegetation classification.

Changes and driving factors of soil water in mixed-species plantations and different precipitation scenarios on the Loess Plateau of China

The implementation of the “Grain-for-Green” program in China led to the extensive introduction of artificial vegetation, thereby intensifying evapotranspiration and the overuse of water resources. Thus, selecting suitable ecological vegetation and planting patterns to save water is a major challenge in the region. Three typical plants were selected in the Loess Plateau of China. The plants had been growing for 13 years. The soil water dynamics were studied based on measurements and Hydrus-1D modeling simulations under different precipitation scenarios (wet, normal, and dry years) and planting patterns (Stipa monoculture (S), a mixture of Stipa and Medicago (SM), and a mixture of Stipa, Medicago, and Caragana (SMC)). The results indicated that the soil water contents with S and SM were 25 % and 8 % higher than the stable field water capacity (SFC), respectively, whereas the SMC was 33 % lower than the SFC in the 0–100 cm depth in relatively normal precipitation years. The evapotranspiration was lowest under S (296–524 mm), followed by SM (351–628 mm) and SMC (368–669 mm). The soil water storage were 19–91 % and 12–58 % higher under S and SM than SMC. The soil desiccation intensity was more severe under SMC (0.3–0.5) than SM (0.5–1.1) and S (0.6–1.4). The soil water storage increased significantly with the annual precipitation (P<0.05), and increased by 54–85 % in relatively abundant water scenarios compared with scarce water scenarios according to Hydrus-1D model simulations. Partial least squares path modeling demonstrated that the soil saturated hydraulic conductivity (path coefficient = 0.478) and soil porosity (–0.703) had significant effects on soil water storage (P<0.01). The results further suggested that using shallow-rooted grass as the dominant plant would reduce water usage in areas with water scarcity, and mixed-species plantations (i.e., a mixture of shallow-rooted and deep-rooted grass) could reduce the loss of sediment in regions.

Seed functional ecology in Brazilian rock outcrop vegetation: an integrative synthesis.

Rock outcrop vegetation is distributed worldwide and hosts a diverse and unique flora that evolved under harsh environmental conditions. Unfortunately, seed ecology in such ecosystems has received little attention, especially regarding seed traits, germination responses to abiotic factors and the potential role of phylogenetic relatedness on such features Here, we provide the first quantitative and phylogenetically-informed synthesis of the seed functional ecology of Brazilian rock outcrop vegetation, with a particular focus on quartzitic and ironstone campo rupestre. Using a database of functional trait data, we calculated the phylogenetic signal of seven seed traits for 371 taxa and tested whether they varied among growth forms, geographic distribution, and microhabitats. We also conducted meta-analyses that included 4,252 germination records for 102 taxa to assess the effects of light, temperature, and fire-related cues on the germination of campo rupestre species and explored how the aforementioned ecological groups and seed traits modulate germination responses. All traits and germination responses showed a moderate-to-strong phylogenetic signal. Campo rupestre species responded positively to light and had maximum germination between 20-25 ºC. The effect of temperatures beyond this range was moderated by growth form, species geographic distribution, and microhabitat. Seeds exposed to heat shocks above 80 °C lost viability, but smoke accelerated germination. We found a moderating effect of seed mass for in responses to light and heat shocks, with larger, dormant seeds tolerating heat better but less sensitive to light. Species from xeric habitats evolved phenological strategies to synchronise germination during periods of increased soil water availability. Phylogenetic relatedness plays a major role in shaping seed ecology of Brazilian rock outcrop vegetation. Nevertheless, seed traits and germination responses varied significantly between growth forms, species geographic distribution and microhabitats, providing support to the regeneration niche hypothesis and the role of functional traits in shaping germination in these ecosystems.

The need for a strict delimitation of early tree life stages in vegetation ecology

AbstractAimFor practical and theoretical purposes, ecological studies commonly classify trees into five major life‐cycle stages: seed, seedling, sapling, juvenile and adult. Whereas the seed and adult stages are usually accurately delimited across studies, there are discrepancies and ambiguity in the categorization of seedlings, saplings and juveniles, which can significantly affect the conclusions of community ecology studies. Here we propose a standardized set of criteria intended for community‐level research for delimiting these three stages based on biological and ecological rationales.MethodsWe assessed the relevance of such standardization by conducting a meta‐analysis of the effects of two human‐caused disturbances (defaunation and logging) on each early tree life stage and examining differences in effect sizes and confidence intervals among: (1) studies that match our delimitation criteria, (2) studies that do not match these criteria, and (3) all studies grouped together regardless of the criteria they used.ResultsWe found stronger effects with narrower confidence intervals when considering only the studies that matched our standardized delimitation criteria. In fact, the proportion of significant effects was between 1.7 (defaunation) and 5.4 (logging) times higher in studies matching our delimitation criteria than in studies that do not match them, probably because confidence intervals were 2.3–3.1 times smaller in the former group than in the latter. For logging studies, the direction of the effects changed in 30%–50% of the cases when comparing the results from all data and studies not matching our criteria with the results of the studies matching our criteria, always from non‐significant to significant effects.ConclusionsThese findings underscore the need for an ecologically meaningful categorization of early tree life stages based on standardized measures to increase the confidence, accuracy, reproducibility and generalization in plant biology and community ecological research. Synthesis efforts will particularly benefit from this standardized protocol.

Diversity of Aquatic and Coastal Vegetation in the Lublin Coal Basin Complex - Long-Term Changes

Natural resources are fundamental to the survival and development of human populations, and their exploitation is associated with problems such as resource depletion and environmental degradation. Within the borders of the Lublin Coal Basin (LZW) there is the Łęczna-Włodawa Lake District, which includes over 60 lakes. It is one of the most valuable natural areas in the Lublin Voivodeship and the entire region. Due to the undoubted impact of LZW, as well as the lack of detailed botanical studies in the existing literature, research has been undertaken since the 1980s to analyse the floristic and ecological vegetation of aquatic and coastal plants of 6 lakes in the mine's impact zone. Macrophytes are recognized by the WFD as one of the key groups suitable for freshwater biomonitoring and for ecological classification purposes. The conducted research confirmed the progressive degradation of the analyzed lakes. Since the 1990s, there have been significant changes in the use of the area covered by the analyses. The share of built-up areas has significantly increased, but also the share of surface waters. The share of built-up areas has significantly increased, but also the share of surface waters. The qualitative and quantitative structure of macrophytes has undergone very significant changes towards a reduction in the number of species and phytodiversity. The share of species in fertile habitats has increased. Despite the introduction of various forms of legal protection in this area, changes in the depletion of biodiversity are continuing.

Temporal accumulation and lag effects of precipitation on carbon fluxes in terrestrial ecosystems across semi-arid regions in China

Precipitation (PRE) plays a vital role in hydrological processes, ecological vegetation, and land-atmosphere interactions in semi-arid regions. Previous research has mainly focused on the impact of PRE on large-scale regional climate change and ecological evolution. However, there have been few studies on the long-term effects of PRE on carbon fluxes in these regions, especially the time-accumulation and -lag effects. Here, we employed observational data from the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL) and integrated multiple data sources, including remote sensing and carbon flux simulation data, to quantitatively assess the lagged response of carbon fluxes to PRE and elucidate the underlying mechanisms from multiple perspectives. Characterization of PRE, soil water content (SWC) and carbon fluxes at SACOL qualitatively reveals the existence of a time-delayed response of carbon fluxes to PRE, both on monthly and finer daily temporal scales. The average lagged response of net ecosystem exchange (NEE) and gross primary productivity (GPP) to accumulated PRE (APRE) is approximately 42 days. When considering time-accumulation and -lag effects, the combined direct and indirect effects of APRE on NEE and GPP increase by 0.37 and 0.58, respectively. Notably, preceding APRE primarily exerts a direct effect on current carbon fluxes, whereas the impact of SWC at a depth of 0.1 m is primarily mediated through the memory effect of preceding APRE, resulting in an indirect effect on carbon fluxes. These findings emphasize the importance of preceding APRE. Significantly, our subsequent study indicates that the delay in NEE and GPP responses to APRE also extends to approximately 40 to 50 days at the regional scale. Our findings emphasize the significant time effects of APRE on carbon fluxes, and considering these effects will contribute to a better understanding of the interplay between PRE and vegetation over semi-arid regions in China.

Grime’s ecological strategies reveal contrasting patterns in alkaline and loess grasslands

Studying the relationship between biodiversity patterns and processes in vegetation has been at the centre of interest in vegetation ecology for several decades. By studying the biomass of loess and alkaline grasslands along a water and salinity gradient, we aimed to analyse species diversity and Grime’s competitor-stress tolerator-ruderal (CSR) functional strategy patterns. We aimed to test the following hypotheses: i) The biomass and species richness scores and the species composition are significantly different between the sampled grassland community types. ii) The sampled communities are well separated based on the CSR strategy spectrum. iii) The amount of green biomass and litter are positively correlated with competitiveness and negatively with stress tolerance. The biomass and species richness scores and the species composition of the sampled communities along the sampled gradients were significantly different; the highest species richness, evenness and Shannon diversity values were found in loess grasslands. The highest level of litter accumulation was found in alkaline meadows. The communities were well separated in the ordinations but surprisingly, calculation of coordinates for CSR strategy types have not shown clear separation of the grassland community types. All the communities were proven to be characterised by a high level of stress (located in the right corner of the CSR ternary diagram), but they markedly differed in the magnitude of competition and levels of disturbance expressed in the differences of ruderality. These results might suggest that even in highly stressed communities the community composition is strongly dependent on the differences in disturbance intensity (e.g., intensity and duration of grazing) and it is also strongly influenced by the competitive ability of constituting species.

A Risk Assessment of the Vegetation Ecological Degradation in Hunshandake Sandy Land, China: A Case Study of Dabusennur Watershed

In the context of climate change, it is essential for sustainable development to assess the risks associated with climate change and human-induced vegetation degradation. The Hunshandake Sandy Land provides a variety of ecosystem services and is a substantial ecological security barrier in the Beijing–Tianjin–Hebei area of China. This study used the Normalized Difference Vegetation Index (NDVI) to analyze the spatiotemporal variation trend in vegetation in the Dabusennur Watershed using linear trend analysis and the GeoDetector model to identify the main drivers of vegetation change in the watershed. Finally, the study assessed the risk of ecological degradation in the vegetation of the watershed. The results show that the NDVI in the study area has had a fluctuating trend in the last 22 years, and the change has been small. Precipitation and groundwater depth are the key factors affecting vegetation change. The NDVI reaches its maximum value when the groundwater depth is at 2.75 m. The vegetation ecology of the basin is relatively fragile, mainly with medium risk and large risk. To cope with the ecological risk of vegetation degradation caused by climate change, appropriate water use strategies should be formulated to ensure ecological water use. The present study’s outcomes provide the basis for developing ecological engineering solutions in the arid and semi-arid parts of northern China.

Artificial intelligence and remote sensing for spatiotemporal analysis and prediction of vegetation changes: a case study of El Oued, northeastern Algeria

This study investigates vegetation ecology and rangeland degradation in the arid and desert regions of northeastern Algeria from 2015 to 2023, with predictions extending to 2031. Utilizing remote sensing techniques, specifically Landsat 8 and Landsat 9 imagery, and the Modified Soil Adjusted Vegetation Index (MSAVI), we mapped and analyzed changes in vegetation cover. The QGIS MOLUSCE plugin facilitated spatiotemporal analysis, revealing significant natural and anthropogenic impacts on a study area. Less degraded rangelands have also seen an increase, from 44,110,116 hectares in 2015 to 48,481,851 hectares in 2023, due to drought, overgrazing, and socioeconomic pressures. With a slight decrease to 48,450,495 hectares projected for 2031. This suggests efforts in land rehabilitation and sustainable rangeland management are yielding positive results, though there remains room for improvement. The study recorded that Agricultural croplands have experienced a slight decrease from 1,404,153 hectares in 2015 to 1,350,693 hectares in 2023. However, a modest increase to 1,587,242 hectares is projected by 2031. The findings indicate that Oases date palm areas have increased from 1,287,342 hectares in 2015 to 1,630,197 hectares in 2023, with further growth to 1,816,296 hectares anticipated by 2031. Our research highlights the critical role of remote sensing in monitoring vegetation dynamics within arid and desert ecosystems. The methodology provides a robust framework for similar studies, emphasizing the necessity for ongoing monitoring using advanced télédétection technologies. To mitigate further degradation and preserve these fragile ecosystems, the implementation of sustainable land management practices is essential.

Distribution of plant species Iris sibirica and its vegetation affinity in Slovakia

Iris sibirica is a threatened plant species of the Central European flora, but its distribution and vegetation ecology in Slovakia have not been studied so far. Therefore, we aimed to compile a complex chorology of this species and to analyse phytosociological plots with the species occurrence. Our results suggest that Iris sibirica occurs almost in the whole Slovakia, with two distributional centres situated in the south-western region (Pannonian bioregion) and in the southern regions of central Slovakia (Carpathian bioregion), but a higher proportion of recent records was identified in the Carpathians. Vegetation classification using the TWINSPAN algorithm divided 80 vegetation plots into 5 clusters. They were interpreted syntaxonomically as follows: i) Calthion palustris alliance, ii) Deschampsion cespitosae alliance, iii) Molinion caeruleae alliance, iv) vegetation of the successional stages and transitional status between wet meadows (Calthion palustris and Molinion caeruleae) and fens (Scheuchzerio palustris-Caricetea fuscae), and v) vegetation with a transitional status between hygrophilous, fen vegetation of the alliances Molinion caeruleae, Caricion davallianae, Caricion fuscae and mesic habitats. Variation in the species composition of vegetation plots, analysed using detrended correspondence analysis (DCA) and interpreted using Ellenberg indicator values for vascular plants, showed a shift along the first DCA axis from taxa typical for nutrient-rich and shaded but thermophilic sites to taxa of open and relatively cold habitats on nutrient-poor soils. The second DCA axis corresponded to the moisture gradient, which controlled the pattern of plant species richness.

Square-grid sampling to address the vegetation patterns of declined Mediterranean forest ecosystems

Palo Laziale Wood is a relatively small biotope (129 ha) situated along the coast of the Metropolitan Area of Rome, Lazio region, Italy. Despite being one of the region's remaining patches of an ancient oak floodplain broad-leaved forest, it conserves numerous priority habitats and species of high conservation interest. The vegetation consists mainly of Turkey oak stands with small temporary ponds and flooded meadows. The forest underwent a dieback in 2003, triggered by a significantly hot and dry summer. In 2018, an ecological restoration project (LIFE PRIMED LIFE17 NAT/GR/000511) was initiated to restore Palo Laziale’s ecosystems. This paper presents the methodological approach employed to assess the vegetation ecology of a degraded forest ecosystem. Such an investigation was a key component of the Adaptative Restoration Plan of the Project. It provided the baseline necessary for designing and calibrating the planned direct conservation actions on the target habitat types (91M0: Pannonian-Balkanic turkey oak-sessile oak forests, 3170*: Mediterranean temporary ponds, 5230*: Arborescent matorral with Laurus nobilis, etc.) and establishing reference values to enable long-term monitoring. Plant taxa comparison from 1 ha square-grid sampling and multivariate analyses were carried out to group species and identify environmental and Ellenberg-based drivers. Six ecologically distinct units were found, eventually confirming the distinctive ecological heterogeneity of Mediterranean ecosystems. Amongst these, the hygrophilous vegetation has resulted to be the one mainly affected by the dieback outbreak. Due to the high heterogeneity, introduced by the massive tree mortality, the method of regular 1 ha squares turned out to be a reliable alternative to random vegetation sampling plots (e.g., phytosociological relevés) to disentangle ecological patterns of fragmented and disturbed habitats.

Analysis of Vegetation Environmental Stress and the Lag Effect in Countries along the “Six Economic Corridors”

Climate conditions have a significant impact on the growth of vegetation in terrestrial ecosystems, and the response of vegetation to climate shows different lag effects with the change in spatial pattern and category of the ecosystem. Exploring the interaction mechanism between climate and vegetation growth is helpful to promote the sustainable development of the regional ecological environment. Using normalized vegetation index (NDVI) and meteorological data, based on univariate linear regression and partial correlation analysis, this study explores the temporal and spatial pattern and change trend of vegetation cover in regions and node cities along the “six economic corridors”, and analyzes the environmental stress of vegetation growth and the lag effect of climate response. This study shows that there are great differences in the overall vegetation coverage along the “six economic corridors”. The vegetation coverage in Southeast Asia is the best and that in central and West Asia is the worst. The vegetation coverage in the study area shows an improvement trend, accounting for 39.6% of the total area. There are significant differences in the lag effect of vegetation response and the main climate factors affecting vegetation growth, which is related to the diversity of vegetation and climate characteristics. In this study, we selected regions along the “six economic corridors” that exhibit large latitude and altitude gradients, diverse climate types, and significant seasonal changes and spatial differences in climate conditions as our research areas. Additionally, we considered the impact of different regions and various types of vegetation on their response to climate change. This is of great significance for gaining a deeper understanding of the response mechanism of global climate change and vegetation ecology. Furthermore, our research can provide valuable information to support the ecological environment protection of different typical vegetation against extreme climates, ultimately contributing to the sustainable development of “the Belt and Road”.

Wetland vegetation composition and ecology of Lake Abaya in southern Ethiopia.

Wetland vegetation and ecology of Lake Abaya in the southern Ethiopia was studied to determine floristic composition, plant community type and vegetation ecology. A total of 102 plots were laid along transects that were set up preferentially across areas where there were rapid changes in vegetation or marked environmental gradients to collect data on estimate of percentage aerial cover of plant species and environmental variables. Vegetation data was analyzed by agglomerative hierarchical cluster analysis using similarity ratio as a resemblance index and Ward's linkage method. Multivariate data analysis was performed using appropriate packages in R version 2.14.0. Canonical Correspondence Analysis (CCA) was used to explore the relationship between the species composition and environmental variables. The environmental data included in the CCA were determined using stepwise backward and forward selection of variables by ANOVA test. Statistical measurement regarding species diversity, richness and evenness of the plant community types was carried out by using Shannon-Wiener diversity indices. A total of 92 plant species belonging to 66 genera and 34 families were identified. Families Poaceae, Asteraceae, Fabaceae, Cyperaceae, Solanaceae, Euphorbiaceae and Amaranthaceae account for about 56.99% of the total proportion. Based on the cluster analysis, five plant community types were identified. The most important factors influencing the plant species composition and pattern of wetland plant communities were water drainage, water depth, land use, slope, altitude, and hydrogeomorphology. Therefore, these factors should be considered in future management and protection under the circumstance of climate change and human activities.

Experimental Study of Vegetative Properties in Zeolite–Biochar-Improved Ecological Revetment Substrates

The vegetation of the ecological substrate plays a crucial role in restoring shoreline ecology. This study focused on using zeolite and biochar as substrate modifiers, specifically utilizing the Cynodon dactylon from Central China for vegetation. A pot vegetation experiment was carried out to compare the effects of different ratios of zeolite and biochar. The vegetation indices, including germination index, plant height, and coverage rate, were analyzed and discussed. The results revealed that zeolite primarily influenced the germination index of Cynodon dactylon, while biochar had a more significant impact on germination percentage, germination energy, plant height, and coverage rate. This study discovered that the seed germination effect of the improved substrate initially increased with zeolite content and then decreased. The average germination percentage was 63.96%. Conversely, it decreased with an increase in biochar content, resulting in an average germination percentage of 55.45%. Zeolite and biochar caused a decrease and increase in substrate pH by −0.11 and 0.4 on average, respectively. The germination of each substrate showed a negative correlation with pH. Additionally, the average coverage and plant height decreased with an increase in biochar content. However, the inclusion of 6% zeolite led to an increase in coverage and plant height. Specifically, the average plant height increased by 3.92 cm and the coverage by 7.48%. Our research identified the optimal ratio of zeolite and biochar as 6% zeolite and 0% biochar, showcasing good overall vegetative properties. These findings offer insights for further understanding the vegetative effects of zeolite–biochar-modified substrates and optimizing substrate schemes for ecological vegetation projects.

Spatiotemporal dynamic of soil erosion and the key factors impact processes over semi-arid catchments in Southwest China

The heterogeneity of geographic environments and vegetation types plays a crucial role in determining soil erosion patterns. Highlighting the influence of environmental factors and their gradient changes on soil erosion is key to effective control and management. In this study, conducted in the arid-hot valley area of the Jinsha River, one of the main sand-producing areas in the Yangtze River Basin, we considered the topographic factors and land cover and applied the Revised Universal Soil Loss Equation (RULSE) with geographic information system (GIS) was applied to quantify the contribution and change pattern of different factors to soil erosion in the arid-hot valleys. Then, the spatial and temporal patterns of soil erosion in 2000 and 2015 were analyzed, showing erosion amount of 1812.96 t/(km2·a) and 1965.98 t/(km2·a), respectively. The increase in erosion was attributed to the frequency of heavy rainfall events. In terms of spatial distribution, strong soil erosion has been mainly observed in arid-hot basins, such as Yuanmou and Huaping. The soil erosion modulus (SEM) was closely connected to topographical elements, increasing incrementally with slope. High soil erosion areas were predominantly distributed across slopes between 18° and 36°. In contrast, SEM decreased gradually with increasing altitude, with strong erosion occurring primarily below 2000 m. SEM for different land use types followed this order: bare land > cultivated land > grassland > forest > paddy land. Based on the relationship between vegetation cover and soil erosion, the area could be roughly divided into three types of area by vegetation coverage: erosion control areas (30% vegetation coverage), erosion-vegetation transition areas (30–70%), and vegetation control areas (>70%). These results provide an essential reference for assessing soil erosion patterns and implementation of ecological vegetation restoration measures in arid-hot valleys.

Mechanical Behaviors and Structure Safety of a Tunnel Crossing a Water-Rich Fault Fracture Zone—A Case Study

To study the potential disasters caused by tunnels crossing water-abundant fault areas, this study takes the Jinyunshan Tunnel as an example, and studies the groundwater flow law between different rock layers, the interaction between surrounding rock hydrostatic pressure and soil pressure, and the mechanical features and safety of the lining during construction by combining field tests and finite element simulation analysis. The results show that the displacement change rate of the tunnel vault reaches 2.8 mm/d, and the maximum earth pressure and hydrostatic pressure are 2.3 MPa and 1.15 MPa, respectively, both at the bottom of the tunnel in section II. When the tunnel enters the fault fracture zone from the V surrounding rock, the bending moment of the lining increases by 222.78% at the left haunch and 60.87% at the bottom of the right wall. The axial force of the right spandrel increases by 2579.2%, and the left spandrel increases by 221.18%. The safety factor of the two sections is greater than 2.4, indicating that the overall structure is in a safe state, but the safety factor of the second right shoulder is 2.54, which is close to the safety threshold of 2.4. The research results provide a basis for the safety design and construction safety of tunnels through water-rich sections in similar fault fracture zones, and provide a reference for reducing groundwater loss and protecting ecological vegetation.

A Conversation on the UH Botany Department, Vegetation Ecology, and Life with Professor Emeritus Dr. Dieter Mueller-Dombois

A Conversation on the UH Botany Department, Vegetation Ecology, and Life with Professor Emeritus Dr. Dieter Mueller-Dombois

Improvement of land surface vegetation ecology inhibited precipitation-triggered soil erosion in the alpine-cold river source area – A case study in Southern Gansu, China

Study regionSouthern Gansu Plateau (SGP), located in the northeastern region of the Qinghai-Tibet Plateau, is a representative alpine-cold water source area for China’s large rivers, such as the Yellow River and Yangtze River. Study focusIdentifying the contributions of dominant factors to the regional soil erosion rate (A) is important for understanding the environmental processes and benefits of water and soil conservation, although related studies have seldom been conducted in alpine-cold regions such as the SGP. Accordingly, the main objectives of this study are (1) to determine the spatiotemporal dynamics of soil erosion and its driving factors in the SGP area; (2) to quantify the relationship between the main influential factors and soil erosion; and (3) to separate the contributions of the above factors to variations in regional soil erosion on the SGP. New hydrological insights for the regionThe multiyear average regional A for the SGP region was calculated as 24.18 t·hm−2·a−1, corresponding to an overall low intensity of regional soil erosion. The contributions of various time-varying factors, such as rainfall, vegetation cover, and conservation practices, to the reduction in A were −20.01%, 81.07%, and 21.95%, respectively, indicating that the improvement in land surface vegetation ecology dominated the decrease in A under the background of climate warming. The findings are expected to contribute to soil and water conservation in alpine-cold river source regions.